Beam Scanning Reflectarray For Millimeter Wave Imaging

In recent years,the technology in the field of antennas and microwaves has developed rapidly.The frequency bands used by electronic devices have expanded to millimeter waves,and millimeter wave imaging technology has been widely researched by domestic and foreign scholars because of its unique advantages of small radiation and high imaging resolution.The millimeter wave can transmit clouds,fog,dust,etc.in a specific atmospheric window band,and have unique advantages such as infrared rays and X-rays.It can realize the ability to work without weather intervention and time limit.Therefore,millimeter wave imaging technology has great potential in the field of remote sensing imaging.In the remote sensing millimeter wave imaging system,the antenna is one of the core of the system,and the performance of the antenna can determine the working efficiency and accuracy of the system.According to the development needs of the new remote sensing millimeter wave imaging system,it is necessary to design a high performance antenna with high gain,low side lobes and beam scanning function,and because of circularly polarized electromagnetic waves,it has artifact removal in millimeter wa ve imaging technology.Because of this unique requirement,this paper analyzes the performance index of the antenna,explores the working principle of the beam scanning reflectarray antenna,and design a circularly polarized beam scanning reflectarray antenna.In this paper,the multi-focus phase compensation scheme is finally selected,and two different reflective array antennas operating in the Ka-band and centered at 35 GHz are modeled and simulated.The unit of the first type of reflectarray is a single layer of unequal-length cross-shaped microstrip patch,and the feed is composed of a corrugated horn and a spacer circular polarizer.The second type of reflectarray is a double-layer rectangular microstrip patch,and the feed source is combined with a dual mode cone horn to realize linear polarization-circular polarization conversion of electromagnetic waves.Finally,the beam-scanning reflectarray antennas in the form of polarization conversion are processed and tested.The results meet the requirements of the system and can be applied in remote sensing millimeter wave imaging equipment.