Improving the directivity accuracy due to the spillover effect in the planar near-field measurement systems

This paper describes a systematic approach to alleviate this problem for reflector antennas where a detailed simulated or measured feed pattern is usually available. The simulated or the measured pattern of the feed is used to calculate that portion of the spillover power which is not captured in the near-field measurements. Using this calculated power a simple correction can be implemented to the directivity and therefore the overall directivity accuracy will be improved. The discussed method is successfully applied for an offset reflector antenna measured in the UCLA bi-polar planar near-field facility.