Study Of Airborne Conformal Antenna With Low-Profile And Wideband

With the continuous and rapidly improvement of airborne communication technology.Meanwhile,the requirements for the functions of communication systems and equipment are also constantly increasing,besides,the install environment of antennas is more complicated overtime,and thus the requirements about antenna size and performance are becoming more stringent.In the USW band,in order to adapt to the development of airborne communication system,the key technologies such as broadband,low profile and conformation of antenna have become the focus of airborne antenna study.In this paper,several methods of broadband antenna and antenna broadband are introduced,and the application of antenna loading and impedance matching technology is studied,and the broadband low profile conformal antenna in V/UHF band is mainly designed.This paper can be divided into three parts:Firstly,an ultra-wideband antenna based on loaded monopole is simulated.Five loading positions are selected with lossy and lossless mixed loading.The parameters of loading elements are optimized through optimization algorithm,which can smooth the impedance curve in working band.And then,the matching network is introduced.Similarly,the algorithm is employed to optimize the values of network elements,and finally make the monopole work in the frequency range of 17 times with the VSWR less than 3.Secondly,an airborne conformal antenna based on Vivaldi antenna is designed.Combining the conformal position on the plane and the broadband requirement of the antenna,the front and rear double Vivaldi antenna structure is adopted,and the curvature of the conformal surface is utilized to make the Vivaldi antenna have a omnidirectionality to some extent.Because of the enough space for front antenna,the front antenna is improved to reduce the VSWR,meanwhile,it can weaken the deterioration of radiation efficiency caused by resistance;due to the smaller installing space,the rear antenna has adopted the traditional Vivaldi antenna structure with two resistors loaded.By using the front and rear antennas to work simultaneously and the front and rear antennas' radiating sides are different from each other,the radiation characteristics at horizontal plane of the antenna are improved,and the VSWR is basically satisfied.Thirdly,a low profile airborne blade antenna based on monopole is designed.The installation environment of the antenna requires the antenna to be located inside the wing with a certain conformal requirement.By studying the impedance characteristics and radiation characteristics of a monopole antenna with tilted shape on the relatively large vertical ground,it is illustrated that the rhombic radiator structure can make the high-frequency impedance more gentle and the pattern roundness better.In order to further improve the matching of the low frequency,the rhombic monopole with a rhombic coupled feed structure is optimized,and the feed structure is connected with the coupled radiator at the end,which makes the VSWR in the whole frequency band less than 2.By fine-tuning the shorting position of the coupled feed structure,the out-of-roundness of the pattern can meet the requirements at last.