[amsat-bb] Re: Making a Circular Polarized antenna
ko6th_greg at hotmail.com
Sun Oct 25 12:45:53 PDT 2009
Interesting visual program! But, I don't see a way to offset the two antennas in space, only in phase. I agree that if you put two antennas in the same plane and 180 degrees out of phase, they will nicely cancel each other out. But if they are offset, then the linear signals will cancel, while a CP signal will have rotated 180 degrees in passing through that offset, and will be in-phase at the second antenna. No?
> From: ve4yz at mts.net
> To: ko6th_greg at hotmail.com; amsat-bb at amsat.org
> Subject: RE: [amsat-bb] Making a Circular Polarized antenna
> Date: Sat, 24 Oct 2009 20:08:49 -0500
> Above link has a wonderful 3D graphic display of waves. Give it a try.
> You can adjust V, H, phase, and then display sum of the 2 waves.
> I use it mainly to show how circular polarization comes about.
> The sum of 2 waves in the same plane ( 180 degrees rotated ), 180 degrees
> out of phase ( 1/2 wavelength ) is a nul which probably would be out
> performed by a rubber ducky.
> > -----Original Message-----
> > From: amsat-bb-bounces at amsat.org
> > [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Greg D.
> > Sent: October 24, 2009 7:34 PM
> > To: amsat-bb at amsat.org
> > Subject: [amsat-bb] Making a Circular Polarized antenna
> > Hi folks,
> > Just curious...
> > One of the ways to make a circularly polarized antenna is to
> > feed two linearly polarized antennas in-phase, but mount one
> > them 90 degrees rotated from the other, and 1/4 wavelength
> > ahead of it.
> > Couldn't one also mount the two antennas 180 degrees rotated
> > and 1/2 wavelength ahead?
> > The reason I ask is that I have some flat panel 2.4 ghz
> > "Wi-Fi" antennas, and the mounting holes work out best that way.
> > The only effect I can think of is that the array will
> > probably pick up signals from both left and right
> > polarizations, which could actually be handy.
> > Greg KO6TH
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