High Performance Microwave Filter Design And Realization Based On Planar-And Dual-Layer-Coupled Scheme

In this dissertation, various filters design with high performance and compact size to meet different pratical application limits is proposed, based on the planar- and dual-layer- coupled schemes. These research results with high application merits are attractive for the practical filter design in the modern wireless communication systems.In Chapter I, various methods and structures for the filter design is introduced. At present, the multi-layer-coupled schemes with the merits of high coupling effect, compact size, and various architectures are highly developed in the field of filter design. However, the filter using the multi-layer-coupled scheme remains a great challenge.In Chapter II, the characteristics and equivalent topology network models of the various symmetric- and asymmetric-coupled transmission lines are introduced and investigated. Meanwhile, some sub-structures with equivalent circuit models in the multi-layer-coupled scheme are concluded and introduced. Finally, an example with important guiding significance of the filter design is employed, using the coupled transmission lines theory and hybrid microstrip/CPW structure.In Chaper III, the coplanar waveguide detached-mode resonator (CPW DMR) with multiple resonances and controlled stopband bandwidth and hybrid microstrip/CPW structure are employed to propose the ultra-wideband (UWB) bandpass filter. Besides, based on the quarter wavelength (λ/4) meander slot-line,λ/4 embedded CPW resonator, andλ/4 meander defected microstrip structure (MDMS) with the narrow stopband characteristics, the UWB bandpass filter with ultra narrow dual- and quad-notches can be employed.In Chapter IV, the methods of the novel dual-band bandpass filter are investigated. First, the stepped-impedance resonator (SIR) with the loaded stepped- impedance stub (SIS) is introduced. These resonators have the merits of independent adjusted dual- resonances and various coupled scheme, comparing to the conventional SIR. Based on this SIR with SIS, two dual-band bandpass filters with the narrow bandwidth responses and wide bandwidth responses are employed, respectively. Then, the microstrip embedded spiral-resonator (ESR) with multi-resonances is introduced. Based on the nove resonator, dual-band bandpass filters with low insertion loss, compact sizes are implemented to meet the wireless local area networks (WLAN) dual-band applicantion. Finally, based on the power transmission characteristics of the dual-layer-coupled microstrip/slot scheme, the multiple transmission zeros mechanism of the structure is investigated. And then, a dual-band bandpass filter with seven transmission zeros, high passband selectivity, and high stopband rejection level is employed.In Chapter V, the operated characteristics of the symmetric- and asymmetric- coupled structure are investigated, and a bandpass filter with a wide stopband is employed based on the symmetric- and asymmetric-coupledλ/4 shorted resonators. Besides, the characteristic of the hybrid microstrip/DGS/CPW structure is investigated. Based on this novel scheme, the narrowband bandpass filter with compact size, high selectivity, and wide stopband is proposed to meet the bluetooth system limits. Then, a novel hybrid microstrip T-stub/DGS cell is employed. Based on the novel cells and various interdigital-coupled scheme, the second- and fourth-order filters have the merits of very wide stopband more than 12f0 with a strong rejection greater than 30 dB and relatively compact sizes. In addition, a hybrid microstrip/interdigital DGS cells with adjusted resonance and dual-transmission zeros is employed. Based on the novel cells, the narrowband coupled effect of the interdigital coupled scheme with short-stubs and the defected microstrip structre (DMS) with low radiation and high capacitance- coupling, a filter has the merits of an excellent passband selectivity more than 420 dB/GHz and the wide stopband up to 3.75 times of the operated center freuquecy is proposed. Finally, the hybrid microstrip/complementary split ring resonator (CSRR) based resonator is employed to design the wideband bandpass filter with high selectivity and relatively wide stopband.In Chapter VI, the research on the filter design of this dissertation is concluded. Besides, the potential research and applications of the filter based on the multi-layer coupled schemes for the future wireless communication system are predicted.