Re: NEC-LIST: cosecant squared beam

"Chester Thomas Walker" <w1325700_at_qub.ac.uk> writes:
> hello
>
> i am a final yaer student in elecricak and electronics and am trying to
make
> an air survallence radar with a cosecant squared pattern from an array of
> dipole antennas by varying the phase and amplitude between elements in the
> array. i would be very garefull if any one has any ideas on this, or could
> suggest a good book or website to help with the research

You've described a fairly straightforward pattern synthesis problem. One way
to do it is to set up a model in Excel which calculates the far field
pattern by explicitly summing the contributions from each element. Then you
set up a goal function for your desired pattern, and let Excel's solver
iterate the amplitude and phase to get as close to the pattern as you need.

Another approach would be to determine the required aperture distribution by
transforming the far field pattern (using a discrete Fourier transform).

Both of these approaches would neglect the mutual interaction of the
dipoles. If you need to model this, then what you can do is set up an
appropriate NEC model of the dipoles, with parameterized excitation. Use an
external optimizer like GENOPT to iterate the parameters.

>
> cheers
>
> chester
>
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