| As a key component in wireless communication system,an antenna can transmit and receive electromagnetic wave,serving as a transverter between guided wave and free space wave.With the rapid development of wireless communication and radar detection,miniatrurized,multi-functional and integrated antennas are more and more popular,which needs to investagate novel method of designing antennas.Spoof surface plasmon polaritons(SSPP)is a special electromagnetic mode in surface,causing by resonant interaction between electromagnetic wave and electromagnetic media.In the media,the SSPP is oscillation of free electrons collectively,and out of the media,the SSPP shows a surface wave propagating along the media interface,which gives rise to its unique properties,such as deep-subwavelength,field enhancement and strong dispersion,etc.Thus,SSPP is applied widely in the design of microwave components and antennas.Based on the theories of dielectric physics and plasmon photonics,together with the design principle of electromagnetic metamaterial,the thesis investigates dispersion properties and dispersion engineering of the SSPP,and proposes the design method of frequency scanning antennas,low radar cross section(RCS)antennas,shared aperture antennas,multi-band antennas,etc,based on dispersion engineering of the SSPP.Simulation and experiment results verify the feasibility of the proposed methods.Novelties of the thesis are listed below.(1)Dispersion engineering models of the SSPP and the tightly-coupled SSPP are proposed in theory via analyzing dispersion property of the SSPP and researching theory of dispersion engineering of the SSPP.Firstly,dispersion equation of the SSPP on metallic periodic corrugated slab is deduced,and an analytic equation between the SSPP dispersion and the geometric parameters of the slab is obtained,based on the theories of dielectric physics,electromagnetic wave and optoelectronics,etc.Then,from the views of mode matching and wave vector matching,excitation means of the SSPP are presented.Finally,on that basis,models of dispersion engineering of the SSPP and the tightly-coupled SSPP are established respectively,laying a foundation for the applications of SSPP dispersion engineering in novel antennas design.(2)A method of designing frequency scanning antennas based on hybridization of quasi-TEM mode and SSPP mode is proposed.Firstly,leaky wave theory is analyzed based on periodic system.On that basis,configuration of a frequency scanning antennabased on hybrid mode of the SSPP and quasi-TEM is proposed via integrating the SSPP guiding structure and microwave strip line and introducing periodic perturbations.By engineering quasi-linear region of the SSPP dispersion curve,the frequency scanning antenna with large scanning range property is designed,simulated,and fabricated,as an example.The simulation and experiment results agree well and verify that within 9?12GHz,the antenna enables continuous frequency scanning from-60° to +60° without beam degradation at broadside direction.The proposed antenna based on hybrid mode of the SSPP and quasi-TEM is compatible with conventional microwave circuit,and has the advantages of low cost,low profile and easy to be conformed,promising great value in the applications of LSS-target(the Low altitude,Slow speed and Small Target)detection and missile communication system,etc.(3)Design concept of low RCS antennas based on SSPP dispersion engineering is proposed via introducing absorption theory to low RCS antennas design and serving the SSPP absorber with strong dispersion property as the antenna radiator.Theory of antennas scattering is illustrated.Based on this theory,configuration of the low RCS antenna is proposed,and the design theory and principle are established.By comprehensively engineering weak and strong regions of the SSPP dispersion curve,the SSPP structure enables properties of low insertion loss and strong absorption in two adjacent bands simultaneously.In this way,the SSPP will achieve high-efficiency radiation in band and RCS reduction out of band simultaneously if the SSPP structure is used as an antenna radiator.As an example,the antenna working in C band and with RCS reduction in X band is designed,simulated and measured.Simulated and measured results agree well and verify that total efficiency of the antenna in band(6?8 GHz)is greater than 80%,in X band RCS reduction of the antenna is greater than or equal to 10.00 d B,and within 8.50?9.50 GHz the RCS reduction is greater than 25 d B.Furthermore,the antenna with properties of in-band cross-polarized and out-of-band co-polarized RCS reduction is investaged and designed via loading with SSPP absorber along cross-polarized direction of the low RCS antenna and engineering dispersion of the SSPP radiator and the SSPP absorber.(4)A method of designing structural and functional composite antennas is proposed based on antenna-radome-integrated design philosophy.In detail,the antenna is composed of a two-dimentional SSPP radiator,used as lattice core of sandwich structure,and fibre-reinforced polymer face panel.On the one hand,by engineering dispersion of the SSPP radiator,low insertion loss and strong absorption can be achieved simultaneously in two adjacent bands.Hence,the antenna enables high-efficiency radiation in band and RCSreduction out of band.On the other hand,due to two-dimensional configuration,the SSPP radiator serves as the core lattice of sandwiched structures,enhancing the mechanical strength of the radome panel.Therefore,the proposed antenna integrates three functions:radiating in-band electromagnetic wave,absorbing out-of-band wave and protecting the enclosed antenna,leading to structure-function-integrated antenna design.As an example,a C band antenna with RCS reduction in X band is designed,simulated and measured.Simulated and measured results verify that the proposed antenna can radiate in band with high efficiency and reduce mono-static RCS out of band.Furthermore,quasi-static out-of-plane compression tests illustrate that at the density with little difference,compressive peak strength of the proposed antenna is about 3.50 times to 3D printed honeycomb absorber and 304 SS square honeycomb,and about 6 times to 304 SS corrugation.The proposed structural and functional composite antenna integrates functions of radiation,RCS reduction and mechanical support,promising great value in practical low RCS antennas design(5)Design method of antennas based on tightly-coupled SSPP dispersion engineering is proposed.In the view of electromagnetic radiation,radiation conditions of even-and odd-mode SSPP are illustrated.Power distribution of a short dipole is deduced based on Maxwell's equations.Based on this,an idea of de-coupling near-field reactive energy of a short dipole is proposed by loading with inductive components.Hence,antennas configuration based on tightly-coupled SSPP dispersion engineering are constructed and the corresponding design methods are proposed.In detail,a shared-aperture antenna,a broadside radiation antenna and a dual-band broadside radiation antenna are designed,simulated and measured via loading with SSPP guiding structure,broadside-coupled split resonant ring(BC-SRR)and nested SSPP structure and BC-SRR in near field zone of short monopoles,respectively.Because the tightly-coupled SSPP can enhance field stronger,antennas based on tightly-coupled SSPP will have advantages of compact size,light weight,providing an alternative method for novel high performance antennas design. |
PDF Full Text Request