[amsat-bb] Re: Polarity questions

Clint Bradford clintbrad4d at earthlink.net
Fri Sep 19 12:18:56 PDT 2008


 >>...20-dB, assuming the signal is pure circular  
polarization...linear, then -3 dB...difference between RHCP and LHCP  
is 20 dB...difference between Horizontal and Vertical Linear is 20  
dB...difference between (RHCP or LHCP) and (Horizontal or Vertical) is  
3 dB...the VHF/UHF Manual handbook says 20 -30dB...in the real world,  
expect around 20~25dB loss from being completely cross- 
polarized...Between linear and circular, expect about 3dB loss...

Ahh, thank goodness for the engineers...

Just know that to get started working the FM satellites, you do not  
need to spend much to make successful contacts...Working AO-51 from  
Southern California (which some claim is not a "real world") at a Watt  
or so with an HT and Arrow Antenna is a breeze, and the polarization  
of the Yagi makes no difference in quality of TX/RX signal.

And as you refine your satellite comms requirements, you can spend  
more money!

Clint Bradford, K6LCS
909-241-7666


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