Hi All
I have just finished my patch feed and mounted it on a 60 cm dish.
The patch gain is suposed to be 8.5dbic.
The dish I am using has an f/d ratio of 0.35 which has a gain of 21 dbic.
Am I right in saying that the whole gain with patch is then 29.5 dbic?
If so I think this equates to 26.5 dbi
Is my ERP then nearly 60W assuming no losses?
Thanks and 73
Nick
G1BVI
dbic gain of a Patch feed
Re: dbic gain of a Patch feed
No you are not correct. Only the dish gain counts and that depends on how well it is illuminated. Your patch will have a beamwidth of about 85 degrees. That seems quite narrow for a 0.35 f/D. It would be good for low noise but I assume this is for the uplink where gain is what matters. You are illuminating less of dish area so an efficiency of 50% seems likely. However, I suspect that is already in the calculation as a perfect 60cm dish on 2.45 GHz would have over 23dB gain, so 21dB seems reasonable, perhaps a little high. Most definitely not 26.5dBi
How much less requires some maths. See http://www.qsl.net/n1bwt/chap6-0.pdf for the theory.
It would appear perhaps you have Jim Millers' AMSAT feed? http://www.jrmiller.demon.co.uk/products/patch.html ?
Mike
How much less requires some maths. See http://www.qsl.net/n1bwt/chap6-0.pdf for the theory.
It would appear perhaps you have Jim Millers' AMSAT feed? http://www.jrmiller.demon.co.uk/products/patch.html ?
Mike
Re: dbic gain of a Patch feed
Hi Mike
Thanks for that .
I have the RUH dish, I have had it sitting in the original box since AO40.
The patch I fabricated myself some years back and recently checked it on a network analyser.
After all this time of sufffering house moves and being thrown about in boxes it has survived Hi hi,
Looking at the maths now.........
73
Nick
Thanks for that .
I have the RUH dish, I have had it sitting in the original box since AO40.
The patch I fabricated myself some years back and recently checked it on a network analyser.
After all this time of sufffering house moves and being thrown about in boxes it has survived Hi hi,
Looking at the maths now.........
73
Nick