HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 23, 2010, 10:58 AM
Registered User
Germany
Joined Dec 2010
46 Posts
Discussion
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
Lonestar78 is offline Find More Posts by Lonestar78
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 23, 2010, 12:53 PM
Suspended Account
Netherlands, NH, Edam
Joined Jul 2004
5,535 Posts
Overpriced ...

Cheers,

Sander.
ssassen is offline Find More Posts by ssassen
Reply With Quote  (Disabled)
Old Dec 23, 2010, 01:26 PM
Registered User
Germany
Joined Dec 2010
46 Posts
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
Lonestar78 is offline Find More Posts by Lonestar78
Reply With Quote
Old Dec 23, 2010, 03:37 PM
Registered User
SW England
Joined Aug 2009
799 Posts
Do you like homebrew ?

http://www.rcgroups.com/forums/showthread.php?t=1352583

Nigel.
Devonboy is offline Find More Posts by Devonboy
Reply With Quote
Old Dec 23, 2010, 06:08 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,542 Posts
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
IBCrazy is offline Find More Posts by IBCrazy
Reply With Quote
Old Dec 23, 2010, 06:31 PM
"Once you have tasted flight..
ivanestebanc's Avatar
Gilbert AZ
Joined Jun 2010
219 Posts
Quote:
Originally Posted by IBCrazy View Post
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.
ivanestebanc is offline Find More Posts by ivanestebanc
Reply With Quote
Old Dec 24, 2010, 02:21 AM
Registered User
Germany
Joined Dec 2010
46 Posts
Hi Alex,

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

Best regards
Christian
Lonestar78 is offline Find More Posts by Lonestar78
Reply With Quote
Old Dec 24, 2010, 03:35 AM
Time's fun when ya havin flies
cncoz's Avatar
Qld, AU
Joined Sep 2007
445 Posts
Subscribed !
cncoz is offline Find More Posts by cncoz
Reply With Quote
Old Dec 24, 2010, 06:33 AM
Registered User
Joined Mar 2009
1,113 Posts
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."
flipflap is offline Find More Posts by flipflap
Reply With Quote
Old Dec 24, 2010, 11:56 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,542 Posts
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
IBCrazy is offline Find More Posts by IBCrazy
Reply With Quote
Old Dec 24, 2010, 02:25 PM
Spektrum Dev Team
aaronredbaron's Avatar
United States, IL, Champaign
Joined Apr 2002
1,110 Posts
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
aaronredbaron is offline Find More Posts by aaronredbaron
Reply With Quote
Old Dec 24, 2010, 03:07 PM
Registered User
Hugeone's Avatar
Canada,Quebec
Joined Jan 2005
2,056 Posts
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?
Hugeone is offline Find More Posts by Hugeone
Reply With Quote
Old Dec 24, 2010, 04:40 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,542 Posts
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
IBCrazy is offline Find More Posts by IBCrazy
Reply With Quote
Old Dec 24, 2010, 04:58 PM
crd
Always thinkering
crd's Avatar
United States, FL
Joined Nov 2006
1,249 Posts
Quote:
Originally Posted by ssassen View Post
Overpriced ...

Cheers,

Sander.
the $17.99 of rebate sound like the normal price hehe, $100 is wayyyyy overpriced.
crd is offline Find More Posts by crd
RCG Plus Member
Reply With Quote
Old Dec 25, 2010, 04:35 AM
Registered User
Germany
Joined Dec 2010
46 Posts
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 ;-))
Lonestar78 is offline Find More Posts by Lonestar78
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Mini-HowTo The Skew-Planar Wheel circular polarized omni antenna IBCrazy FPV Equipment 901 Nov 03, 2014 11:23 AM
Discussion Left/Right circular polarized antenna ? SpookiePower FPV Talk 49 Oct 15, 2014 10:23 AM
Discussion Best solution for antenna tracker and 5.8 GHz diversity Lomcevac FPV Talk 0 Nov 28, 2010 08:33 AM
Discussion 18dbi Circular Polarized Patch ? Coyote64 FPV Talk 3 Nov 10, 2010 05:59 PM
Discussion Advantage of a Circular Polarized Patch Ant? Mach61 FPV Talk 2 May 01, 2009 11:53 PM