The Optimization Design And Error Analysis Of Planar Reflectarray Antenna

Reflectarray antenna is one of the promising high gain antennas that combining the forms and principle of the conventional reflector and array antennas.Reflectarray antenna can realize specific shaped beams or pencil beams in certain direction by adjusting the reflection phase of each element.Reflectarray is featured for its low profile,low weight,low cost,high gain,easy fabrication and easy integrated.Thanks to these advantages,the reflectarray has developed many antenna forms and has the promising future.This dissertation is focused on several topics,the wide gain bandwidth performance,multiband optimization and design,shaped beam optimization,error analysis in space environment and applications.The main researches and the novelties are listed below:1.The research of widening the bandwidth of planar reflectarray antennas.Two novel wideband unit cell are proposed,one is the circular patch with four semicircular ring slots and the other is four-arm square spiral structure.These two structures show good performances with reflection phase range of more than 360 degree and linear reflection phase curve.Based on the proposed structures,planar reflectarray using circular patch with semicircular ring slots and planar reflectarray using four-arm square spiral structure are designed,simulated,fabricated and measured.The tested results show that the 1.5-dB gain bandwidth of the former reflectarray is about 24% and the 1-dB gain bandwidth of the latter one can reach to 34.7%,which is excellent compared to other single-layer planar reflectarray antennas.2.The design and optimization of tri-band aperture-reuse planar reflectarray antenna.The aperture of multi-band antenna can operate at different frequencies simultaneously.More frequency bands mean more possibilities of reuse.A tri-band single-layer aperture-reuse reflectarray utilizing multi-parameter sweeping method and particle swarm optimization(PSO)algorithm is designed.The multi-parameter sweeping method is first introduced in the design of tri-band reflectarray antenna.The triple nested square ring with rotation is adopted as the phasing element,several independent parameters such as the length of outer square,ring width,ring gap and rotation angle are combined to simulate.The database of element reflection phase group and several parameters at the frequencies of 10 GHz,15 GHz and 20 GHz are constructed.The PSO algorithm is adopted to reduce the total phase error and optimize the unit cell arrangements.The measured results show that proposed reflectarray can work well at X,Ku and K bands.In comparison with other tri-band reflectarrays,balance performance in three bands for 3-dB gain bandwidth and aperture efficiency.The procedure of design and optimization can also be applied to other multi-band aperture-reuse reflectarrays.3.The research of designing and optimization of single-layer planar reflectarray antennas with shaped beams.The biogeography-based optimization(BBO)algorithm is used to optimize the shaped single-layer planar reflectarray based on the topography of mainland China.The BBO algorithm can dramatically reduce the iterations of optimization process compared with PSO and genetic algorithm.The discrete two-dimensional IFFT and FFT methods are utilized alternatively to optimize the four-beam single-layer shaped planar reflectarray.The radiation patterns calculated in MATLAB are similar with results simulated in HFSS,which verifies the feasibility of the two optimization methods.4.The research and exploration of planar reflectarray in engineering application.The theoretical analysis of the relationship between element position and reflection phase error is first carried out.Then the possible deformations of the planar reflectarray are simulated in HFSS to show the influences on radiation patterns.The related improvement measures are also proposed.By improving the existing spaceborne reflectarray element,the transparent quad-key element working on the surface of solar cells and metal-only element using square spiral structure are designed.Spaceborne reflectarray,transparent reflectarray and metal-only reflectarray,are designed based on the previous elements.The simulation results live up to the expectations.