Study Of Hybrid Substrate Integrated Waveguides Exciting And Circuits

In this thesis, the broadband transition from microstrip to folded substrate integrated waveguide(FSIW) is proposed and used in the novel planar magic-T structure. And a new coupler structure based on half mode substrate integrated waveguide(HMSIW) is introduced and applied to six-port circuits. The sizes of FSIW and HMSIW are both half of SIW, which meets the requirement in wireless communication systems.SIW is an improvement of rectangular waveguide and remains the advantages of low loss, high power capacity, high quality value and planar property. And it can be expended to FSIW and HMSIW in order to obtain smaller size and high density. The field of the FSIW is folded in H-plane by means of the middle metal layer. In this thesis, a broadband transition from microstrip to FSIW is proposed and utilized in the design of magic-T. The H-plane and E-plane T-junctions can be integrated into one junction, and the size can be reduced further because of the overlapped structure. And the sum port and difference port work almost in the same frequency range, and the isolation between them is below-40 dB from 6.7GHz to 9.7GHz.The characteristics of six-port circuits are studied. Power divider, hybrid coupler and phase shifter are usually compounded in the circuit. The structure and performance of each component influe nces the six-port circuit directly. A novel coupler structure based on HMSIW is proposed and the 3dB coupler is utilized in six-port circuit with compact size and good performance.The back-to-back transition from microstrip to FSIW, the prototype of magic-T, the 3dB directional coupler and six-port circuit are fabricated and measured with vector network analyze r, Agilent 85058 E. The cutoff frequency of all waveguide transmission lines is 5.4GHz. Due to the influence of SMA connectors and conductor loss, the measured results deviate from the simula ted results a little but still within accepted range.