Gain and Phase Pattern for Dirctional Gain Ant Needed

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

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

Or even rec.radio.amateur.antenna ?

Reply to
Greg Neill

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

M
Reply to
junoexpress

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.

Reply to
MooseFET

You might want to look at

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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.

Reply to
jimp

You might give this a look:

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Have Fun! Rich

Reply to
Rich Grise

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

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Reply to
Eric Jacobsen

Any particular GPS antenna type, maker, or model? Most manufacturers public specifications including the gain pattern, polarization sensitivity, and phase center location.

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.

Chuckle. All my former employers were looking for something fancy, patentable, with superior performance, cheap, and delivered yesterday. I guess times have changed somewhat.

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:

There are also a substantial number of very techy articles on the topic under the IEEE Antennas and Propagation at:

However, you have to be an IEEE member to search and retreive articles.

Note: If you want to try antenna modeling, I recommend 4NEC2:

Lots of models, but mostly wire antennas.

Reply to
Jeff Liebermann

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