RF and mm wave filterssuffers from a common problem of asymmetries in filters transmission response caused by unwanted field couplings between individual resonators. In this paper, unwanted or spurious couplings between non-adjacent resonators are identified in the filter network from the simulation stage and mitigated to the extent possible. A 4-pole Quasi Elliptic Planar Band Pass Filter is fabricated at 48.5 GHz on a Liquid Crystal Polymer (LCP) substrate. An improvement of 6 dB in side lobe imbalance in filter transmission response is obtained. Effect of spurious coupling on band pass filters transmission response is demonstrated through EM simulation. Commensurate measurement results are presented.
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