Ku-band Design Of The Conical Corrugated Horn Feed

Direct broadcast service of digital satellite TV appears in recent years and is now still widely used for the reception of satellite TV. Compared to the traditional land-based TV, it has many advantages, such as wide coverage, low cost entering the family, conditional reception and repay, etc. Therefore, since it came out it developed rapidly in U.S.A., Europe, Japan, etc. It has already formed the huge industry chain. But in our country, it is at the starting stage, and has broad market prospects.The Ku-band conical waveguide receiving antenna, which is designed in this paper, will be applied to the direct broadcast service of digital satellite TV. It is the front of Low Noise Block (LNB), used for illuminating the offset parabolic antenna. Its performance determines the whole performance of the offset parabolic antenna, even though the reception quality of the satellite TV.The main contribution and innovation is as follows:1. The designed antenna's VSWR is smaller than 1.35, which is superior to the reported design level of the similar antenna both at home and abroad. When it used for illuminating the offset parabolic antenna, which aperture is not less than 35cm and focal length to diameter ratio is 0.6, the whole antenna's gain should be higher than 32 dB and its maximum sidelobe level should be less than -28 dB. It has very good performance and suitable for applying to direct broadcast service.2. In the feed structure, we introduce the reflect-cylinder structure to realize dual linear polarization, and study the function of the reflect-cylinder structure.3. Considering the designed antenna should be connected with the microstrip of LNB, we use the structure, which the substrate with 45 angle and the probe with 135 angle, to make sure the outputs of the two probes are on the same plane. We also use the stepped substrate structure to make it easy to install.