An FR4-Based Miniaturized High-Efficiency Double-Sided SISL Longitudinal Slot Antenna Array for 5G Millimeter-Wave Applications

This communication presents a miniaturized, high-gain, and high-efficiency longitudinal slot antenna array, designed using double-sided substrate-integrated suspended line (DSISL). The feeding structure employs double-layer wiring technique, connecting through metalized vias to minimize dielectric loss. By integrating periodic short-stubs transmission lines, a compact feeding structure is leading to a miniaturized size. Moreover, the short stubs can excite longitudinal slots to generate radiation. The subarray and array are fabricated to use multilayer printed circuit board (PCB) technology with low-cost FR4. The measured impedance bandwidth for the subarray and array is 25.5–31.4 GHz (20.7%) and 25.8–31.3 GHz (19.3%), respectively. The maximum measured realized gain is 14.5 and 20.2 dBi, with a radiation efficiency of 95% and 93%, respectively. These findings validate the array has wideband, high gain, and high efficiency and potential for fifth-generation (5G) millimeter-wave (mm-Wave) systems.