Design and realization of complementary couplings filter based on electromagnetic field distributions

This paper presents the complementary couplings filter concept and its microwave wideband filter realization. Three dimensional full-wave electromagnetic modeling is used to analyze field distributions around resonators and coupling mechanism. This allows for an accurate design of complementary couplings filter. New type of wideband quasi-lumped microstrip filter is presented. The exemplary filter has 500 MHz bandwith with center frequency 1.5 GHz and wide stopband up to 6 times fundamental frequency.