Research On Spoof Surface Plasmon Polariton Power Dividers

In the microwave and terahertz range,the electromagnetic waves of Spoof Surface Plasmon Polariton(SSPP)mode can be excited on the surface of sub-wavelength periodic structures.The SSPP mode has similar characteristics to Surface Plasmon Polariton(SPP)mode of the optical band.The SSPP transmission lines and components have controllable operating bandwidth,low crosstalk loss,miniaturization and the advantage of being used in flexible materials.In recent years,SSPP microwave devices and antennas have received extensive attention at home and abroad.This paper is mainly about the research of SSPP power dividers.It is divided into the following three parts:(1)An oval-ring SSPP transmission line is proposed.And,the flaring disappearing ground and a group of gradient oval-ring cells are used to design a transition structure between the oval-ring SSPP waveguide and the coplanar waveguide.The measured results show that the oval-ring SSPP transmission line has low transmission loss in the ultra-wide frequency band.The transmission loss composition of the oval-ring SSPP transmission line is analyzed using the Thru-Reflect Line technology.(2)An oval-ring SSPP power divider with large isolation is proposed.Firstly,the half oval-ring SSPP transmission line with low bending loss is designed,and a pair of stepped impedance structures is added in order to achieve the impedance matching between the half oval-ring SSPP transmission line and the coplanar waveguide.The two-way T-shaped SSPP power divider is designed.The SSPP power divider is designed by connecting an isolation resistor between quarter-wavelength converters.And the characteristics of the gradual quarter-wavelength converter and the position and resistance of the isolation resistor are discussed.The designed T-shaped oval-ring SSPP power divider with a gap achieves high isolation characteristics.The oval-ring SSPP power divider is fabricated,and the measured and simulated results are in good agreement.(3)A four-way oval-ring SSPP power divider and a four-way tooth-shaped double-conductor power divider are proposed.Based on the two-way T-shaped oval-ring SSPP power divider,a single connection junction between four half oval-ring SSPP waveguides and a coplanar waveguide is proposed.On this basis,a new type of four-way oval-ring SSPP power divider is designed.The measurement results demonstrate that the designed oval-ring SSPP power divider can achieve good four equal power distribution characteristics in the ultra-wide working frequency band.According to the dispersion curve and the impedance characteristics of the tooth-shaped dual-conductor SSPP unit,a tooth-shaped two-conductor SSPP transmission line and a transition conversion structure between the designed SSPP transmission line and microstrip line are designed.Based on the method of the electrical coupling,the conversion structure between the SSPP transmission line and the slot line is designed.And then,the four-way tooth-shaped two-conductor SSPP power divider is designed.The simulation results show that the four-way SSPP power divider has good four-way equal power splitting characteristics in the ultra-wide working frequency band.