Research And Design Of Meta-material And Transmitarray Antennas

Metamaterial antenna is a novel research in electromagnetics field in recent years,which attracts wide interest among scholars due to its unique characteristics like multi-band,wideband,miniaturization and high gain.Transmitarray antenna is a new antenna array design with highgain radiation performance and flexibility in design and fabrication,it has been the focus of research by experts and scholars in recent years.This paper begins with the development and current situation of metamaterial and transmitarray antennas researches to analyze the characteristics and research trends of these two antenna designs.Then the frequency band characteristics of CRLH-TL and the working and design theory of transmitarray antennas are researched.Based on these theories four antennas with wide bandwidth and high gain are proposed,each has its own characteristics.Results in this paper can be summarized as follows:1.A wideband and high-gain mushroom CRLH-TL antenna working in 5.4-8.2GHz was designed.Based on the muli-band characteristics of CRLH-TL and the theory of SIW,a welldesigned SIW cavity was introduced into a wideband and muli-band mushroom CRLH-TL antenna,which improved impedance bandwidth and gain of the antenna.This modified antenna achieved measured bandwidth from 5.4GHz to 8.2GHz and highest measured gain of 9.5dBi,the measured results of this antenna agreed well with simulated ones,which validated the superior performance of this antenna design.2.Based on the theory of transmitarray antennas,a transmitarray antenna working at 16 GHz and a dual-band transmitarray antenna working at 16 GHz and 27 GHz were designed.Both triple-layer metal transmitarray units have characteristics of wide frequency passband,low transmission loss and can achieve phase adjustment of about 360 degrees in the working frequency bands.Based on these two units,two transmitarray antennas were designed.The dual-band transmitarray antenna achieved simulated gain of 27.8dBi and 26.9dBi at 16 GHz and 27 GHz,corresponding to aperture efficiency of 78% and 22%,which had excellent performance of dual-band and high gain;another transmitarray antenna achieved measured gain of 26.9dBi and aperture efficiency of 64% at 16 GHz,1dB gain bandwidth of 14% and cross-polarization level bellow-45 dB were achieved as well.The measured results of this design was in good agreement with simulated results,which proved the feasibility and performance of this design.3.Two types of double-layer transmitarray unit designs with low profile were proposed,both units were designed by two layers of 0.5mm thick substrate with total profile of only 3.5mm,and achieved about 360° phase adjustment in the working frequency passband.The unit 1 performed good adaptability in both x and y polarized incident waves due to its symmetrical structure,unit 2 was modified through unit 1 and showed good single-polarization characteristics.Finally,based on unit 2 initial transmitarray antenna was designed and measured,this transmitarray antenna prototype achieved measured gain of 22.8dBi,1dB gain bandwidth of 19% and cross-polarization level below-35 dB at 14 GHz,which matched well with the simulated results and proved the decent performance of this unit design.