Beam-scanning Reflectarray Antenna:Analysis And Design

Reflectarray antenna, benefits from its low profile, light weight and high gain characteristics, has been wildly used in many long distance communication systems. After decades of development, various element analysis model and system design method have been carried out for reflectarrays. However, most of the efforts have been devoted to broadband, multi-band and circular polarization designs. Recently, beam-scanning reflectarray (also known as reconfigurable reflectarray) has been developed and one of its major concerns is to design the electrically controllable phasing element by using MEMS, diodes, liquid crystals and so on. However, the use of electrically controllable elements make the antenna more complex and more expensive.While in this dissertation, two new methods for realizing beam-scanning reflectarray are reported and verified by measured and simulated results. One method used in the linear polarized reflectarray design is the tapering phase compensation method. By properly design the phase delay of elements, beam-scanning performance can be achieved with the help of an array feeder. Another mothed used in the circularly polarized (CP) design is to change the excitation amplitude of element in array feeder and therefore to move the feeder phase center. Thus, results in scanning of the reflected beam.Before investigating CP reflectarray, a new split-ring-related structure is developed for broadband CP design, and based on this structure, a new explanation for element operation mechanism is given. A CP reflectarray antenna with hexagonal split-ring element in hexagonal unit cell is also designed, and it shows a good agreement between simulated and measured results.