Design Of Millimeter Wave Shaped Double Reflector Antenna

Due to the rapid development of millimeter wave in new communication, radar, radio astronomy and remote sensing systems, the researches of millimeter wave antennas have received more and more attention. Reflector antennas are the common form of millimeter wave antennas with the advantages of high gain, low side lobe, simple structure and flexible design. To achieve a millimeter wave multi-beam antenna with high gain and narrow beam angle or a conical beam antenna with omnidirectional radiation characteristics in some certain radar systems or satellite communication applications, we can use flexible shaped reflector antennas. This thesis mainly aims at the researches on millimeter wave shaped dual-reflector antennas.Firstly, the research is on the physical optics (PO) based on the surface current integral method. After that, a matlab program based on the PO is written. The program can calculate the normalized antenna pattern of the parabolic antennas.Then, by use of the matlab program, we do the research on beam width influenced by the aperture fields. On the basis of this, we design a millimeter wave dual-beam dual-reflector antenna with high gain and narrow beam angle by replacing the horn feed with a small aperture dielectric rod antenna to realize the taper amplitude distribution. The gain of the designed 78GHz dual-beam antenna is 38dB and the aperture efficiency is 51.9%. The two beams overlap at -3dB with a 2 degrees beam angle. The antenna can meet the detection requirements well.Finally, the research is on the conical beam reflector antennas applied in point-to-multi-point ground satellite communication coverage. The conical beam antenna can receive a uniform phase distribution on the aperture of the specified direction by shaping the reflectors. Then two shaped dual-reflector conical beam antennas working at 35GHz are designed with a 30° and 60° conical angle, respectively. The conical beam antenna with 30° conical angle has a gain of 13.4dB and a side lobe of -14.3dB. The conical beam antenna with 60° conical angle has a gain of 11.7dB and a side lobe of -15dB. Both of the two antennas have a good circular symmetry in the azimuth plane.