Optimum phase excitations and probe- feed positions inside antenna arrays for the reduction of Cross Polarization radiation in demanding phased array weather radar applications

Abstract

The x-pol antenna radiation pattern can be optimized by 180° out of phase excitation and mirroring the single fed antenna radiators inside the antenna array. In consequence the optimum phase excitation distribution for the Limited Field of View LFoV antenna arrays is investigated in this publication for maximum Cross Polarization Suppression (CPS), not only at broadside, but also for the complete angular e-scan range. Furthermore, different phase excitation distributions, for reducing the xpol radiation from microstrip patch antenna arrays, available from literature sources are reviewed and summarized. In (Vollbracht, 2014b, [2]) it is shown that the patch antenna element factor can be improved in CPS by the well-known “differential feeding technique”. This differential feeding technique will now be further analyzed in array configurations and compared to different phase excitation distributions for single fed antenna arrays. With 3D Full Wave Simulation Results from CST MICROWAVE STUDIO (CST MWS), 1×4 and 2×4 linear antenna arrays are compared and the optimum phase excitation distribution for single fed antenna arrays is identified. Finally the best phase excitation distribution for single fed antennas will be applied for a 4×8 antenna subarray and compared to a differential fed 4×8 antenna subarray. Over the e-scan azimuth range of ±60°, common phase excitation distributions for single fed antenna arrays are establishing only very poor CPS. With the new and clever phase excitation distributions discovered in this publication, the CPS of single fed antennas can be improved significantly.