Design Of Reconfigurable Coupler Based On Half-mode Substrate Integrated Waveguide

Couplers,fundamental passive components,are widely used in microwave and millimeter-wave integrated circuits,such as balanced amplifiers,mixers,and antenna array feeding networks.On the other hand,half-mode substrate integrated waveguide(HMSIW),which feathers small size,low loss,low cost,easy integration with other planar circuits,is widely used in the design of low-loss microwave passive devices.In order to meet the requirements of multiband and multimode in various modern communication systems,this paper will study reconfigurable HMSIW couplers with small size and high performance.A continuously tunable 0-d B coupler(crossover)and a quadrature coupler with wide tunable coupling radio based on HMSIW are proposed.The specific work of this paper is as follows:First,this paper reviews the research of 0-d B couplers(crossovers)and substrate integrated waveguide(SIW)couplers at home and abroad,and discusses various kinds of design methods of planar crossovers and SIW couplers with different operating frequency modes.Second,a frequency-tuning crossover based on HMSIW is presented.The odd-even mode analysis method is used to obtain the closed-form equations for the design of tunable crossover.For verification,a continuously tunable crossover based on HMSIW is implemented,and the tuning frequency is from 2.2 to 5.0 GHz(tuning range of 78%).Good agreement between the simulation and measurement is observed.Finally,a HMSIW quadrature coupler with tunable coupling ratios is designed.Considering the effect of transmission-line electric length on output phase imbalance,two tunable quadrature couplers with different electric lengths based on HMSIW are fabricated,and the measured results agree well with the simulated ones.