Circular-polarized Patch Antenna for 5,8 GHz - RC Groups
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Dec 23, 2010, 10:58 AM
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Circular-polarized Patch Antenna for 5,8 GHz


I found this 13dbi patch for 5,8GHZ
http://www.wirelessnetworkproducts.com/hd27073.aspx

What does the experts here think?
Any good for our application?

Best regards
Christian
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Dec 23, 2010, 12:53 PM
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Overpriced ...

Cheers,

Sander.
Dec 23, 2010, 01:26 PM
Registered User
Jupp, besides that.... half the price would be better.

From my understanding i will lose about 3db gain due to the circular polarization.
As a benefit i can fly more acrobatics, right?

Do you have any experiences with circular polarized 5,8 ghz patches?
Not that easy to find. Maybe you have other recommendations?

Thanks

Christian
Dec 23, 2010, 03:37 PM
Registered User
Do you like homebrew ?

https://www.rcgroups.com/forums/show....php?t=1352583

Nigel.
Dec 23, 2010, 06:08 PM
Engineer for Christ
IBCrazy's Avatar
RIPOFF!!! For two peices of metal less than 3" square $120!!!

And I can assure you that it's not even really circularly polarized but elliptical.

Coyote64 was kind enough to open up one of his and shoew it to me. I'll post a how-to on it soon enough. It would be really easy to build

-Alex
Dec 23, 2010, 06:31 PM
"Once you have tasted flight..
ivanestebanc's Avatar
Quote:
Originally Posted by IBCrazy
RIPOFF!!! For two peices of metal less than 3" square $120!!!

And I can assure you that it's not even really circularly polarized but elliptical.

Coyote64 was kind enough to open up one of his and shoew it to me. I'll post a how-to on it soon enough. It would be really easy to build

-Alex
Perfect Alex, I was close to buy one of these. I will wait for your DIY.
Dec 24, 2010, 02:21 AM
Registered User
Hi Alex,

i am definitly looking forward to your howto.
Allready enjoyed all your other DIYs.

Best regards
Christian
Dec 24, 2010, 03:35 AM
Time's fun when ya havin flies
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Dec 24, 2010, 06:33 AM
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Notice the important remark from lonestar : if your tranmitter antenna is linearly polarized and your receiver antenna is circularly polarized, which is the case discussed here, then you always loose 3dB.

The best case would be to have a circular polarized antenna at the transmitter and at the receiver (it is the case for GPS for example).

more details here :

http://www.antenna-theory.com/basics/antennapol.php

"Suppose now that a linearly polarized antenna is trying to receive a circularly polarized wave. Equivalently, suppose a circularly polarized antenna is trying to receive a linearly polarized wave. What is the resulting Polarization Loss Factor?

Recall that circular polarization is really two orthongal linear polarized waves 90 degrees out of phase. Hence, a linearly polarized (LP) antenna will simply pick up the in-phase component of the circularly polarized (CP) wave. As a result, the LP antenna will have a polarization mismatch loss of 0.5 (-3dB), no matter what the angle the LP antenna is rotated to."
Dec 24, 2010, 11:56 AM
Engineer for Christ
IBCrazy's Avatar
Yes, CP is best when both TX and RX have circular polarization in the same rotation (RHCP or LHCP). I am working on new CP systems. Right now I only have the skew planar wheel antenna tested. I have a helical being tested by dalbert in Florida. I'll make the how-to's as I have time

-Alex
Dec 24, 2010, 02:25 PM
Team Spektrum FPV
aaronredbaron's Avatar
my friend here has been very happy with this iftron 5.8 circular patch on a hobbywireless 200 mw system. http://www.iftrontech.com/Antennas-&...duct_info.html
Dec 24, 2010, 03:07 PM
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Hugeone's Avatar
Quote:
And I can assure you that it's not even really circularly polarized but elliptical.
By elliptical, do you mean it have a linear component?
Dec 24, 2010, 04:40 PM
Engineer for Christ
IBCrazy's Avatar
These antennas attampt to skew the polarization using edge trimming methods. The problem is that the antenna still retains most of it's linear capabilities and only skews the pattern slightly. What results is an elipse for a polarization pattern. This is very good for when you have a linear TX antenna as you will have about 1-2db loss (instead of 3db) when up right and about 5-6db loss in a 90 degree bank. However with a circular TX antenna, there will be some loss and might not reject multipath interference as well.

-Alex
Dec 24, 2010, 04:58 PM
crd
crd
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Quote:
Originally Posted by ssassen
Overpriced ...

Cheers,

Sander.
the $17.99 of rebate sound like the normal price hehe, $100 is wayyyyy overpriced.
Dec 25, 2010, 04:35 AM
Registered User
Merry Christmas to all of you....:-)

This link gives design guidelines for a circular polarized patch antenna:
http://icom.hsr.ch/uploads/media/MegnetMathisRom.pdf

Published on a Conference in 2009.
D. Megnet, H. Mathis, Circular Polarized Patch Antenna for 5.8 GHz Dedicated Short-Range Communication, 39. European Microwave Conference (EuMC) 2009, Rome, Italy, September 28 - October 2, pp. 638-641.

Its so nice to read scientific papers also for hobby purposes and not only at work ;-))


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