Simulation of Interference Visibility on Near Field Phaseless Measurement Reconstructed by Computer Hologram

摘要

The interference visibility qualifies the contrast of the interference in any wave-like system. In the holographic system, the magnitude of the interference is recorded to reconstruct the object wave. Near Field Computer Reconstructed Hologram was first presented to measure antenna's pattern at 2012 AMTA. This new technique does not require the phase information of the scanning data, in which the measurement just is implemented on one surface only. Where a reference antenna has been upgraded into Near Field Scanning System, the interference amplitude is measured by the scanning probe. Furthermore, Computer Reconstructed Hologram Algorithm is applied to the interference amplitude to retrieve the complex field of Antenna under Test. The new term called Interference Visibility needs to be considered for evaluating this novel measurement facility. Because the complex information of AUT is recorded in the interference, it has to be maintained the maximum degree of interference to retrieval the information. Here the unbalance from the power divider is considered as interference visibility to estimate the method. Simulated results show that Back-Projected Imaging Filtering Method is better than Angular Spectrum Filtering Method, and the acceptable accuracy can be obtained for unbalance level larger than -40dB.