Differential-Fed, Dual-Aperture Based, Quasi-End-Fire 5G mmWave Antenna-in-Package Design

A low-profile, wideband antenna-in-package (AiP) design is proposed for 5G mmWave mobile applications. The aperture-coupled feeding incorporated with the microstrip feed line through the slots in the ground is used to excite the patch antenna. Firstly, a thin quarter-wave shorted patch antenna (QW-SPA) with the dominant
${TM}_{1/2,0,0}^{z}$
mode is realized. To broaden the operating band, the QW-SPA is extended along its resonant length so that the
${TM}_{1,0,0}^{z}$
mode can also be excited. The offset introduced into the two slots together with the additional shorting via wall are applied to enhance the beam tilt toward the end-fire direction. The proposed single-patch design shows a wide fractional bandwidth, covering the 5G mmWave band n257 (26.5–29.5 GHz). Furthermore, to increase more beam tilt, the differential-fed, two-patch sub-array formed by two QW-SPAs spaced a half-wavelength at 28 GHz apart is also presented. Compared with the single-patch design, the beam-tilt enhancement of around 10–27 degrees is obtained over the desired frequency band with the peak gain of around 8.2 dBi for the sub-array AiP design.