Research On RF Synthetic Aperture Based On Metamaterial Lens Antenna

Metamaterial planar electromagnetic lens has the capability of broadband operation,and can realize the functions of object detection,communication and target detection on a specific aperture,and realize the integration of functions on a fixed aperture.The antenna gain can be greatly improved when the lens are combined with the feed antenna.Compared with traditional high-gain antennas such as phased array,dielectric lens antenna and reflector antenna,planar lens antenna has many advantages such as simpler feed network,low profile and adjustable electromagnetic phase.However,it still has some limitations: the phase adjustment ability of the lens unit is limited,and the aperture and focal length cannot be flexibly adjusted;The lens unit usually adopts the multi-layered structure of one-quarter wavelength air layer interval,and there are some problems in thickness,loss and matching of the lens;The oblique incidence performance of the lens antenna is poor,and the gain will decrease greatly when the angle exceed ±45.In this thesis,the design method of ultra-wideband wide-angle incident and low-profile metamaterial electromagnetic lens was mainly studied.Two types of metamaterial planar electromagnetic lens in X band and Millimeter wave band were designed.The main contents and contributions of the thesis are summarized as follows:Firstly,the basic principle of electromagnetic lens was introduced.In order to increase the phase regulation capability of lens element and improve pore efficiency,a set of X-band lens element with wider phase regulation capability was optimized and designed based on the equivalent circuit model of third-order band-Pass Chebyshev I filter by using the design method of miniature frequency selection surface.The CST results show that the designed X-band units can cover 360 degree full cycle.Next,based on the above lens unit and the method of real time delay,a complete full-period X-band lens is designed.Due to the multi-layer coupling design of the lens unit,good matching can be achieved without the air layer of interlayer interval one-quarter wavelength,which greatly reduces the thickness.The thickness of the designed X-band lens is 2.6mm.The patch antenna and the Vivaldi antenna were designed as the feed antenna.The CST full-wave simulation results show that the designed X-band lens antenna can cover the range of 8GHz-12 GHz and achieve ±30 oblique incidence performance.The gain of the lens can reach 21.25 dBi when the antenna is vertically incident at the central frequency10 GHz.Then,in order to improve the wide-angle scanning performance of the lens,a multi-period wide-angle scanning lens was designed using the method of Block design and oblique incidence compensation,and the broadband millimeter-wave patch antenna was used as the simulation feed.The designed wide-angle scanning lens has a gain of 27.3dBi at vertical incidence,the gain decreases by 1.5d B at the ±30 scanning angle,the gain decreases by 2.5d B at the ±45 scanning angle,and the gain decreases by 6.4d B at the ±60scanning angle.The designed wide-angle scanning lens has good wide-angle scanning performance.Finally,the dual-period millimeter wave lens and millimeter wave patch antenna were machined.The experiment and simulation results were in good agreement.When the frequency is 30 GHz,the gain of the millimeter wave patch antenna can be increased by15.4d B and the gain of the lens antenna can reach 24.1dBi.The bandwidth of the lens antenna can reach 28GHz-32 GHz.