A Broadband High-Gain Patch Antenna Array for 5G Millimeter-Wave Applications

In this letter, a planar broadband high-gain patch antenna element and its 2 × 4 antenna array are proposed for 5G millimeter-wave (mm-wave) applications. The antenna element consists of two pairs of rectangular patches. Each pair of rectangular patches is connected with a meandered U-shaped thin strip. To enhance the band of operation and simultaneously improve the impedance matching, a stepped narrow strip is introduced and placed between the two pairs of large rectangular patches. A narrow slot is etched along the long wall of the substrate integrated waveguide (SIW) so as to couple the electromagnetic energy to the radiating elements. Based upon the antenna element, a 2 × 4 antenna array is developed for higher gain. To excite these eight elements, a 1-to-8 full-corporate SIW feeding network and a coaxial cable to SIW transition are utilized. To verify the design, the proposed antenna array was fabricated and tested. Experimental results demonstrate the prototype realizes a broad band of 25.32 GHz to 30.94 GHz, well covering the n257 [(26.5 to 29.5) GHz] and n261 [(27.5 to 28.5) GHz] bands. The antenna array obtains a 3 dB gain band of 4.1 GHz with a peak gain of 17.3 dBi. Across the whole operating band, unidirectional radiation characteristics with front-to-back ratios higher than 15 dB and cross-polarization levels lower than −25 dB can be observed.