Miniaturized Bandstop Filter Using Meander Spurline and Capacitively Loaded Stubs

Abstract

A miniaturized bandstop filter (BSF) is introduced in this paper. The filter consists of one meander spurline and a pair of capacitively loaded stubs. The meander spurline with low resonant frequency and improved slow-wave factor exhibits excellent resonant bandgap characteristics which can be modeled by a longitudinally coupled resonator. The design of the proposed microstrip BSF is presented, and its performance is measured. Measurements show that there is a stopband from 2.3 to 5.6 GHz with S21 less than –20 dB. The total length of this BSF equals 23 mm.