An Edge Slot Traveling-wave Array With Dielectric Directors

Due to the characteristics of narrow azimuth beam,wide pitch beam,horizontal polarization and easy to control its aperture amplitude distribution,the waveguide narrow-wall slot array is widely used as a navigation radar antenna.Because a single waveguide slotted antenna can scanning in the azimuth plane only by mechanical scanning,so how to reduce the height of this antenna for decreasing the wind resistance during mechanical scan is a meaningful research direction.The work of this paper focuses on the designing of low sidelobes narrow-wall slotted array,the controlling this antenna's pitch plane's beamwidth in a limited aperture size and improve the gain of this antenna.This paper mainly studied the following aspects:Firstly,the design method of waveguide narrow-wall slot array with low sidelobs is studied.A traveling-wave array operating in X band is designed by simulation software.The sidelobs of its azimuthal plane is lower than-28 dB among the working frequency range.In addition,the method of suppressing the cross polarization level of this type's antenna is studied.The cross-polarization is suppressed more than 25 dB by mounting choke and parallel metal grids.Secondly,the method of compressing the half-power beamwidth when the diameter of the antenna is limited is proposed and studied.By mounting low-loss dielectric plate structures in front of a narrow-wall slot array,the pitch beam width of this antenna is narrowed to a range ofoo323 ? when its height is only 50mm(about1.5?),and the gain is also increased by 1~2dB.A method to decrease the sidelobe of the antenna's H-plane by loading multi-layer dielectric plates is proposed,and the sidelobe level of the antenna's elevation surface is controlled below-15 dB.In addition,the method of loading dielectric rods and parallel metal grids to get a narrow beam is proposed,and the effects of these structures are compared.Finally,an waveguide narrow-wall slot array with dielectric loaded structures is fabricated and measured.The reason of the error is analyzed after comparing the measured results and the simulation results.The measured results are in good agreement with the simulation results,which proves the rationality of the design method which presented by this paper.The proposed antenna has the advantages of low profile when the beamwidth of its vertical plane is set,and the sidelobes of this antenna keep a lowlevel.