Dual-Band Metal Frame Blockage Reduction for 5G mm-Wave Arrays in Mobile Phones

This paper proposes a solution that allows reducing the obstruction from the mobile phone frame to electromagnetic waves in two bands of the mm-wave spectrum. This response is obtained by etching longitudinal corrugations of two different lengths in the metal frame. The corrugations are inspired on the hard surfaces principle, which supports the propagation of electromagnetic waves on metal. The proposed structure is matched to a 50-Ohm source in the following bands: 25.4-27.7 GHz, 28.7-29.9 GHz, and 36.4-40.3 GHz. The realized gain of the mm-wave array with the corrugated frame is higher than the one of the array in free space in the majority of the operating bandwidth. The proposed solution can increase the gain of the array with a normal frame up to 10 dB.