Design of wide-band band-pass filter using MEMS microshield line

This design is presented for the topology of a new planar transmission line and high performance wideband band-pass filter using the planar transmission line. The characteristic impedance of the microshield line is calculated by a conformal mapping method. The novel transmission line is supported by a thin dielectric membrane on a wafer with a cavity so that this transmission line posses low degree of dielectric loss and almost does not suffer from the parasitic influence of radiation and dispersion. Based on the investigation of series stubs and coupling lines of the microshield line, the wideband band-pass filter could be obtained easily by cascaded the stubs or the coupling lines. In this paper, two four-section, planar band-pass filters have been designed based on the microshield line. The insertion loss of both filters are less than 1dB in pass-band with almost 50% relative bandwidth at 45GHz.