Key Technologies For High Frequency Radome

With the development of modern wireless communication technology,the requirement of multi-functional communication system is becoming more and more urgent,which requires high performance radome.In order to ensure the good operation of wireless communication in various situations,it is important to study the design of high performance radome and antenna.Therefore,it is significant for antenna system in the future to combine with omni-directional technologies and frequency selection technologies to realize multiple functions of antennas.On the other hand,with the development of 5G technology and the internet of things technology are increasing rapidly,it is necessary to install MMW antenna radomes.Moreover,in recent years,scholars also focus on the radome which is used to realize the communication between two dielectrics.So in this dissertation,the research hotspots of antenna radome in recent years are studied and analyzed.The specific contents of main achievements are as follows:1.The design of high gain omni-directional circularly polarized antenna is studied.From the theory of slotted coaxial,the electric field of slotted coaxial is analyzed.Based on slotted coaxial theory,two designs of high gain omni-directional circularly polarized antennas are proposed by using the slotted structure of outer conductor and polarization changing technology.(a)A circular polarized antenna with slotted outer conductor is designed with single arm helical structure.Firstly,low loss medium is wrapped around the monopole antenna to protect the antenna and fix the metal scarfskin.Secondly,the single arm helical slots are etched on the metal scarfskin,and the slots are excited to radiate the circularly polarized electromagnetic waves.In addition,for the improved far-field axial ratio,rectangular slots with axial direction are etched on the scarfskin to adjust the amplitude of the radiation field components in the far-field.(b)A high gain circularly polarized antenna based on coaxial structure with inclined slots is proposed.Firstly,two disks are used at the top and bottom of the antenna to support the whole antenna system.Secondly,three groups of inclined slots with different sizes are etched on the metal scarfskin to radiate omni-directional circularly polarized waves.The rectangular slots perpendicular to inclined slots are etched on metal scarfskin.By adjusting the proportion of dimensions of two groups of slots,a good omni-directional circular polarization axial ratio perdormance is achieved in the azimuth plane.2.The technique of miniaturized-element frequency selective surface is studied.Based on the basic theory analysis of FSS,several realization methods of miniaturized-element FSS are studied,such as fractal structure,metal loops,and meatal via.Then,based on the practical application,a double-layer miniaturized-element FSS for radome with A-sandwich type is designed.The FSS is composed of two mirrored and symmetrical FSS,The interlayer is a honeycomb layer with low dielectric constant to improve the performance of the passband.In order to reduce the effect of space loss and protect the FSS metal patch,we utilize the dielectric plate which has the same dielectric as substrate to cover the FSS.The miniaturization methods by etching square loop and loading metallized via are analyzed respectively.Combining with the two miniaturization methods.The effects of Jerusalem cross end length,honeycomb thickness and periodic parameters on the frequency response and bandwidth of FSS are studied.3.The radome for EM wave propagation across interface communication is studied.At first,with the study of the antenna field area,the propagation of the antenna in Fresnel region by subsource radiation is studied.Based on the Huygens–Fresnel principle,a new method of air-seawater across interface communication is proposed.In order to verify the feasibility of the proposed method,a thick metal plate with via is used to simulate seawater with good conductivity,and a plane wave is used to illuminate thick metal plate to simulate electromagnetic wave incident into seawater.The result shows that using the Fresnel zone in the thick metal plate,the EM wave propagation across interface can be realized.Then,a radome is proposed to constrate a Fresnel zone in water.The radome is composed of a spherical cavity for placing the antenna and a dielectric tube for constructing the Fresnel region.By comparing the results of the received 7GHz EM signal,GPS signal and call response with or without radome,the validity and engineering feasibility of the radome are verified.4.The Ka band MMW radome is studied in detail.Based on the electrical properties of the radome,the influence of radome on the electrical performance of different antennas is analyzed.Reflection coefficient and insertion phase delay of uniform thickness solid dielectric radome are also analyzed by wave matrix.Then,the effects of radome with structure of flat,cone and truncated cone on the wave propagation and insertion phase delay of standard horn antenna at different frequency points are studied,respectively.According to the results,the feasibility of the truncated cone shaped radome is analyzed.Finally,a truncated cone shaped radome which works in Ka band with uniform thickness solid wall is designed and fabricated.The inner surface of the radome has a spherical dent for conformal.The transmission performance of radome is calculated and analyzed by using standard gain horn.The designed radome is applied to the waveguide slot array with triangular grid arrangement,and the results show that the radome has good transmittance and insertion phase delay.