A NEW COMPACT QUAD-BAND BANDPASS FILTER USING QUAD-MODE STUB LOADED RESONATOR

摘要

A new compact quad-band microstrip bandpass filter designed using a quad-mode stub-loaded resonator (SLR) is proposed. The equivalent circuit of the SLR consists of one even mode and two odd resonant modes, used to create passbands operated at 1.8, 2.4, 3.5, and 5.2 GHz, corresponding to global system for mobile communications, wireless local area networks, and worldwide interoperability for microwave access applications. The filter is compact in size because only two sets of resonator are used by means of the quad-mode behaviors. Furthermore, 0° feed structures is used to set at least one transmission zero on each side of each passband, resulting in high skirt selectivity. Experimental results show good agreement with the simulated results.