[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Experience with K3TZ patch -> updated webpage

Hello Mike, Achim et al

> If you look at the testing notes at the K3TZ web site, you'll notice
> that the patch is neither RHCP or LHCP, it is *linear*.

Tim's web page is a bit out of date. In my private communication with both 
Tim K3TZ and Charlie G3WDG I have learned that Tim's patch design is indeed 
circularly polarised, as designed. There was an error in Tim's testing regime 
somewhere. So a test of the K3TZ design versus the G3RUH design is still 

> That said,
> the absolute gain of the patch seems irrelevant since the overall gain
> is determined by the size of the dish and the feed's ability to
> properly illuminate the dish. Increasing the gain of the feed further
> would only serve to underilluminate the dish and reduce the capture area.

You are quite right, and I would guess that any comparative testing would say 
more about the efficiency of the different patches, depending on materials 
and construction quality.

I don't know if it is possible to change a patch feed design to exhibit 
different gains, this would allow for dishes of different f/D ratios to be 
used with them. As it stands we are limited to dishes with an f/D ratio of 
around 0.4 which is not useful for many offset fed satellite dishes. I find a 
patch to be more asthetically pleasing than a helix.

I hope the above makes sense, I have a steaming headache !

> 73 Mike W4LNA

Jonathan  HB9DRD/G4KLX

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org