Research On Miniaturized Microwave Passive Components Techniques Based On Substrate Integrated Waveguide

Substrate integrated waveguide(SIW)simultaneously integrates the characteristics of rectangular waveguide and microstrip line,with the merit of planarization,low loss and easy integration.However,as compared with other planar guided-wave structures such as microstrip and coplanar waveguide,SIW is with bucky physical size,which restrains its applications in microwave circuits and systems,especially for the applications with strict requirements on system integration,such as terminals of wireless communication and outdoor units of the digital microwave communication.Hence,investigation on the new techniques for size-miniaturization of SIW structure,and exploration of novel design methods and implementation techniques for miniaturized SIW passive components,are with long-term scientific significance and important application values.Based on the emerging demands on size miniaturization for SIW microwave passive components and guided-wave structures,intensive investigations on the loading-type techniques for the miniaturization of SIW have been carried out in this dissertation,by using the triunity research methodology incorporating theoretical analyses,numerical simulations and experimental verifications.Fundamental theory and key techniques for the design of miniaturized SIW circuit unit cells based on partiallyand fully-patterning with electromagnetic structures have been discussed,with compact bandpass filters and phase shifters being implemented.Finally,design technique for the SIW power combiner/divider loaded with different material has been explored.Main research works and contributions in this dissertation are listed as below:1.A design method for miniaturized half-mode substrate integrated waveguide(HMSIW)resonant cavity is proposed.Aiming at the issues that conventional SIW cavity is with bulky size and inconvenient for practical applications,and performance of the current patterning-type techniques for size miniaturization of SIW cavity is limited,the idea of introducing stepped-impedance structure into complementary split-ring resonator is proposed.As a result,the stepped-impedance complementary split-ring resonator(SICSRR)is implemented and loaded into HMSIW cavity to form miniaturized HMSIW-SICSRR resonant cavity.The utilization of stepped-impedance structure can effectively enhance the size-tuning flexibility of the complementary split-ring resonator,so that to realize size miniaturization of the cavity.On this basis,a miniaturized bandpass filter made of the proposed HMSIW-SICSRR resonant cavity is realized,which achieves size reduction of 90% as compared with its conventional HMSIW cavity counterparts.Finally,a miniaturized dual-band resonant cavity is implemented by loading the HMSIW cavity with SICSRR on double sizes,as well as compact dual-band filters are realized,with size reduction of 85% as compared with its conventional HMSIW counterparts.2.A design mehotd for miniaturized SIW phase shifter and transmission line is proposed.Aiming at the issue that conventional SIW transmission lines and phase shifters are with large physical size,a design technique for wideband miniaturized phase shifter and transmission line based on slow-wave half-mode substrate integrated waveguide(SW-HMSIW)is proposed.Medium properties of the microstrip polyline unit cell are studied by using the theory of equivalent medium of the transmission line.Subsequently,the guided-wave characteristics and slow-wave effect of the SW-HMSIW patterned with uniform microstrip polyline unit cells is investigated by using the field theory of guided waves,and influences from sizes of the microstrip polyline unit cell on the guided wave characteristics and slow-wave effect are also analyzed.On this basis,a wideband miniaturized equal-width equal-length SW-HMSIW phase shifter is implemented by tuning sizes of the microstrip polyline unit cells differently to generate various phase shift.Compared with its conventional SIW counterparts,the proposed SW-HMSIW phase shifter achieves a size-reduction over 60%.Subsequently,a non-uniform microstrip polyline unit cell is proposed to form a SW-HMSIW structure that is double-side-patterned with the proposed non-uniform unit cells.The theory of equivalent medium and the theory of guided waves are utilized to investigate the medium characteristics,guided-wave characteristics and slow-wave effect of the proposed SW-HMSIW.Moreover,a compact prototype of the double-side-patterned SW-HMSIW transmission line is implemented,which achieves size-reduction of 66% and 32% on transverse dimension as respectively compared with its conventional SIW and HMSIW counterparts which are with the same dominant cutoff frequency.3.A design technique for isolation-enhanced wideband SIW power combiner/divider is proposed.Aiming at the issue that isolation enhancement and bandwidth extension are difficult to be simultaneously taken into account,a design technique for wideband SIW power combiner/divider based on the coupling network matching for isolation improvement is proposed.Based on the principle of ports isolation in the multiport Riblet coupling network,a five-port SIW power combining/dividing circuit is proposed.Subsequently,with the small reflection theory,a SIW absorbing termination loaded with V-shaped absorbing material is proposed and integrated with the five-port SIW unit cell to realize an absorbing-material-loaded wideband SIW power combiner/divider.It achieves size reduction over 10% as compared with its conventional SIW counterparts,and about 36% fractional bandwidth with an isolation over 16 dB and an amplitude variation less than ±0.5dB.