----- Original Message ----- From: "Edward Cole" kl7uw@acsalaska.net To: "Douglas Quagliana" dquagliana@aol.com; "amsat" amsat-bb@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 LHCP.
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 need it.
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.
73" de
i8CVS Domenico