Compact Ultra-wideband (UWB) bandpass filter with wideband harmonic suppression

Abstract

A compact microstrip bandpass filter with Ultra-wideband passband is presented in this paper. The filter is designed based on a transmission line bandpass filter with three short-circuited stubs separated by two non-redundant unit elements. Each of the uniform non-redundant unit elements is replaced by a lowpass filter to shrink the physical size of the filter and to reject the second unwanted spurious harmonic of the passband. The filter is successfully designed and the design is verified by full-wave EM-simulation and the experiment. Excellent agreement between theoretical, EM-simulated, and measured results is attained. The filter exhibits a good performance with very low insertion loss of less than 0.6 dB at the mid-band frequency.