Study On The Unidirectional Transmission Characteristics Of Spoof Surface Plasmon Polaritons Controlled By Magnetic Field

With the rapidly development of microwave communication technology,there are higher requirements for the performance of non-reciprocal unidirectional transmission devices.In recent years,many researchers have made new explorations on the regulation of electromagnetic wave unidirectional transmission.New design schemes for non-reciprocal transmission have been proposed one after another,and good scientific research results have been achieved.In the microwave frequency band,spoof surface plasmon polaritons(SSPPs)have unique properties such as good subwavelength confinement,low-loss and highly-efficient transmission.The use of flexible and ultra-thin planar guided wave structures can well control the transmission of electromagnetic surface waves,which increases the degree of freedom for controlling the transmission of electromagnetic waves.The design of miniaturized,low-loss and high-efficiency transmission plasmonic devices based on planar ultra-thin SSPPs waveguides has broad application prospects in the field of microwave communications.Based on the combination of SSPPs waveguide and gyromagnetic ferrite,this paper carries out theoretical analysis and experimental verification to control the nonreciprocal unidirectional transmission of electromagnetic waves.The main content and conclusions of this paper are as follows:1.Study on design and transmission characteristics of plasmonic circulator.The unidirectional transmission of waves is controlled based on the interaction between the resonance modes of the gyromagnetic ferrite and the SSPPs modes.A plasmon circulator with broadband,high transmission efficiency and easy realization is designed.The results show that when electromagnetic waves are incident along different ports in the frequency range of 6.0-10.0 GHz,the electromagnetic energy is transmitted along a single channel to another port,the insertion loss is greater than 0.5d B,and the return loss and isolation are less than 12 d B.The proposed plasmonic circulator has good unidirectional transmission characteristics and backward isolation performance.The transmission characteristics of the structure were analyzed by numerical simulation and equivalent circuit model theory,and samples of the plasmonic circulator were processed and experimentally measured.The simulation results,equivalent circuit model and measurement results are in good agreement.2.Study on design and transmission characteristics of plasmonic nonreciprocal coupler.By analyzing the unidirectional surface modes of the gyromagnetic ferrite and the modes coupling effect between the waveguide.A compact and low-loss nonreciprocal structure is designed.The results show that in a specific frequency range,the plasmon nonreciprocal coupler has good unidirectional transmission characteristics.The magnetic field is used to control the unidirectional transmission of electromagnetic waves under different conditions.One case is unidirectional transmission when the same magnetic field is incident on different ports;The other case is the unidirectional transmission under different magnetic fields when the same port is incident.In order to achieve a greater extent of regulation of electromagnetic waves,a double-ring gyromagnetic ferrite structure is introduced.By controlling the direction of the magnetic field,the electromagnetic waves are transmitted along different channels,which increases the extent of freedom in controlling the unidirectional transmission of electromagnetic waves.The non-reciprocal coupling characteristics of the structure are calculated and analyzed based on the coupled modes theory.The research has potential application value in the field of surface wave transmission controlled by magnetic field,and the design of high-efficiency non-reciprocal couplers.