Compact microstrip coupled-line bandpass filter with two cross-couplings for creating multiple transmission zeros

摘要

A compact coupled-line bandpass filter with two capacitively cross-coupled paths to create multiple transmission zeros is proposed. The locations of transmission zeros can be adjusted by varying the values of cross-coupled capacitances so as to improve the filter selectivity. Specifically, a 4th-order microstrip coupled-line bandpass filter centered at 4.9 GHz with a 3-dB bandwidth of 6% and six transmission zeros is implemented and examined.