Design of quasi-optical subsystem for millimeter-wave imaging system

Methods of quasi-optical subsystem is researched to improve the spatial resolution of the millimeter-wave imaging system. On the basis of characteristics comparison of different design methods, fundamental Gaussian beam method is introduced in detail and formulas are given. Relationship between waist radius and gain of feed antenna is researched. Effects of beam truncation are discussed and lens as the focusing element is designed as well. At last, the quasi-optical subsystem for millimeter-wave imaging systems is designed with fundamental Gaussian beam method. Design process is easy to carry out and all parameters are given by formulas. So the quasi-optical design is practical for millimeter-wave imaging system.