A Millimeter-Wave Phase Correction Metallic Lens Loaded Planar Cassegrain Antenna With Wide-Angle Multibeam Radiation

A novel millimeter-wave (mm-wave) wideband wide-angle multibeam metallic lens loaded planar Cassegrain antenna with a compact three-layered parallel plate waveguide (PPW) configuration is proposed. In order to meet the challenge of obtaining wide-angle radiation in the design of multibeam PPW reflector antennas, a phase correction approach based on a convex metallic lens over the output of a conventional Cassegrain beamformer is investigated. It is found that a significant reduction from −5.6 to −12.7 dB in the maximum sidelobe and an increase of about 2.6 dB in the gain are realized by the ±60° wide-angle scanning beams of the antenna with the help of the loaded lens. A Ka-band fabricated prototype with a milled and 3-D printed composite structure experimentally verifies a wide bandwidth of 35%, stable multibeam radiation with a scanning range of ±60° accompanied with a scanning loss of less than −3.5 dB and sidelobes of lower than −10 dB, a gain of up to 18.1 dBi, and an estimated radiation efficiency of 80%. With the good operating properties, compact geometry, and low architecture complexity, the proposed antenna would be attractive for future mm-wave applications.