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Old Feb 17, 2011, 10:33 PM
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Have fun skiing Alex! I need to hit the slopes again too before it all melts =)
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Old Feb 18, 2011, 06:12 PM
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Bay Area California
Joined Dec 2009
296 Posts
Hi all,

Well after having a bunch of fun making the Vee I decided to start making a cloverleaf antenna. I used 0.027 copper magnet wire just to try it out before I get some .035 mig wire. I did everything to the best of my ability and understanding of the instructions but Im not getting much performance out of the antenna when used along with a rubber ducky for the VRX. Below are some pictures I took to see if anyone can help me out.

Thanks



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Last edited by matyou; Feb 18, 2011 at 06:26 PM.
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Old Feb 18, 2011, 07:17 PM
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If I understand correctly, you need a circular polarized antenna on both sides; tx and rx, to get good performance. Rubber ducky is linearly polarized.
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Old Feb 18, 2011, 07:24 PM
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Bay Area California
Joined Dec 2009
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With a linear and a circular antenna you lose about 3db but still should work. I have a feeling that I did something wrong.
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Old Feb 18, 2011, 07:26 PM
Tesla's Workshop
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USA, CA, Torrance
Joined Nov 2004
2,446 Posts
dbi Mismatch Basics

V to V = 0dbi
V to H = -26dbi
i.e. dbi can change from 0 to -26dbi in a 90 degree bank

CP to L (V or H) = -3dbi
Stays -3dbi when the antennae change angles

CP to CP = 0dbi
Stays 0dbi when the antennae change angles

RHCP to LHCP = -26dbi
Stays -26dbi when the antennae change angles

So one should see a marked improvement in multipath rejection and consistancy of video in a turn but not longer range with a CP and L combo.

Jeff
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Old Feb 18, 2011, 07:57 PM
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Bay Area California
Joined Dec 2009
296 Posts
Jeff,
Have you tried this antenna yet? I wonder why I cant get any good performance from it? Does it look right?

Matt
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Old Feb 18, 2011, 08:03 PM
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USA, IN, Bloomington
Joined Aug 2007
833 Posts
Quote:
Originally Posted by workshop View Post
V to V = 0dbi
V to H = -26dbi
i.e. dbi can change from 0 to -26dbi in a 90 degree bank

CP to L (V or H) = -3dbi
Stays -3dbi when the antennae change angles

CP to CP = 0dbi
Stays 0dbi when the antennae change angles

RHCP to LHCP = -26dbi
Stays -26dbi when the antennae change angles

So one should see a marked improvement in multipath rejection and consistancy of video in a turn but not longer range with a CP and L combo.

Jeff

Doesn't a -3dbi change translate roughly into losing half your distance (range)? If so, this sounds like a lot. I'm trying to decide if I can mix CP and inverted Vs on different planes but have the same vertical patch on my rx.
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Old Feb 18, 2011, 08:33 PM
Tesla's Workshop
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USA, CA, Torrance
Joined Nov 2004
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I've tried the antenna on the bench and it burrows through walls! Simply amazing...

I've used CP on the RX side for years and it changed the hobby. -3bdi down still means two miles (w/ standard rubber duck on the TX) but with a consistant image of which I can depend.

NOW... with CP on both sides, I am really excited...

Jeff
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Old Feb 18, 2011, 09:22 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,393 Posts
Quote:
Originally Posted by matyou View Post
Hi all,

Well after having a bunch of fun making the Vee I decided to start making a cloverleaf antenna. I used 0.027 copper magnet wire just to try it out before I get some .035 mig wire. I did everything to the best of my ability and understanding of the instructions but Im not getting much performance out of the antenna when used along with a rubber ducky for the VRX. Below are some pictures I took to see if anyone can help me out.

Thanks



I can see many problems:
1. Your angles are not correct. You need to come off that center conductor at 45 degrees with each element.

2. You are using RG174 coaxial cable. Chances are you heated it up too much and the center element shifted internally. RG174 has poor heat characteristics.

3. We have no idea where you are mounting this. Location makes a difference.

4. You need a CP antenna on the RX side too. Try a helix or another cloverleaf. Multipath with omnis is a killer. Believe it or not, when receiving with a linear omni antenna, a CP antenna makes the multipath problem worse!

5. The thin wire will distort very easily in the wind causing sporadic power level changes. VTX units do not adapt well to this.

-Alex
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Old Feb 18, 2011, 09:23 PM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
10,393 Posts
Quote:
Originally Posted by workshop View Post
I've tried the antenna on the bench and it burrows through walls! Simply amazing...

I've used CP on the RX side for years and it changed the hobby. -3bdi down still means two miles (w/ standard rubber duck on the TX) but with a consistant image of which I can depend.

NOW... with CP on both sides, I am really excited...

Jeff
And I've got some new stuff coming out soon. Wait until you try it

-Alex
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Old Feb 18, 2011, 11:42 PM
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USA, CO, Durango
Joined Sep 2010
670 Posts
Quote:
Originally Posted by IBCrazy View Post
And I've got some new stuff coming out soon. Wait until you try it

-Alex
Wow already?! Glad I haven't started building this one yet
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Old Feb 19, 2011, 03:02 AM
Me a long time ago
Flypoppa's Avatar
London N.E. UK
Joined Jan 2007
6,093 Posts
I thought that the original had 4 elements, but now I see 3. Would a 4 be better?
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Old Feb 19, 2011, 08:11 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by volto View Post
Wow already?! Glad I haven't started building this one yet
Build this one. It is the center piece of it all. All of my other antennas are Rx antennas that revolve around this one.

-Alex
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Old Feb 19, 2011, 08:13 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,393 Posts
Quote:
Originally Posted by Flypoppa View Post
I thought that the original had 4 elements, but now I see 3. Would a 4 be better?
They are different antennas. The 4 lobe is the skew-planar-wheel. The 3 lobe is the cloverleaf. The cloverleaf has higher gain, but less reverse polarity rejection.

-Alex
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Old Feb 19, 2011, 08:36 AM
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Drednox's Avatar
Joined Jan 2011
203 Posts
Question:
What's type of mig wire is better to use? Steel, carbon steel, high or low nickel content, aluminum? Also, did you run into any problems soldering the wire?
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