Research on quasi-optics and feed antenna for Millimeter wave imaging system

The quasi-optics sub-system of Millimeter-wave focal plane arrays imaging system includes the design of system parameters, multi-beam design of focusing element and design of feed antenna. Design of focusing element decides the spatial resolution and the maximum field of view of the system. The design and arrangement of the feed antenna related to the overflow efficiency and the spatial sampling rate of the system. In this paper, fundamental mode Gaussian beam method is taken to design quasi-optics, and focusing lens antenna is designed with the principle of optical path difference of feed sources on optical axis. In this paper also proposed a new kind of dielectric rod antenna with new structure as the feed source to the lens. The simulation and measurement show that the multi-beam lens antenna has a better wide-angle scanning feather. The feed antenna has broader wave band, lower side lobe, lower mutual coupling, lower cross polarization, and the gain of it can be changed by changing its length but not the section area. It is easier to form a close feed array which can realize an effective exposure to the lens or the reflector antenna with less overflow loss.