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Old Sep 05, 2012, 01:47 PM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
784 Posts
Quote:
Originally Posted by IBCrazy View Post
The antenna is made from two lengths of wire whose lengths are:

Wire length in inches = 23675/f in MHz

Or for you metric folks

Wire length in mm = 601345/f in MHz

So for:

910MHz = 26"/660mm
910MHz = 26.02"/660.8mm
1280MHz = 18.49"/469.8mm
1280MHz = 18.50"/469.8mm
2.4GHz = 9.66"/245.5mm
2.4GHz = 9.86"/250.6mm or it could be 2.450GHz = 9.66"/245.4mm
5.8GHz = 4.08/103mm
5.8GHz = 4.08/103.7mm

Now you need to calculate your quarter wavelength which is simply 1/8 of your wire length.

Quarter wavelength in inches = 2960/f in MHz
Quarter wavelength in inches = 2959.4/f in MHz

Or

Quarter wavelength in mm = 75168/f in MHz

So for:

910MHz = 3.25"/84mm
910MHz = 3.25"/82.6mm
1280MHz = 2.31"/60mm
1280MHz = 2.31"/58.7mm
2.4GHz = 1.2"/31mm
2.4GHz = 1.23"/31.3mm or it could be 2.450GHz = 1.21"/30.7mm
5.8GHz = .51"/13mm

You may notice this is a little longer than the true electrical quarter wavelength such as that is used in the BiQuad tutorial. Admittedly, I don't know why this is the case, but it appears to work best 1-2% longer than the electrical wavelength, so we'll go with it.

Speed of light: 299,792,458 m/s =>
4 * 75168 * 1000 / 299,792,458 = 1.002933836. This is just 0.3%, not 1-2%.


-Alex
Alex, great tutorial except for the maths and rounding. See above comments .

Martin
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Old Nov 06, 2012, 06:50 PM
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LittleG's Avatar
Raleigh, NC
Joined Jan 2007
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Can the skew planar antenna be used on both the video transmitter and video receiver?

Would using the skew planar on both ends (vtx and vrx) provide a better video link?

I was just wondering if this can be used this way as oppose to using the clover leaf on the video transmitter and skew planar for the video receiver.
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Old Nov 06, 2012, 07:25 PM
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United States, UT
Joined Jan 2011
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I don't have any data on that.

I have used the skewed planar wheel on Vtx, because it resists multipathing like no other antenna.

Then I use the fan stack for omni,

and the Helical for directional (however, alex and hugo have been working on some new options for a directional antenna)
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Old Nov 06, 2012, 09:34 PM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by LittleG View Post
Can the skew planar antenna be used on both the video transmitter and video receiver?

Would using the skew planar on both ends (vtx and vrx) provide a better video link?

I was just wondering if this can be used this way as oppose to using the clover leaf on the video transmitter and skew planar for the video receiver.
It's all speculation. I used to use two cloverleafs until I invented the Mad Mushroom. Now I have a CL on the transmitter and a Mad Mushroom on the receiver. The MM works as a transmitter antenna as well, but the CL does an equal job and I'm too lazy to go change all my planes over right now

-Alex
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Old Nov 06, 2012, 10:27 PM
Team White Llama!
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Joined Jan 2008
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I've flown CL to CL, SPW to SPW, helical to CL, helical to SPW, Crosshair to etc.etc.etc.etc.etc.


as long as they are two well designed and built antennas, the differences should be minimal(although the directionals are obviously better, and certain antennas are really really good (turbine)).
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Old Nov 16, 2012, 12:40 PM
Jake Wells
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Joined Oct 2012
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Quote:
Originally Posted by IBCrazy View Post
The antenna is made from two lengths of wire whose lengths are:

Wire length in inches = 23675/f in MHz

Or for you metric folks

Wire length in mm = 601345/f in MHz

So for:

910MHz = 26"/660mm
1280MHz = 18.49"/469.8mm
2.4GHz = 9.66"/245.5mm
5.8GHz = 4.08/103mm

Now you need to calculate your quarter wavelength which is simply 1/8 of your wire length.

Quarter wavelength in inches = 2960/f in MHz

Or

Quarter wavelength in mm = 75168/f in MHz

So for:

910MHz = 3.25"/84mm
1280MHz = 2.31"/60mm
2.4GHz = 1.2"/31mm
5.8GHz = .51"/13mm

You may notice this is a little longer than the true electrical quarter wavelength such as that is used in the BiQuad tutorial. Admittedly, I don't know why this is the case, but it appears to work best 1-2% longer than the electrical wavelength, so we'll go with it.

-Alex
3.25" = 82mm. I think the 84 came over from the Clover.
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Old Nov 16, 2012, 01:34 PM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
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Thanks Jake,

See also my earlier post:
http://www.rcgroups.com/forums/showp...&postcount=701

Not meant to insult IBC, but you better take the theoretical wavelength and add 1 - 4% to it instead of simply taking these numbers. There's no such thing as FPV for dummies afaic .

Martin
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Old Nov 29, 2012, 04:34 PM
Some call me the other guy!
DoctorAudio's Avatar
Milwaukie , Oregon
Joined Feb 2003
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So if you can put a patch on your RADIO TX?
Why can't you put a Cloverleaf on you radio TX?
Has anyone tired this.
I made a Skew planner for my GPS and it got me much better rx indoors.
I know it is just way to big to be on and small quad, but it did get me a better rx signal.

Just wondering!
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Old Nov 29, 2012, 04:42 PM
Engineer for Christ
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^Some people have done that but the results are mixed. It's hard to say how much it helps.

-Alex
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Old Nov 29, 2012, 04:47 PM
Some call me the other guy!
DoctorAudio's Avatar
Milwaukie , Oregon
Joined Feb 2003
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Well my RF knowlegable brother.
I think you should try it!
Since you are the man when it comes to building these antennas.
In theory it should work better. I am just thinking of what would make the radio TX, have more range and not need the sometimes working 1W tx booster!
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Old Nov 30, 2012, 09:30 AM
Registered FPVer :)
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Switzerland, LU, Buchrain
Joined Aug 2006
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Quote:
Originally Posted by DoctorAudio View Post
Well my RF knowlegable brother.
I think you should try it!
Since you are the man when it comes to building these antennas.
In theory it should work better. I am just thinking of what would make the radio TX, have more range and not need the sometimes working 1W tx booster!
RC rx antennas (usually simply stripped coaxial cable) are linear polarized. The SPW, CL etc. antennas are circular polarized. You would loose 3dB by using a CP antenna on the tx, but standard linear antennas on the receivers. So, unless you are ready to also replace the rx antennas and find a way to solve the issues involved with the fact that most rx's are diversity receivers, you can use such antennas. It has been done sucessfully and yes, one gets more range that way.
However, there is the fact that regular 2.4Ghz RC systems, even when "boosted" with better antennas, are by far not on par with long range systems. On the other hand, unmodified 2.4Ghz RC systems are way capeable enough to deal with regular RC flying. So, people which are serious about FPV flying usually opt for a long range system and the regular RC users simply have no real reason to care.

An easy way to get somewhat better range with a 2.4Ghz radio is to use a higher gain whip antenna which is still omnidirectional or then opt for a directional antenna at the cost of haveing to point yourself always towards the plane.

HTH

Markus
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Old Nov 30, 2012, 09:50 AM
..in a Johnny Cash voice.
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Canada, NS, Beaver Bank
Joined Aug 2010
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Thanks IB! The SPW really has been the shiznit for a couple of weeks and I'm already building the crosshair. CP added so much fun and signal reliability I'll be sure to pay all the good vibes forward. Thanks mate.
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Old Nov 30, 2012, 09:52 AM
Some call me the other guy!
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Milwaukie , Oregon
Joined Feb 2003
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Your right!
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Old Dec 21, 2012, 04:31 PM
THEY MOSTLY COME OUT AT NIGHT
chimaera's Avatar
Kaysville, Utah
Joined Jul 2005
1,253 Posts
Any plans to make a build tutorial for MM? I need one or even better the SH.



Quote:
Originally Posted by IBCrazy View Post
It's all speculation. I used to use two cloverleafs until I invented the Mad Mushroom. Now I have a CL on the transmitter and a Mad Mushroom on the receiver. The MM works as a transmitter antenna as well, but the CL does an equal job and I'm too lazy to go change all my planes over right now

-Alex
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Old Dec 22, 2012, 05:58 AM
i do all my own crashes
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Joined Oct 2012
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There's no such thing as FPV for dummies
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Old Dec 22, 2012, 08:26 AM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
784 Posts
Quoting me Skeeter?

http://www.rcgroups.com/forums/showp...&postcount=707
http://www.rcgroups.com/forums/showp...postcount=7764

Never mind, it can't be emphasized enough, to prevent disappointments.

Martin
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Old Dec 23, 2012, 11:16 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by chimaera View Post
Any plans to make a build tutorial for MM? I need one or even better the SH.
No. How many rip-offs of the cloverleaf do you see? I'm not having my latest innovations ripped off. Npt only does it infuriate me, but I also need to look after my family and crew. The dishonest people have ruined it for the DIYers. I have a family and several people who work for me who rely on a paycheck to consider now.

It sucks, but the skew wheel still works fine. It's just not as good as the MM, that's all. I think the days of my tutorials might be over

-Alex
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Old Dec 24, 2012, 01:26 AM
THEY MOSTLY COME OUT AT NIGHT
chimaera's Avatar
Kaysville, Utah
Joined Jul 2005
1,253 Posts
Quote:
Originally Posted by IBCrazy View Post
No. How many rip-offs of the cloverleaf do you see? I'm not having my latest innovations ripped off. Npt only does it infuriate me, but I also need to look after my family and crew. The dishonest people have ruined it for the DIYers. I have a family and several people who work for me who rely on a paycheck to consider now.

It sucks, but the skew wheel still works fine. It's just not as good as the MM, that's all. I think the days of my tutorials might be over

-Alex
No worries, I always thought you were being very generous. you have given far more to this community than most. Thank you for what you have provided for us DIY'rs. It is unfortunate watching certain others climb all over each other to make a buck.I hope your ventures pay off.
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Old Dec 25, 2012, 11:33 PM
Real 3D FPV
luciduous's Avatar
Joined Jul 2007
70 Posts
Intellectual Property concerns...

Quote:
Originally Posted by IBCrazy View Post
No. How many rip-offs of the cloverleaf do you see? I'm not having my latest innovations ripped off. Npt only does it infuriate me, but I also need to look after my family and crew. The dishonest people have ruined it for the DIYers. I have a family and several people who work for me who rely on a paycheck to consider now.

It sucks, but the skew wheel still works fine. It's just not as good as the MM, that's all. I think the days of my tutorials might be over

-Alex
Hey IBCrazy,
I've tried to get a response from you a number of times on using the cloverleaf/ SPW combo on my 3D FPV Helmet http://www.fullspectrumfpv.com and its pertinence regarding infringement on your intellectual property. I have never wanted to step on your shoes, and like I've said, I'm not charging anything extra for these antennas. I just want the people who buy my helmets to have the best experience possible! I guess I can link my customers to your site, if you'd prefer the traffic, but I'd rather just build them myself and send you a royalty or something. Please let me know so I don't keep feeling like I'm stealing something, especially after reading your last post. Thanks so much for all you have done. I would never want to keep food off your table.
Sincerely,
Luke Matthew Jacobs
(luciduous)
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Old Dec 27, 2012, 11:16 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by luciduous View Post
Hey IBCrazy,
I've tried to get a response from you a number of times on using the cloverleaf/ SPW combo on my 3D FPV Helmet http://www.fullspectrumfpv.com and its pertinence regarding infringement on your intellectual property. I have never wanted to step on your shoes, and like I've said, I'm not charging anything extra for these antennas. I just want the people who buy my helmets to have the best experience possible! I guess I can link my customers to your site, if you'd prefer the traffic, but I'd rather just build them myself and send you a royalty or something. Please let me know so I don't keep feeling like I'm stealing something, especially after reading your last post. Thanks so much for all you have done. I would never want to keep food off your table.
Sincerely,
Luke Matthew Jacobs
(luciduous)
Luke,

I appreicaite your concern. The Skew -wheel is not mine. It never was. It was invented in 1953. I simply brought it to life here. The cloverleaf, however as well as the Crosshar, Mad Mushroom, and PepperBox are mine. If you want to build for yourself you are of course free to do so. For sale, you can buy antenna sets for resale from me and then re sell them as a distributor (They are caled the "BluBeams", or you can build the Skew-Wheel yourself and sell those. I make no claims to the skew wheel.

-Alex
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Old Dec 27, 2012, 05:14 PM
FPV junkie
m_beeson's Avatar
United States, UT
Joined Jan 2011
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Quote:
Originally Posted by IBCrazy View Post
Luke,

I appreicaite your concern. The Skew -wheel is not mine. It never was. It was invented in 1953.

I make no claims to the skew wheel.

-Alex
Alex,

Without your diligent research and your build logs, we would not have the availability and the increased knowledge base in the FPV community.

I know that OMM and others have done a lot of research that you have been able to expound upon, but you have made it possible for me and others to build this antenna for our selves, to our specific frequencies.

You could have kept your findings to yourself, and you probably should have, but you can't reverse time, and I appreciate your contribution.


-Mike
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Old Dec 28, 2012, 03:44 PM
..in a Johnny Cash voice.
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Canada, NS, Beaver Bank
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Quote:
Originally Posted by IBCrazy View Post
I think the days of my tutorials might be over
-Alex
That, sucks.
..and thank you.
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Old Dec 29, 2012, 12:34 AM
Real 3D FPV
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Joined Jul 2007
70 Posts
Quote:
Originally Posted by IBCrazy View Post
Luke,

I appreicaite your concern. The Skew -wheel is not mine. It never was. It was invented in 1953. I simply brought it to life here. The cloverleaf, however as well as the Crosshar, Mad Mushroom, and PepperBox are mine. If you want to build for yourself you are of course free to do so. For sale, you can buy antenna sets for resale from me and then re sell them as a distributor (They are caled the "BluBeams", or you can build the Skew-Wheel yourself and sell those. I make no claims to the skew wheel.

-Alex

... Ok, good. Atleast now I know how to work this into my online shop. Distributor Status accepted... website changes commencing... actually, I will probably just include the whips that come with the vid Rx and mention your cloverleaf Tx antenna as the best choice... Grr, maybe I can provide a subsidy for customers... starting to think like the government now. lol.

p.s. hey everybody, wheres the fpv chat room on the internet? Shouldn't there be atleast ONE!!!???
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Old Dec 29, 2012, 12:42 AM
FPV junkie
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United States, UT
Joined Jan 2011
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Quote:
Originally Posted by luciduous View Post
... Ok, good. Atleast now I know how to work this into my online shop. Distributor Status accepted... website changes commencing... actually, I will probably just include the whips that come with the vid Rx and mention your cloverleaf Tx antenna as the best choice... Grr, maybe I can provide a subsidy for customers... starting to think like the government now. lol.

p.s. hey everybody, wheres the fpv chat room on the internet? Shouldn't there be atleast ONE!!!???
That's what we're missing on this forum...
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Old Dec 29, 2012, 12:45 AM
Real 3D FPV
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Quote:
Originally Posted by m_beeson View Post
That's what we're missing on this forum...
The subsidy or the chat room?

I can probably come up with both...
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Old Dec 29, 2012, 12:58 AM
Real 3D FPV
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Joined Jul 2007
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FPV Chatroom : http://zippychat.com/room/yiusv
(i made it)



Subsidy: $100 off my FS-1 helm if you buy IBCraZys Blubean x2 for left/right channel

sheesh, pretty damn good for 13 minutes of time~

cheers, Luke
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Old Dec 29, 2012, 01:31 AM
FPV junkie
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United States, UT
Joined Jan 2011
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I belong to a snowmobile forum which has a chat room. It's a pretty cool feature.

Who knows, we may be able to get one here.
http://www.rcgroups.com/forums/showthread.php?t=1797332

Quote:
Originally Posted by luciduous View Post
FPV Chatroom : http://zippychat.com/room/yiusv
(i made it)



Subsidy: $100 off my FS-1 helm if you buy IBCraZys Blubean x2 for left/right channel

sheesh, pretty damn good for 13 minutes of time~

cheers, Luke
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Old Dec 29, 2012, 12:34 PM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by luciduous View Post
... Ok, good. Atleast now I know how to work this into my online shop. Distributor Status accepted... website changes commencing... actually, I will probably just include the whips that come with the vid Rx and mention your cloverleaf Tx antenna as the best choice... Grr, maybe I can provide a subsidy for customers... starting to think like the government now. lol.
I am ready when you want to stock the BluBeams. I usually keep a few in stock at my house for emergency needs... ok, I keep all stock at my house. It's a zoo. I still can't believe all that I send out comes out of a small 2 bedroom house in the middle of the mountains. I even have the fire place and wood burning stove as heat. It truly is the exact opposite of what everyone would expect. I find the irony amusing.

-Alex
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Old Dec 29, 2012, 04:46 PM
FPV junkie
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United States, UT
Joined Jan 2011
3,400 Posts
It sounds like a little slice of paradise


Quote:
Originally Posted by IBCrazy View Post
I am ready when you want to stock the BluBeams. I usually keep a few in stock at my house for emergency needs... ok, I keep all stock at my house. It's a zoo. I still can't believe all that I send out comes out of a small 2 bedroom house in the middle of the mountains. I even have the fire place and wood burning stove as heat. It truly is the exact opposite of what everyone would expect. I find the irony amusing.

-Alex
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Old Dec 30, 2012, 11:21 AM
Real 3D FPV
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Joined Jul 2007
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Quote:
Originally Posted by IBCrazy View Post
No. How many rip-offs of the cloverleaf do you see? I'm not having my latest innovations ripped off. Npt only does it infuriate me, but I also need to look after my family and crew. The dishonest people have ruined it for the DIYers. I have a family and several people who work for me who rely on a paycheck to consider now.

It sucks, but the skew wheel still works fine. It's just not as good as the MM, that's all. I think the days of my tutorials might be over

-Alex
I just came across another circularized product out there at phatshark. (ya i know i misspelled it)


Is there any way to keep china from stealing all of our innovations? (especially yours, since we are on the subject)

I've looked a lot into patenting and the such on my own projects, but really... how much will a patent protect if phatstark just covers up the antenna with a shell, in this case?

I'm sure it's much more frustrating to you, Alex, than anybody else within this thread. I don't blame you for just keeping the details of the MM to yourself. I'd do the same thing. That's why I have always second guessed exposing the guts of my own 3d fpv helmet. It's not too complicated, but I always feared seeing a copy of it show up on some chinese site for 1/3rd of the price. Sheesh, I would still be upset if it was listed for twice the price!
It's a brave new world, I guess...
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Old Dec 30, 2012, 11:55 AM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
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Luciduous, I don't care that you try to ingratiate yourself with Alex, you apparently need to.
However, the Skew-Planar Wheel was designed by W1FVY and W1IJD in the 1960s.

Btw, you mean SpiroNet antennas? Are they SPW or CL?

Martin
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Old Dec 30, 2012, 12:10 PM
Registered User
SW England
Joined Aug 2009
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Exactly!

And just to set the record straight, the Skew-Planar was first discussed by myself and OMM for FPV use, here
http://www.rc-cam.com/forum/index.ph...rojects/page-2

Note, this was before IBCrazy (Alex) came on the scene and then created and popularised his 'Cloverleaf'.

None of these antenna discussions and subsequent designs have ever been subject to 'intelectual propery' or such like. I mean, how can you discuss and evolve something in the public domain, such as these open forums and then complain about others 'stealing' your design?

Granted, Alex has done a great deal to prompote Circular Polarisation for FPV use, but without the ideas and development of others before him, it may never have come to anything.

Nigel.
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Old Dec 30, 2012, 12:20 PM
Registered FPVer :)
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Switzerland, LU, Buchrain
Joined Aug 2006
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Quote:
Originally Posted by Martin. View Post
Luciduous, I don't care that you try to ingratiate yourself with Alex, you apparently need to.
However, the Skew-Planar Wheel was designed by W1FVY and W1IJD in the 1960s.

Btw, you mean SpiroNet antennas? Are they SPW or CL?

Martin
They are both, SPW and CL. You buy them in pairs. They are stamped out of a copper foil and the build tolerances are significant. Angles of attack are barely even among the lobes, resulting in varying omnidirectionality. They are untuned, just "tested". They are probably ok to buz arround in close proximity.

Markus
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Old Dec 30, 2012, 12:35 PM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
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Thanks Markus, valuable information!

When comparing the two in general, is there any good reason to use CL instead SPW on the plane, except the better VSWR, less weight and less drag? SPW's optimal VSWR ~ 1.25 is near to perfection already and the weight/drag savings for higher frequencies are negligible. So what's CL's killer feature?

Thanks,
Martin
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Old Dec 30, 2012, 04:03 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,679 Posts
Okay, I am a real newb at this FPV stuff, but in the short time that I have been looking into these antennas, I am under the impression that it is preferred to use the skew planar wheel on the base station and cloverleaf (3 segment) circular polarized antenna at the transmitter. Am I mistaken here?

I understand that both need to be the same RH or LH on the polarization.

Have not had a chance to read the entire thread yet.

Ken
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Old Dec 30, 2012, 09:41 PM
Real 3D FPV
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Quote:
Originally Posted by Martin. View Post
Luciduous, I don't care that you try to ingratiate yourself with Alex, you apparently need to.
However, the Skew-Planar Wheel was designed by W1FVY and W1IJD in the 1960s.

Btw, you mean SpiroNet antennas? Are they SPW or CL?

Martin
Martin, if you don't care that I'm trying to ingratiate myself with Alex, why mention it? And I'm not talking about the SPW, I'm talking about the Cloverleaf that Fatshark obviously is using in their antenna set. It says on the description they are using 3 lobe and 4 lobe antennas, the 'standard' combo used now. And that means the Cloverleaf and SWP antennas. But don't get me wrong, I don't know everything that's going on in the market. I found the Fatshark Spironet combo on ReadymadeRc.com which I'm pretty sure is Alex's site. So, I dunno. I just know I don't wanna ride on anyone's coat tails. I'm busy trying to make my own.

Quote:
Originally Posted by Devonboy View Post
Exactly!

None of these antenna discussions and subsequent designs have ever been subject to 'intelectual propery' or such like. I mean, how can you discuss and evolve something in the public domain, such as these open forums and then complain about others 'stealing' your design?

Granted, Alex has done a great deal to prompote Circular Polarisation for FPV use, but without the ideas and development of others before him, it may never have come to anything.

Nigel.
I'm just talking about the Cloverleaf. I know that's a different thread, but this is all in response to Alex's copycat problem comment above. I just brought up 'intellectual property' because I'm taking my activities from personal use to commercial sales with my own activities, and I don't want to cross the 'copyright' boundary. Alex has a problem with design stealing when someone makes what he made and sells it online(times100). Like he said, make your own, that's cool. Just don't be surprised when karma smacks you after selling a bunch of them online!

How's that for ingratiating? lol
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Old Dec 31, 2012, 05:25 AM
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Thanks Markus, valuable information!

When comparing the two in general, is there any good reason to use CL instead SPW on the plane, except the better VSWR, less weight and less drag? SPW's optimal VSWR ~ 1.25 is near to perfection already and the weight/drag savings for higher frequencies are negligible. So what's CL's killer feature?

Thanks,
Martin
Regarding the spiros, drag or weight are almost no concern. Yes, the spiro CL is a wee bit smaller and thus drag is a very little less, but I doubth you could easily measure the difference. The spiro CLs weight is 7.53gr, the SPWs weight 8.52gr (so almost exactly on gram more) when I measure them. But that's probably also because the cable of the CL is shorter (IMHO it's too short anyways). Regarding the spiros - I would only recommend them to someone expecting a lot of crashes, read a total beginner who flies in closer proximity anyways. For serious applications they are IMHO even dangerous. Mostly because of their unpredctable omnidirectionality. The latter is a consequence of the dome which does not let you know how the lobes are positioned relative to the plane and because of their horrible build tolerances.

In general, most people seem to make better experiances with CL on the tx, SPW on the RX. From personal experiance the difference is small, very small. I'd say build tolerances could even make an SPW/SPW pair better. But then, who flies CL / SPW combos anyways if one is up for pushing limits? I think to buz around up to 3km out (with a GOOD CL/SPW, definately not possible with the spiros) the fact wether you use an SPW on the plane or CL does not matter really. It also does not so much matter if you use a directional antenna on the ground.

I think we should not forget the history of the CL and also where the CL/SPW combo "is best" comes from. Alex initially had trouble makeing an SPW with a good VSWR. That's why he came to the CL. If you read the initial threads, this info might be still there. Anyways, the slightly higer gain at the cost of omnidirectionality was and is just a side effect. These days, where serious antenna manufacturers use vector network analyzers to tune their antennas to good VSWR values, that simply does not really matter anymore. It maybe still is a concern for DIYers though which obivousely can't tune an SPW to perfection. However, in the beginings, CL / SPWs in fact outperformed pure SPW/SPW pairs for the back then better VSWR of the CL antennas (alas the reasons outlined above). These days, people request CL/SPW pairs because they don't know better and producers offer them because of the demand.

HTH

Markus
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Old Dec 31, 2012, 07:45 AM
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@Luciduous, it was just an observation and it gave you the chance to 'score' as well, which you did . No hard feelings. Everybody is trying to protect his/her designs --with very good reasons--, although that's nearly impossible. Even without tutorials on the net there's still the possibility of reverse engineering which in case of antennas seems very easy. So we better live with it and also try to offer things that others don't have, like customer service. I say "we" because I work in the software-business where we have the same problem.

@Markus, thanks again for that detailed explanation. So you're saying the better VSWR is CL's only advantage over SPW? A quick calculation shows that VSWR 1.25 vs. VSWR 1.00 is only 0.054dB loss which gives the SPW only 0.6% less range. Theoretically. So that's 6m on 1km. I'm neglecting different gain for the moment.

Martin
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Old Dec 31, 2012, 07:47 AM
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I wish also to thank all for their comments. You have helped to answer my questions.

Ken
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Old Dec 31, 2012, 08:01 AM
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Originally Posted by Martin. View Post
@Luciduous, it was just an observation and it gave you the chance to 'score' as well, which you did . No hard feelings. Everybody is trying to protect his/her designs --with very good reasons--, although that's nearly impossible. Even without tutorials on the net there's still the possibility of reverse engineering which in case of antennas seems very easy. So we better live with it and also try to offer things that others don't have, like customer service. I say "we" because I work in the software-business where we have the same problem.

@Markus, thanks again for that detailed explanation. So you're saying the better VSWR is CL's only advantage over SPW? A quick calculation shows that VSWR 1.25 vs. VSWR 1.00 is only 0.054dB loss which gives the SPW only 0.6% less range. Theoretically. So that's 6m on 1km. I'm neglecting different gain for the moment.

Martin
Yes. The CL even has a slight dissadvantage if you want in that it's not fully omnidirectional. You can see this if you look at the radiation graphs Alex posted somewhere in the CL thread. But this should not over weighted. Propperly built CL and SPW antennas can be intermixed withouth careing much in real live.

There is one thing in your statement that cougth my atenntion. One of course can build an SWP with a perfect VSWR of 1.00 I have no problems to build them so as I have a virtually perfect VSWR. In other words, it's not inherent to the antenna construction or such. It just takes tweeking and of course you need propper equipement to measure.

So, to repharse your statement, the advantage of the CL is that it's easier to end up with one that has a better VSWR and a tiny better gain at the cost of some omnidirectionality.

Markus
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Old Dec 31, 2012, 09:11 AM
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Yes. The CL even has a slight dissadvantage if you want in that it's not fully omnidirectional. You can see this if you look at the radiation graphs Alex posted somewhere in the CL thread.
Markus
Reason I dont use CL on my copters. I have spw on the vtx and turbine on the vrx. Gives me all round coverage
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Old Jan 05, 2013, 01:40 PM
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hey guys, just starting to build my own antennas, curious what the suggested lenghts are for stripping rg316...just enough core to get in the pin. then how much unsulation do i leave on the core vs how far back do i strip the outer sheath/shield..
thaNKS

All going to an sma connector

I jsut threw one together and the shield barely made the shoulder of the connector so i dabbed a bit of solder for contact and crimped er up... I dunno if i trust it lol
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Old Jan 05, 2013, 11:41 PM
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I put an elbow on the Vtx because I lay it flat, and then I stick the Vtx antenna up about 9".

It has to be supported, but it gets best results at that height for me.

Quote:
Originally Posted by elliott000 View Post
hey guys, just starting to build my own antennas, curious what the suggested lenghts are for stripping rg316...just enough core to get in the pin. then how much unsulation do i leave on the core vs how far back do i strip the outer sheath/shield..
thaNKS

All going to an sma connector

I jsut threw one together and the shield barely made the shoulder of the connector so i dabbed a bit of solder for contact and crimped er up... I dunno if i trust it lol
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Old Jan 06, 2013, 12:12 AM
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All good on the antenna, i just have a pain in the ass making the sma nice lol my first one shorted out. Is the shielding supposed tp touch the outer case of the sma?
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Old Jan 06, 2013, 02:04 AM
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Yes.

When I make that connection, I slide the collar up the coax, get everything prepped to length, and then I solder the pin with a little dab of solder (not too much or it wont fit). I have found that the crimp can fail and then your antenna is less efficient.

then I pull the shield over the sma, and pull the collar down with a little of the sma neck exposed. I put plenty of flux on the gap and work my solder in. then you want to get it cooled down as quickly as possible.

best to use rg 316.

Quote:
Originally Posted by elliott000 View Post
All good on the antenna, i just have a pain in the ass making the sma nice lol my first one shorted out. Is the shielding supposed tp touch the outer case of the sma?
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Old Jan 22, 2013, 12:29 PM
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If I am making a Cloverleaf/Skew Planar Set for 1280MHz, should I make both antenna's with the same wavelength and quarter wavelength's, or should I do it exactly like you have on your instructional pages: (Clover 1280MHz = 18.9"/479.5mm (quarter 1280MHz = 2.36"/60mm) , and Skew 1280MHz = 18.49"/469.8mm (quarter 1280MHz = 2.31"/60mm)

This is my first time attempting this, so I would like to do it right.
Thanks!
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Old Jan 23, 2013, 09:10 AM
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Originally Posted by Borister View Post
If I am making a Cloverleaf/Skew Planar Set for 1280MHz, should I make both antenna's with the same wavelength and quarter wavelength's, or should I do it exactly like you have on your instructional pages: (Clover 1280MHz = 18.9"/479.5mm (quarter 1280MHz = 2.36"/60mm) , and Skew 1280MHz = 18.49"/469.8mm (quarter 1280MHz = 2.31"/60mm)

This is my first time attempting this, so I would like to do it right.
Thanks!
IMHO a somewhat funny question. It's the first time you do it and you intend to divert from the instructions? :-)

Seriousely, stick to the tutorials TO THE LETTER. The CL needs somewhat longer lobes to be resonant on the same frequency as a given SPW for a given wavelenght.

Markus
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Old Jan 23, 2013, 04:10 PM
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Markus, the question is not as silly as it seems. There's been a lot of discussion here about what exact lengths to use. Alex's tutorials are self-contradictory at this point. Don't get me wrong, these are great tutorials, but the exact lengths are just confusing. These tutorials recommend to use 1.003 for SPW and 1.024 for CL, relative to a free-space wavelength, whereas this website recommends 1.045 for SPW:

http://www.ve3byt.com/SkewPlanarAntenna

My CL's, based on 1.024 lengths all resonate a little too high, which confirms above findings. Maybe I'm terribly wrong, but could the first pages of these tutorials intentionally be imprecise, to fool the copycats? I could have made construction errors, but that doesn't explain the above differences.

Anyway, following the tutorials to the letter still gives good antennas. Perhaps not perfect in terms of impedance, but range does not really suffer.

Martin
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Old Jan 24, 2013, 10:41 AM
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Originally Posted by Martin. View Post
Markus, the question is not as silly as it seems. There's been a lot of discussion here about what exact lengths to use. Alex's tutorials are self-contradictory at this point. Don't get me wrong, these are great tutorials, but the exact lengths are just confusing. These tutorials recommend to use 1.003 for SPW and 1.024 for CL, relative to a free-space wavelength, whereas this website recommends 1.045 for SPW:

http://www.ve3byt.com/SkewPlanarAntenna

My CL's, based on 1.024 lengths all resonate a little too high, which confirms above findings. Maybe I'm terribly wrong, but could the first pages of these tutorials intentionally be imprecise, to fool the copycats? I could have made construction errors, but that doesn't explain the above differences.

Anyway, following the tutorials to the letter still gives good antennas. Perhaps not perfect in terms of impedance, but range does not really suffer.

Martin
Hi Martin,

I wrote "The CL needs somewhat longer lobes to be resonant on the same frequency as a given SPW for a given wavelenght." How much depends on factors which are different for everyone as their production methods and materials will differ too. It takes a significant effort to even be able to reproduce antennas with consistant results. That's very very true on 5.8Ghz at least.
So, posting a correction factor here does not help those without the possibilties to measure the outcome as that correction is smaller than the expected deviation from the targeted frequency anyways. Those who can measure the outcome and reached the point where they get reproduceable consitant behaviour will easily find out the correction factor that matches their way and material. So I repeat, those who can't measure, and if I'm not mistaken the OP falls into this cathegory are definately served best to blindly follow the tutorlials.

HTH

Markus
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Old Jan 25, 2013, 03:30 PM
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Markus (or anyone with the experience) what do you suggest to do about the thickness of the coax? When I solder the ends right up to the coax, the thickness of the coax is not precise, and changes thing significantly. So after I measured very carefully to make the metal the right length, when I put it together, the frequency is altered by a factor of X due to the lack of precision with the coax. Is there a workaround, or at least a way to keep the precision that I started with?

Boris
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Old Jan 25, 2013, 06:16 PM
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It would be very cool to have these as a plug and play solution for frsky rx's.

Would there be any advantage to having on e on the rx, and the frsky 7 db directional antenna? (I know there is a 3db penalty - but would there be a reduction in multipathing?)
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Old Jan 28, 2013, 05:11 AM
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Originally Posted by Borister View Post
Markus (or anyone with the experience) what do you suggest to do about the thickness of the coax? When I solder the ends right up to the coax, the thickness of the coax is not precise, and changes thing significantly. So after I measured very carefully to make the metal the right length, when I put it together, the frequency is altered by a factor of X due to the lack of precision with the coax. Is there a workaround, or at least a way to keep the precision that I started with?

Boris
IMHO the thicknes can be in relation to the freuqency. That said, I usually use RG316 for all antennas, or alternatively semi rigid cable. For 1.2Ghz antennas RG 58 can be used as it's stiffer and totally ok for that freuncy.

On 5.8Ghz, there are so many other factors, that careing for the thikness of the cable is just one of them. Without being able to measure it's shooting into the dark, and adjusting for the cable in your particular case could make things worse or better.

So, as mentioned earlier, and at the risk of sounding like a broken record, build to the tutorials if you can't measure. If you CAN measure, make test builds and ajdust your design slightly to get it where it should be. Measures - especially on 5.8Ghz - definately will differ among everybody due to differences in the building methods, materials used and so on.

HTH

Markus
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Old Feb 18, 2013, 02:05 PM
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IBCrazy:

I have found out that I have two beacons in my area.
One is on 1.3ghz somewhere. west of my house.
The other is SouthWest of my house. One seem to mess with 5.8ghz 3 seconds intervals.
The 1.3GHZ is on 4 second intervals.
So, I can no longer practice my FPVing out side of 100 yards and 50 feet up!
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Old Feb 18, 2013, 03:10 PM
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^900MHz or 2.3GHz. There's your cure. You could also use a directional antenna and aim away from the interfering sources and stick with your current bands.

-Alex
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Old Feb 18, 2013, 04:14 PM
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Hahaha, I want to continue to use 2.4ghz as control.
I am going to boost my 2.4 ghz.
The price on LRS sytems is to much for me right now.
That would mean buying 4 rx's
The HK Open LRS sucks butt.
I just bought 4 1.3ghz vtx's, 2 RX's, 2 Notch filters, 3 voltage regulators and a set of antennas from Sierra RC.
The good thing is everything is working well and preforming as suggested. I will just have to fly somewhere else for now!
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Old Feb 20, 2013, 07:54 AM
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5.8ghz CP Construction Questions

I am going to have a go at making the IBCrazy CP Rx antenna. I have read the tutorial , but I have a couple of questions.

I want to build it straight off the back of a suitable hacked SMA plug as the attached sketch,which is a view looking into the end of the plug with the lobes omitted for clarity

Is that OK? or have I read somewhere that it is important that there is a certain length of Coax supplying it?

If it is OK, to put it straight on the plug, and I intend to solder the horizontal legs directly to the shield casing, do I shorten the 1/4 wave horizontal legs attached to the shield by 1/2 the diameter of the plug?

Ie which is the correct way to do it, Sketch 1 or 2.

Looking forward to anyone's help
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Old Feb 20, 2013, 08:23 AM
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Originally Posted by ppuxley View Post
I am going to have a go at making the IBCrazy CP Rx antenna. I have read the tutorial , but I have a couple of questions.

I want to build it straight off the back of a suitable hacked SMA plug as the attached sketch,which is a view looking into the end of the plug with the lobes omitted for clarity

Is that OK? or have I read somewhere that it is important that there is a certain length of Coax supplying it?

If it is OK, to put it straight on the plug, and I intend to solder the horizontal legs directly to the shield casing, do I shorten the 1/4 wave horizontal legs attached to the shield by 1/2 the diameter of the plug?

Ie which is the correct way to do it, Sketch 1 or 2.

Looking forward to anyone's help
First off, to build the antenna directly onto the connector is a bad idea. The rx or tx will viloate the nearfield of the antenna big time, heavily influencing its directional behaviour to the negative. You would need an adaptor cable which on 5.8Ghz (based on the 13mm figure you gave for a quarter wafe I asume that's the target frequency) is yet another bad idea because of the introduced loss of the connectors.

Apart from this, nobody can give you the right answer. In theory you would have to subtract the distance from the center to the mass connection from your wave lenght, but that's only the theory. In reality, build tolerances and actual measures depend on the way you construct this, depend on the materials used, the amount, diameter and kind of wires, the amount and kind of solder used and so on. It thus could easily be that for your very situation, not compensateing it would be the right thing to do or the other way round. You would have to build many antennas, and measure them out with a vector network analyzer rated for that frequency band to get an idea of what's needed for your particular way to build the antenna or not.

Don't get this wrong, you can build the antenna and provided you don't make a mistake, the result will most likely outperform the stock whip antennas. Just do not expect wonders. Build tolerances on 5.8Ghz are so tight that I for example also do not manage to build two identical antennas although I built already hundereds of them and even though I use certain jigs and tricks etc. They are probably close, but in the end, every single antenna I build and measure out requires tweeking, read tuning, to end up where I want it to be.

HTH

Markus
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Old Feb 20, 2013, 08:45 AM
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Markus
Thanks for your reply.
I have no problem in constructing on the end of a piece of RG316 if that moves it away from the Rx interference and is the better thing to do.
What should the length of that coax be?
I only proposed building it directly off the plug because that was what it looked like for the ones IBCrazy markets, here

http://www.readymaderc.com/store/ind...roducts_id=459

What is it about the construction shown there that stops it being affected by being close to the Rx?
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Old Feb 20, 2013, 10:51 AM
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Originally Posted by ppuxley View Post
Markus
Thanks for your reply.
I have no problem in constructing on the end of a piece of RG316 if that moves it away from the Rx interference and is the better thing to do.
What should the length of that coax be?
I only proposed building it directly off the plug because that was what it looked like for the ones IBCrazy markets, here

http://www.readymaderc.com/store/ind...roducts_id=459

What is it about the construction shown there that stops it being affected by being close to the Rx?
He made that in the begining, but later on clarified that those antennas should be used with an extension cable. Then, the first antennas also were designed for the lower bands, where aditional cables do not have the same impact like on 5.8Ghz.

RG316 is actually not rated for 5.8Ghz. However, if you keep the overal lenght < 12cm the negative effects remain negletable. Just in case you heard that or are otherwise under such an impression: The lenght of the cable does NOT have to be a multiple of the wavelenght. As for the minimum lenght, keep it at one wavelength, but better 1.5 wavelenghts. I usually make them 7cm as this results in a rigid enough setup but also keeps the tx/rx out of the nearfield.

Should you need longer cables, use semi-rigid cable that is rated for such high frequencies.

HTH

Markus
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Old Feb 20, 2013, 12:17 PM
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Originally Posted by markus123456 View Post
He made that in the begining, but later on clarified that those antennas should be used with an extension cable. Then, the first antennas also were designed for the lower bands, where aditional cables do not have the same impact like on 5.8Ghz.

RG316 is actually not rated for 5.8Ghz. However, if you keep the overal lenght < 12cm the negative effects remain negletable. Just in case you heard that or are otherwise under such an impression: The lenght of the cable does NOT have to be a multiple of the wavelenght. As for the minimum lenght, keep it at one wavelength, but better 1.5 wavelenghts. I usually make them 7cm as this results in a rigid enough setup but also keeps the tx/rx out of the nearfield.

Should you need longer cables, use semi-rigid cable that is rated for such high frequencies.

HTH

Markus
Markus
That's great thanks-7cms it is
Patrick
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Old Feb 20, 2013, 12:43 PM
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Now for the Tx!

Quote:
Originally Posted by ppuxley View Post
Markus
That's great thanks-7cms it is
Patrick
I am doing this set up for a nano Fpv system on a small Quad (Hubsan X4)
Obviously weight and space is the issue for the Tx. There will not be the need for great range, but if possible I would want to use it around the house, ie in different rooms.
The stock antenna that comes with the Tx 5813 (20mW) is a simple braided wire whip of about 4cms, soldered directly to the Antenna pad of the board.

Do I have any options for improving that? By tuning the length ,for example.
A small dipole or a V would be possible, for weight and space, but would it offer any advantage?

Any suggestions or do I just stick with the stock one.

Patrick
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Old Feb 20, 2013, 03:43 PM
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Quote:
Originally Posted by ppuxley View Post
I am doing this set up for a nano Fpv system on a small Quad (Hubsan X4)
Obviously weight and space is the issue for the Tx. There will not be the need for great range, but if possible I would want to use it around the house, ie in different rooms.
The stock antenna that comes with the Tx 5813 (20mW) is a simple braided wire whip of about 4cms, soldered directly to the Antenna pad of the board.

Do I have any options for improving that? By tuning the length ,for example.
A small dipole or a V would be possible, for weight and space, but would it offer any advantage?

Any suggestions or do I just stick with the stock one.

Patrick
I suggest to build a CL antenna using RG316 and thin wire (i.e. 0.6mm silver coated copper). If you solder that directly onto the tx module, the added wight will only be around 1gr. That would be the only improvement I see. Changeing the wire does not help that much or if you really i.e. create a pot antenna (dipole similar to what's inside a whip antenna) that adds a similar amount of weight like a CL but would not be even close quality wise.

So, either add a CL, or life with the short wire. The lenght for 5.8Ghz should aprocimately be 300/5.8/4*0.97 alas about 12.5 mm. Btw, 300/5.8 is the wavelenght in milimeter. You would need a quarter wave long wire as it's a simple monopole. Hece the division by four. The 0.97 is a factor to adapt this theoretical length as it would be in the vacuum to the fact that you fly out in the air (have an athmosphere) which slows the speed at which the waves propagate through air slightly down.

HTH

Markus
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Old Feb 20, 2013, 04:27 PM
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Quote:
Originally Posted by markus123456 View Post
I suggest to build a CL antenna using RG316 and thin wire (i.e. 0.6mm silver coated copper). If you solder that directly onto the tx module, the added wight will only be around 1gr. That would be the only improvement I see. Changeing the wire does not help that much or if you really i.e. create a pot antenna (dipole similar to what's inside a whip antenna) that adds a similar amount of weight like a CL but would not be even close quality wise.

So, either add a CL, or life with the short wire. The lenght for 5.8Ghz should aprocimately be 300/5.8/4*0.97 alas about 12.5 mm. Btw, 300/5.8 is the wavelenght in milimeter. You would need a quarter wave long wire as it's a simple monopole. Hece the division by four. The 0.97 is a factor to adapt this theoretical length as it would be in the vacuum to the fact that you fly out in the air (have an athmosphere) which slows the speed at which the waves propagate through air slightly down.

HTH

Markus
Thanks. This thing is tiny, I just don't think there is space for a clover leaf, small, though a 5.8ghz CL is, I think I have no choice but to stay with the plain wire, which simply attaches to the antenna pad with no gnd connections

So , just to be clear,are you saying I should shorten the wire, from its present length of around 40mm to about 12.5mm.
I could attach a short length of RG316 in its place and remove 12.5mm of shield to expose the centre , thinking of your earlier advice to keep the active part of he antenna away from the Tx/Rx to avoid near field violations- does that help in anyway?
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Old Feb 20, 2013, 05:14 PM
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Thanks. This thing is tiny, I just don't think there is space for a clover leaf, small, though a 5.8ghz CL is, I think I have no choice but to stay with the plain wire, which simply attaches to the antenna pad with no gnd connections

So , just to be clear,are you saying I should shorten the wire, from its present length of around 40mm to about 12.5mm.
I could attach a short length of RG316 in its place and remove 12.5mm of shield to expose the centre , thinking of your earlier advice to keep the active part of he antenna away from the Tx/Rx to avoid near field violations- does that help in anyway?
Yes, that could help, but if you add that RG316, then adding the three lobes on top of it should not really be so much more work... The difference in eliminateing interfereance would be hughe though. You must know I would not necesairly add the CL for range (although that would come in as an added bonus), but to elimiate the otherwise terrible interferance which are often so bad that they really can kill the fun of the FPV experiance.

Markus

Markus
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Old Feb 20, 2013, 05:50 PM
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Originally Posted by markus123456 View Post
Yes, that could help, but if you add that RG316, then adding the three lobes on top of it should not really be so much more work... The difference in eliminateing interfereance would be hughe though. You must know I would not necesairly add the CL for range (although that would come in as an added bonus), but to elimiate the otherwise terrible interferance which are often so bad that they really can kill the fun of the FPV experiance.

Markus

Markus
It's not the extra work of doing the three lobes, after all, it's the messing around with these things that is all part of the fun!, it's just I don't think there is the space to fit three 13mm lobes in below the rotors and off the ground. The weight of the FPV gear is only around 5g (50 mah 1s lipo 2g, camera1g and Tx 1g) , so a 1g addition is significant!, but I will look at it, though- how would the CL have to be oriented?
This is not mine, but the set up will be like this- see photo.
http://www.fpvhub.com/index.php/topic,9678.0.html
(That is a 1cm grid on the cutting board)There will be very little space, and I need to consider the greater possibility of the damage the CL might cause to the Tx in an accident over a piece of flexible coax or wire.
Thanks again for all your advice
Patrick
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Old Feb 21, 2013, 12:14 AM
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He made that in the begining, but later on clarified that those antennas should be used with an extension cable. Then, the first antennas also were designed for the lower bands, where aditional cables do not have the same impact like on 5.8Ghz.

RG316 is actually not rated for 5.8Ghz. However, if you keep the overal lenght < 12cm the negative effects remain negletable. Just in case you heard that or are otherwise under such an impression: The lenght of the cable does NOT have to be a multiple of the wavelenght. As for the minimum lenght, keep it at one wavelength, but better 1.5 wavelenghts. I usually make them 7cm as this results in a rigid enough setup but also keeps the tx/rx out of the nearfield.

Should you need longer cables, use semi-rigid cable that is rated for such high frequencies.

HTH

Markus
Perfectly said!
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Old Feb 21, 2013, 03:46 AM
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Now we need to bend the radius in our "S". I did this by taking my pliers and making small bends all the way around the 1/2 wavelength side until the end met with the middle of the antenna. The tip of the wire should meet the center at a ~105 degree angle. It will not (and should not) intersect at 90 degrees.

-Alex
Alex
I made a SKW last night for 5.8ghz (actually 5705Mhz), really just as a trial run and to understand it.
I am now thinking I will make a jig. In drawing the segment up, I have come up with a different enclosed angle from your approx 105 degrees and I cant understand what I am doing wrong Any advice?

If the radius (the 1/8th wave length ) is R
and
The arc length is 2R

By calculation I get the angle as (2R/2pi*R)*360,ie 360/pi, which equals 114.5916 degrees.

Where am I going wrong? ,is it because the arc is not circular or is it simply the difference between theory and practice , due to the corner bend radii, for example?
( the dims on my sketch account for a wire width of 0.8mm, having said that the angle should be independent of the actual radii)
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Old Feb 21, 2013, 05:01 AM
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Alex
I made a SKW last night for 5.8ghz (actually 5705Mhz), really just as a trial run and to understand it.
I am now thinking I will make a jig. In drawing the segment up, I have come up with a different enclosed angle from your approx 105 degrees and I cant understand what I am doing wrong Any advice?

If the radius (the 1/8th wave length ) is R
and
The arc length is 2R

By calculation I get the angle as (2R/2pi*R)*360,ie 360/pi, which equals 114.5916 degrees.

Where am I going wrong? ,is it because the arc is not circular or is it simply the difference between theory and practice , due to the corner bend radii, for example?
( the dims on my sketch account for a wire width of 0.8mm, having said that the angle should be independent of the actual radii)
Your jig looks ok, and trust me, the angle per se is not the most important thing as long as it stays within certain limits.

People tend to overthink these things. Of course you try to do it as good as possible - but consider this. The resulting behaviour of your antennas will be influcenced by many other factors like materials used, amount of solder applied, way you construct them, the source of your cable and connectors (even if its the same type as someone else uses) and so on. On the lower frequency bands, these influences are much less but not so on 5.8Ghz. I do not try to scare you off, but make you something clear. No matter how theoretically perfect you calculate your antenna, there is no way to predict how exactly your very antenna will perform. You could build 1000 antennas with your jig, and I guarantee you every single antenna would resonate in a range of up to 200Mhz apart and you would end up with antennas with an acceptable return loss and others with a really bad one. You would need a vector netowork ananlyzer to measure out the outcome of your antenna. You then could potentially optimise the design/build style and could end up with a really good result (after many attempts). I asume you do not have this option, and as such, just build the antennas and enjoy. If you do not make a big mistake, they WILL perform better than stock whip antennas, but you will not be able to make an optimal pair without measuring. So just build your jig, make antennas and enjoy our great hobby.

HTH

Markus
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Old Feb 21, 2013, 05:13 AM
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So just build your jig, make antennas and enjoy our great hobby.

HTH

Markus
Ok, so I will build!
In reading all the this stuff as a Newb you try to heed the warnings about accuracy, especially for 5.8ghz, but i get the message that in the end with other influences and no test equipment it will always be a bit trial and error.
But I will go with" if you make no big mistakes, it will be better than the stock antennae"
Thanks
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Old Feb 27, 2013, 11:30 AM
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Another example of SPW benefits

Another example video of the benefits of using Circular polarity . This is 5.8 Ghz CL Tx. Admittedly, the dipole antenna on the left is trying to read a CP signal (I've heard its 3 db loss), so maybe it would be a little clearer if I was transmitting with a dipole antenna. But the difference is still amazing.

This Tx signal was in a house, going through many walls and doorways, lots of bouncing going on.

Circularized Polarity benefits over Dipole antenna (0 min 44 sec)


-Luke
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Old Mar 01, 2013, 02:59 PM
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910 antenna used for 1280

I built a cloverleaf and skew planar antenna, from your instructions for a 910 system. They work very well and I thank you for sharing the plans.

I wondered how much range would be lost if I used the 910 antenna with my new 1280 system? If it is substantial, I will build a 1280 antenna set.

Thank you.
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Old Mar 02, 2013, 03:55 PM
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It will work for a while but the advantage will be lost, your SWR will be like 2.5 which will distory the VTX!
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Old Mar 02, 2013, 08:54 PM
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^actually it will be worse than 2.5:1. Closer to 6:1. It will not only over heat the transmitter, but the antenna will no longer be circular. One of the things that makes the Skew wheel work is that the current direction changes in the middle of the lobe.

-Alex
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Old Mar 26, 2013, 11:25 AM
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Well I just read the whole thing from pg one! Made for some very Good info and reading GREAT info here for anyone who wants a better image- I am going to give it a go just wanted to give all those who posted a BIG Thank You Again I say GREAT WORK!!!
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Old Mar 27, 2013, 08:13 AM
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Okay, I got a small problem.
A day ago me and a buddy tried to fly on 1.3 together.
He was on 1280mhz using an Readymade rx with a skyhammer on the RX and a Cloverleaf on the transmitter!
I was flying on 1258 using 2 x Sierra RC upgrade saw filter RXs'.
I have a Eagle eyes, with a Skew on one RX, and the 10 DBi Crosshair.
Now here is the issue.
When I would get close to his quad he could see my video.
Now I never saw more than a little IF when he got close to my antenna but my signal was drowning him out.
Now we are both running Sierra RC 800 mw VTXs'.
His RX does not cover 1258mhz.
So why did he see my video and I almost didn't know he was near my antenna until he was right on top of it?
Also this happened all over the place.
If this make a difference, He is running a Dragon link system and I am running a boosted 2.4GHZ LRS.
I say that because I am running a Low Pass filter on my VTX and he is running a notch filter on his RC transmitter.
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Old Mar 27, 2013, 11:10 AM
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^The problem is you are swamping the VRX. The only option is a Racewood receiver with a SAW filter upgrade.

-Alex
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Old Mar 27, 2013, 02:32 PM
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Pfff, 800 mW just 22 MHz away...
Even if your low pass filter is exactly rated for 1258 MHz it will swamp anything near 1300 MHz easily; no filter is perfect. I don't know Racewood receivers but I guess they have excellent channel-separation.

Martin
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Old Mar 27, 2013, 02:39 PM
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Well we are going to split up my RXs' and see if that helps.
Since all of my stuff is brand new now.
I am going to place him on 1280 and I will stay on 1258.
I have Saw filters on both on my RXs.
Will report back later today.
We got some videoing to do this weekend if weather holds out.
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Old Mar 27, 2013, 03:01 PM
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Originally Posted by Martin. View Post
Pfff, 800 mW just 22 MHz away...
Even if your low pass filter is exactly rated for 1258 MHz it will swamp anything near 1300 MHz easily; no filter is perfect. I don't know Racewood receivers but I guess they have excellent channel-separation.

Martin
The racewood with the SAW upgrade only looks at +/- 8MHz of the selected channel. The cut off band is very strong. It is the only VRX I know of that doesn't get walked on by nearby transmitters on adjacent channels. Of course, all of mine have the real Comtech modules in them as well.

-Alex
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Old Mar 27, 2013, 03:40 PM
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Let me say this after finding out that I had bought 2 x 433mhz notch filters and put them on my VTX.
I have had awesome performance with the VTXs and RXs, I got from Sierra RC.com.
Peter was awesome, in taking care of me.
Didn't even hesitate, in sending me the right ones.
I got all of my new systems from him and quick shipping.
I think I am going to need more stuff, I hate moving stuff from one bird to the other!
Alex:
What is the cut off on the Sierra RC receivers?
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Old Mar 28, 2013, 09:38 PM
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? What do you mean cutoff? I don't think I fully understand you.
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Old Mar 29, 2013, 03:02 PM
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In relation to this statement.
Quote:
Originally Posted by IBCrazy View Post
The racewood with the SAW upgrade only looks at +/- 8MHz of the selected channel. The cut off band is very strong. It is the only VRX I know of that doesn't get walked on by nearby transmitters on adjacent channels. Of course, all of mine have the real Comtech modules in them as well.

-Alex
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Old Mar 30, 2013, 01:21 PM
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Originally Posted by DoctorAudio View Post
Okay, I got a small problem.
A day ago me and a buddy tried to fly on 1.3 together.
He was on 1280mhz using an Readymade rx with a skyhammer on the RX and a Cloverleaf on the transmitter!
I was flying on 1258 using 2 x Sierra RC upgrade saw filter RXs'.
I have a Eagle eyes, with a Skew on one RX, and the 10 DBi Crosshair.
Now here is the issue.
When I would get close to his quad he could see my video.
Now I never saw more than a little IF when he got close to my antenna but my signal was drowning him out.
Now we are both running Sierra RC 800 mw VTXs'.
His RX does not cover 1258mhz.
So why did he see my video and I almost didn't know he was near my antenna until he was right on top of it?
Also this happened all over the place.
If this make a difference, He is running a Dragon link system and I am running a boosted 2.4GHZ LRS.
I say that because I am running a Low Pass filter on my VTX and he is running a notch filter on his RC transmitter.
This is exactly what happens at the field with 5.8ghz FV system too! When another FPVer flies between the LOS of my airplane and the RX, I get the other FPVer's video. Positioning your stations farther apart helps. However the problem is still there, when the other airplane is closer to your RX, the problem is still there. One possible solution is to have you or your friend remake their antennas. I assume you're both using right hand polarized antennas, so you could remake your antennas to LHP, this way there is a 26dBi loss when the RX is listening for the other polarized TX and yours would be fine.
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Old Apr 06, 2013, 12:16 PM
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RC spin-off

This has nothing to do with RC, but it's just a nice spin-off. I use these antennas at home with great success. I used to have severe microwave oven interference causing internet connection drop-outs. While the oven is on, I usually have no wireless signal at all . As explained here a mw oven typically has 1 RF leakage, which is 7 times my wireless signal power.

Since installing this SPW/CL combi at the router and a CL at my pc, the problem seems to be over. Needs further testing but anyway these antennas look way cool.

Martin
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Old Apr 06, 2013, 01:07 PM
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Originally Posted by Martin. View Post
This has nothing to do with RC, but it's just a nice spin-off. I use these antennas at home with great success. I used to have severe microwave oven interference causing internet connection drop-outs. While the oven is on, I usually have no wireless signal at all . As explained here a mw oven typically has 1 RF leakage, which is 7 times my wireless signal power.

Since installing this SPW/CL combi at the router and a CL at my pc, the problem seems to be over. Needs further testing but anyway these antennas look way cool.

Martin
Hi Martin,

I did the same thing and yes that works out nice. The biggest problem though is the fact that most PCs don't allow you to mount an external antenna, and going CP to linear on the built in antenna kills the effect. But if you can replace the antenna on the PC side of things this is a winner.

Markus
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Old Apr 06, 2013, 02:55 PM
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Hi Markus,

You're right, also PCs/laptops with inbuilt antennas will sacrifice signal strength due to polarisation loss of 3 dB. Perhaps I should mount one linear and one circular polarized antenna on the router.

I had to modify the router though. It had two external but fixed antennas, connected to the board via u.fl connectors. Ordered 2 u.fl to RP-SMA pigtail cables and mounted those instead. I could have ordered u.fl to SMA but for me it's better to keep all pc-stuff at RP-SMA.

Next step will be directional CP antennas for my PCs. They have to connect with one fixed router only. It looks like my router transmits on both antennas so I could even put one omni and one directional antenna on it .

Martin
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Old Apr 09, 2013, 04:34 PM
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Please enlighten me ... very confused here

Hi

While I was troubleshooting some issues I have ... I used a multi-meter in the continuity test mode ... the one that beeps when the two probes touches each other ...

so I was under the impression that all of my CP antennas .. CL, SPW, and also the dipoles of the Dragon link RX and the DL TX antenna , Stock VRX and VTX antennas

all of the antennas mentioned above .. There should be no continuity between the center pin and the surrounding ground of the SMA connector .. it should always be an open circuit and so I should not get a beep ..

I'm sure I'm messing something big in here .. so to my surprise

All of my CP Antennans (From RMRC) gave me a beep

FrSKY 2.4 Gh2 7db stock factory patch antenna gave me a beep

All of the stock (factory) antennas that come with any VTX/VRX and DL RX Dipole, DL TX antenna .. no beep

Also RMRC cross-hair antenna - no beep



I don't understand ... totally confused in here ... getting mixed results here

Khaled
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Old Apr 09, 2013, 05:28 PM
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CP's will show a short across the leads.
Patches and dipoles should not be shorted!
My 5.8 patch and 1.3 and 900 don't have a short.
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Old Apr 09, 2013, 05:57 PM
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Sorry ... got it now ... some antennas are designed to be shorted and others are not ...

So That FRsky 2.4 Ghz factory made patch antenna is defective or what ??

the center pin and the outer shield seems to be shorted ...

Khaled
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Old Apr 10, 2013, 04:24 AM
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Not necessarily. A dc-short could act open at an RF-null. Some patches use a supporting construction that is a short for dc and other than designated frequencies.

Your best bet is to hook it up a VSWR meter and verify its RF-impedance.

Martin
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Old Apr 10, 2013, 08:15 AM
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Thanks a lot ...

Much appreciated

Khaled
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Old Apr 18, 2013, 04:44 PM
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I see a lot of talk about what antennas to use on your FPV gear, but where can I find some recommendations for antennas on the Control side of the equation?

I recently upgraded my Turnigy 9x to the FrSky module because I was having serious range issues with the stock RF module and rx.

It appears that FrSky uses two quarter-wave monopoles on their Rx. I thought quarter-wave monopoles required a ground plane and would not work at altitude? Am I misinterpreting something? Is there something about the two antennas in close proximity that negates this requirement?

Would I be better off replacing these monopoles with something different? If so, what?

The orientation of the Tx is fairly constant, while the orientation of the Rx is always changing. Should I put a couple SPW's on the Rx, and leave the stock 2dB on the FrSky module?

Thanks for helping out an RF Newb.
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Old Apr 19, 2013, 05:11 AM
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Quote:
Originally Posted by XDmToter View Post
I see a lot of talk about what antennas to use on your FPV gear, but where can I find some recommendations for antennas on the Control side of the equation?

I recently upgraded my Turnigy 9x to the FrSky module because I was having serious range issues with the stock RF module and rx.

It appears that FrSky uses two quarter-wave monopoles on their Rx. I thought quarter-wave monopoles required a ground plane and would not work at altitude? Am I misinterpreting something? Is there something about the two antennas in close proximity that negates this requirement?

Would I be better off replacing these monopoles with something different? If so, what?

The orientation of the Tx is fairly constant, while the orientation of the Rx is always changing. Should I put a couple SPW's on the Rx, and leave the stock 2dB on the FrSky module?

Thanks for helping out an RF Newb.
For controll, circular polarisation is not so well suited because of the size of the antennas. The usual answer to this is "go UHF", that said buy a long range system. I recommend RangeLink ( www. rangepiloting.com ) as it works rock stable, is feature rich and reasonably priced.

You can of course thinker with your FrSky setup, but if you want a reliable, serious, no brainer solution, go UHF.

Markus
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Old Apr 27, 2013, 01:28 PM
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Hi all sorry if question has been asked before.
Why would one not use these circular polarized antennas on the model Tx and Rx units ? for example my Spectrum DX8 and the AR6210 receiver.

If it works for the video system on which ever frequency you choose, wouldn't it also improve the reliability of the flight control system on 2.4 gig ?

Many thanks
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Old Apr 27, 2013, 01:52 PM
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Because of the way the receiver antenna is designed.
It would require re design of the rx's input.
Radio would be easy, but not the rx.

I added a 2.4 2-watt booster.
I am very happy with mine and have gone 2 miles out with no issues.
I know many complain about Spektrum having issues. But Since I added the booster I have not had issues.
I would not use the antennas that come with the booster. I would get a 2.4 patch and you will be very happy with it at 2 miles..
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Old Apr 27, 2013, 06:01 PM
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Quote:
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Because of the way the receiver antenna is designed.
It would require re design of the rx's input.
Radio would be easy, but not the rx.

I added a 2.4 2-watt booster.
I am very happy with mine and have gone 2 miles out with no issues.
I know many complain about Spektrum having issues. But Since I added the booster I have not had issues.
I would not use the antennas that come with the booster. I would get a 2.4 patch and you will be very happy with it at 2 miles..
For the same amount of money (or even less) you can get the orange LRS from hobbyking and not run into all the problems related with a booster. Moreover, you could go out 5 miles with ease and safety margin and would not run into the risk of being acused by others of having shot down their models just because they heard you are operating a booster.

Just my 2 of course.

Markus
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Old Apr 27, 2013, 06:05 PM
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Hi all sorry if question has been asked before.
Why would one not use these circular polarized antennas on the model Tx and Rx units ? for example my Spectrum DX8 and the AR6210 receiver.

If it works for the video system on which ever frequency you choose, wouldn't it also improve the reliability of the flight control system on 2.4 gig ?

Many thanks
You would have to terminate one of the antennas inside of the rx with a 50 ohms resistor, then use the other antenna connection. It's doable, but usually not worth the effort as you would have to get ufl connectors, propperly tuned antenans etc. etc. These days LRS systems are cheap and buy you more reliability and range.

Markus
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Old Apr 27, 2013, 06:49 PM
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Tried that and followed the instructions to the T. Orange LRS
500 feet out is all the distance I could get with the stock firmware.
I then try to update the firmware and never used more than 3.3 volts to program.
Nothing but issues!
I have no need to go 5 miles.
For what I do 1 mile is far enough.
By the way , my booster setup cost 58 bucks.

https://images-na.ssl-images-amazon....iL._SY100_.jpg
Still cheaper than an OrangeLRS.

It cost me:
Turnigy Transmitter Muff - Black 1 IN STOCK
OrangeRx Open LRS 433MHz TX Module (JR/Turnigy compatible) 1 IN STOCK
OrangeRx Open LRS 433MHz 9Ch Receiver 1 IN STOCK

Shipment EMS Express to USA (MAX 1kg) NO LIPO $27.25
Taxes $0.00
Total $93.85

Markus, I haven't had any issues with anyone else flying 2.4 anything in my area or around me.


Quote:
Originally Posted by markus123456 View Post
For the same amount of money (or even less) you can get the orange LRS from hobbyking and not run into all the problems related with a booster. Moreover, you could go out 5 miles with ease and safety margin and would not run into the risk of being accused by others of having shot down their models just because they heard you are operating a booster.

Just my 2 of course.

Markus
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Old Apr 28, 2013, 06:02 AM
Registered FPVer :)
markus123456's Avatar
Switzerland, LU, Buchrain
Joined Aug 2006
2,853 Posts
Quote:
Originally Posted by DoctorAudio View Post
Tried that and followed the instructions to the T. Orange LRS
500 feet out is all the distance I could get with the stock firmware.
I then try to update the firmware and never used more than 3.3 volts to program.
Nothing but issues!
I have no need to go 5 miles.
For what I do 1 mile is far enough.
By the way , my booster setup cost 58 bucks.

https://images-na.ssl-images-amazon....iL._SY100_.jpg
Still cheaper than an OrangeLRS.

It cost me:
Turnigy Transmitter Muff - Black 1 IN STOCK
OrangeRx Open LRS 433MHz TX Module (JR/Turnigy compatible) 1 IN STOCK
OrangeRx Open LRS 433MHz 9Ch Receiver 1 IN STOCK

Shipment EMS Express to USA (MAX 1kg) NO LIPO $27.25
Taxes $0.00
Total $93.85

Markus, I haven't had any issues with anyone else flying 2.4 anything in my area or around me.
I can't comment on your issues with the Orange LRS. Actually its the same as open LRS which is known to work well. At the same time it's know to not be plug and play really. This is among other things the reason why there is amarkte for LRS systems like RangeLink, DragonLink, EzUhf and others. Anyways, I do not recommend anyone to use a booster, but you are surely free to do whatever you like.

Markus
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Old Apr 28, 2013, 07:05 AM
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DoctorAudio's Avatar
Milwaukie , Oregon
Joined Feb 2003
4,488 Posts
Well Markus:
Some things work great for you and doesn't work well for others.
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