Research And Design Of Novel Metal-Only Reflectarray Antenna

Reflectarray antennas, a novel type of antennas, retaining the features of simple-structure and high-gain as conventional parabolic reflectors, having the advantages of phased array antennas such as low-profile, low-mass, and beam reconfiguration capability, are widely used in satellite communications, space exploration, radar technology and other fields. However, reflectarray antennas generally work with a narrow operating bandwidth, which limits the further application of the reflectarray antennas into the broadband wireless communications. To solve above problems, this thesis further studies the methods to broaden the bandwidth of metal-only reflectarray antennas.The main work and innovations of this article are as follows:1. Based on the study of the phase shift characteristics of elements for metal-only reflectarrays and the working principle of the single-layer multiple-resonance structure, a novel metal-only element with single-layer multiple-resonance structure is presented, which can provide a linear phase response with a dynamic phase range in excess of 500 degrees and shows good bandwidth characteristics within 13.6% of the band.2. With an offset feed configuration, a metal-only reflectarray consisting of 9x9 proposed elements and a pyramid horn as the feed is designed and simulated; the simulation results show that the main beam deflection angle(θ, (?)) is (20°,0°) and the maximum gain is 19.9dB at 13.1GHz with 13.6%, 1dB gain bandwidth, in line with expectations of the design indicators.3. According to the less than 360 degrees actual phase range of element and unachievable phase compensation for reflectarray, the conventional array theory approach is used to analyze how the phase shift range of element affects the radiation charateristics of the reflectarray antenna. Consequently the phase shift ranges resulting in 1dB gain decrease and 3-dB gain decrease of reflectarray antennas are respectively figured out in different cases, which can provide a theoretical guidance to the engineering design of reflectarrays, especially for large reflectarrays and sub-wavelength technology.4. In view of the problem that the reflection phase curve linearity and phase shift range of traditional microstrip elements for reflectarrays can’t meet the design requirements at the same time, improvement methods about size change are proposed for the design procedure of the traditional patch and square ring. The proposed design methods are very helpful to reduce the error of the phase compensation and improve the radiation characteristics of the reflectarray antennas.