Research On Minituarization Of Substrate Integrated Waveguide Passive Components

As the wireless especial mobile communication technology dramatic developed,the electronic systems get trends of high integration, miniaturization, low cost,multi-function, etc. Simultaneously, the electromagnetic environment is becoming more and more complex due to the applications of large numbers of electronic systems. In order to select demanding signals and suppress interferences, the research of passive components with miniaturized circuit size, high performance is becoming a hotspot. As a new planar dielectric waveguide structure, substrate integrated waveguide (SIW)owns advantages of high quality factor, low radiation loss and high isolation and it has become an important option to design microwave and millimeter wave circuits .However, SIW get a drawback of being too large for compact circuit applications due to its cut-off property. It has limited the applications of SIW to microwave especial lower microwave frequency band.To overcome this issue, this dissertation is devoted to foundational research of developing miniaturization methods for SIW technology. Based on these methods,numbers of high performance, compact microwave and millimeter wave passive components have been implemented. The main contributions and novelties can be summarized as:(1) A novel defected ground structure (DGS) has been proposed and it has been applied to compact SIW devices design. Employing high pass characteristics of SIW and low pass feature of DGS, a pass-band can be realized. The proposed DGS get a hairpin structure. This unique shape effectively enlarges its equivalent capacitor. And the parallel stub lines of DGS dramatically decrease its equivalent inductance. Thus, a higher quality (Q) factor can be achieved which leads to a low insertion loss. At the same time, as the signals in the passband is working on a transmission mode, low insertion loss and good return loss performance can be fultiled. In addition, to overcome the problem of poor output ports isolation of traditional SIW power dividers, a new SIW power divider has been proposed based on the balanced structure of four ports magic-T.The proposed design effectively improves the output ports isolation and it also gets merits of low insertion loss and miniaturized circuit size. It can effectively expand its applications to microwave and millimeter wave circuits.(2) For the first time, this dissertation proposes a hybrid SIW structure. The structure is realized by embedding a stripline resonator into the cavity of a SIW resonator. Therefore, it can support co-transmission of two modes: TEM mode and TE101 mode. Making used of the two transmission modes, a dual-band frequency response can be introduced. As the two modes are irrelative, the mutual coupling of them can be ignored and the two passbands can be independently controlled. And the hybrid structure is good for circuit miniaturization as the inserted stripline takes no extra circuit layout. On the other hand, when the resonant frequency of the stripline is near the passband of the SIW filter, a transmission zero (TZ) can be produced according to signal interaction principle. Considering the resonant frequency of stripline is out of the passband, it can be regarded as non-resonant node (NRN). However, traditional NRN, it is a single mode structure, so the number of TZ is the same as the number of NRN. This dissertation proposes a new NRN structure with multi-resonant feature. Then more TZ can be realized by exploiting its multi-resonant features. It also breaks the limitation of traditional NRN. And it greatly expands the application of NRN in the high selective frequency response situation. What's more, the new NRN is embedded in the volume of SIW, it does not occupy extra circuit size which is very beneficial for compact circuit applications.(3) This dissertation for the first of time proposes a hybrid structure of quarter-mode SIW (QMSIW) and co-planar waveguide (CPW). The hybrid structure is realized by etching a CPW resonator across the coupling window of two magnetically coupled QMSIW resonators. By making use of complimentary property of QMSIW and CPW, the CPW resonator not only generate an in-band transmission pole, but also introduces extra electric coupling to the two magnetically coupled QMSIW resonators that greatly improves the frequency selectivity of the structure. And the etched CPW does not take extra circuit size as it is embedded in the coupling region of two QMSIW resonators which is very beneficial for circuit miniaturization. To further improve the selectivity of the filter, mixed electric and magnetic source-load coupling is applied in filter design. The mixed coupling can generate more TZ compared with traditional one that greatly enhances the frequency selectivity.(4) This dissertation for the first of time proposes a dual-mode complimentary split ring resonator (D-CSRR) loaded half mode SIW (HMSIW) structure. Traditional CSRR loaded SIW transmission line earns left-hand property that allow transmission of signals with frequencies lower than the cut-off frequency of SIW. Then miniaturized circuits can be realized. However, the CSRR loaded SIW structure gets drawbacks of narrow working bandwidth and high insertion loss. This dissertation proposes a novel D-CSRR loaded HMSIW structure by exploiting the electromagnetic duality of SRR and CSRR. The proposed structure can effectively widen the working bandwidth,lowers the insertion loss and expand its application range. Also, due to dual left-hand property of D-CSRR loaded HMSIW, the frequency of signals can be further lower than the cut-off frequency of HMSIW. Then the circuit size of the proposed structure is dramatically reduced that can be comparable with its counter parts of micro-strip line and CPW. It is inherits the characteristic of SIW that gets low insertion loss. This makes the proposed structure a good candidate for microwave and millimeter wave applications.All of the proposed desgins are based on standard single layer or two layers PCB process. And the theory, simulation and measurement results agree well that verify the correctness and effectiveness of the research in this thesis.