A Compact Coplanar Waveguide (CPW)-Fed Zeroth-Order Resonant Filter for Bandpass Applications

A new CPW-fed bandpass filter based on zeroth order resonant (ZOR) technique is presented in this paper. Proposed filter structure is designed on a CPW single layer where via is not required, hence reduces fabrication complexity. The property of metamaterial of ZOR has been utilized to reduce the filter size. The proposed structure is symmetrically CPW-fed and contains tuning-fork stub, which connects patch to CPW ground plane. The metamaterial properties are characterized by plotting dispersion diagram of proposed structure. The experimental result of proposed filter design shows an insertion loss of 0.51dB, return loss of 22.5 dB with fractional bandwidth 61.5% at centre frequency 2.60GHz. The size of the filter is 0.45 lambda g x 0.36 lambda g (lambda g is the guided wavelength at centre frequency).