Study And Design Of Multi-beam Reflector Antenna

This paper aimed at the research and design of multi-beam parabolic antenna in Ku-band. By palcing plurality of feed at the focal plane of the reflecting surface, the multi-beam of antenna can be achieved. And for the angle diversity mutli-beam antenna is less widely used compared with spatial diversity in Ku-band, this paper proposed that relector antenna can be used in angle diversity when the separate feed with small relevant in beam was palced at the focal position of the reflecting surface as close as possible.In the specifical design, it is proposed to use the dielectric rod antenna as the feed of relector antenna to replace the conventional horn antenna by comparing the differences between a horn and a dielectric rod antenna. Then an orthogonal mode transducer(OMT) is designed to achieve the isolation of transceiver and receiver. The dielectric rod antenna and OMT were optimized as a whole dual-polarized structure and a variety of performance parameters such as VSWR, the peak gain, isolation of the ports and HPBW were given to achive the requirements of system design.Using the optimized dual-polariziton dielectric rod antenna as the feed of reflector system, the radiation characteristics was researched with a single feed to decide the caliber and focal diameter ratio of the reflector and the placement to install the feed. Then two dielectric rod feed were arraying in order to achieve multi-beam performance. Three metal separators were used to solve the problem of the electromagnetic mutual coupling after feed arraying and the effect on radiation performance of support structure was also researched. Finally, a dual-beam parabolic reflector antenna was designed with index requirements meeting.In the operating frequency band, the VSWR of each port is less than 1.5, the isolation between two different ports is no more than-30 d B, the gain of each beam is no less than 45 d B, the cross-polarization isolation of the beams is no less than 35 d B, and the beam angle between two symmetrical beam is about 0.75 times of beam width. This reflector antenna achieved a small size, dual independent beam, high gai n, narrow beam angle, low cross-polarization level. There is a certain value in the angle diversity of troposphere communication.