Application Research On Hybrid Substrate Integrated Waveguide Circuits

Directional coupler is a microwave device widely used in microwave system.Its essence is to distribute microwave signal according to a certain proportion.Directional couplers play a very important role in RF circuits and can be used for signal separation,isolation,and mixing,such as signal power monitoring,source output power magnitude stabilization,signal source isolation,sweep tests of transmission and reflection.As one of its main applications,the six-port device is widely used in communication receivers to achieve a simplified structure and size reduction.In this thesis,an improved miniaturized dual-layer wideband substrate integrated waveguide small aperture coupler based on the waveguide Bethe hole coupling theory is introduced.The coupler utilizes the characteristic that the bandwidth of the TE₁₀ mode in the SIW is much wider than that of the metal waveguide,and designs a miniaturized waveguide wide-walled coupler on higher frequency band of the TE₁₀ mode of the SIW.Such a coupler can achieve 3dB wideband strong coupling with limited size.On this basis,we made a further study and found that the size of the coupler can be further reduced by utilizing transmission line with lower power.Therefore,following the idea of HMSIW,we designed a HMSIW miniaturized double-layer wideband aperture coupler.Under the premise that the reduction is nearly half,the same effect of wideband strong coupling is achieved.Finally,combining a broadband phase shifter basing on CSRR technology,two six-port devices are realized.The six-port device is small in size,wide in bandwidth,and stable in phase,making it ideal for application in communication receiving systems.