Mathematical modelling of the radiation fields from microwave primary-feed antennas

The paper discusses primary-feed modeling techniques as applied to microwave horns having cylindrical and rectangular geometries. With reference to the cross-polarized radiation fields predicted by the models, it is noted that for smooth-walled horns the predicted peak levels may differ from actual measurements by as much as 20 dB. It is found that the E-field model yields good accuracy in predicting the cross-polar performance of small microwave horns. It also aids in the identification of the source of cross-polarized field components and provides a means for optimizing the performance of small conical horns.