I am wondering if anyone has data for a directional gain antenna
(DGA).
Any particular GPS antenna type, maker, or model? Most manufacturers
public specifications including the gain pattern, polarization
sensitivity, and phase center location.
What I would need are the gains and the phase of the antenna as
a function of (phi,theta). I am working with a group that has such an
antenna, but I think that their work is not very good.
One of the joys of antenna modeling is to verify the model with field
tests. From experience, it's very close to impossible to produce any
of the pretty looking antenna patterns found in the literature and
produced by the various modeling programs, using a field test. There
are just too many variables involved in testing the antenna to even
come close. If you suspect that they're doing a rotten job, you might
want to analyze your test setup errors and variations. They're quite
substantial.
I am not
looking for anything fancy or even that good in terms of performance:
Chuckle. All my former employers were looking for something fancy,
patentable, with superior performance, cheap, and delivered yesterday.
I guess times have changed somewhat.
I am doing some performance analysis using beamforming algorithms for
GPS signal acquisition, and I want to incorporate DGA into my analysis
and get some basic results as to how much the DGA improves
performance. (Of course, any work I do, I would cite the use of your
data).
So, reading between the lines, you're apparently looking for data on
an existing 1.5Ghz beam forming antenna. Sorry, I haven't seen one.
All the GPS antennas I've played with have a static hemispherical
pattern (patch, panel, choke ring, quadrifilar, etc). I can see what
you're trying to do (point the GPS antenna at a specific satellite) to
improve the overall sensitivity. Good idea but potentially expensive
and complex.
You might want to clarify if you're looking for beam forming or beam
steering technology. They're quite different. Beam steering simply
points the major lobe in the desired direction and ignores what
happens to the sides. Beam forming does the same thing, but also puts
gain nulls in the direction of interference sources.
I suggest that you look into manufactories and technology used for
2.4GHz wireless beam forming and beam steering. For example, Airgo
has such a beam forming system, but it's only in one axis, and you
need two axis control. Also look into models for military phased
arrays, usually used in radar and space systems. That's fairly close
to what you're doing. I did a fast Google search for any patterns or
models, but didn't find any. If you would kindly specify the type of
antenna that you're working on, I'll see if I can find a suitable
model and program which can be used to generate the gain and phase
plots. Something like this:
<
http://802.11junk.com/jeffl/antennas/HandHeld/>
There are also a substantial number of very techy articles on the
topic under the IEEE Antennas and Propagation at:
<
http://www.ieeeaps.org>
<
http://www.comsoc.org>
<
http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=8>
<
http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7727>
However, you have to be an IEEE member to search and retreive
articles.
Note: If you want to try antenna modeling, I recommend 4NEC2:
<
http://home.ict.nl/~arivoors/>
Lots of models, but mostly wire antennas.