HobbyKing.com New Products Flash Sale
Reply
Thread Tools
This thread is privately moderated by IBCrazy, who may elect to delete unwanted replies.
Old Oct 22, 2012, 03:48 PM
Registered User
JLT_GTI's Avatar
Oviedo
Joined Jun 2010
2,322 Posts
On question about antenna combos..

Is better to have a combo skew planar on plane and cloverleaf on the Video RX .... or have both swp?
JLT_GTI is offline Find More Posts by JLT_GTI
RCG Plus Member
Latest blog entry: CL-415 GuanLi
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 22, 2012, 03:52 PM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
774 Posts
Quote:
Originally Posted by FPV_Habu_Flyer View Post
Regarding CP antennas it says that a skew planar on the transmitter and receiver offers 15km range in all directions! Wow! Its also says that a skew planar on the transmitter combined with an IBCrazy helical offers 80km range! Seriously!? Not to mention this is done while also rejecting multipathing.
In ideal situations your range depends on antenna gains (tx and rx), transmitted power and receiver sensitivity, neglecting the theoretical frequency dependency for the moment. You may simply add dB's. What I mean for example, a -x dB worse antenna may be compensated by a +x dB more powerful transmitter or a +x dB more sensitive receiver (assuming low enough noise floor).

An example:
Doubling your distance costs +6dB signal strength. So 15km with two 1dBi SPW's is possible but only when using quite high power or a very sensitive receiver, or a combination of both. Say you get 1km with 20dBm power and -90dBm receiver sensitivity. Then at 15km your signal is about 24dB less (4 times 6dB). So that needs 44dBm tx power or a -114dBm receiver.

Note that SPW has very low gain, so theoretically its range is less than a 3dBi whip or a 2.15dBi dipole. But it has better coverage and CP helps solving a couple of problems, which actually extend your range in practise. But I wouldn't advertise SPW as "the" long range antenna.

Martin
Martin7182 is offline Find More Posts by Martin7182
Reply With Quote
Old Oct 22, 2012, 04:05 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,475 Posts
Quote:
Originally Posted by JLT_GTI View Post
On question about antenna combos..

Is better to have a combo skew planar on plane and cloverleaf on the Video RX .... or have both swp?
It's all speculation, actually. I have best results with 2 cloverleaf antennas. Most people prefer a clover on the aircraft and a skew wheel on the ground. Others have better results running 2 SPWs. I guess it all depends on what we consider better. Hard to say, honestly, but after flying with an SPW just for kicks, I went back to the cloverleafs.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
Reply With Quote
Old Oct 22, 2012, 04:06 PM
Registered User
United States, NC, Wilmington
Joined Aug 2011
769 Posts
Those ranges are not what Alex (IBCrazy) claims, these are from CircularWireless (Sircana). That is a CircularWireless SPW and they are referring to their Helical as well and it is 12.5db.

The setup the claim 80Km is the one Roberto did 100Km with and on 800mW (I think is what he said). The 15Km for the SPW comes from Sircana, he said one of his customers told him he did 15Km on two SPWs. I will try and find the post.

So they are possible but not the norm.
MASHTON is offline Find More Posts by MASHTON
Reply With Quote
Old Oct 22, 2012, 04:08 PM
Registered User
JLT_GTI's Avatar
Oviedo
Joined Jun 2010
2,322 Posts
Quote:
Originally Posted by IBCrazy View Post
It's all speculation, actually. I have best results with 2 cloverleaf antennas. Most people prefer a clover on the aircraft and a skew wheel on the ground. Others have better results running 2 SPWs. I guess it all depends on what we consider better. Hard to say, honestly, but after flying with an SPW just for kicks, I went back to the cloverleafs.

-Alex
I asked one guy who build them locally and he told me that he only build swp because they have greater performance than cloverleafs..

it puzzled me because in most places i see people using them in combos and even in ebay there are combos allways spw+clover ...

So shouldnt be wrong using 2 skews?
JLT_GTI is offline Find More Posts by JLT_GTI
RCG Plus Member
Latest blog entry: CL-415 GuanLi
Reply With Quote
Old Oct 22, 2012, 04:14 PM
Registered User
United States, NC, Wilmington
Joined Aug 2011
769 Posts
Quote:
Originally Posted by MASHTON View Post
Those ranges are not what Alex (IBCrazy) claims, these are from CircularWireless (Sircana). That is a CircularWireless SPW and they are referring to their Helical as well and it is 12.5db.

The setup the claim 80Km is the one Roberto did 100Km with and on 800mW (I think is what he said). The 15Km for the SPW comes from Sircana, he said one of his customers told him he did 15Km on two SPWs. I will try and find the post.

So they are possible but not the norm.
Here is a link to the post on FPVLabs. It was done on 1.5 watts.

http://fpvlab.com/forums/showthread....2-DISCONTINUED
MASHTON is offline Find More Posts by MASHTON
Reply With Quote
Old Oct 22, 2012, 04:34 PM
polyfractal's Avatar
United States, SC, Charleston
Joined Jun 2012
113 Posts
Quote:
Originally Posted by JLT_GTI View Post
I asked one guy who build them locally and he told me that he only build swp because they have greater performance than cloverleafs..

it puzzled me because in most places i see people using them in combos and even in ebay there are combos allways spw+clover ...

So shouldnt be wrong using 2 skews?
In theory, the Cloverleaf + SPW is the best combination.

The cloverleaf has a lower theoretical SWR and a higher gain. It makes a poor receiving antenna because "the reverse polarization rejection pattern is very erratic and varies between -8 and 19dBi. " [source]. Basically, this means you'll still suffer multipath interference because the antenna doesn't reject all of the incorrectly polarized rf. However, this has no bearing on it's ability to transmit, so the higher gain and lower SWR are advantageous

The SPW has a slightly lower gain but is much better at rejecting incorrectly polarized rf. Another quote: "the reverse polarization rejection pattern is much better and more uniform than the Cloverleaf, making it excellent for the receiving end." [source]

Now, this is all in theory. In practice, it depends on how well you've built your antennas and how you have them configured in your plane. If you have a properly tuned and configured setup, the CL+SPW setup should be superior.

Edit: And I should point out that the advice of experts (IBcrazy) carry a lot more weight than what I have to say
polyfractal is offline Find More Posts by polyfractal
Site Sponsor
Last edited by polyfractal; Oct 22, 2012 at 08:42 PM.
Reply With Quote
Old Oct 22, 2012, 04:49 PM
Registered User
United States, MN, Orono
Joined May 2011
568 Posts
Quote:
Originally Posted by Martin. View Post
In ideal situations your range depends on antenna gains (tx and rx), transmitted power and receiver sensitivity, neglecting the theoretical frequency dependency for the moment. You may simply add dB's. What I mean for example, a -x dB worse antenna may be compensated by a +x dB more powerful transmitter or a +x dB more sensitive receiver (assuming low enough noise floor).

An example:
Doubling your distance costs +6dB signal strength. So 15km with two 1dBi SPW's is possible but only when using quite high power or a very sensitive receiver, or a combination of both. Say you get 1km with 20dBm power and -90dBm receiver sensitivity. Then at 15km your signal is about 24dB less (4 times 6dB). So that needs 44dBm tx power or a -114dBm receiver.

Note that SPW has very low gain, so theoretically its range is less than a 3dBi whip or a 2.15dBi dipole. But it has better coverage and CP helps solving a couple of problems, which actually extend your range in practise. But I wouldn't advertise SPW as "the" long range antenna.

Martin
Edit*- Ok, I just flew the Stryker again. I went out about 1.5 miles and could have gone much further, but there was a nasty headwind, so I'll just try again tomorrow. I actually don't think range is my problem right now, and I probably shouldn't be emphasizing it so much. I keep getting lines on my screen and static when I turn, but I get the same thing at 1.5 miles or 10 feet...

Correct me if I'm wrong, but I think this could be the result of multipathing. As you can see, I fly in an area with tons of houses, trees, and obstructions such as water towers. I'm definitely not getting crystal-clear video.

This is why I want to experiment with CP antennas. Unlike some of you, I'm not flying in an empty farm-field out in the country. That's why I switched to 1.3Ghz in the first place. Before I start adding high-gain antennas, I want to make sure I'm using the right kind of equipment. I can keep going out further, but I want to make sure that the lines I keep seeing aren't because I'm almost out of range (which I'm certain they aren't at just 1.5 miles).

Thanks for all the help,
Jim
FPV_Habu_Flyer is offline Find More Posts by FPV_Habu_Flyer
Last edited by FPV_Habu_Flyer; Oct 22, 2012 at 08:25 PM.
Reply With Quote
Old Oct 22, 2012, 04:57 PM
Registered User
Joined Oct 2011
897 Posts
Hello, I'm new to this thread: I see that there is a treasure house of information on page one, and I'm going to be studying it.

Just from the get go, I'm lost on one point, and would like to "just see" if I can get a quick steer towards a product ID / vendor...

This query may be (liikely will be) poorly formed due to my not yet having sufficient knowledge / understanding to ask right, so that being said:

I understand that to get maximum range from simple 5.8ghz entry level FPV TX / RX kits an extra antenna is a good idea. I understand that many FPV'ers make home brew "clover leaf" antannae. I also understand that there is a recently arrived on the market compact antenna that looks a bit like an AWACS disk, it seems usually white coloured, selling for between $50- and $70-, that does what a very good home brew cloverleaf antenna will do, considerably extending potential range on 5.8ghz equipment.

If my beliefs are correct, then this antenna will be well known to at least a few keen FPV enthusiasts, some of whom will surely find and read this post.

I aplogize in advance for any pain endured by tripping over my solecisms (being generous to myself), or just plain ignorance.

If you can, would you please post a link towards any likely candidates to be this mythical antenna I seek?

Thanks!
syzygyQ is offline Find More Posts by syzygyQ
Reply With Quote
Old Oct 22, 2012, 05:14 PM
polyfractal's Avatar
United States, SC, Charleston
Joined Jun 2012
113 Posts
Quote:
Originally Posted by syzygyQ View Post
Hello, I'm new to this thread: I see that there is a treasure house of information on page one, and I'm going to be studying it.

Just from the get go, I'm lost on one point, and would like to "just see" if I can get a quick steer towards a product ID / vendor...

This query may be (liikely will be) poorly formed due to my not yet having sufficient knowledge / understanding to ask right, so that being said:

I understand that to get maximum range from simple 5.8ghz entry level FPV TX / RX kits an extra antenna is a good idea. I understand that many FPV'ers make home brew "clover leaf" antannae. I also understand that there is a recently arrived on the market compact antenna that looks a bit like an AWACS disk, it seems usually white coloured, selling for between $50- and $70-, that does what a very good home brew cloverleaf antenna will do, considerably extending potential range on 5.8ghz equipment.

If my beliefs are correct, then this antenna will be well known to at least a few keen FPV enthusiasts, some of whom will surely find and read this post.

I aplogize in advance for any pain endured by tripping over my solecisms (being generous to myself), or just plain ignorance.

If you can, would you please post a link towards any likely candidates to be this mythical antenna I seek?

Thanks!
The 5.8 GHz SpiroNET Antenna Set perhaps?

polyfractal is offline Find More Posts by polyfractal
Site Sponsor
Old Oct 22, 2012, 08:13 PM
Registered User
United States, MN, Orono
Joined May 2011
568 Posts
Quote:
Originally Posted by MASHTON View Post
Those ranges are not what Alex (IBCrazy) claims, these are from CircularWireless (Sircana). That is a CircularWireless SPW and they are referring to their Helical as well and it is 12.5db.

The setup the claim 80Km is the one Roberto did 100Km with and on 800mW (I think is what he said). The 15Km for the SPW comes from Sircana, he said one of his customers told him he did 15Km on two SPWs. I will try and find the post.

So they are possible but not the norm.
What would you say "the norm" is with a skew planar on the transmitter and a 9.5dbi helical? More than a 13dbi yagi with stock tx antenna?
FPV_Habu_Flyer is offline Find More Posts by FPV_Habu_Flyer
Reply With Quote
Old Oct 22, 2012, 08:34 PM
... where is it ?!
ro.bi.'s Avatar
United States, CA, SF
Joined Jul 2011
449 Posts
Quote:
Originally Posted by ro.bi. View Post
My 5.8 FoxTech w/ Skew Planar (4 lobes) on vrx & stock (plastic, articulated) on vtx has better penetration than my 1.2 SunSky w/ stock antennas (plastic, articulated) on both vrx/tx Flying stock 2.4 9x radio ... 12V from a 3s Lipo FPV cam is a GoPro What can I do to get the best out of the 1.2 SunSky vrx/tx !? Thanks
Maybe I should mention I fly a Witespy quad ...
Also, the best reception on the 800mW sunsky I get with the strange combo: channel 7 on vrx & channel 4 on Vtx?
ro.bi. is offline Find More Posts by ro.bi.
Reply With Quote
Old Oct 22, 2012, 10:20 PM
Registered User
Joined Oct 2011
897 Posts
Quote:
Originally Posted by polyfractal View Post
Yes, that's the one.

Nice!

Thank you.
syzygyQ is offline Find More Posts by syzygyQ
Reply With Quote
Old Oct 23, 2012, 09:36 AM
Registered FPVer :)
markus123456's Avatar
Switzerland, LU, Buchrain
Joined Aug 2006
2,849 Posts
Quote:
Originally Posted by MASHTON View Post
Those ranges are not what Alex (IBCrazy) claims, these are from CircularWireless (Sircana). That is a CircularWireless SPW and they are referring to their Helical as well and it is 12.5db.

The setup the claim 80Km is the one Roberto did 100Km with and on 800mW (I think is what he said). The 15Km for the SPW comes from Sircana, he said one of his customers told him he did 15Km on two SPWs. I will try and find the post.

So they are possible but not the norm.
So they are possible but not the norm

Very true! I had occasions where I could fly with still flyable picture out to 6km on a CL/SPW combo on 5.8Ghz using the 200mW SkyRf based setup. However, that's not the norm. Range depends on many factors like the weather conditions (i.e. air humidity), and the noise floor and of course the freuqency band used.
Obviousely the weather can vary a great deal, but so can also noise floor. It would be better if people would post average range estimations which usually are significantly less than what could be achived one day under best conditions. Oh, and "best conditions" is also a difficult term as i.e. good weather to get best ranges does not have to be the same as what humans usually consider to be good weather.

Just my 2 of course.

Markus
markus123456 is offline Find More Posts by markus123456
Reply With Quote
Old Oct 23, 2012, 03:17 PM
Expat
Japan
Joined Apr 2010
3,031 Posts
Would an iPhone or netbook (with wifi function enabled) nearby a 2.4/2.5 vrx cause interference? I don't mean a wifi hub, just an appliance that uses it.
TheNiceGuy is offline Find More Posts by TheNiceGuy
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion How to calculate flight time - guide ikorman Multirotor Talk 11 Dec 30, 2011 07:22 PM
Discussion How many FPV pilots in the world? rbmaze FPV Talk 10 Aug 03, 2011 06:16 AM
Poll Would you be interested in buying Ready to Fly FPV airplanes from a new FPV store? FPVNOW FPV Aircraft 36 Oct 06, 2010 08:56 PM
Discussion Can this cam be used for FPV ? SpookiePower FPV Talk 8 Sep 12, 2010 07:12 AM
Cool How cool would this be for FPV Kai_Shiden FPV Talk 2 May 11, 2009 07:41 PM