FPGA Central

Hi,

I am wondering if anyone has data for a directional gain antenna
(DGA). 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. I am not
looking for anything fancy or even that good in terms of performance:
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).

You can reply either on the ng or to my e-mail address.


Thank you very much,

Matt Brenneman

"junoexpress" <[email protected]> wrote in message
news:[email protected] ups.com...
> Hi,
>
> I am wondering if anyone has data for a directional gain antenna
> (DGA). 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. I am not
> looking for anything fancy or even that good in terms of performance:
> 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).
>
> You can reply either on the ng or to my e-mail address.

Why not try over in one of the Ham radio groups?

Or even rec.radio.amateur.antenna ?

On Apr 3, 9:17 am, "Greg Neill" <gneill...@VEsympatico.ca> wrote:
> "junoexpress" <MTBrenne...@gmail.com> wrote in message
>
> news:[email protected] ups.com...
>
> > Hi,
>
> > I am wondering if anyone has data for a directional gain antenna
> > (DGA). 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. I am not
> > looking for anything fancy or even that good in terms of performance:
> > 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).
>
> > You can reply either on the ng or to my e-mail address.
>
> Why not try over in one of the Ham radio groups?
>
> Or even rec.radio.amateur.antenna ?

Excellent idea: thank-you very much for the suggestion.

M

On Apr 3, 6:09 am, "junoexpress" <MTBrenne...@gmail.com> wrote:
> Hi,
>
> I am wondering if anyone has data for a directional gain antenna
> (DGA). 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. I am not
> looking for anything fancy or even that good in terms of performance:
> 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).
>
> You can reply either on the ng or to my e-mail address.

Beware of where the center of rotation is. For a simple structure
picking the right point is easy. For complex designs, it will be a
bigger problem. Perhaps the best way to go would be to take an easy
to measure point as the basis during the measurements and then to
shift the point in the calculations to make the expression the
simplest.

In sci.physics junoexpress <[email protected]> wrote:
> Hi,

> I am wondering if anyone has data for a directional gain antenna
> (DGA). 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. I am not
> looking for anything fancy or even that good in terms of performance:
> 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).

> You can reply either on the ng or to my e-mail address.


You might want to look at www.eznec.com

He has a NEC based product that has a free demo version, a modestly
priced version, and a professional version.

Basically, the demo version has limitations on the number of elements,
the modest version a much higher limit on the number of elements and
won't do some obscure stuff like model buried antennas, while the pro
version will.

There are others.


--
Jim Pennino

Remove .spam.sux to reply.

On Tue, 03 Apr 2007 06:09:06 -0700, junoexpress wrote:
>
> I am wondering if anyone has data for a directional gain antenna
> (DGA). 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. I am not
> looking for anything fancy or even that good in terms of performance:
> 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).

You might give this a look:

http://www.arrl.org/catalog/8047/

Have Fun!
Rich

On 3 Apr 2007 06:09:06 -0700, "junoexpress" <[email protected]>
wrote:

>Hi,
>
>I am wondering if anyone has data for a directional gain antenna
>(DGA). 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. I am not
>looking for anything fancy or even that good in terms of performance:
>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).
>
>You can reply either on the ng or to my e-mail address.
>
>
>Thank you very much,
>
>Matt Brenneman

I'm not sure what you're asking so I'll see whether you can clarify it
a little.

Are you saying that you are working with a particular directive
antenna and you'd like to know the radiation gain pattern?

Or are you saying that you'd like to know how to measure the pattern
of a particular antenna?

If you have an antenna that you're working with, the best thing to do
would be to see whether the manufacturer of the antenna publishes a
data sheet for that antenna that includes the gain pattern (it's
common for them to do that).

If you want to measure it yourself, that's a big task and must be
undertaken very carefully in order to get usable results. Usually
one needs an anechoic chamber to do this, and that alone is difficult
to achieve.

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

On 3 Apr 2007 06:09:06 -0700, "junoexpress" <[email protected]>
wrote:

>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.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 [email protected]
# http://802.11junk.com [email protected]
# http://www.LearnByDestroying.com AE6KS