Miniaturization Research And Direction Finding Application Of Planar Helical Antenna

With the advantages of ultra-wideband,circular polarization,and wide beam,the planar spiral antenna can realize the interception of most target signals and is widely used in the field of electronic reconnaissance and direction finding.The development trend of miniaturization and integration of modern electronic reconnaissance and direction-finding equipment has put forward higher and higher requirements for the miniaturization of planar spiral antennas.In this thesis,it mainly studies the miniaturization of planar spiral antennas,relevant simulations and tests verify that the planar spiral antennas designed in this thesis can achieve good impedance characteristics and circular polarized radiation performance in the target frequency band,and achieves the goal of miniaturization.Main contents of this thesis are as follows.1.Design of a classic Archimedean spiral antenna: Based on the principle of non-frequency-varying antennas and the radiation mechanism of Archimedean spiral antennas,a planar spiral antenna with a working frequency band of 2 to 18 GHz is designed in detail,including: spiral radiating surface,microstrip exponentially graded balun and absorption cavity.Simulation results show that the antenna can achieve ultra-wideband characteristics.2.Design of miniaturized planar spiral antenna: On the basis of Archimedean spiral antenna,a miniaturized planar spiral antenna with a working frequency range of 2 to 18 GHz is designed.The feasibility of the design is verified by simulation and measurement,which show that compared with the classic Archimedean spiral antenna,the improved antenna achieves ultra-wideband characteristics while realizing miniaturization.The antenna is applied to a two-dimensional interferometer direction finding system,which can realize the two-dimensional direction finding function with wideband,wide angle of view and high precision through the reasonable baseline configuration.3.Design of miniaturized four-arm spiral antenna: Based on the analysis of the characteristics of Archimedean spiral and equiangular spiral,a new type of spiral curve is designed,which has the advantages of wound closely and variant spiral growth rate and can be adjusted flexibly.Based on this new spiral curve,a miniaturized four-arm spiral antenna with a working frequency range of 0.8 to 4 GHz is designed.Simulation results show that,compared the classic Archimedean spiral antenna,the improved antenna not only has a smaller diameter but also has the better performance of low frequency,verifying the feasibility of the method.At the same time,with coordination of the network for forming modes,and the antenna can realize two working modes: sum mode and difference mode.It can be used in the phase-and-amplitude comparing direction finding system which can realize the two-dimensional direction finding function of wideband and has the advantages of simplicity and reliability.