NEC-LIST:Gain for helical antennas

Dear friends,

I'm an italian student of electronic engineering an I doing a dissertation for
Antennas examination at the Politecnico di Torino.

The argument is helical antennas used at beam mode and normal mode.

I yields simulations with NEC-2, The antennas are over a perfect ground plane.
>From results there's a thing that make me wonder: the gain function sweep
theta angle (for the cases azimuth 0 and 90 degrees) of every antennas has
double angles that I'm waited..

So mean that the HPBW (half power beam width) is double respect those defined
by the Kraus's theory in your book "Antennas"; converseley the maximum gain it
ok (I hope it!).

A gain function as this hasn't integral sweep theta equal to 4*pi srad but
higher thant this.

I've thinked that is an effect of the infite and perfect conductor ground
plane that I used in the model of every antennas, that it changes the current
distribution at the interface.

How I shall to interpret these result? What is the cause? How I can to obtain
the real gain function? Is there any mistake of evaluation that I'm doing?

If anyone can answer me, I will thank so much!

Bye, Claudio Siviero.

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