Tunable electromagnetic band gap-embedded multimode resonators for ultra-wideband dual band, lower-ultra-wideband and upper-ultra-wideband applications

Three ultra-wideband (UWB) microstrip band-pass filters (BPFs) are proposed using tunable electromagnetic band gap (EBG)-embedded multiple-mode resonator (MMR) and fork resonator. In the first case, a compact dual-band BPF is implemented using a cascade of a multimodal fork resonator with tunable EBG. The fork resonator forms the basic structure yielding multiple band-pass realisations and the EBG selects the desired bands. This yields a compact dual-band BPF with sharp cut-off characteristics, wide bandwidth and low insertion loss. In the second case, a lower UWB filter is proposed by tuning an EBG-embedded MMR with parallel coupled microstrip line. Open circuited coupling stubs are introduced within the EBG structure to suppress higher order pass bands. In the third case, an upper UWB BPF is proposed in a similar manner as the lower UWB filter. However, the EBG-embedded MMR structure and the coupling technique are different. It is shown that the measured results are well matched to the predicted ones in terms of insertion/return losses over the plotted frequency range of 0.1-20.0-GHz. All simulations were performed with advanced design system (ADS) momentum (2.5D method of moments).