Horn antenna analysis as applied to the evaluation of the gain-transfer method

An important condition that has to be satisfied when implementing the gain-transfer method is that the fields in the test zone of the measurement facility should be as close to the plane wave as possible. In this paper, the effect of amplitude and phase deviation from a perfect plane wave, on gain measurements for microwave aperture antennas, conducted via the gain-transfer method, is determined and quantified. The pyramidal horn antenna is used as a basis for all calculations as it is the universal standard for microwave antenna gain measurements. Coupling, between the antenna being illuminated and the test zone fields, is evaluated by means of the reciprocity theorem. Test zone field variations are simulated and the effect thereof, on the predicted measured gain, is illustrated.