Long Bo Lens Antenna Multibeam Study

Luneberg lens antenna is a spherical layered medium lens antenna, and its main feature is its capability of focusing the incident wave to a point on the spherical surface. Due to its own spherical symmetry and good antenna properties, it has many advantages such as the multi-beam, wideband, wide range of scan angle and low costs. Thus, Luneburg lens antennas are widely used in many areas such as satellite communications, navigation, radar anti-jamming, etc. This thesis presents the studies on some key techniques in multi-beam Luneberg lens antennas. The thesis mainly contains the following several parts:Firstly, the importance and research status of Luneberg lens antennas are introduced. The principles of lens antennas are also described, and the analysis and optimal design approaches of Luneberg lens antennas are also reviewed.Secondly, the optimal design of high-performance feed for Luneberg lens antenna is presented. A Ku dual band corrugated feed horn is designed, fabricated and measured. The orthogonal dual-probe structure is adopted in the horn to get the dual linear polarization. Moreover, the radiating aperture of the horn has a corrugated structure, thus a good axial symmetry of the radiation pattern, low sidelobe and low cross polarization are obtained. As compared to an original Ku-band horn feed with dielectric rod, the corrugated horn has no dielectric loss, and the total antenna efficiency is higher when used for the same Luneberg lens.Thirdly, the study on Ku/Ka transceiver for one satellite simultaneously is presented. Considering the focus excursion phenomenon occurred in the case of simple combination of Ku/Ka feed for the same Luneberg lens antenna, a method of feed array is proposed in this thesis. Based on the original design of the Ku/Ka feed, the radiation aperture has been minimized to reduce the array element spacing. Based on numerical simulation, the proposed method partially solved the problem of the focus excursion.Fourthly, focused on the measurement of Luneberg lens dielectric material, a cylindrical cavity is designed and manufactured for the measurement of complex dielectric constants for low loss dielectric materials. By using the high Q cavity of the cylindrical TE01n mode, high accuracy of the measurement in low loss dielectric materials is obtained.Finally, the kind of hemisphere lens with metal ground is studied through numerical simulation. As compared to the whole sphere lens, it is easy to install and the size of antenna is reduced. In addition, a scheme for the multi-beam satellite tracking system is presented in this thesis, and it is very useful for practical engineering.