| With the development and progress of Electronic Science and Technology,the use of radio waves is moving towards a higher sub millimeter-terahertz band,and has been widely studied and applied in radar imaging,non-contact security,target detection and tracking and other fields.In addition,as one of the core components of wireless communication system,the beam scanning ability of antenna will directly affect the performance of the whole system.The research content of this project is terahertz scanning antenna,which is mainly divided into three parts: terahertz scanning imaging system,terahertz monopulse scanning antenna and laser controlled scanning antenna.Terahertz imaging is one of the two key technologies in terahertz field.In this paper,the mechanical structure design of the imaging system based on the shaped double reflector structure is carried out,and two sets of experimental devices are designed for outdoor and indoor imaging respectively.The indoor close-range imaging experiment results are given,and the imaging effect is ideal.In addition,based on the focal plane array imaging system,three kinds of imaging optical receiving systems with good performance are designed by using single lens,double cemented lens and double lens structure respectively.At 850 GHz,the imaging performance is simulated and analyzed: the maximum field of view is up to 17 °,the resolution can reach 0.143 °,and the scanning can be realized within 30 ° of the elevation plane.Terahertz monopulse scanning antennas are mainly used in positioning systems.Two monopulse scanning antennas are designed in this paper.One of them is a mechanical scanning antenna based on the quasi optical theory and technology,which adopts the combination of flat mirror and ellipsoidal mirror.The central frequency of the antenna is 340 GHz.Simulation shows that the gain of sum beam and difference beam can both reach more than 50 dB,the sidelobe level of sum beam is below-20 dB,the zero depth and imbalance of difference beam are less than-20 dB and 1dB respectively,the sum-difference contradiction is less than 4dB.In addition,the indicators such as cross-polarization also meet the requirements,and the bandwidth can reach 10 GHz.At the same time,the antenna can scan within ±30 degrees on the elevation plane and 360 degrees on the azimuth plane.The other is a planar super lens scanning antenna which is based on the beam steering theory of transmission array and with the "cross & square-circle contour" patch structure.CST simulation shows that the gain is more than 25 dB and the sidelobe level is less than-15 dB.And in theory,two-dimensional scanning can be realized in elevation plane and azimuth plane.The laser controlled scanning antenna is a new type of scanning antenna.In this paper,the transmission and reflection scanning schemes based on laser control are designed and completed at 220 GHz.For the transmission scheme,the horn gain test,ITO performance test,and sandwich structure loss test have been completed,and the black-and-white contrast experiment and the shortening distance experiment have been completed when the optical control performance test cannot be carried out(Due to the high loss of optical path and the low power density of irradiation on silicon wafer,it is impossible to verify its ability of bunching and scanning).The former proves that the light intensity(optical power density)can indeed control the pass rate of sub millimeter-terahertz wave,and further illustrates the feasibility of transmission optical control performance test;the latter shows that shortening the distance can improve the experimental effect.Finally,the PCB performance test is carried out to verify the correctness of the transient Fresnel zone plate pattern design.For the reflective scheme,for the same reason,only the black-and-white contrast experiment is carried out,which proves that the reflectivity of sub millimeter-terahertz wave increases gradually with the increase of laser power,and verifies the feasibility of the reflective optical control performance test. |
PDF Full Text Request