Study On The Properties Of EBG Structure And Its Application In Antennas

Electromagnetic Band Gap(EBG),as a special periodic artificial electromagnetic material,has attracted the attention of scholars all over the world since it is introduced in the 1980 s.Surface wave bandgap and in-phase reflection bandpap are two important bandgaps of the electromagnetic band gap structure,which are determined by their own unique bandgap characteristics.Electromagnetic bandgap structures are widely used in the fields of antennas and microwaves to reduce the coupling between antennas,improve antenna radiation performance and suppress Simultaneous Switching Noise(SSN),etc.And the in-phase reflection bandgap can be used to achieve the low profile design of the antenna and to reduce the Radar-Cross Section(RCS)design.In this thesis,the mushroom-like EBG structure are the focus of research.The generation mechanism,simulation method and applications in antennas of surface wave bandgap and in-phase reflection bandgap of EBG structure are introduced,respectively.The specific work is as follows:Firstly,by using the method of increasing equivalent inductance L,a miniaturized three-band EBG structure is designed by introducing the planar spiral groove line.And its equivalent parallel LC circuit is analyzed in theory.Compared with the mushroom-like EBG structure of the same size,the center frequency of surface wava bandgap of the EBG structure is reduced by 2.6 GHz.Secondly,the application of EBG structure surface wave bandgap in microstrip circularly polarized antenna is studied.A single-point 2.4GHz microstrip slot circularly polarized antenna is designed and a mushroom-like EBG structure covering the antenna working frequency band is loaded around antenna to suppress the propagation of the surface wave of the microstrip antenna.Simulation and measurement results show that the 3-d B axial ratio beamwidth of the microstrip circularly polarized antenna can be effectively improved by loading the EBG structure around the antenna.The measurement result of 3-d B axial ratio beamwidth was 252°.Thirdly,the application of in-phase reflection bandgap of EBG structure in dielectric resonant antenna is studied.A dielectric resonant antenna(DRA)with cross-slotted gap coupling feed is designed.By using the in-phase reflection bandgap of the EBG structure,the EBG structure is used as the reflective floor of the DRA.The top gain of the DRA is increased by 0.61 d Bi.The tail lobe radiation and cross polarization level of DRA are reduced.