A direct matrix approach to 3-D antenna radiation-pattern estimation from partially-scanned spherical near-field data

Far-field radiation-pattern estimation is explored for the case of partially-scanned spherical near-field data resulting from physical limitations of an antenna under test or associated measurement systems. A direct matrix approach, based on spherical-wave expansions, is found to be simple and effective for constructing the 3-D radiation pattern from partially-scanned near-field data. Criteria to determine the minimum near-field data for full 3-D pattern reconstruction is explained. The concept of the direct matrix approach is demonstrated for a mobile antenna and a horn antenna. An additional benefit of this approach is the reduction of the scan time for antenna measurements.