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Old Apr 29, 2009, 02:40 PM
Registered User
Ottawa, ON. Canada
Joined Oct 2006
300 Posts
Discussion
Advantage of a Circular Polarized Patch Ant?

I have two omnis (3dbi and 5dbi) and a 14dbi patch. I am using a single receiver so I thought I would try an 8dbi patch.

NGhobbies has three different types - right circular polarized, left circular polarized and vertical/horizontal 8dbi flat patch.

I understand that if I go with the third option, I need to have the tx ant pointing straight up with the patch ant pointed in the general direction of the plane with the coaxial coming out of the bottom for best reception.

If I go with the circular polarized patch, I understand that the orientation of tx ant is irrelevant and orientation of the patch is irrelevant provided it is pointed in the general direction of the plane but I will lose 3dbi relative to the non-circular polarized version. So the main advantage is I can do wild aerobatics with no signal strength loss but the disadvantage is that I will lose range. Is this correct?

Does it make a diff whether I choose right or left circular considering I only have one receiver?

If you were to use only one 8dbi patch and planned on flying in front of it, what would you choose? circular polorized? or linear?

thx
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Old May 01, 2009, 07:51 PM
Registered User
Joined Jul 2003
128 Posts
This is the best Thread i have found for circular polarization:
http://www.rcgroups.com/forums/showt...t=polarization


Doesn't matter which circular direction!
Post #26 sums it up nicely!
Recommended antenna lead length is under 12in to prevent signal loss.

Most of the FPV vendors who sell antennas stock them with the 4ft leads

I just ordered a pair (Rt/Lt) with custom 3" lead length for $47ea from: http://www.l-com.com/item.aspx?id=21787


Also picked up this 5 dBi omni with great angle specs but needs a SMA Male /N Female adapator:
http://www.l-com.com/item.aspx?id=22055
http://www.l-com.com/item.aspx?id=5349

Going to try the Oracle w/ vertical omni and circular patch facing up then try two circular patches facing slightly up and angled away

yeah ha
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Old May 01, 2009, 10:53 PM
Seeing the Farside.
Blaze.45's Avatar
Seattle WA, USA
Joined Aug 2005
4,285 Posts
Quote:
Originally Posted by Mach61

1) So the main advantage is I can do wild aerobatics with no signal strength loss but the disadvantage is that I will lose range. Is this correct?

2) Does it make a diff whether I choose right or left circular considering I only have one receiver?

3) If you were to use only one 8dbi patch and planned on flying in front of it, what would you choose? circular polorized? or linear?

thx
1) Yes.

2) No practical difference.

3) If both antennas are nearly identical in advertised specs, shape, and size.

Circular for close to med range where your antenna changes direction quite a lot, aka aerobatics or flying directly above, etc etc.

Linear for med to long(er) range where your antenna is on a gentle path, aka a glider flying long range, etc etc.

This is general info. There are many little "gotchas".
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