Full-wave analysis of a compact bandpass meandering resonator filter using method of lines

Abstract

Full-wave analysis based on the method of lines and the generalized transmission line equations is applied for the design of a small-size wide stopband bandpass filter. The analytical calculation in the direction of propagation and using nonequidistant discretization enables the analysis of the method of lines to be efficient for structures that can be divided into cascaded subsections along the propagation direction of the wave. The proposed filter consists of a pair of meandering uniform impedance resonators and feeding lines. Wide stopband and high selectivity as well as compact size of the filter are achieved due to the effect of multipath between the feeding points and the resonators that leads to suppression of the first and second harmonic of the filter. The modes distribution and the scattering parameters of the designed filter are computed and studied, leading to an achievement of a passband return loss greater than 18 dB and insertion loss about 1.7 dB. The designed filter is fabricated and tested, where good agreement is found between the numerical and experimental results.