Research On Ultar-Wide Band Antenna For Passive Direction-Finding

A conformal antenna is proposed which conforming four-arm Archimedean spiral antenna to rotating paraboloidal has two uses.One is used as an antenna for passive direction-finding,the other is used to be a parabolic reflector.When it is used as former, it still have characters as four-arm Archimedean spiral antenna ,such as ultra-wide band,circular polarzation,multi-modes directional patterns.When it severs as parabolic reflector,its gain and sidelobe level reach applied requirement.Also compared to independence,comformal antenna spares much space.A parallel,staging and united method is put into practice.The discussion is divided into two parts,which are four-arm comformal spiral antenna research and parabolic comformal reflector research.Each part still has three steps.For part 1,the steps are the study of performance and controlled variable of Arichemedean antenna,the comparison between plane shape and comformal shape,and the distinction between two-arm and four-arm.The aims of three steps are the basic design of Archimedean antenna,the differences of performance,the theory of direction-finding and feeding.At last,the three conclusions are united to benefit ultra-wide band performance and direction-finding performance of four-arm comformal Archimedean spiral antenna.As well as part 1,the part 2 also have three steps and three aims.The steps are ideal reflector research,the differences between ideal reflector and comformal reflector ,and optimal comformal reflector.The aims are the basic design of parabolic reflector,the variation of performance,the optimal design of the conformal reflector.Finally ,three conclusions are united to benefit gain and sidelobe level performance of the optimal reflector.Above all ,the optimal design of two parts is combined to decide the final form of the four-arm Archimedean spiral comformed to rotating paraboloidal.In the practical significance,the comformal shape is especially suitable for solving the problem that how to configrate caliber between active radar antenna and passive radar antenna.Due to the conformal form ,the antenna of passive radar could be used as reflector of the active radar .As a result,the contradition that interference and covering is created if the antennas are placed nearly and the grating lobe is generated if the antennas are installed far away is avoided.