Abstract:In order to effectively reduce the size of Xband filter and passband loss,the structure of substrate integrated coaxial line (SICL) is studied.A stepped impedance resonator (SIR) type SICL bandpass filter is proposed,and a planar structure that provides excitation from the coplanar waveguide (CPW) to the SICL resonator is designed for the connection between the SICL resonator and other planar circuits,so that the filter can be measured.The simulation results show that the filter has excellent passband characteristics with center frequency of 10 GHz, bandwidth of 1.5 GHz,size of 13 mm×7 mm, and insertion loss of -0.8 dB.