Characteristic Investigations On Novel Artificial Magnetic Conductor Structure And Its Applications In High-performance Antennas

As one kind of metamaterials or metasurfaces,artificial magnetic conductor(AMC)structure is a periodic structure with special electromagnetic properties,which can reflect incident plane wave in phase at a specific frequency band.When used in application of antenna designs,limitations of designs of traditional antennas are broken,which would bring huge changes and improvements for antennas in wireless communication systems.With the development of wireless communication technology,to satisfy the demand for high-performance and smart millimeter-wave system and mobile communication system,requirements of the antenna performance become higher and higher.High-efficiency and multi-function antennas are becoming the development trend of modern microwave,millimeter wave antenna.Therefore,it has very high academic value and application value to do researches on novel AMC structures and its applications in antennas for enhancing the efficiency and achieving multi-functional features.To satisfy the requirements of antennas in modern wireless communication systems,aiming at the existing research limitations of theoretical analyses of AMC structure and its applications in antennas,some in-depth researches have been conducted and concluded in this thesis.The novelty of this thesis is mainly indicated by paper publication and patient application,and the main contents can be summarized as:1.High-efficiency and integration design of millimeter-wave LTCC antenna array using AMC structure:Using low-temperature co-fired ceramics(LTCC)technology,a novel design based on AMC structure is presented to improve bandwidth and radiation gain of a millimeter-wave patch antenna.Consideing the losses of different transimission lines using LTCC material,a low-loss dual-layer laminated waveguide(LWG)feeding network is proposed,and a performance comparison and feasibility analysis are given.A compact transition between LWG and rectangle waveguide(RWG)in a LTCC substrate is proposed,and a back-to-back test structure for measurement is designed for demonstration of the performance.Combining the AMC-based antenna and the above LWG feeding network with the transition,a high-efficiency mmW LTCC patch antenna array is presented,moreover,two engineering improvements are proposed.The measured results demonstrate a good and stable performance.These works provide some useful guidance for designs of millimeter-wave system using LTCC technology.These works have been published in IEEE Transactions on Antennas and Propagation,and 2013 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference(CSQRWC),2013 IEEE International Workshop on Electromagnetics(iWEM).2.Characteristic analysis of novel stub-loaded AMC structure and non-periodic AMC structure and their applications for high-performance antennas:A stub-loaded AMC structure is proposed and analyzed using the equivalent circuit method.When employed as the ground plane of a probe-fed patch antenna,the effects of non-periodic distributions of stubs on antenna performance are investigated and discussed.By approapriate optimizing the arrangement of the stubs,the surface current density on AMC surface and electric field density on the radiation aperture become more uniform,which obviously improve the bandwidth,gain and aperture efficiency of the antenna.Based on above analysis,the stub-loaded AMC can be equivalent to a rectangle AMC structure(RAMC).According to the design strategy of parasitic patches,the dimensions and arrangements of these RAMC cells in the artificial ground of a probe-fed patch antenna are discussed.Three designs of high-performance microstrip antennas using non-periodic RAMC structure are proposed.The measured results demonstrate the high-efficiency and stable high-efficiency radiation performance in a wide band.These works provide great space of development for designs of high performance antennas.These works have been published in IEEE Antennas and Wireless Propagation Letters and 2015 Asia-Pacific Microwave Conference,and one patent is applied for high-gain microstrip antenna using stub-loaded AMC structure.3.Novel polarization-rotation AMC structure and its characteristics analysis:A novel polarization-rotation AMC(PRAMC)structure is firstly proposed,and characteristic analysis using the equivalent circuit model is given.According to the analyses of Floquet Harmonics,the scattered field on the PRAMC surface is investigated,and analyses of dyadic reflection coefficient and surface impedance tensor are carried out.In terms of the amplitude and phase of the dyadic reflection coefficient,the polarization rotation property and its influence factor are analyzed.Then a PRAMC structure with a large bandwidth is densigned,which can contribute to a circularly polarized wave.In addition,the structural evolution of the PRAMC structure is proposed,and performance comparisons of several PRAMC structures are given.Finally,design strategy of the PRAMC structure is concluded.These works provide a good theoretical guidance for theoretical analysis and design of AMC structure.These works have been published in IEEE Transactions on Antennas and Propagation,IET Electronics Letters,and 2014 European Microwave Conference.Moreover,these works also obtain the best paper award in 15th IEEE Graduate Student Competition,organized by IEEE AP/MTT HK Chapter and Chinese university of Hong Kong.In addition,one patent is applied for low-profile polarization rotated reflective surface using PRAMC structure.4.Applications of PRAMC structure in novel low-pofile wide-beam circular polarization antennas and polarization-reconfigurable antennas:The proposed PRAMC is applied for the first time to design dipole antennas for the generation of circular polarization radiation.The two designs of low-profile,wideband and widebeam circularly polarized dipole antennas are proposed.By performance comparison,the dual-via PRAMC-based antenna has more symmetrical and wider circular polarization beam.On the basis of above analysis,the PRAMC structure is applied in a pair of horizontal dipole antennas placed crosswisely,and a novel multi-polarized dipole antenna is proposed,which can achieve three polarization states of right-handed,left-handed circular polarization(RHCP,LHCP)and +45°linear polarization(LP).Combined with a RFIC switch-based network,a novel polarization-reconfigurable mechanism is obtained.These works provide a good guidance for the design of simple and novel reconfigurable antenna,and provide technical reference for achieving the multi-function requirement of the modern wireless communication system.These works,together with above works,have been published in IEEE Transactions on Antennas and Propagation and 2015 Asia-Pacific Conference on Antennas and Propagation.Now,one paper has been accepted by IEEE Transactions on Antennas and Propagation.