High-Gain Millimeter-Wave Antenna-in-Display Using Non-Optical Space for 5G Smartphones

This article presents a high-gain display-integrated antenna topology, for the first time, embedding radiating traces into a nonoptical space, referred to as the dead space (DS), which is the edge part of the display panel; however, it does not perturb the optical illumination of the display. Thus, the proposed antenna topology is denoted as antenna-in-display (AiD). To fit the extremely narrow embedding conditions of the given DS (= 0.03 \lambda _{0} at 28 GHz), a new-shape coplanar waveguide (CPW)-fed folded dipole antenna was devised and efficiently tailored in the DS area. The bottom side of the panel was modified to render the effect of a coplanar defected ground structure (CDGS) for antenna minimization, and a new asymmetrical antenna geometry was proposed for wideband impedance matching and broadside radiation pattern. Compared with conventional studies, the proposed antenna concept provides an improved gain resulting from the good conductive metal in DS, the complete display visibility, and touch sensor compatibility, whereas the previous antenna-on-display (AoD) approaches inherently suffer from the limited gain obtained at the expense of lower conductivity of the optically invisible antenna electrodes. Because the proposed AiD concept enables the direct fabrication of antenna traces into the DS area of the display panel, eliminating need for an additional film, a lower package profile, and cost reduction can be achieved. The proposed prototype was fabricated and verified using an actual smartphone. The measured data confirm 12.32 dBi gain, 54.3% radiation efficiency, and 3 dB gain bandwidth larger than 3 at 28 GHz.