Dual-Polarization and Dual-Band Conical-Beam Array Antenna Based on Dual-Mode Cross-Slotted Cylindrical Waveguide

Abstract

Two designs of conical-beam array antennas are presented for different fifth-generation applications. They are based on slotted cylindrical waveguides and a travelling-wave topology, where the waveguide is used to progressively excite a cross-slot array. A total of 384 cross-slots, formed by transversal and longitudinal slots, are grouped in rings of eight equally-spaced cross-slots. The propagation of TM01 and TE01 modes in the cylindrical waveguide can provide dual polarization by the independent excitation of transversal and longitudinal slots, respectively. Firstly, a dual linearly-polarized antenna design in the 37-40 GHz band is presented, conforming a high-gain conical-beam pattern. Secondly, a similar antenna design working in the 5G dual-band of 26-30 GHz and 37-40 GHz is also presented. In this last case, transversal and longitudinal slots are designed to radiate at two different frequency bands of 26-30 GHz (vertical polarization) and 37-40 GHz (horizontal polarization), recently assigned for very high-speed 5G applications. The dual-band design has been prototyped by combining 3D-printing and CNC milling techniques to experimentally validate the proposed topology, providing high experimental performance. Directive tilted omnidirectional coverages with peak realized gains around 14 dBi have been obtained, as well as a total efficiency between 83% and 90% for both frequency bands.