Ultra-wideband planar bandpass filters with improved stopband performances

Abstract

The objective of this PhD thesis is to propose various structures of multi-mode resonator (MMR) for innovative exploration of ultra-wideband (UWB) bandpass filters with improved upper-stopband performances. All the UWB filters developed in this thesis can be primarily divided into the four categories: lowpass embedded UWB bandpass filter, electromagnetic bandgap (EBG) embedded MMR bandpass filter, shunt short-circuit loaded UWB bandpass filter and notch-band UWB bandpass filter. These UWB bandpass filters had been designed towards achieving the FCC-regulated UWB frequency spectrum which required good performance in the UWB passband and high/deep rejection in the out-ofband. In addition to the filter performance, size miniaturization is also the major goal of my research work. To evidently prove the theoretical results of those proposed UWB filters, all of those filters were designed and fabricated on the dielectric substrate, namely, RT/Duroid 6010 with substrate thickness 0.635 mm and loss tangent 0.0023. The measured results were all matched with the simulated results over a wide frequency range.