Rearch Of Leaky Wave Antenna Based On Spoof Surface Plasmon

Leaky wave antenna based on the spoof surface plasmon polariton(SSPP)is widely used in high-resolution radar,wireless communication and other fields.It has excellent performance such as small-volume integration,high gain,directionality,frequency dependent beam scanning and so on,which attracts the attention of many researchers.In this paper,the dispersion characteristics of the SSPP transmission line are analyzed and the leaky wave antenna based on the SSPP is designed using the method of full wave electromagnetic simulation and prototype measurement.Major work and innovation are summarized as follows:Firstly,a SSPP transmission line is designed.The transmission line consists of three parts:coplanar waveguide,matched converter and SSPP waveguide.With the excitation of coplanar waveguide,the transfer structure between coplanar waveguide and SSPP waveguide is a quarter ellipse,which solves the problem of wave vector mismatch between coplanar waveguide and SSPP.The unit structure of SSPP waveguide is H-type periodic groove structure.The relationship between the dispersion characteristics of SSPP and its ability to restrain electric field is analyzed,and the influence of the unit structure size on the dispersion characteristics is analyzed.The unit structure dimensions and operating frequency band of SSPP transmission line are determined according to the dispersion curve.Secondly,a circularly polarized leaky wave antenna based on SSPP is designed.Its operating frequency range is from 4GHz to7GHz.Through periodic and asymmetric loading of circular metal patches on both sides of the SSPP transmission line,the electromagnetic wave propagating along the transmission line will excite the patches placed nearby by coupling,which will in turn generate electromagnetic radiation.By using the perturbation technique,the electric field direction on the structure surface will be changed,so that the leaky wave antenna can realize the circular polarization performance.The measured axial-ratio 3d B bandwidth is 31.3%and the maximum radiation gain is 8.25d Bic.Thirdly,a leaky wave antenna based on SSPP with high gain is designed.Based on the aforementioned leaky wave antenna,two schemes are proposed to improve the antenna gain and change the omnidirectional radiation of the antenna into directional radiation,namely,the introduction of Perfect Electric Conductors(PEC)or Artificial Magnetic Conductors(AMC)as the reflection surface of the antenna.The plane reflects the downward radiation wave into the upper space,and the bidirectional radiation becomes the unidirectional radiation,therefore the radiation gain of the antenna is increased about 3d B.Through the optimization design,the optimal distance between the PEC reflection plane and the antenna is 0.3?₀(?₀the vacuum wavelength for the broadside radiation),and the optimal distance between the AMC plane and the antenna is 0.075?₀,which is only 25%of the PEC case.Therefore,AMC-grounded SSPP leaky-wave antenna features more compact profile than the PEC-grounded one.