Circularly polarised antenna

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Re: Circularly polarised antenna

Postby Mark Hitchman » Mon Mar 26, 2012 8:05 am

Funny you should say that as I was going to PM you to see when it was, I am keen. I have 3 models ready to go on 1010mhz, a 66" Zephyr, 2M glider and the tricopter, have also ordered the 5.8ghz 200mw micro module and receiver module from foxtech to put on something, maybe my kinetic.
I am definitely keen to fly with other people fpv or at least see other peoples setups in person.

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Re: Circularly polarised antenna

Postby zann68 » Sat Mar 31, 2012 2:58 pm

Got a question on these Clover Leaf antenna's. Has anyone tried putting one of these on your Transmitter? Looks to me if it will help the Video Tx/Rx why not the you radio as well. Just a thought. :?:
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Re: Circularly polarised antenna

Postby RCModelReviews » Sat Mar 31, 2012 6:33 pm

I am aware that some folk have use them on their RC gear but I don't actually see the point.

RC gear continues to work fine with the occasional frame loss -- but occasional frame loss really screws up your video.

Cloverleaf antennas do not have as much range as dipoles -- because they sacrifice gain for a more omnidirectional pattern - so using them will reduce the maximum range of your RC gear and, when you fly out of range, there's little chance of recovering the situation by re-orienting your transmitter (which can certainly save you if you're using dipoles).
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Re: Circularly polarised antenna

Postby zann68 » Sat Mar 31, 2012 8:21 pm

RCModelReviews wrote:I am aware that some folk have use them on their RC gear but I don't actually see the point.

RC gear continues to work fine with the occasional frame loss -- but occasional frame loss really screws up your video.

Cloverleaf antennas do not have as much range as dipoles -- because they sacrifice gain for a more omnidirectional pattern - so using them will reduce the maximum range of your RC gear and, when you fly out of range, there's little chance of recovering the situation by re-orienting your transmitter (which can certainly save you if you're using dipoles).


I find your comment on range reduction puzzling. I thought the idea behind the clover leaf antennas to help with range and drop out issues. Is the antenna on the Rx has something to do with this as well? Everything I read here and see on video on how superior a clover leaf style antenna is to a standard dipole type. The reason I brought this up was people fly so far out with FPV and using 2.4g radios. I'm wishing to be able to fly out a good range myself. The thought of losing my plane or worse hitting something with it is a fear of mine. I'm not trying to fly 10 miles or such but when you get a mile or 2 out an RC plane gets real small. I have a 2w booster coming to piggy back my 2.4g Tx. I've seen some wicked results with this setup.

By the way your video's and this forum have been great!! Keep up the good work!! Still learning from you and everyone else here

Thanks in Advance for any input on my questions
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Re: Circularly polarised antenna

Postby rogueqd » Sun Apr 01, 2012 1:35 am

zann68 wrote:I find your comment on range reduction puzzling. I thought the idea behind the clover leaf antennas to help with range and drop out issues.

RCModelReviews wrote:RC gear continues to work fine with the occasional frame loss -- but occasional frame loss really screws up your video.

If your RC receiver only get's one good 'frame' of stick positions a second the plane will continue to fly fine, maybe a little unresponsive but enough to turn around and fly back to a stronger signal. If you have only one good frame of video (so 29/30ths of a second of static and 1/30th of a second you get a flash of picture) you're not going to see enough to tell what direction you're flying in.

Video is a lot less tolerant of static than RC signals. Your usable video range is, roughly speaking, when your signal get's to around 50% strength, or even 99% if you want to record nice scenery, but your usable RC range is down to (roughly) 5%, strength.

CP antennas make the 50% mark further out, but bring the 5% mark closer. For video you want the 50% point as far away as possible, for RC you want the 5% point as far as possible.
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Re: Circularly polarised antenna

Postby zann68 » Mon Apr 02, 2012 12:32 am

Ohh, ok I understand what your saying.

Thanks for the class on this.
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Re: Circularly polarised antenna material

Postby KWolter » Sat Apr 07, 2012 2:24 am

I've been debating what material to use for 5.8GHz antennas as well. Copper is great but it has a problem. Copper oxide is resistive and high frequencies travel on the outer most part of the conductor, something known as skin effect. The result of copper oxide is obvious, keep it nice and shiny and all is fine. I though about using enamel coated wire but the enamel reduces the velocity factor of the wire. How much is something I need to research.
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Re: Circularly polarised antenna

Postby RCModelReviews » Sat Apr 07, 2012 7:01 pm

I think a very thin coat of clear polyurethene over the antenna wire may help.

I noticed a significant reduction in performance when the thin copper coating on the antennas I built with MIG wire corroded but the effect has been less noticeable on my solid copper ones.

Maybe polishing your antenna will become part of the regular FPV maintenance schedule :-)
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Re: Circularly polarised antenna

Postby KWolter » Sat Apr 07, 2012 9:56 pm

Humm, I'm thinking I might try some 22AWG silver plated Cu wire. There's some on eBay for a reasonable price.

Aluminum would be okay too, aluminum oxide is an insulator. Soldering to it is not so easy though.
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Re: Circularly polarised antenna material

Postby Shotglass » Sun Apr 08, 2012 12:47 am

KWolter wrote:I though about using enamel coated wire but the enamel reduces the velocity factor of the wire. How much is something I need to research.


its way too thin to have any noticeable effect
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