Characteristics of a CPW mushroom-like resonator and its application to wideband EBG filter

This paper proposes a novel structure called a compact coplanar waveguide (CPW) mushroom-like resonator (CCMR), which exhibits remarkable bandgap characteristics by only one single unit. The same pattern has been adopted in the compact microstrip mushroom-like resonator (CMMR) as reported previously and here is applied to CPW. When compared with CMMR, the new structure has advantages of easy fabrication and low cost due to its single-layer configuration. To investigate the CMMR deeply, the effect of structural parameters, including patch size and diameter of via, on bandgap characteristics are analyzed in detail. Also, the 1-D CCMR EBG filter is studied for various numbers of cells. Finally, the wideband CCMR EBG filter using united cells method (UCM) is designed, fabricated, and measured. The correction and validity are confirmed by the results of simulation and experiment.