Quasi-Reflectionless Signal-Interference Wide-Band Bandstop Filters

摘要

A new class of transversal signal-interference wideband bandstop filter (BSF) with quasi-reflectionless stopband is presented. Its basic BSF section is composed of two in-parallel transmission-line segments, two lossy quasi-distributed series-type resonators inserted at the inter-connection points of these lines, and input/output power-matching stages. In this manner, the RF-input-signal energy that is not transmitted throughout the stopband range is mostly dissipated by the resistors of these series resonators to attain the quasi-reflectionless property. Formulas and guidelines for the design of the proposed quasi-absorptive signal-interference BSF section are given. Also, theoretical examples of quasi-reflectionless single-section and optimization-based two-section BSF designs to realize increased stopband attenuation and bandwidth are shown. For practical-validation purposes, a 2-GHz microstrip prototype is constructed and characterized.