Study On Dual-Reflector And Reflectarry Compact Antenna Test Ranges

Compact Antenna Test Range(CATR)can be used for the measurement of high-frequency large-aperture antennas.It uses the conversion unit to generate pseudo-plane waves in a small space,forming a near-field region suitable for antenna measurement,which is called the Quiet Zone(QZ).The CATR is mainly divided into lens CATR and reflector CATR.Reflector CATR is widely used,and the reflector is usually used as the conversion unit.Because of its wide measurement frequency band and high effective measurement aperture,it has been widely concerned.The CATR with planar reflectarray as the conversion unit is rarely studied.Compared with curved surface structure,planar reflectarray antenna has the advantages of simple structure,mature processing and low cost,which is one of the research hotspots of scholars in China and abroad.In this thesis,the dual-reflector CATR and the reflectarray CATR are designed with the reflector and the reflectarray antenna as the research objects.The main research contents of this thesis can be summarized as the following two parts:1.Two types of dual-reflector CATR,biased Gregory and biased Cassegrain,are designed.The dual-reflector antenna contains two reflectors.Compared with the single-reflector antenna,it increases the design flexibility and is conducive to controlling the aperture field distribution.In this thesis,the ray tracing method based on geometric optics theory is used to design the shaped reflector of the dual-reflector CATR.According to the principles of energy conservation and light propagation law,the reflector is meshed and extrapolated from inside to outside.The mirror parameters of the reflector are obtained by solving the linear equations,and the shape design of the two reflectors with established initial positions is completed,so that the spherical wave emitted by the feed is transformed into a pseudo-plane wave after passing through the dual-reflector system.Based on the above algorithm flow,this thesis designs the application program of shaped dual reflector antenna,and uses this program to design two sets of dual reflector CATR.In the QZ,the amplitude fluctuation of the two designed CATR is within 1.5 d B,the phase fluctuation is within 10.6°,and the crosspolarization isolation is close to 30 d B.2.A stepped reflectarray CATR is designed.The planar reflectarray antenna is a new type of antenna which combines the characteristics of planar antenna and array antenna.It has many advantages such as low profile,easy processing and low cost.Firstly,a single parabolic cylindrical CATR is designed to determine the basic parameters of the reflectarray antenna.Then,with the square patch as the basic unit,a reflectarray antenna with 3500 units is designed.Finally,by analyzing the QZ performance of the reflectarray antenna,the edges of the array is optimized into stepped shapes,and a hole is "opened" in the middle to improve the QZ performance,and the design of the reflectarray CATR is completed.The test results show that the amplitude fluctuation in the QZ of the reflectarray CATR at the center frequency point is within 2.47 db and the phase fluctuation is within 10°.