Reasearch Of Wideband And Dual-polarization Reflectarray Antennas

Reflectarray antenna possesses both advantages of conventional parabolic reflector antenna and phased array antenna,such as light weight,small volume,low cost,easy fabrication and easy deployment.Thus,it is widely used in the fields of wireless communication systems for long distance,such as advanced capabilities radar,long-distance communication,space measurement and deep space exploration.However,due to the disadvantages of the narrow bandwidth,the developments and applications of reflectarray antenna have been restricted.In the first part,the paper firstly introduces the conception and principle of reflectarray antennas especially for the design and analysis of reflector unit which is the most important part in design of reflectarray antennas.In order to solve the problem of narrow bandwidth,the paper puts forward a novel structure composed of composite metallic and dielectric mediums which used as the basic element of reflectarray antenna.Phase shift of the structure can reach 360 degree in the frequency of 11GHz~14GHz.More importantly,curves of phase shift in each frequency have high linearity and parallel to each other.After that,a wideband reflectarray antenna is designed by compensating for the phase delay of all reflector units from feed to aperture plane.Illuminating feed of the system is horn which is a common option for reflector antennas.The novel composite dielectric and metallic reflectarray antenna consists of with the gain of which being 22.65 dB at the center frequency and a 22.56% bandwidth being achieved with 1-dB gain variations.In the second part,a dual polarization reflectarray antenna and a reflectarray antenna with special beam point is designed by the method of compensation for phase delay.The two kinds of reflectarray antennas listed above both consist of 256 elements with conical-horn being their feed.The max gain of dual polarizarion can achieve 23.52 dB and its 1.5dB bandwidth is 20.38% with the performance of its cross-polarizationg being less than-20 dB in its half power beamwidth.Accordingly,the main beam’s direction of the other antenna is precisely designed to-30? at the center frequency of 13 GHz with its max gain being 21.17 dB and the performance of its cross-polarizationg being less than-20 dB in its half power beamwidth.