Investigations On High Efficiency Reflectarray Antennas

As one kind of the large aperture antennas,Reflectarray antenna combines the advanteages of tranditional reflector and that of phase array together,appealing to attentation and study widely.Large aperture antenna accounts more and more in many fields such as wireless communication,radar,space tracking,etc.and these systems,in turn,put higher requirements on the antennas.Based on the application background,we have finished the study on reflectarray antenna design and analysis,especially concerned the problem on how to improve aperture efficiency.The work foucus mainly on element design,the whole structure parameters and optimization on reflection plane design.To be specific,it mainly contaions four aspects as following.To begain with,the background and significance of reflectarray antenna are introduced followed with recent and future applications.At the same time,typical elements and their working principle are illustrated.All abover lay a solid foudmation to later study.Then,the working mechanism follows,including analysis on broadband techniques and aperture efficiency.The widely used method on phase compensation which is based on ray theory is illustrated in this part.To verify its viability,a reflectarry is designed with this approach.Finishing the theory study,the design on high efficiency reflectarray begains with reflection element analysis.A multi-resonant microstrip element is obtained,achieving a suffent phase shift range and having a potential to realize broad band with almost parallel phase shift curves on different frequencies.And then,element testing refering to Waveguide Simulator has been carried out to test characters of the element,showing a perfect match.At the next stage,the research moves on to analysis on aperture efficiency and approaches of improving the accuracy of phase compensation.Structural parameters such as feed position and ortation are analysed.In addition,the method of compensating phase difference based on illuminating field is proposed and illustrated to perfect the design flow.According to the design procedures,a reflectarray woring on Ku-band with 3-dB bandwidth 28.6% and aperture efficiency of 64% is achieved.And then,the validity of this procedure is verified with the reflectarray structure designed based on ray theory,and the comparison on aperture efficiency illustrates the priority of the innovation method.