[amsat-bb] Re: Crossbooms ... my questions
howard at howardlong.com
Wed Jan 10 18:10:41 PST 2007
> As a reasonably long time licensed ham (40 years), but
> very new to satellites, I would like to ask the brain trust
> whether CP antennas are really needed. I am ready to buy a
> set, but in poking around the net, I found this exchange by
> Mike , K6MYC, about not using CP antennas:
> Look at http://www.qth.com/ka9fox/ant-nest.txt
> Look towards the bottom, and Mike's replies are in caps.
> I do not have the real estate for separate 144/432 antennas
> for terrestrial and sat. I have the az/el rotors.
> So whats the thought on this? Should I just go with a pair
> of H-pol beams and leave well enough alone, or should I go
> with the CP antennas?
I may have misubderstood, but it looks like Mike is saying use two stacked
yagis in the same linear polarisation instead of one CP antenna.
My practical experiences don't agree with Mike's.
Having polarisation switching on LEOs in my opinion is worth several dB more
than doubling your boom length or stacking.
If I had a pair of linear yagis and did not want to go CP, I would mount
them orthogonally and switch between them during the pass to avoid nulls.
73, Howard G6LVB
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