Antenna analysis by near-field measurements

Typical planar near-field antenna pattern testing employs a probe transport mechanism which scans a probe in a plane very close to the test antenna. A theoretical error analysis is developed and used to generate tolerance requirements in near-zone measurement of airborne antennas. The major error sources discussed include limited size scan plane, probe position errors, inaccuracies of test instrumentation, and multiple reflections on the measurement plane. Simple expressions based on measured near-field data are presented for predicting worst-case errors in computing the far-fields properties of these antennas.