A 3-D-printed Wideband Millimeter-Wave Fan-Beam Antenna With Flat-Top, Sharp Cutoff Patterns, and Beam-Scanning Capability

This article presents a wideband millimeter-wave (MMW) fan-beam antenna with a flat-top, rapid cutoff radiation pattern, and beam-scanning capability through the use of 3-D printer technology. The proposed antenna, consisting of several periodic structures that composed of dielectric and air slabs, is fed by the WR-28 waveguide. By tuning the ratio of dielectric slab thickness to that of unit cell, the effective permittivity is controlled flexibly. The phase distribution on the aperture is carefully modulated in this way to devote high-quality flat-top patterns. In addition, the beam can be continuously scanned within the angle range of 70° without scarifying the gain performance dramatically. For demonstration, a prototype with boresight fan-beam radiation is first fabricated and measured. The proposed antenna achieves an impedance bandwidth of 50% from 24 to 40 GHz. Measured results indicate that the wide beamwidth patterns show flat-top and sharp cutoff performance. Both E-plane and H-plane patterns draw low cross polarization (smaller than −22 dB). Another prototype, aiming to verify the beam-scanning capability, is investigated. Measured results demonstrate the performances of the proposed antennas. With such favorable electrical performance, simple structure, and low-cost fabrication, the proposed antenna is a promising candidate for 5G MMW and satellite applications.