Dual-Band Antenna-on-Hinge Concept for Millimeter-Wave Foldable Mobile Devices

This letter presents the first demonstration of a dual-band antenna-on-hinge (AoH) concept for mmWave foldable mobile devices. The AoH repurposes the metal hinge frame itself as a slot radiator at 28 GHz and 37 GHz, complemented by an LTCC-based strip pad cavity feed using indirect coupling. A 1×4 AoH array with symmetric dummy elements to suppress side lobes and enhance antenna gain is designed and fabricated. Both simulations and measurements on a passive prototype confirm S₁₁ < -10 dB over 27.1-28.45 GHz and 36.9-38 GHz. The peak realized gain of 9.6 dBi at 28 GHz and 10.1 dBi at 37 GHz is confirmed while maintaining cross-polarization levels greater than 15 dB. A maximum 3dB beam steering angle is confirmed at ±45° at 28 GHz. By eliminating the need for a separate antenna cover, the AoH ensures full compatibility with existing mmWave foldable devices and offers a promising solution for future multi-foldable form factors.