Total Array Gains of Millimeter-Wave Mobile Phone Antennas Under Practical Conditions

TL;DR

This study introduces a new measure called total array gain for millimeter-wave mobile antennas, comparing uniform linear and distributed arrays under practical conditions, revealing the distributed array's superior performance and robustness.

Contribution

The paper defines and evaluates total array gain for millimeter-wave antennas on mobile phones, demonstrating the advantages of distributed arrays over linear arrays in real-world scenarios.

Findings

Distributed array achieves up to 8 dB higher median gain than ULA.

Distributed array maintains more consistent gain across orientations.

ULA can experience outage gains as low as -15 dB due to shadowing.

Abstract

This paper studies a gain of an antenna array embedded on a mobile device operating at a millimeter-wave radio frequency. Assuming that mobile phones at millimeter-wave range operate with a single baseband unit and analog beamforming like phased arrays, we define a total array gain denoting a path gain of the phased antenna array in excess to the omni-directional path gain. The total array gain circumvents the ambiguity of conventional array gain which cannot be uniquely defined as there are multiple choices of a reference single-element antenna in an array. Two types of 8-element patch antenna arrays implemented on a mobile phone chassis, i.e., uniform linear array (ULA) and distributed array (DA) both operating at 60 GHz, are studied. The gain evaluated in a small-cell scenario in an airport shows that DA achieves higher median and outage gain by up to 8 and 6 dB than ULA when different orientations of the mobile phone are considered along with body torso and finger shadowing. There are always postures of the mobile phone where ULA cannot see the line-of-sight due to directionality of the patch antenna and of body and finger shadowing, leading to outage gain of -15 dB in the worst case. The DA has much smaller variation of the gain across different orientations of the phone, even when the human torso shadowing and user's finger effects are considered.

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