Wideband Dual Polarization Multibeam Large Radio Telescope Antenna Research And Design

The signals in the universe are different from each other, with very wide frequency ranges and different polarization, so the wide band and dual polarization observation techniques of radio astronomy are expected for development. In order to improve the sensitivity and resulting power of radio telescope with single reflector, the radio telescope antenna is required to have big radiation diameter to radiate electromagnetic wave, and have multiple beam for observation at the same time. Therefore, the effective area of reflector must be increased and more feeds are configured in the focal plane. The big reflector and the multiple feeds compose a multi-beam radio telescope antenna which can improve the sensitivity and resolution. In order to achieve the rapid development of radio astronomy technology in terms of the sensitivity and resolution in China, the researches of radio telescope with the largest diameter in the world is now under work-FAST (Five hundred meters Aperture Spherical Telescope). Aiming at the background of FAST, the main work of this paper is focused on the study of wide-band, dual-polarization and the multi-beam large radio telescope antenna. The main contents are as follows:The wide-band and dual-polarization horn feed is analysed and designed. First of all, the design process of the ridge horn feed according to the horn ridge waveguide theory is investigated. Then, the C band ridged feed horn is designed through the optimization design and the performance of it is tested to ensure the correct process of the feed. Finally, according to the design process of the C band feed, the broadband dual polarization feed that meet the requirement of FAST is designed, and the tolerance performance analysis of the designed feed is carried out to verify the feed meeting the needs of practical application.The multi-beam feed is designed. Firstly, according to the theory of partial focal, the partial focal characteristics of FAST are analyzed. Secondly, the geometric structure of the multi-beam focal plane feeds is designed and the space of the two adjacent feeds is calculated. Finally, the mutual coupling effects among the multiple feeds are analyzed.The pattern of the large radio telescope antenna is analyzed and calculated. Based on the far-field radiation characteristic of forward-feeding paraboloid antenna, the radiation pattern of the multi-beam radio telescope antenna is computed, and the maximum gain of the radio telescope antenna is calculated.