Re: How does this POTY antenna work??

Paul Randall G3NJV

Beautifully engineered indeed. However that coaxial link from the waveguide to the Kuhne box will introduce loss and thus degrade the rx noise figure compared to what you might get with the more direct connection found inside a typical LNB.

Perhaps someone has done comparative measurements on these two approaches?

Sent from my Galaxy

-------- Original message --------
From: Colin G4EML <colin@...>
Date: 19/05/2021 10:48 (GMT+00:00)
Subject: Re: [UKMicrowaves] How does this POTY antenna work??

The Kuhne down converter does exactly the same job as a regular LNB. It just has a coax input instead of having an integral antenna. That arrangement simply connects an external antenna to it.

It is not really correct to call that a POTY antenna. The POTY is the name of a specific design, not a generic term.

Colin G4EML

On 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  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:

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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