[amsat-bb] Patch antenna behavior questions (kinda long)

["Tim Zibrat" <tzibrat@xxxxxxxxxxxx>]

I have been working on a patch antenna for 2400 MHz.  I have one simulated
using Ansoft Ensemble SV and I'm pretty sure I have a winner, but I am
unsure of a few things.  I figure some of you antenna gurus can help me out.

1. To obtain circular polarization, I've been told that an Axial Ratio as
close to 1 as possible is most desirable.  My latest design achieves this.
When I plot the Near E-Field, and animate it through a phase offset of
0-360º, it sure looks like LHCP to me.  My question is, what is the desired
Near H-Field behavior?  I have also plotted this parameter and I'm not sure
what I am supposed to get.

2. I've also plotted the Current vectors through a phase offset of 0-360º
and it too looks like LHCP to me.  This sounds right to me but confirmation
from someone who knows would be appreciated.

3. The program plots what they call a Scattering Matrix.  I was told this
has to do with the S-parameters.  However, I don't see a way to separate out
S11, S12, etc.  What I get is a plot of Scattering Matrix magnitude in dB,
which shows that at the design frequency of 2.4 GHz, the plot lies
around -10.5 dB.  Is this good or bad?  I do have a choice to plot
magnitude, phase, real and imaginary parameters.  Does this correspond to
S11, S12, S21, S22?

4. There is a lot of reference to Phi and Theta.  What do these correspond
to?  I plotted the Magnitude of the Real E-Field (V) vs. Theta in polar
coordinates and it looks to me like a beamwidth plot (which is what I'm
after).  I don't think that is what it is however.

I know, so many questions....  any help would be appreciated.  Anybody know
of some good reference materials that you don't have to have a Ph.D. to
understand?

If you need to see some pictures of the plots I'm talking about, jump on
over to my website at:
http://home.adelphia.net/~tzibrat/2400mhzpatch/patch1.html

It seems to change everyday!

Thanks in advance!!!

Regards,
K3TZ

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