A 3-D-Printed Dual-Band Waveguide-Fed Hexagonal Cavity Slot Array for mmWave Applications

This paper introduces a dual-band slot array antenna based on a hexagonal cavity design for millimeter-wave (mmWave) communication systems. The proposed antenna array is manufactured using direct metal laser sintering (DMLS) 3D printing and electroless plating, enabling the fabrication of a compact and high-performance structure. To ensure stable dual-band operation with wide impedance bandwidth and high gain, the design incorporates a hexagonal cavity and a polarizer structure. The TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> and TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> modes of the cavity are analyzed for in-phase radiation across all radiating elements, while the polarizer corrects the tilted <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i>-field to enhance radiation. A stepped waveguide feeding network is employed to achieve compact element spacing, supporting high integration density without performance degradation. Experimental results for an 8×8 antenna array prototype demonstrate stable dual-band operation over the n257 and n260 bands, achieving impedance bandwidths of 10.7% and 9.6%, and gains of 24.5 dBi and 25.2 dBi for the respective bands, with low cross-polarization levels of approximately −30 dB.