Design of Compact Coplanar Waveguide Bandpass Filter with Composite Right/Left-handed Resonators

Design and performance of a coplanar waveguide (CPW) bandpass filter (BPF) using Composite Right/Left-handed (CRLH) Zeroth-order Resonators have been studied. The unit cell of the CRLH CPW comprises of series interdigital capacitor and shunt stub inductors embedded between two sections of CPWs. The Bloch analysis is applied based on the S parameters to derive the characteristics of the eigen-modes (Bloch modes), from which the right/left-handed frequency band and the zeroth- order resonant frequency are clearly determined. Then, the susceptance slope parameter of the resonator is extracted and the admittance (J-) inverters are introduced to synthesize a capacitively coupled CPW BPF. The measured performance agrees with the simulated one. They show that the size of the filter is greatly reduced (more than 60%) when compared to a conventional structure.