Re: How does this POTY antenna work??


John Fell
 

Chris,
The pic shows a circular patch feed for 2.4GHz , similar to the POTY type .The N elbow feeds 2.4GHz RF to the patch element .
His site says he uses a 20W PA , so depending on the attenuation along the TX cable , he should put in a reasonable signal .

My system outputs 1.5W via a 5m run of LDF450 Heliax via an 80cm offset - that puts my signal at -5dB relative to the Beacons on QO100.

The SMA lead will connect a probe inside the round waveguide to the downconverter behind the assembly. An LNB is a downconverter , in this case a block + antenna .The N elbow plug will carry downconverted RF and DC to the shack end unit that will supply the required output RF for the radio in use.

What is interesting to see is the conical horn and rear choke flange (?) . I would be interested to know what interactions /pattern distortion occur on 2.4GHz .
Certainly the feed will be more efficient than open ended waveguide at 10GHz .

73
John
G0API

On Wed, 19 May 2021 at 10:32, Chris Wilson <chris@...> wrote:


  19/05/2021 10:19

I am slowly getting into amateur satellite work and runa 1.8 meter prime focus dish with a POTY antenna for 2.4GHz TX and a coaxial LNB for circa 10.5GHz reception. I know the LNB down converts to around 940 MHz using an intermediate frequency.

I heard a very nice signal from a chap who appeared to know a lot about the hardware used, so looked him up on qrz.com  He was using a POTY antenna the like of which I have not seen before. It has a feed horn and appears to feed the RX side without an LNB directly to a Kuhne down converter. How might that work, I thought down converters expected a lot of gain from the LNB and an already down converted signal, to some extent, done within the LNB?


I placed a photo of this nicely looking engineered device here:

http://www.chriswilson.tv/DJ8EI.JPG

It appears there's no LNB but the RX antenna is inside the POTY tube itself.


Thanks for any insight to this newbie!

--
       Best Regards,
                   Chris Wilson.
mailto: chris@...






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