Re: [amsat-bb] BBQ Dish and G3RUH Patch Focal Point Help

[Anthony Monteiro <aa2tx@xxxxxxxxxxx>]

Hi Bruce,

This combination isn't going to work very well since
the BBQ dish needs a feed beamwidth of around
60-75 degrees, depending on which model you have,
but a patch has a beamwidth around 120 degrees.
The patch will tremendously over-illuminate
the dish which is why you can't find the focus.

To use this dish with a circular feed, you would need
to build a helix. But before you do that, did your dish
come with a dipole feed?

Consider that a helix feed with this dish would give you
around +18 dBi (circular) gain but a proper dipole feed
should get you more like +23dBi (linear) so even after
losing the 3 dB for the polarization mismatch, the dipole is
better by at least a few dB.

73,

Tony AA2TX

---

At 08:20 PM 10/19/2003 +0000, Bruce wrote:


>   I have a 2' x 3' screened BBQ dish and a G3RUH Patch Feed.
>
>   I can't seem to find the correct focal point for this
>combination.
>
>   I have tried 12 13 and 14 inches and there does not seem to be
>much differance in the recieved sig.

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