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SATCOM - Space and Satellite Monitoring Forum Forum for the discussion of the Space Shuttle, Satellites, Military Satcom, and Amateur Radio Satcom communications.

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Old 09-26-2013, 3:32 PM
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Default X-Wing SatCom antenna ground plane question

I didn't want reopen the old thread so I'm starting a new one.

I built the X-Wing antenna that was in MT in 2010 and I've been using it for a few years.
(My compliments to the developers. It has been a great antenna.)

I've never had it permanently installed.
I just drag it out for a few days or so when I get the urge to do some UHF satellite listening.
(I worked on the very first SatCom RF payload back in the late 60's so I have a vested interest.

In addition to all the scanners I now have a number of DVB-T USB dongles and they make 'looking' around on the satellites more interesting.

Now, I'm thinking of placing the X-Wing in a permanent location and I have a question about the ground plane/screen.

The hardware cloth I've been using is 1/2" squares and the stock size I could get back then was 36" x 10'.
So, my ground plane is 36" x 48".
I've been thinking about adding another 12" to the one side to make it 48" x 48",

So ....
My question is, has anyone had a chance to compare the effect of a smaller ground plane on the antenna performance.
Is it worth all the trouble to do that?

By the way, I'm using an RF Bay, Inc. LNA-580 low noise preamp (0.7dB NF, 23dB gain) within the antenna base and I 'think' I'm hearing everything that can be heard there.

Rich
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Old 09-26-2013, 11:41 PM
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Too bad MT is not around any more and that antenna guy is not writing those great articles.

Normally this type antenna would only require a ground plane a little bigger than a half wavelength across at the lowest frequency but the MT X-wing is purposely designed to point up and to the sides with the main lobe covering about 20 to 60 degrees above the horizon and work in many different areas of the globe.

I would stick with the recommended 48" X 48" ground plane unless you have equipment to evaluate a smaller one at your specific location.
prcguy


Quote:
Originally Posted by rbm View Post
I didn't want reopen the old thread so I'm starting a new one.

I built the X-Wing antenna that was in MT in 2010 and I've been using it for a few years.
(My compliments to the developers. It has been a great antenna.)

I've never had it permanently installed.
I just drag it out for a few days or so when I get the urge to do some UHF satellite listening.
(I worked on the very first SatCom RF payload back in the late 60's so I have a vested interest.

In addition to all the scanners I now have a number of DVB-T USB dongles and they make 'looking' around on the satellites more interesting.

Now, I'm thinking of placing the X-Wing in a permanent location and I have a question about the ground plane/screen.

The hardware cloth I've been using is 1/2" squares and the stock size I could get back then was 36" x 10'.
So, my ground plane is 36" x 48".
I've been thinking about adding another 12" to the one side to make it 48" x 48",

So ....
My question is, has anyone had a chance to compare the effect of a smaller ground plane on the antenna performance.
Is it worth all the trouble to do that?

By the way, I'm using an RF Bay, Inc. LNA-580 low noise preamp (0.7dB NF, 23dB gain) within the antenna base and I 'think' I'm hearing everything that can be heard there.

Rich
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Old 09-27-2013, 6:17 PM
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I was hoping that someone had already done some comparison testing.

So, today I did my own testing.
I saw a slight improvement with the 48" x 48" ground plane as shown in the attached screen captures.

Not really enough that I would worry about it, but since I cut up the hardware cloth already, I'll go ahead and make it 48" x 48".

Rich

36" x 48"


48" x 48"
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