Numerical model & design of wideband band reject filter with closed loop rectangular resonator

Abstract

ABSTRACT Numerical model of a wideband band reject filter using closed rectangular loop resonator is presented using transmission lines. The prototype design of wide band reject filter centred at 3 GHz with lower cut-off frequency of 2 GHz and upper cut-off frequency of 4 GHz is fabricate from the optimal values obtained from the numeric model on a substrate (FR4) with a dielectric constant of 4.3, loss tangent of 0.02–0.03 and substrate height of 1.6 mm. For bidirectional operations, the length-to-width ratio of filter is 2:1. The impedance of the transmission line which is connected between input and output ports is taken as double the feed line impedance while the impedance of the other half wavelength is considered as four times the feed line impedance. The design has obtained bandwidth of more than 60%. It is observed that the full wave electromagnetic results are in good agreement with the experimental and numerical results.