A fully probe corrected near-field far-field transformation technique employing plane-wave synthesis

摘要

The far-field behavior of an antenna under test (AUT) can be obtained byexciting the AUT with a plane wave. In a measurement, it is sufficient if theplane wave is artificially generated in the vicinity of the AUT. This can beachieved by using a virtual antenna array formed by a probe antenna which issequentially sampling the radiating near-field of the AUT at differentpositions. For this purpose, an optimal filter for the virtual antenna arrayis computed in a preprocessing step. Applying this filter to the near-fieldmeasurements, the far-field of the AUT is obtained according to thepropagation direction and polarization of the synthesized plane wave. Thismeans that the near-field far-field transformation (NFFFT) is achieved simplyby filtering the near-field measurement data. Taking the radiationcharacteristic of the probe antenna into account during the synthesisprocess, its influence on the NFFFT is compensated. The principle of theplane-wave synthesis and its application to the NFFFT is presented in detailin this paper. Furthermore, the method is verified by performingtransformations of simulated near-field measurement data and of near-fielddata measured in an anechoic chamber.