Design Of Ultra Wideband Conformal Load-bearing Antenna And Influence Mechanism Of Its Structural Deformation

Ultra-wideband conformal load-bearing antenna is a kind of highly integrated multifunctional antenna.It embeds ultra-wideband antenna into the carrier platform structure,which has good mechanical bearing capacity and can realize electromagnetic radiation,and has broad application prospects.However,UWB conformal load-bearing antenna also brings new problems.On the one hand,there is a lack of appropriate UWB antennas that can be used for conformal loading.For example,(1)As a typical UWB circularly polarized antenna,the planar equiangular spiral antenna is not easy to be conformal to the low-profile of the platform structure due to the large longitudinal size of its balun,(2)As a typical UWB linear polarization antenna,the radiation performance of Vivaldi antenna depends on the opening size of the slot line.To achieve high gain,it is necessary to increase the antenna size,which affects its application in conformal bearing antennas.On the other hand,the coupling relationship between the structure part of the UWB conformal load-bearing antenna and the antenna is relatively complex,and its structural parameters will directly affect the electrical characteristics of the antenna.In addition,as a part of the carrier platform,the UWB conformal load-bearing antenna will inevitably produce a certain degree of structural deformation when the platform is subjected to external loads,which further affects the electrical characteristics of the antenna.Therefore,in view of the above two aspects,the main research work of this thesis is as follows:(1)Low-profile design of planar equiangular spiral antennaAiming at the problem that the planar equiangular spiral antenna is difficult to conformal with the carrier platform due to the existence of traditional balun,a design scheme of lowprofile planar equiangular spiral antenna is proposed.Firstly,according to the design theory of planar equiangular spiral antenna,the design of antenna radiator is carried out.Secondly,for the purpose of low profile,the traditional balun is improved,and two kinds of low-profile planar equiangular spiral antenna working in the frequency range of 2-17 GHz are obtained:one is the planar equiangular spiral antenna fed by bending balun,the other is a spiral antenna with a planar equiangular shape that is fed by a spiral tapering microstrip line.Finally,the planar equiangular spiral antenna fed by spiral tapered microstrip line is processed and tested.The results show that the VSWR of the antenna is less than 2 and the axis ratio is less than3.5d B in the operating band,and the profile size is only 0.8mm of the thickness of a dielectric substrate,which achieves the design requirement of low profile.(2)High-gain design of Vivaldi antennaAiming at the problem of low gain at low and high frequency ends of Vivaldi antenna,a design scheme of high-gain Vivaldi antenna is proposed.Firstly,the traditional Vivaldi antenna operating in the frequency range of 2-17 GHz is obtained by optimizing the structure parameters of the antenna.Secondly,the gradual grooved structure is loaded on the edge of the metal radiator to improve the gain of the antenna at the low frequency.Then,a metamaterial structure with left-handed characteristics is designed and loaded at the opening of Vivaldi antenna to improve the gain of Vivaldi antenna at high frequency.Finally,the combination of two ways of tapered slot structure and loaded metamaterial is superimposed to obtain a new high-gain Vivaldi antenna,which improves the gain at 2GHz by 2.8d B compared with the traditional antenna,and the gain in the 10-17 GHz band is improved by2 d B on average compared with the traditional antenna to achieve the high-gain design effect.(3)Design of UWB conformal load-bearing antenna and analysis of influence mechanism of structural deformationFirstly,based on the high-gain Vivaldi antenna,the UWB conformal load-bearing antenna element structure is constructed.Using the control variable method,analyze the relationship between the influence of the bearing layer on the electrical characteristics of the UWB antenna element,and provide a basis for the structural design of the UWB conformal loadbearing antenna element.Secondly,the array design of the UWB antenna element is carried out to obtain the UWB conformal load-bearing antenna array form and analyze its electrical characteristics.At the same time,the finite element model is established by the separation entity modeling method to analyze the mechanical properties of the UWB conformal loadbearing antenna array.Finally,the effects of bending and torsion on the electrical properties of UWB antenna elements and arrays are studied.In addition,a structural deformation test platform is designed and a method for measuring and reconstructing the deformed antenna is proposed.