Research And Application Of Reflectarray Antenna In Reflector Antenna

In recent years,the demands on frequency resources of electromagnetic waves in communication systems are significantly increased,and applications of millimeter waves and higher frequency bands such as terahertz band are more and more popular.However,in conventional high-frequency applications,there are still some possible problems because of the limited machining accuracy of conventional reflector antenna.However,as a new type of antennas,reflectarray antennas combine the advantages of reflector antennas and array antennas,e.g.,ease of fabrication and good high-frequency performances.Therefore,the study of combining reflectarray antennas and dual reflector antennas is performed in this paper.In the first chapter,we introduce the background and significance of the selected topic,and also briefly introduce the development history of reflectarray antennas.Then we describe the researches and applications of reflectarrays with reflector antennas in recent years.In the second chapter,the fundamental working principles and design method of ring-focus reflector antenna are introduced.Then a shape optimization scheme of the ring-focus antenna based on genetic optimization algorithm is proposed.Finally,according to practical engineering requirements,a 0.6m shaped ring-focus antenna that operates in Ku-band is designed which eventually satisfies the design targets.In the third chapter,the working principle of reflectarrays is introduced firstly.Then we propose the scheme of using a reflectarray as a subreflector in a ring-focus antenna and also give the design method and calculation formula of the array phase distribution.This scheme not only has the unique advantages of the ring-focus antenna in small and medium aperture applications,but also solves the problem that the traditional reflector antenna is difficult to ensure the fabrication accuracy in high frequency applications.Finally,correctness of the design method are verified by the simulated results.In the fourth chapter,we firstly introduce the design method of the conventional reflectarray cell for dual-band applications.Then a novel dual-band reflectarray cell is proposed.Based on the related theory in Chapter 3,a dual-band ring-focus reflector antenna with a reflectarray subreflector is further proposed.The related design method is also given,and it mainly puts forward the optimization method of cell size matching in the two frequency band.Simulation results verify the correctness of the design method.Finally,we fabricated a 0.3m dual-band ring-focus reflector antenna operating in K and Ka bands.The aperture efficiency corresponding to the maximum realized gain in the two bands exceeds 52%,and the 1.5dB gain bandwidth can reach 19.6% and 15%,respectively.In the fifth chapter,the research works in this article are summarized,and some prospects for future work are also given.