A Compact filter based on Substrate Integrated Coaxial Line Technology

A compact filter based on substrate integrated coaxial line technology(SICL) and implemented with spur stepped impedance resonator(SSIR) is proposed. Unlike previous filter structure.the resonant unit of this filter is introduced by electromagnetic coupling, which generates two transmission zeros outside the band, improving the out-of-band rejection ratio of the filter. The filter is designed at the center frequency of 9GHz with the bandwidth Of 1.5 GHz, which can be used for the resonant unit of a millimeter-wave radar oscillator.