Re: NEC-LIST: Definition of Gain

Good day George,

    I have one point of view on the antenna gain issue; the definition
of antenna gain should mimic as closely as possible the definition
gain for other system elements. Interface issues, impedance match and
polarization match, should be treated separately. Including interface
issues would make the gain dependent on the system in which the
antenna is to be used, and not just a property of the antenna itself.

    Javier's polarization question does raise an important point. I
don't know the NEC definition for VP and HP gains, but I can think of
some simple tests to find out, if it's not in the manual. In any
case, my proposals for antenna gain are as follows, similar to the
usual textbook definition:

1. Gain (unqualified) = (maximum power density )x(4 pi R^2) / (Power in).

2. Gain for a specific polarization = (Maximum power density for the
polarization) x (4 pi R62)/ Pin.

The second definition means that power radiated in the other
polarization direction or component would be counted as waste, like
ohmic loss.

Doug Miron
Received on Tue Mar 07 2000 - 04:26:46 EST