Ka-band Dual-plane Reflector Array Antenna Design

With the rapid development of millimeter wave transmitter and receiver for applications in the fields of communications, radar and remote sensing, the high performance MMW antennas is more demanding. However, either parabolic reflector or Cassegrain reflector is restricted to manufacture and conformal design due to curvature and volume. To overcome these disadvantages, the planar reflector antennas on Ka-band become the research highlights. Reflect array antenna is a more feasible candidate by utilizing different elements with appropriate phase compensations. The design key lies in the achievement of the prescribed phase shifts and phase distribution. Fresnel zones, which consists of circles with the constant phase zones, are preferable to realize the appropriate phase distribution, because that the elements are much easier to design and less sensitive to minor movement of the feed. A folded compact reflect array is focused which utilizes a polarization grid as the upper reflecting plane which brings a reduction of antenna depth and gets rids of blocking from the feed, sub-reflector and bracing structure.In this thesis, a Ka-band dual planar reflect-array antenna is investigated. A folded compact reflectarray at35GHz is designed with Fresnel zone phase distribution. The novel C-patch units are proposed to compensate phase and twist polarization. The semi-reflecting grid is designed as the upper reflecting plane. The influence of focal diameter ratio on the aperture efficiency of the whole antenna is further studied to obtain the optimized design. The realized gain of24.9dB is achieved with the corresponding reflection coefficient of-12.45dB for a focal diameter ratio of0.5. An antenna prototype with diameter of66mm is manufactured and tested. The result shows the reflection coefficient of-11.5dB and realized gain of23.5dB.