DESIGN OF MICROSTRIP CROSS SHAPED BANDPASS FILTERS WITH RECONFIGURABLE BANDWIDTH AND NOTCH FOR WIDEBAND AND ULTRA-WIDEBAND APPLICATIONS by TENG CHENG Thesis Supervisor: Prof. Kam-Weng Tam Electrical and Computer Engineering In this thesis, the reconfigurable microwave bandpass filters (BPFs) is studied with focus on the bandwidth and notch tuning. To this end, a simple multi-mode resonator (MMR) called cross shaped resonator (CSR) is analyzed in chapter 2; and some wideband and ultra-wideband (UWB) BPF designs using this CSR are introduced in chapters 2, 3 and 4. Following this basic study in chapter 2, a wideband BPF with reconfigurable bandwidth is designed based on a CSR with open stubs and parallel coupled microstrip line (PCML), the CSR can exhibit 3 poles and 2 zeros, while the PCML are simultaneously placed at the input/output of the CSR to enhance the frequencydispersive coupling degree. The bandwidth can be reconfigured by varying the characteristic impedance of the open stubs, the prototype reports reconfigurable fractional bandwidth (FBW) tuning range is from 20% to 38% when the center frequency is located at 6 GHz. Besides, a wideband BPF intergrading reconfigurable bandwidth and notch is presented based on a cascaded CSR with 4 poles and 3 zeros, in order to realize a wide passband even within UWB range, the parallel coupled three-lines (PCTL) are added at the input/output, the simulation results show 82% to 115% FBW tuning range when center frequency is fixed at 6.2 GHz, and the notch is tuned from 3.8 to 5.1 GHz. The bandwidth and notch can be tuned independently