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Gain and Phase Pattern for Dirctional Gain Ant Needed

Discussion in 'Electronic Design' started by junoexpress, Apr 3, 2007.

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  1. junoexpress

    junoexpress Guest

    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
     
  2. Greg Neill

    Greg Neill Guest

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

    Or even rec.radio.amateur.antenna ?
     
  3. junoexpress

    junoexpress Guest

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

    M
     
  4. MooseFET

    MooseFET Guest

    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.
     
  5. Guest


    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.
     
  6. Rich Grise

    Rich Grise Guest

    You might give this a look:

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

    Have Fun!
    Rich
     
  7. 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
     
  8. 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:
    <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.
     
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