[amsat-bb] Re: 70cm Yagi and AO-51

kc6uqh kc6uqh at cox.net
Tue Jan 1 12:22:10 PST 2008

Theoretical circular  to linear loss is 3dB either LH or RH vs any angle of 
linear polarization. A linear polarized antenna rotated in the field of a 
circular polarized wave will show no change with rotation.
The amount of variance that is measured on circular antennas comes from the 
pattern of the circular antenna being elliptical and not circular. This is 
refered to as the axial ratio and in practice anything less than a 3 dB 
varance is considered good. A standard helix antenna is typically 4-5 dB. 
This is a +/- value in addition to the 3 dB loss for cir to lin conversion.

----- Original Message ----- 
From: "Andrew Rich" <vk4tec at people.net.au>
To: "OZ1MY" <oz1my at privat.dk>; "Amsat-Bb at Amsat. Org" <amsat-bb at amsat.org>
Sent: Tuesday, January 01, 2008 7:54 AM
Subject: [amsat-bb] Re: 70cm Yagi and AO-51

> If I have this correct.
> 1. LHCP recieved on a RHCP can knock your signal down by some 20dB
> 2. LHCP matched with LHCP will result in a good signal.
> So how does a linear antenna equate when receiving a circular signal ?
> And the other way around, a circular receiving a linear signal ?
> ----------------------------------------------------------------------------
> Andrew Rich VK4TEC
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list