Research On Wideband Reflectarray Antenna Based On Novel Element�'

Reflectarray antennas have been undergoing a rapid development due to their small volume, light weight, low loss, simple unit structure, flexible phase controlling and ease to fabricate. In this paper, we focus on how to design high-performance microstrip reflectarray units and how to achieve wideband and beam-scanning performance.In the first chapter, the research background and significance of the topic are summarized, and the development history of reflectarray antennas and the research status and hotspot in recent years are reviewed. Then, the research content of the paper is put forward.The basic theory and design methods of microstrip reflectarray antennas are presented in the second chapter. Then, the radiation characteristics, aperture efficiency and bandwidth of relfectarray antennas have been analyzed in detail. Then, the simulation setup of units and the advantages as well as disadvantages of several typical microstrip units are introduced in order to design a novel element for wideband application.A novel unit on the basis of theoretical analysis is put forward in the third chapter. Then a 10×10 elements wideband reflectarray antenna is designed and measured based on the novel element in a frequency band of 9.5 ~ 15 GHz. The simulated and measured results show a 28% bandwidth for 3-dB gain drop, a 44% bandwidth for side lobes below-10 dB and the main beams have little deviation.The research emphasis of this article is put in the fourth chapter, and two reflectarrays working in terahertz band are designed. Moreover, they are fabricated and measured. The measured results agree reasonable with the simulated results. The first reflectarray can achieve a 31% bandwidth from 0.225 to 325 THz for 3-dB gain drop, the peak gain of 33.9dBi and the main beams has little deviation in the designed frequency band. The second reflectarray can achieve frequency beams scanning ability. The main beams can scan in the range of 30 o when frequency changes from 0.2 ~ 0.3 THz. Moreover, the gain is in a range of 25.93 ~ 30.3dBi, corresponding to the aperture efficiency at 30 ~35%.In the fifth chapter, a novel dual polarized microstrip element is proposed that can be applied to designs of folded reflectarray and circular polarized reflectarray for bandwidth enhancement. Then, a 15×15 elements wideband folded reflectarray antenna is designed and a 30% bandwidth for 1-dB gain drop is achieved.In Chapter 6, the research works of the paper are summarized, and the future works are predicted.