Some Studies Of Microwave Passive Devices Based On Composite Right/Left-Handed Transmission Lines And Substrate Integrated Waveguides

In recent years, with the rapid development of wireless communication technology and integrated circuit technology, the tendency of modern microwave and millimeter-wave systems is miniaturization, highly integration, multifunctional, reliable and low-cost. Higher requirements are put forward for filters, couplers and other passive components which are considered as the important parts of microwave and millimeter-wave systems. In this dissertation, the applications of composite right/left-handed (CRLH) and improved substrate integrated waveguide (SIW) technology in the design of microwave passive components are investigated systematically, and a series of high-performance, miniaturized microwave devieces such as bandpass filters and couplers are proposed.Firstly, the basic principles and synthesis of left-handed material and the theory of CRLH transmission lines are introduced; a brief introduction to the design method of metamaterial based on network theory and full-wave simulation is presented; and novel designs of CRLH transmission lines are proposed. Based on the principle of traditional broadside-coupled coplanar waveguide (CPW) coupler, CRLH structure is applied to the design of directional coupler, and two miniaturized broadside-coupled CPW directional couplers are proposed. By using odd/even-mode transmission line theory, the equivalent circuit models of these couplers are analyzed in detail.Then, the modal dispersion behaviors of electromagnetic bandgap (EBG)-loaded half-mode SIW (HMSIW) and CRLH HMSIW are studied. To further demonstrate their applications, a miniatrurized CRLH bandpass filter is developed by loading two EBG structures and an interdigital capacitor in the HMSIW, two slot lines are used to weaken the coupling between EBG structures and interdigital capacitor. A compact rat-race coupler including three sections of EBG-loaded HMSIWs with -90°phase delay and one section of CRLH HMSIW with +90°phase advance is also realized.After that, a new kind of SIW resonator with a complementary split ring resonator (CSRR) etched on the top metal plane of the SIW cavity is proposed in this dissertation. And a compact fourth-order cross-coupled SIW filter operating at the cutoff frequency of the traditional SIW resonator is realized by this new resonator. Furthermore, a new type of evanescent-mode SIW bandpass filter by loading CSRRs on the top and bottom metal planes of SIW is investigated. Compared with the traditional third-order SIW filter, its area is reduced by 40%, and its out-of-band rejection characteristic is very attractive. Finally, the topological structure of dual-band SIW bandpass filters based on two coupling paths between source and load is analyzed. A planar SIW dual-band bandpass filter and a multi-layered dual-band bandpass filter with quarter-folded SIW cavities in low temperature co-fired ceramic (LTCC) have been designed and fabricated. Furthre, based on the degenerate dual-mode resonator theory, a novel dual-mode dual-band SIW bandpass filter with two dual-mode SIW cavities vertically are designed. The presented dual-band filters can operate at independent frequencies with controllable bandwidths, and high skirt-selectivity is also achieved with high isolation between two passbands. Compared with the planar SIW dual-band filter, the multilayer folded SIW structure keeps good performances, highly integration but smaller size.