[amsat-bb] Re: Arecibo and circular polarization using cheap yagis
domenico.i8cvs at tin.it
Fri Apr 16 09:04:07 PDT 2010
----- Original Message -----
From: "Edward Cole" <kl7uw at acsalaska.net>
To: "Douglas Quagliana" <dquagliana at aol.com>; "amsat" <amsat-bb at amsat.org>
Sent: Thursday, April 15, 2010 11:49 PM
Subject: [amsat-bb] Re: Arecibo and circular polarization using cheap yagis
> Or you can split the feedline equally if one
> antenna is spaced 1/4 wavelength ahead of the other. The relation of
> the fed elements determine whether you get RH or LH CP. The center
> conductor is connected to one side of the fed element (this is called
> the + side). If the antenna to the rear (or not with extra feedline)
> is vertical with "+" straight up and the other antenna has its "+"
> element pointing to the right, you get RHCP. Reverse it and you get
> 73, Ed - KL7UW, WD2XSH/45
Hi Ed, KL7UW
Please find here a necessary amendment to your statement:
We assume that you are looking from the rear of the antenna in direction
of propagation and one antenna is spaced 1/4 wavelenght ahead of the other.
If the dipole of the rear antenna is vertical with "+" straight up and if
the dipole of the front antenna is horizontal and has its "+" element
pointing to the left then you get RHCP. Reverse it and you get LHCP
In a separate email I have sent to you a drawing showing how two linearly
polarized components shifted 90° one to the other adds togheter to generate
a circularly polarized wave but I can send the same drawing to everybody
> For antennas in the "X" configuration (back antenna "+" up and
> to the left, front antenna "=" up and to the right for RHCP.
If the signe "=" is a typing mistake and you means " - " (minus)
then your statement is correct.
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