A class of high-selectivity microstrip transversal bandpass filter using non-resonating nodes

A new type of high-selectivity microwave planar bandpass filter is reported. It exploits the use of non-resonating nodes to generate the maximum number of inter-resonator electromagnetic (EM) couplings in a transversal configuration. Furthermore, it is exclusively shaped by parallel-coupled transmission-line segments, thus leading to a compact and simple circuit. The operating principle of the proposed bandpass filter topology is described. Also, its experimental usefulness is confirmed with the development and testing of a microstrip filter prototype at 1.4 GHz that implements a quadruplet with cross couplings.