Experimental determination of the electromagnetic field in the near-zone of a high power UHF pyramidal horn antenna

The far-zone characteristics (directive gain, main-lobe beamwidth, side-lobe structure) of pyramidal horn antennas are fairly well known and, for the most part, easily predictable. However, as the observation point moves within the far-zone boundary, predicting the radiated field characteristics becomes much more difficult. Preliminary results of an intensive effort utilizing electrically small electric (dipoles) and magnetic (loops) probes to map the field in the region immediately in front of a high power UHF pyramidal horn antenna are presented. The measured values are compared with values obtained from a theoretical model. The application of these data to electromagnetic hazard considerations is discussed.