Contoured-beam antenna using smoothly shaped dual-reflectors for broadcasting satellites

✍ Scribed by Kazuyoshi Shogen; Hayato Nishida

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 817 KB
• Volume: 76
• Category: Article
• ISSN: 8756-6621
• DOI: 10.1002/ecja.4410760407

✦ Synopsis

Previously, the authors have proposed a design method of a shaped dual-reflector contoured-beam antenna with virtual multihorns with a view to applications to the broadcast satellite BS-3. In such a design, there were discontinuities on the main reflector.

In this paper, a method for eliminating these step discontinuities is studied for the dual-reflectors. The current distribution on the main reflector corresponding to the desired radiation pattern is determined by optimization depending on the constraint gain of the far field. Note that the optimization method for the aperture phase distribution was known for a single smoothly shaped contoured-beam antenna. Also, in this paper, an optimization method for the amplitude distribution is proposed anew. Further, by adding a restriction to the phase difference between the adjacent elements in the optimization of the phase distribution, the step discontinuity on the reflector is eliminated. By means of this method, an antenna made of a main reflector with an aperture diameter of 2.3 m is designed at 12 GHz whch is the frequency of the downltnk of the broadcast satellite.

Most of Hokkaido, Honshu, Shikoku, Kyushu, and Okmawa is covered by a radiation pattern with more than 40 dBi and other remote islands with more than 28 dBi. A one-half scale model is fabricated and the radiation pattern is measured at 22 GHz. The results agree well with the numerical results. Also, the sidelobe and the cross-polarization characteristics of this antenna sufficiently satisfy the technical standards in RR.AP 30.