Compact Ultra-Wideband Bandpass Filter With EBG Structure

Two bandpass filters (BPFs) for ultra-wideband (UWB) applications are proposed using the uniplanar compact- electromagnetic bandgap (UC-EBG) and the foliated UC-EBG (FUC-EBG) structures for size reduction. The sizes of the proposed UWB BPFs are reduced by 20 ~ 22% compared to the conventional one with the microstrip multiple-mode resonator (MMR). Both EBG structures are shown to cause a slow-wave effect, which is required for compactness and the characteristic impedance Z
c
close to 50 Omega, which is needed for wideband match.