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Old Jun 04, 2007, 09:57 AM
Registered User
United States, CA, San Diego
Joined Sep 2005
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Question
Use of Omnidirectional 2.4 ghz antenna?

Has anyone used an omnidirectional antenna like the one listed below on a diversity receiver? I am curious because I was thinking of trying one of these along with one of the 12dbi patch antennas that I got from FutureHobbies.

http://www.hyperlinktech.com/web/hg2412u.php

Maybe this isn't even necessary? I'm going to be using the FutureHObbies 1W transmitter along with their diversity setup. I thought that maybe a good compromise between distance and range would be a bigger omni like the one above used in conjunction with the high-gain vertical/horizontal polarized patch antenna.

What do you guys think?

Thanks,

capn
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Old Jun 04, 2007, 10:43 AM
JettPilot's Avatar
Miami
Joined Apr 2005
10,675 Posts
The omni will work close in, so you do not have to aim the patch, that will give you both good long and short distance video.

I standard vertical and a patch will also work very well on a diversity receiver for the same purpose. The vertical would give you a little better medium range as it has gain to the sides. The omni might give you a very slight less dropouts in very close range than the standard vertical, so if super clean production quality video while you are close in the pattern is important to you, the omni might be worth the extra money. If you want good medium and long range, I would use a vertical antenna with the patch instead of omni.

JettPilot
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Old Jun 04, 2007, 11:20 AM
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twinturbostang's Avatar
Germantown, MD
Joined Mar 2006
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I have used an omni in conjunction with a patch on a diversity setup. Works quite well for short range flying around, and longer range in a particular direction.

The antenna you linked to might not be a good candidate though due to the gain. Omni's have 360 degrees of coverage, but as you go higher and higher with the gain, you loose vertical range. Someone else gave a good example once.... think of it as a doughnut. As the gain increases, you flatten the doughnut some. So you get farther range to the sides, but less above (or below) you. Take a look at the gain patterns on that link and you will see what I mean. It's pretty flat.
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Old Jun 04, 2007, 12:04 PM
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Kilrah's Avatar
United Arab Emirates, Dubai
Joined Sep 2006
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Yes, if you check the diagram the vertical beamwidth it 8... and half of that being in the ground! An omni in conjunction with a patch is good, but stay with a 0-3dB omni and use it when you're close.
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Old Jun 04, 2007, 12:36 PM
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zaguruinzasky's Avatar
Verona - Italy
Joined Jan 2007
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you're right Kilrah, the vertical range is very poor:

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Old Jun 04, 2007, 12:38 PM
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Verona - Italy
Joined Jan 2007
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what is the best combination (if any) of antennas with a diversity receiver to have omni directional capability? a couple of 3db omni? if yes with same angle or.. ?
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Old Jun 04, 2007, 01:25 PM
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United States, CA, San Diego
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Thanks guys! So I should just stick with the standard omni that came with the Futurehobbies setup? I could just use one of the 12dbi patches in that case, along with the small whip.

This brings up another question...should I go with vertical or horizontal polarization with the patch? Also, what exactly is the difference between vertical and horizontal polarization?
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Old Jun 04, 2007, 02:22 PM
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Kilrah's Avatar
United Arab Emirates, Dubai
Joined Sep 2006
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Vertical or horizontal is the same antenna, just turned 90
If your TX antenna is vertical most of the time, install the RX one it vertically, etc so they use the same polarization.

I just come back from flying with 8dBi patch and standard whip, I like this a lot as I'll be able to still have very good range alll around as the whip is already good for a few hundred meters. If I want to fly far, then I'll go where the patch points.
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Old Jun 04, 2007, 03:13 PM
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zaguruinzasky's Avatar
Verona - Italy
Joined Jan 2007
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Quote:
Originally Posted by Kilrah
I just come back from flying with 8dBi patch and standard whip, I like this a lot as I'll be able to still have very good range alll around as the whip is already good for a few hundred meters. If I want to fly far, then I'll go where the patch points.
That's what I was thinking about, where do I find a diagram of the standart whip ?

Thanks!
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Old Jun 04, 2007, 10:50 PM
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Boston, MA
Joined May 2007
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Don't use anything more than 8dbi on an omni, the beam width is ridiculously low, you'd have 7-10degrees to work with, its like a pancake.
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