A novel compact configuration for dual-mode microstrip resonators and dual-band bandpass filter applications

Abstract

In this article, a novel compact dual-mode resonator formed by a square loop having folded arms and mitered bends is proposed.Degenerate modes can be excited by shifting the gaps between the folds. Thus, the center frequency can be arranged at a fixed value because the total electrical length of the proposed configuration is not changed. A novel compact dual-mode dual-band bandpass filter is also designed by locating the one resonator within the other. Additionally, to suppress the harmonic of the first passband, open-circuited stubs are connected to the end of the feedlines. Two dual-mode dual-band bandpass filters with the elliptical and linear phase filtering characteristics for both passbands have been designed, fabricated, and tested. Calculated, simulated, and measured results are in a good agreement. © 2012 Wiley Periodicals, Inc.