| High-gain reflector antennas are widely used in radar and CATR(Compact Antenna Test Field).The CATR can provide a quasi-plane wave test area with excellent performance at a short distance,and imitate the far field for antenna radiation,radar cross section tests,and multi-target detection.However,due to the large volume and heavy weight of the traditional parabolic antenna of CATR,and the curved surface structure of manufacturing is difficulty,it is currently a research hotspot to study technologies such as light-weight and integrated reflector antennas.In this dissertation,the new reflector of 3D-printed technology,reflectarray and metasurface polarization control technology are used to improve the performance of reflector antenna.A series of high-performance new millimeter-wave reflectors with broadband,high gain and light weight are explored and researched from the aspects of radiation unit,mechanical reconfigurability,new processing technology and millimeter-wave electromagnetic control metasurface of millimeter-wave reflector,and it is suitable for reflector surface CATR system.The main reserch of the dissertation is as follows:1)Research on lightweight millimeter-wave parabolic antenna and CATR.(1)Research on a new type of reflector antenna based on 3D-printed.In order to solve the problems of traditional millimeter-wave parabolic antennas,a high-precision and lightweight reflector antenna was designed using photosensitive resin3D-printed and metallization.Due to the easy to shape of the photosensitive resin material,the 0.07 mm layer thickness photocuring printing is used to realize the high-precision manufacture of the parabolic antenna.And the 3D-printed surface is metallized to obtain good reflective milliwave characteristics.Electromagnetic simulation optimization was carried out for the antenna.And the error analysis of the antenna machining accuracy on the reflection is reserched.The measured results show that a good re flection effect on millimeter-wave signals in the entire Ka-band Compared with the traditional milling-processed all-metal aluminum material,the antenna can reduce the weight by more than 50%,which is of great significance for the lightweight and integra tion of the millimeter-wave reflector antenna.(2)Research on the move ment characteristics of Quiet Zone(QZ)with array feed reflector antenna.In order to satisfy the requirements of the moving target test,the moving characteristics of the QZ with array-feed reflector antenna are reserched.The phase control of the feed is used to realize the Q Z scanning function.The results show that when the phase of the 1×3 array and the 2×2 array feed changes,the beam pointing of the array feed is changed,and the movement of the quiet zone is realized,which meets the requirements of testing the moving target.2)Research on broadband millimeter-wave reflectarray antenna(1)Research on ultra-broadband millimeter-wave dielectric reflectarray.Aiming at the narrow bandwidth of general metamaterial structures,a lightweight ultra-wideband dielectric reflectarray antenna is proposed.The top layer of the reflectarray unit is a rectangular parallelepiped dielectric resonator with a fixed height and a width of L,the middle layer is a matching support dielectric layer,and the bottom dielectric plate is coated with copper as a reflective layer.By adjusting the width of the dielectric block on the top layer of the reflectarray,the equivalent dielectric constant of the d ielectric resonator unit is changed,so as to control the change of the reflection phase.The different phases on the elements collectively produce a constructive interference in a different direction,producing the main lobe.According to the phase distribution of the units,corresponding to the reflection phase of different elements,the size of each element on the surface is obtained to design the reflectarray.The top dielectric structure and middle matching layer of the dielectric reflectarray are printed with photosensitive resin material 3D-printed.The measured results show that the gain reaches 25.8d Bi～28.9d Bi from 27.5GHz to 38 GHz and the 3d B gain bandwidth is 32.1%.In 28～35GHz,the measured aperture efficiency is greater than 30%;the 3d B beam width of the E-and H-planes are both 5.4°,and the main beam is relatively stable in Ka-band.(2)Research on millimeter-wave reconfigurable reflectarray antennas.The mechanically reconfigurable ultra-wideband reflectarray antenna is composed of a double-layer dielectric,the upper plate is in the same position,and the lower plate is a double-sided structure,which can be mechanically flipped to realize dual-frequency operation.The top layer of the reflectarray unit adopts a square patch externally loaded open resonant ring to increase the phase compensation range of the high frequency-band,and the middle layer uses a loaded resonant ring to compensate the phase smoothness of the low frequency-band to achieve broadband characteristics.The designed microstrip reflectarray controls the reflection phase by changing the dimensions of the square patches on the top and bottom layers of the unit.The upper and lower double-layer structure operates at 27.5～30.5GHz.For the mechanically reconstructed,the upper s tructure is unchanged and the lower structure is turned over to make the metal plate as the ground,and it operates at 30.2GHz～34.5GHz.The measured results show that when the operating frequency is from 27.5GHz to 34.5GHz,the gain reaches 27.2d Bi～28.0d Bi,the gain bandwidth of-1d B is 22.6%,and the aperture efficiency is above 24%,of which the aperture efficiency reaches 39% at 28 GHz.The E-and H-plane 3d B beamwidths both reach5.3°.The proposed mechanically reconfigurable reflectarray antenna has low sidelobes,high gain and wide operating bandwidth.At the same time,the reflectarray aperture is rotated by 45° to reduce the influence of edge diffraction on the main radiation pattern,thereby reducing the side lobes below-20 d B.3)Research on Metamaterial Tunable Devices Applied to CATR.(1)Polarizer research based on an inverted Cassegrain CATR.In order to reduce the cross-polarization of the CATR on the inverted Cassegrain reflector,it is reserched that the sub-reflector has a 90° polarization co nversion function,which can improve the cross-polarization characteristics of the CATR.We designed a ultra-broadband polarization conversion reflective metasurface,which uses a rhombic hollow structure to achieve 90° linear polarization conversion,and through the analysis of the surface current distribution on the structure,the physical mechanism of broadening the frequency band and achieving high conversion rate is reserched.The measured results show that in the frequency band of 14.2-36GHz(with the relative bandwidth of 86.9%),the polarization conversion rate PCR is greater than 90%.(2)Research on the graphene polarizer based on the composite reflector CATR.In order to solve the problem that a single detection system cannot meet the detection of multi-target in the near field,a millimeter wave/terahertz composite detection system is used.The CATR technology is conformally integrated with the reflector constriction field and the graphene polarizer,and is applied to the hardware-in-the-loop simulation and testing of the millimeter-wave/terahertz composite detection system.The graphene polarizer we designed is based on silicon dioxide crystal material,which is composed of metal grids,diamond structures and graphene strips,and has the function of transmitting terahertz and reflecting millimeter waves.The simulation results show that the polarization converter rotates the linear polarization direction by 90° in the frequency range of 0.5THz to 3THz,the conversion rate is greater than 90%,the relative bandwidth is as high as142.9%,and the transmission conversion rate can reach more than 70%. |
