Research On Key Technology Of Conformal End-fire Antenna Arrays For Low Frequency Airborne Applications

With the continuous development of modern information and military technology,air strike,even the space strike force has gradually become the leading force as fighter is a well-deserved leading role.However,it is still very difficult to install a low profile,conformal antenna which can realize broadband performance,vertical polarization pattern and end-fire pattern simultaneously on such platforms with limited size.The design of wideband antenna with low profile height and vertical polarization is extremely challenging.It is always difficult to achieve low profile or airborne conformal antennas that will not affect the performance of the antenna and the airborne.Therefore,this work designed two antennas which can realized vertical polarization,broadband beam and low-profile height.Log-periodic array antenna structure is applied in this thesis.Specifically,we decreased the profile height and the transverse dimension of the antennas by means of capacitance loading at the top of the physical section.Two different feeding structures of the log-periodic monopole array are analyzed and designed for end-fire beams antenna.One phased array antenna realizes ?45 scanning in horizontal plane.The flush-mounted vertical polarized antenna and array are studied in this thesis,in particular,the author focused on the low profile characteristics and end-fire radiation performance of the proposed log-periodic arrays.The antenna performance under different feeding structures,and the antenna performance with cavity-embedded is discussed.The main content of this paper is divided into four chapters.The first chapter analyzed and summarized the current development status of low profile,end-fire airborne antenna.The second chapter analyzed the relevant theory of the research topic.The third chapter analyzed and designed the first wideband low-profile end-fire antennas based on log-period monopole and different top loading forms,covering the bandwidth of 1.19-11.7 GHz.Three different kinds of monopole elements are introduced,their performances and characteristics are analyzed,and the principle of capacitance loading and the equivalent circuit are described.A low-profile,end-fire antenna operates in the UHF band(300-900 MHz)is designed in the fourth chapter,a different feeding forms from the third part is adopted.The performance and characteristics of the feeding structure are introduced in detail.The results of scanning array made of 16 cells are analyzed.The performance of the antenna array after the cavity-embedded is also analyzed.Two proposed antennas designed in the third and fourth chapter are tested and verified.The test results show that the two antennas designed in this paper have obvious advantages in low profile performance,bandwidth range and meet the designing requirements.