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Old Feb 28, 2011, 03:58 PM
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Originally Posted by devfor View Post
asa2,

it looks like you know what you are doing.

Just be careful that you use a hot iron and don't push down on the tracks around the RF module too hard.
They can be a bit fragile.

And remember to visually inspect for shorts before you power it up.

good luck

Ren
Thanks
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Old Feb 28, 2011, 05:09 PM
Whats the wrst that can happn?
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Alex, I have an off topic question for you since you're the RF guru...and I probably don't have enough info for you to make a solid conclusion, but just wanted your opinioin.

I discovered an awesome place to fly, BUT about 300 feet from the take off location facing in the opposite direction (south) is a huge approx 25ft diameter dish pointed roughly at a 45 degree angle up towards the sky (behind the Lucent office in Illinois), which I do not know if it's transmitting or receiving. Is this a potential concern for RF interference with a 433 UHF Rx and 910 VTx FPV setup even if I be will 300+ feet away and will be flying behind and away from it?
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Old Feb 28, 2011, 06:26 PM
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Here's my attempt at a SPW for 5.8GHz - took me a good hour of slow work, but I'm quite pleased with it I'm not happy that the upper arms don't perfectly overlap the lower ones though ... challenge for my next one!





Thanks for the detailed instructions! Now to test it!


David
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Old Feb 28, 2011, 08:03 PM
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Quote:
I'm not happy that the upper arms don't perfectly overlap the lower ones though ...
Hi David!

Your SPW look awesome. The angle between the two quater wave lenght is about 100 degrees, therefore they cannot overlap the lower ones. Alex might give a better answer....

-Hugo (from TrueRC....)
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Old Mar 01, 2011, 08:49 AM
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Originally Posted by Hogster View Post
Here's my attempt at a SPW for 5.8GHz - took me a good hour of slow work, but I'm quite pleased with it I'm not happy that the upper arms don't perfectly overlap the lower ones though ... challenge for my next one!





Thanks for the detailed instructions! Now to test it!


David
Hugo is correct. You built that antenna quite well! I am very impressed with the work of you guys! Keep it up

-Alex
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Old Mar 01, 2011, 08:51 AM
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Originally Posted by AdamChicago View Post
Alex, I have an off topic question for you since you're the RF guru...and I probably don't have enough info for you to make a solid conclusion, but just wanted your opinioin.

I discovered an awesome place to fly, BUT about 300 feet from the take off location facing in the opposite direction (south) is a huge approx 25ft diameter dish pointed roughly at a 45 degree angle up towards the sky (behind the Lucent office in Illinois), which I do not know if it's transmitting or receiving. Is this a potential concern for RF interference with a 433 UHF Rx and 910 VTx FPV setup even if I be will 300+ feet away and will be flying behind and away from it?
Just don't fly in front of it's beam. Remember, satellite dishes are not necessarily powerful (despite their large size). What they do is compress a signal into a narrow high intensity beam. It could be a multipathing issue if you were standing right next to it, but at 300 feet away, I wouldn't worry about it.

-Alex
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Old Mar 01, 2011, 08:54 AM
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Originally Posted by aSa2 View Post
Hello,
just made a SP antenna. Does that look right?


and I have a question:
I have FatShark 100mW 2.4GHz transmitter witch has a wire instead of antenna. Can I just solder the coaxial with SP instead of that wire?


Thanks
That looks well built. I would put a small amount of hot glue or liquid electrical tape (or even paint) on the feed point of that antenna to keep it from shorting out. The skew-wheel is fairly wide band, so small amounts of dielectrics such as glue affect the frequency very little.

-Alex
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Old Mar 01, 2011, 09:00 AM
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First, my apology if this has been asked before, but could I benefit from using the skew planar or the cloverleaf on my Spektrum transmitter?
Possibly. It would certainly keep your signal from dropping out when banking. It would also give more consistent signal strength.

-Alex
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Old Mar 01, 2011, 01:51 PM
Whats the wrst that can happn?
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Thanks Alex!

Quote:
Originally Posted by IBCrazy View Post
Just don't fly in front of it's beam. Remember, satellite dishes are not necessarily powerful (despite their large size). What they do is compress a signal into a narrow high intensity beam. It could be a multipathing issue if you were standing right next to it, but at 300 feet away, I wouldn't worry about it.

-Alex
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Old Mar 07, 2011, 08:11 PM
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Here is a video of a SkewPlanar antenna that I'm about to solder. However, I'm worried that it might be LH Polarized. I'm trying to make all my antenna RHP. I think my cloverleaf at the end is RHP. Can someone who knows about these things tell me which my antenna are?

http://www.youtube.com/watch?v=O_9wyLqjnOU

Sorry for the crappy video. View in HD to see the detail.
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Old Mar 07, 2011, 09:43 PM
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Yes, that's LHCP. You need to bend the elements 90 degrees and you'll have RHCP.

-Alex
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Old Mar 07, 2011, 10:20 PM
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Going to test mine out tomorrow, going CP on both antennas and cant wait!

Will let you guys know how it goes. I will be using a Skew Planar / Cloverleaf.
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Old Mar 08, 2011, 12:34 AM
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You will be amazed at your video quality improvement. I certainly was
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Old Mar 08, 2011, 03:31 AM
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The way I remember which polarisation an antenna will be is by looking at single element from the outside.
It depends on which way the element 'leans' from the bottom point to the top point.

So, an element that looks like this \ is leaning to the left = Left Hand CP

and an element that looks like this / is leaning to the right = Right Hand CP

Nigel.
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Old Mar 08, 2011, 05:17 AM
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Old Mar 08, 2011, 07:20 AM
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Soldering of connections

I am hoping to build this antenna for 2.4GHZ but am having slight problem understanding the way that it is connected to the coax feed. I can see that the two arms of the antenna are soldered at right angles at the mid point of the long sides. Is that where the screen of the coax is soldered? That leaves the four ends of the arms. Do they get soldered together with the inner of the coax?

Peter
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Old Mar 08, 2011, 07:21 AM
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Peter - Yes, that is correct. The 4 ends get soldered to the coaxial cable cienter element, the shield gets soldered to the cross junction.

-Alex
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Old Mar 08, 2011, 12:01 PM
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Thanks Alex,

Which do you recommend the pin wheel or three leaf clover?

Peter
Quote:
Originally Posted by IBCrazy View Post
Peter - Yes, that is correct. The 4 ends get soldered to the coaxial cable cienter element, the shield gets soldered to the cross junction.

-Alex
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Old Mar 08, 2011, 12:11 PM
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For the TX I recommend the cloverleaf. For RX I recommend the skew-planar wheel.
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Old Mar 08, 2011, 12:41 PM
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Oops had mine backwards lol, had my Clover on the RX and vice versa. I will switch it out before I fly!
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Old Mar 13, 2011, 09:58 PM
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Quote:
Originally Posted by Devonboy View Post
The way I remember which polarisation an antenna will be is by looking at single element from the outside.
It depends on which way the element 'leans' from the bottom point to the top point.

So, an element that looks like this \ is leaning to the left = Left Hand CP

and an element that looks like this / is leaning to the right = Right Hand CP

Nigel.
Now that's an explanation I can understand. I could never quite figure out L/H, R/H polarization until now. Thanks.
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Old Mar 14, 2011, 01:14 PM
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Hi, I'm going to build a spw antenna for my 2.4Ghz vrx and a cl for the vtx.

I have a question regarding the intersection angle of the spw.

Quote:
Originally Posted by Ibcrazy
The tip of the wire should meet the center at a ~105 degree angle. It will not (and should not) intersect at 90 degrees.
After using this online calculator:

http://www.handymath.com/cgi-bin/arc18.cgi?submit=Entry

I find the angle should be more like 114 degrees.

What angle is correct?
Am i overthinking this?

Cheers
crezz
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Old Mar 14, 2011, 02:10 PM
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You are overthinking it The point of that statement was just to keep people from trying to force a 90 degree intersection.

-Alex
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Old Mar 14, 2011, 04:42 PM
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Hi everyone,

IBcrazy,you are a genius.I have built and try your CL antenna on 2.5 ghz and I must say that I have never been able to get such a clear video in all directions of flying since i have started FPV 2 years ago.I have try all sorts of omnis,patch,etc(except yagi) and I have always had noise.I have used the CL antenna on both the TX and RX and up to now I have push it to 1 km with crytal clear video( need some tweaking on my Dragon Link set up before pushing further).I will post a picture of the antenna and a video asap.Thanks again for sharing your ideas with us,Continue the good job.

God Bless,
Anthony.
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Old Mar 15, 2011, 12:12 AM
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I'm glad to hear that

It's stories like that which push me to develop even more stuff and post it here. Helping people be successful in FPV is why I post on this forum.

Have fun!

-Alex
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Old Mar 16, 2011, 05:55 PM
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I got a chance to run Hugo's 5.8 GHz pinwheels through the our new Agilent 9912A FieldFox RF analyzer today and got the attached results for VSWR. Any comments?

Unfortunately we don't have the network analyzer or vector voltmeter "option" licenses yet, just the CAT (cable/antenna test) and SA (spectrum analyzer) .
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Old Mar 16, 2011, 06:46 PM
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That's impressive for 5.8GHz. Looks like the elements were a bit short.

Mine aren't nearly as neat as his for sure. I also like to run a small section of coaxial cable to get the antenna away from the transmitter. The Fresnel zone is very small at 5.8GHz.

-Alex
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Old Mar 16, 2011, 07:06 PM
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Unfortunately the analyzer tops out at 6 GHz so I couldn't run it much wider, but it looks like 1.5 might be as good as it gets. I was lucky to track down an adapter kit that could handle RP-SMA to N-type today, let alone feed lines, but it is definitely very sensitive to objects (like fingers) in close proximity.

Here's the 5.4-6.0 GHz VSWR sweep.
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Old Mar 16, 2011, 08:59 PM
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Thx for sharing that with us.

1.5 is really not bad considering the frequency, a different after-shave and you might get different results
Did you test both?

Next ones will have a small coax (1/2 wave length)
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Old Mar 16, 2011, 09:19 PM
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Hey Hugo, thanks for sharing the antennas with me, I just wish I had the license codes to enable the network analyzer so I could have plotted an impedance sweep on a Smith chart.

Post #226 had two attached images, one for each antenna's VSWR. The better of the two ranged from 1.5-1.8 and the other from 1.7-2.0

Next step is to get a regulator fro my RangeVideo tx and do some coastal ground testing. I might build a helical antenna for that work as I have some nice LOS shots ranging from 6-18 km.
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Old Mar 17, 2011, 07:29 AM
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Originally Posted by Hugeone View Post
Thx for sharing that with us.

1.5 is really not bad considering the frequency, a different after-shave and you might get different results
Did you test both?

Next ones will have a small coax (1/2 wave length)
Or humidity will even change it. I bet a short run of coaxial cable will lower SWR due to the antenna being farther away from the test device. I make my 5.8 GHz antennas with about 1 wavelength or so coaxial and the antenna is formed into it. I also make it so the feed acts as a balun

-Alex
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Old Mar 17, 2011, 03:58 PM
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Produced a couple of these great antennas at work today



Thanks again for your great instructions Alex!


David
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Old Mar 17, 2011, 10:11 PM
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Those look fantastic.
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Old Mar 18, 2011, 03:27 PM
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Hi Alex,
Can you tell me if I can use RG58 50ohmn coax to connect antenna to the RX on 433mhz.Its a bit hard for me to find RG174 for the moment.I just want to make an extension.

Thanks,
Anthony.
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Old Mar 18, 2011, 06:51 PM
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Yes RG58 will work. In fact, I recommend it over Rg174.

-Alex
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Old Mar 18, 2011, 08:26 PM
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My skew planar wheel for my 2.4Ghz vrx.
I have used a length (1/2wave length)) of semirigid coax and 1.0mm mig wire.
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Old Mar 18, 2011, 08:40 PM
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Originally Posted by IBCrazy View Post
Or humidity will even change it. I bet a short run of coaxial cable will lower SWR due to the antenna being farther away from the test device. I make my 5.8 GHz antennas with about 1 wavelength or so coaxial and the antenna is formed into it. I also make it so the feed acts as a balun

-Alex
The result with a random 50cm (~10 lambda) SMA feed line was a bit better.
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Old Mar 19, 2011, 08:54 AM
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Ask for inspection :)

Do you think this looks good?



Thanks
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Old Mar 19, 2011, 09:59 AM
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doh.
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Old Mar 19, 2011, 10:04 AM
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I expect you'll have some non-ideal behaviour due to the proximity of the coax shield to the leg of the element that it is taped to. This could be modelled or measured but you need to have the tools and know how to use them...
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Old Mar 19, 2011, 04:18 PM
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http://www.mwjournal.com/Journal/Com...tenna/AR_8587/
What do you think about this type of antenna?
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Old Mar 19, 2011, 05:28 PM
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I just spent the last hour and a half attempting to build this and it's really making me mad. I still don't think it's right. Can someone tell me what I'm doing wrong?
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Old Mar 19, 2011, 05:32 PM
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Quote:
Originally Posted by dimar View Post
http://www.mwjournal.com/Journal/Com...tenna/AR_8587/
What do you think about this type of antenna?
Interesting but the axial ratio is quite poor which means it would not perform well for multipath rejection.

OMM
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Old Mar 19, 2011, 10:22 PM
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I just spent the last hour and a half attempting to build this and it's really making me mad. I still don't think it's right. Can someone tell me what I'm doing wrong?
That looks fine to me. It's LHCP from the pictures. What do you think is wrong with it?

-Alex
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Old Mar 20, 2011, 01:05 AM
RC = FUN
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I just felt like it wasn't aligned correctly or something.

I actually flew with that and the cloverleaf today.

When flying towards, away, and banking at distances I ha perfect video. But if I ever turned within 100-200 feet it would sometimes go to static, but not to the point of my linear (non cp?) antennas. I went out to 3/4 of a mile, and will start to push and test it once my DL arrives! -Tyler
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Old Mar 20, 2011, 03:18 PM
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And you were about ready to give up FPV due to frustrations

Those that aren't switching to circular polarization have no idea what they're missing.
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Old Mar 20, 2011, 03:53 PM
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+1 for Circular polarization. off topics, Alex any news about the antenna for the DL.

Anthony.
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Old Mar 20, 2011, 03:56 PM
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Originally Posted by IBCrazy View Post
And you were about ready to give up FPV due to frustrations

Those that aren't switching to circular polarization have no idea what they're missing.
Not give up, I just wanted to go simpler. I'm still thinking about the fatsharks though

Alex, how do I test if it's a 1.0? Isn't their supposed to be a way if your impendence (I may have made that up, but it sounded right lol) is a 1.0?

Could I send it to you or could I check with a radio shack multimeter? -Tyler
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Old Mar 21, 2011, 07:38 AM
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Why send it back to me? I measured and prebent the wire for you. At the very worst the SWR is 1.2 which is still excellent.

Yes I am willing to test it for you, but why not just fly it? I am certain it will work well.

-Alex
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Old Mar 21, 2011, 07:39 AM
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+1 for Circular polarization. off topics, Alex any news about the antenna for the DL.

Anthony.
Coming soon. I still need to work out a few bugs. This got pushed on the back burner while I finished the design of the CP BiQuad antenna.

-Alex
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Old Mar 21, 2011, 11:49 AM
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Thanks Alex,can't wait to try it.Will it be easy to built?.

Anthony.
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Old Mar 21, 2011, 04:42 PM
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I've exchanged some emails with Alex about this but thought it might be helpful in this wider discussion. Like many now, I'm switching to Cloverleaf (plane) and Skew Planar Wheel (ground). I'm currently trying to figure out the best way to integrate the SPW into my ground station. Last night I bought a styrofoam half ball from the local art store and sanded out the inside of it to make a dome for my fragile SPW. I've got a styrofoam wheel to close up the bottom and, though it's not pretty, I've got a nice dome to mount on the end of a pvc pole. HOWEVER...

While I understand this antenna should be mounted high, I now understand that I can't extend the coaxial from the antenna to the receiver without serious signal loss. So I believe that leaves me with mounting the receiver under the dome and extending the RCA and power connections from my receiver down the pole from my antenna/receiver to my ground station. So here's my question: what's the best way to extend those connections?

Years ago I remember trying to extend RCA lines to my stereo and I never was able to do it without creating a strong humming sound. Is there a good way to extend that RCA cable or some special connection?

How about the power cord? I remember reading somewhere that power cords out of your ESC shouldn't be extended. Does this apply to the receiver?

Thank in advance.
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Old Mar 21, 2011, 08:06 PM
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Quote:
Originally Posted by Infernal Bill View Post
I've exchanged some emails with Alex about this but thought it might be helpful in this wider discussion. Like many now, I'm switching to Cloverleaf (plane) and Skew Planar Wheel (ground). I'm currently trying to figure out the best way to integrate the SPW into my ground station. Last night I bought a styrofoam half ball from the local art store and sanded out the inside of it to make a dome for my fragile SPW. I've got a styrofoam wheel to close up the bottom and, though it's not pretty, I've got a nice dome to mount on the end of a pvc pole. HOWEVER...

While I understand this antenna should be mounted high, I now understand that I can't extend the coaxial from the antenna to the receiver without serious signal loss. So I believe that leaves me with mounting the receiver under the dome and extending the RCA and power connections from my receiver down the pole from my antenna/receiver to my ground station. So here's my question: what's the best way to extend those connections?

Years ago I remember trying to extend RCA lines to my stereo and I never was able to do it without creating a strong humming sound. Is there a good way to extend that RCA cable or some special connection?

How about the power cord? I remember reading somewhere that power cords out of your ESC shouldn't be extended. Does this apply to the receiver?

Thank in advance.
Someone in another thread here in the forum used a network patch cable. This sounds like a good idea for this kind of application as they are shielded, and the connetors are of good quality too. It's also easy to get the propper matching receptables etc. and since they have eight wires, you should be pretty much all set with one cable going down from the mast to your ground station.

Well, at least thats what I intend to try out to solve the same problem.

Markus
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Old Mar 21, 2011, 09:28 PM
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Here are the antennas that I decided to make this weekend. I used 0.035" mig wire for the vee, the cloverleaf and the SPW. I just realized that the mig wire is flux core wire. I hope the flux core does not affect the performance of the antennas. I decided to make the antennas RHCP. Anyways thanks to Alex for the great tutorials. I will make a helical in the coming week hopefully.


Matt
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Old Mar 21, 2011, 11:01 PM
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Those look good, Matt. Flux core won't hurt the antenna at all. However I must warn you, once you fly the cloverleaf/SPW combination, that Vee/patch will forever remain in a box

-Alex
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Old Mar 22, 2011, 12:04 PM
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Anybody selling these for 2.4ghz?
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Old Mar 22, 2011, 12:32 PM
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Yes:

http://www.readymaderc.com/store/ind...roducts_id=396

I also sell them individually. See my blog for details.

-Alex
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Old Mar 24, 2011, 09:47 AM
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What is the difference between having four wires and three? in gain?
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Old Mar 24, 2011, 10:03 AM
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Very little difference in gain. I find the cloverleaf is a better TX antenna. Some here prefer the skew-planar wheel.

-Alex
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Old Mar 24, 2011, 12:48 PM
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http://www.lindenir.com/2.html
This kind of antenna could also be interesting for the receivers... hemispherical circularly polarized antenna, developed by genetic algorithms, probably patented.
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Old Mar 24, 2011, 03:13 PM
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...
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Old Mar 24, 2011, 10:42 PM
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Here is another picture:


Some more informations about the math behind:
http://www.hindawi.com/journals/ijap/2008/197849/

Even with polar coordinates for modeling. Let's warm up 4NEC2 ...]
Been there, done that!

(not easy to build and it did not work well at all)

OMM
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Old Mar 25, 2011, 02:23 AM
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Those look good, Matt. Flux core won't hurt the antenna at all. However I must warn you, once you fly the cloverleaf/SPW combination, that Vee/patch will forever remain in a box

-Alex
hi alex
i am new to FPV and still trying out the range and video quality of my 900mhz 200mW stock whip RX TX from hobbyking
this SP antenna will/should be my next mod to the system
did i understand clearly by the quote above u mean that the range of the SP system will be approximately the same as with a Vee Vtx and patch Vrx but with much better video quality ?
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Old Mar 25, 2011, 08:46 AM
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hi alex
i am new to FPV and still trying out the range and video quality of my 900mhz 200mW stock whip RX TX from hobbyking
this SP antenna will/should be my next mod to the system
did i understand clearly by the quote above u mean that the range of the SP system will be approximately the same as with a Vee Vtx and patch Vrx but with much better video quality ?
Sort of...

Theoretically range is 40% less, but that is almost NEVER realized. Most will get 2-3X the range out of a CP system as they do a linear system due to multipath problems regarding linear polarization. OMM got 2km on 10 mw on his Quadcopter! So did Marc Antonio on his airplane.

-Alex
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Old Mar 25, 2011, 08:46 AM
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Been there, done that!

(not easy to build and it did not work well at all)

OMM
Thanks, for that, Mike. I almost tried it
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Old Mar 25, 2011, 09:39 AM
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Linear polarization is only good for the stationary TX and RX (like wifi) and also used primarily because antennas are cheaper.

Circular is always used for non-stationary TX or RX in the professional applications (like satellite communication).

RC electronics just doesn't seem to use it, probably due to costs and size. I am glad someone is exploring this now. It could also be theoretically possible to have video tx on the 2.4ghz and use 2.4ghz radio (like FASST), both with opposing circular polarizations. Someone should try it.
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Old Mar 25, 2011, 11:33 AM
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Sort of...

Theoretically range is 40% less, but that is almost NEVER realized. Most will get 2-3X the range out of a CP system as they do a linear system due to multipath problems regarding linear polarization. OMM got 2km on 10 mw on his Quadcopter! So did Marc Antonio on his airplane.

-Alex
thanks for the reply
i am using futaba fasst for my RC
so in theory a 200mW 900mhz system with SP antennas should be adequate for my standard RC range (i hope) .. i don't intend to go beyond 2km for now
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Old Mar 25, 2011, 11:37 AM
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I would suggest a cloverleaf on the TX and a skew-planar wheel on the RX. I have found this to be the best combination. On paper the skew-planar wheel on both ends is better. In practice, I find the cloverleaf to be better on the TX.

-Alex
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Old Mar 25, 2011, 07:56 PM
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I've been looking, but can't seem to find any discussion about the SMB connectors - where to get them, and what to use to crimp coax on one. Does one use the same ones for soldering an antenna directly as well as for crimping coax? I am sure its somewhere - could someone direct me to this info?
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Old Mar 25, 2011, 08:28 PM
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I would suggest a cloverleaf on the TX and a skew-planar wheel on the RX. I have found this to be the best combination. On paper the skew-planar wheel on both ends is better. In practice, I find the cloverleaf to be better on the TX.

-Alex
great .. thanks again
the type/thickness of wire used should not be an issue right ? as long a it holds up against the wind and does not deform so easily
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Old Mar 25, 2011, 10:07 PM
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great .. thanks again
the type/thickness of wire used should not be an issue right ? as long a it holds up against the wind and does not deform so easily
Yes, any wire will do. I use steel wire for a mig welder. Old Man Mike prefers memory wire. Copper wire is a bit soft, so go with steel.

-Alex
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Old Mar 29, 2011, 03:40 AM
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Yes, any wire will do. I use steel wire for a mig welder. Old Man Mike prefers memory wire. Copper wire is a bit soft, so go with steel.

-Alex
Hi Alex,
do you mean that the wire gauge has no effect on the antenna performance? Is it just a matter of mechanical strenght? I am presently preparing a couple of antennas for the 5,8GHz Tx/Rx that came in yesterday. I have plenty of enamelled copper wire of awg#28 (diam 0,32mm). Will it work at 5,8GHz?
Just as a matter of test, I made one antenna with 12 petals (all at 45deg from ground and 60 deg appart from each others). It was much easier to make than I was expecting. What I do is to CA glue all petals on a small piece of paper before soldering (materialising the ground "plane" with angular positions). I think I can easily do much more but I have no clue whether this would bring performance. What is your opinion?
What would be the best number of petals for Tx and Rx antenna?
Pat
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Old Mar 29, 2011, 07:21 AM
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I mean that wire thickness has very little effect on antenna performance. However I am finding that the number of lobes the antenna has will change it's SWR. Thus last night I changed the equation and numbers slightly to fit the empirical values I was getting in my frequency sweeps.

Typically, I prefer a 3 lobe for the TX and 4 lobe for the RX. I am working on a few multi lobe units now, but they will require tuning stubs to resonate properly.

-Alex
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Old Apr 02, 2011, 11:28 AM
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Wow! So many jokes, so little time!
Building a batch of these liked to have killed me about 3 hours ago. No really! Had talked to IBC about welding the antennas together. Mainly because I see some being made & as a welder I just kinda cringe. No one else seems to have gtaw'd any. Tigging them sure makes it stronger and way easier to join to the cable electrode. Tho the cheap PTFE coax I had laying around really doesn't like it much.

So having some 3/32" ER70S2, 1/16" ER316 & some 14ga Romex (Oxidized copper house wiring) laying around I started a few. :P

Then my ears started ringing.
And my ear went numb.
Uh oh..... I think all welders know what that means. > : (
Yup sure enough. 120cuft tank of argon was showing 22psi. Had 1800-1900psi in it when I started working 45-60min before. Filled up the garage with Argon & I just never heard it leaking. And that's WITH the garage door open 1 stop. (small gas lens on the torch will run OK at extremely low flow rates.) Gas line split inside the machine.
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Old Apr 06, 2011, 10:43 AM
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Originally Posted by Toysrme View Post

...

Then my ears started ringing.
And my ear went numb.
Uh oh..... I think all welders know what that means. > : (
Yup sure enough. 120cuft tank of argon was showing 22psi. Had 1800-1900psi in it when I started working 45-60min before. Filled up the garage with Argon & I just never heard it leaking. ...
Yikes, glad you are alright neighbor!
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Old Apr 06, 2011, 12:45 PM
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Rx/Tx

Hello,

Just wonder, if spw antenna does not work well with LawMate, what would be the best choice of tx and rx for, let us say, 2.4 and 1.3 GHz?

Thanks
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Old Apr 06, 2011, 03:10 PM
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Hello,

Just wonder, if spw antenna does not work well with LawMate.....Thanks
That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
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Old Apr 06, 2011, 03:27 PM
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That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
It was started on the first post of this thread
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Old Apr 06, 2011, 03:43 PM
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It was started on the first post of this thread
I have three SPW antennas and six Lawmate receivers. I also have the test equipment to accurately measure performance. There is no problem. The first page needs to be corrected.

OMM
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Old Apr 07, 2011, 06:10 AM
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Thanks, that answers my question
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Old Apr 07, 2011, 05:28 PM
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That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
It doesn't work at all with my 1.2GHz Lawmate RX's. Maybe you have a different revision than I do?

I get good RSSI and signal strength reading, but the frame rate drops to 3 frames per second. I have 3 Lawmates and all get the same results.

-Alex
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Old Apr 07, 2011, 06:02 PM
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It doesn't work at all with my 1.2GHz Lawmate RX's. Maybe you have a different revision than I do?

I get good RSSI and signal strength reading, but the frame rate drops to 3 frames per second. I have 3 Lawmates and all get the same results.

-Alex
Frame Rate? That is not an RF/antenna issue. It sounds like you have a problem with the video levels. In fact, a very good RF signal can show up a problem with incorrect video levels because of video sync/saturation issues. Do you have a video generator to make sure the sync and video levels are correct? Here is what I use:

http://www.elexp.com/tst_pg68.htm

You also need a scope with special video sync to adjust it correctly.

With the lawmates you can only adjust levels on the TX side. Even without the correct video test equipment, you could mark the current position and try adjusting the TX levels to a point where it will work. Monitor the video white/yellow levels to make sure you are not into saturation.

OMM
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Old Apr 07, 2011, 10:41 PM
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That makes some sense, but why would it work fine with a helical antenna? I can place the TX right in front of the helical and get no problems. I fly with a cloverleaf and go 400 feet out and it's still flashing screen at about 3 frames per second. With the cloverleaf, I get no signal at all. This happens with all three of my Lawmate RX's.

I can check the sync on my oscilloscope. I'll see what I am getting there.

-Alex
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Old Apr 08, 2011, 01:04 AM
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That makes some sense, but why would it work fine with a helical antenna? I can place the TX right in front of the helical and get no problems. I fly with a cloverleaf and go 400 feet out and it's still flashing screen at about 3 frames per second. With the cloverleaf, I get no signal at all. This happens with all three of my Lawmate RX's.

I can check the sync on my oscilloscope. I'll see what I am getting there.

-Alex
First step might be to connect the output of the Lawmate to a monitor and not a digitizer for the PC. You probably have a TV which has a direct video input. You should then be able to tell what the analog signal is really doing instead of depending on digitizers that often do a poor job with anything other than a direct camera input.

OMM
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Old Apr 08, 2011, 08:50 AM
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Well, it's not a sync I don't think. Total loss of signal (static) at 600 feet away. I will try connecting it to an old TV.

I'm not the only one who has this problem either. Many have reported the SPW does not work with airwave 5.8GHz modules. That's why I avoid all the confusion of "it doesn't work" and post the issue.

-Alex
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Old Apr 08, 2011, 12:07 PM
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Well, it's not a sync I don't think. Total loss of signal (static) at 600 feet away. I will try connecting it to an old TV.

I'm not the only one who has this problem either. Many have reported the SPW does not work with airwave 5.8GHz modules. That's why I avoid all the confusion of "it doesn't work" and post the issue.

-Alex
so the question remains open?!
OMM has lawmates that work with SPW and IBCrazy has som that don't

IBCrazy, as I understand, you use lawmate with spw on tx and helical on rx, for 1.3?

OMM - what frequency are you on?
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Old Apr 08, 2011, 12:32 PM
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so the question remains open?!
OMM has lawmates that work with SPW and IBCrazy has som that don't

IBCrazy, as I understand, you use lawmate with spw on tx and helical on rx, for 1.3?
Yes I fly the SPW on the plane and a helical on the ground. It works very well.

I tend to err on the side of caution in most of my posts. However, if it you have to decide between me and OMM, take OMM's advice over mine. He knows more than I do... far more.

-Alex
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Old Apr 08, 2011, 01:06 PM
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after bending some wires to get the approximate size of the SPW and CL ... i think i will just go with the Vee 1st
on my 900mhz setup the size of the SPW or the CL is just too cumbersome to put on the plane (cloudsfly glider)
it will just have to wait for me to get a 5.8 video setup

btw off topic .. tested the Vee with stock whip RX in the house earlier .. very very good results walking around with the goggles ... almost perfect video .. beats the crap out of the stock whip Tx antenna ... will be taking it out for a flight tomorrow
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Old Apr 08, 2011, 05:40 PM
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..OMM - what frequency are you on?
1280 Mhz (the only legal frequency for ham radio license)


Quote:
Originally Posted by IBCrazy View Post
....I tend to err on the side of caution in most of my posts. However, if it you have to decide between me and OMM, take OMM's advice over mine. He knows more than I do... far more.

-Alex
That's a very nice compliment, Alex. However, even though it should not be a problem and I don't see it here, that does not mean there isn't a problem with your system that can be fixed. I know that you take care in your testing so we must be missing something. It is always interesting to find the root cause of something that does not make sense at a theoretical level. Here are a few other ideas:

1) Perhaps some lawmate RX units have an RF input that does not block DC and somehow there is a voltage across the antenna input that gets shorted with a grounded antenna like the SPW. That might take down the overall voltage enough to cause problems with the video output. I'm reaching here but it might be worth a quick check with the voltmeter to see if there is any voltage at the antenna input.

2) RF interference geting into the digitizer either from the nearby TX or receiver self oscillation. You could try testing with attenuation pads on both RX and TX to see if things change.

3) Video and Sync levels which are not processed correctly by the digitizer. I still think this is the most likely issue. It will be most interesting to hear what results you get with an analog monitor.

Whatever the cause, it would drive me crazy until I found the root problem. The biggest concern is that it could be an indication of something marginal that could eventually show up even with antennas that are now working OK with your system.

OMM
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Old Apr 09, 2011, 02:48 PM
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1280 Mhz (the only legal frequency for ham radio license)
Actually, that might not be the case anymore. I tested a VTx with a 1256MHz channel! I also have an RX with that channel too. Just barely inside of the HAM spectrum.

-Alex
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Old Apr 11, 2011, 11:41 AM
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Flew out to 3.25 miles on my SPW and 5 turn helical at 1280 mhz this weekend. No range record, but great video and had fun! If I had a plane that could make it, i'm sure it could go MUCH farther.
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Old Apr 11, 2011, 11:58 AM
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Flew out to 3.25 miles on my SPW and 5 turn helical at 1280 mhz this weekend. No range record, but great video and had fun! If I had a plane that could make it, i'm sure it could go MUCH farther.
And you never tuned yours either
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Old Apr 12, 2011, 09:20 AM
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No, really dont have to for my kind of flying I guess. Seriously though, I would have to really figure out how to get something to fly longer to be able to outrange my home made antennas that you designed.

It looks like I have moved on from the part of my FPV experience where I try to get the best video range and quality, now I need to ponder on what plane I can keep in the air for 45+ minutes...
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Old Apr 15, 2011, 12:43 PM
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OK IBCrazy, this is the Antenna I am about to buy (i think), first of all I was told (by you I think) that having a long co-ax going to the antenna is BAD, but this one has it, (my patch has a 2' one as well)
http://www.boostervision.com/cart/sc...?idProduct=122


first of all I am running 900mhz. I have a good 3dbi whip antenna on 1 Rx and a 9 dbi patch on the other reciever. and a v pole on the rx I was about to buy a 5 dbi magnetinc base whip to replace the 3 dbi. Would I be better off just making a clover leaf? I was wondering if I have a circular polarity clover on 1 rx, patch on the 2nd rx and a v-pole on the tx would it work well? what about is I put a clover leaf on the Tx , would my standard patch antenna on the rx still work well with the CP antenna on the tx? I don't know about mixing types of polarity and if the circular will still work well with the linear polarity antennas on the rest of my setup?
What would be the best and cheapest/easiest upgrades to do with antennas on m,y current setup?

like I said I have a 8dbi patch on 1 900mhz rx, a 3 dbi whip on the second 900mhz Rx. and an oracle between them. And I have a V-pole (or several stock omni-pole whips) for my tx's (1x 500mw and 1x 200mw) What is the best upgrade and can I just switch out half of the diversity set up to circular polarity clover on 1 of the rx's. Do I need to put one on the rx and the Tx? or am I better off just getting the bigger whip antenna and sticking with my current setup.? please help me IBCrazy or I will be too! lol
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Old Apr 19, 2011, 09:18 PM
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So if each lobe when laid flat intersects the center at around 105 degrees, and each ground leg is separated by 90 degrees, when looking down from the top, where should the + leg be in relation to the next ground leg? Should they be right over each other? 5-10 degrees of overlap?
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Old Apr 20, 2011, 03:25 AM
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angle of meet

I have been trying to make a jig for a 5.8 version and found this calculator useful as you can enter the degrees and establish the arc length (in our case 1/2 wavelength

http://www.analyzemath.com/Geometry_...ea_sector.html

the angle for a 1/4 wavelength of 13 mm is around 115 degrees

hope this is of use

pme
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Old Apr 20, 2011, 06:45 AM
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I stopped by Hobby Lobby (craft store) looking for the memory wire. Are we talking the gold colored wire?? That is solderable?? Anyone got a snap or sku #?/ Thanks
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Old Apr 20, 2011, 07:50 AM
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I have been trying to make a jig for a 5.8 version and found this calculator useful as you can enter the degrees and establish the arc length (in our case 1/2 wavelength

http://www.analyzemath.com/Geometry_...ea_sector.html

the angle for a 1/4 wavelength of 13 mm is around 115 degrees

hope this is of use

pme
Lots of people are making jigs, but I find hand forming faster, oddly. I bend the wire around a marker

Here's how I do it: I run the wire through a home-made wire straightener which is nothing more than a set of two rollers and a block of wood with a hole in it. The straightener looks just like a mig welder wire feed with a spring tesnioner to keep the rool from unreeling except it's wood.

The straightened wire gets marked at 1/4 wave, 3/4 wave and 1 wavelength and then gets cut off the spool. I then take the wire and wrap it around a round former. For 2.4GHz, I use a 1" PVC pipe glued to a peice of pywood with a weight on it (to keep it from moving). 5.8GHz I simply wrap around a marker in my hand. I actually over bend the wire, then pull lightly on the ends to de-stress the curve to exactly where I want it. I then grab the wire at the 1/4 wave marks with pliers and bend it.

To solder, I lay the forms against a couple of carpenter's speed squares. Magnets help hold the wire where I want it. Then I simply reach insert my cable and solder it all up.

-Alex
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Old May 13, 2011, 01:32 AM
Time's fun when ya havin flies
cncoz's Avatar
Qld, AU
Joined Sep 2007
445 Posts
For what It's worth...
I made a set of CP's for my 5.8Ghz parkflier, hope to try them tomorrow.
I worked this template out to help with bending, might be useful to someone.
If the antennae perform well I'll post pics.
Cheers !
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Old May 14, 2011, 04:32 AM
There's magic in those wings !
khaled_abobakr's Avatar
Joined Nov 2006
4,851 Posts
deleted ... I couldn't ask the right question ?? I'll post again when I know the right question to ask

Thanks IBCrazy for the info in your blog and in aerial video systems

Khaled
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Last edited by khaled_abobakr; May 15, 2011 at 08:36 AM.
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