Comparing gains of 28 GHz module-based phased antenna arrays on a 5G mobile phone

Implementation of an antenna array on a 5G mobile phone chassis is crucial in ensuring the radio link quality especially at millimeter-waves. However, we generally lack the ability to design antennas under practical operational conditions involving body effects of a mobile user and multipath propagation. Therefore, in this paper, we study gains of three phased antenna array configurations at 28 GHz that can be implemented on a mobile phone chassis, and we compare them to find the most robust configurations. The arrays are formed by placing two sets of 4-element dual-polarized patch antenna arrays, called two modules, at different locations of a mobile phone chassis. The gains we study concern antenna and link gains of the array. Spherical coverage is statistics of realized antenna gain over solid angle, while total array gain is a link gain determined by the power at the receive array output port in relation to the omni-directional pathloss. Our numerical approach to evaluate the gains is based on state-of-the-art methods such as simulations of radiated fields from an antenna element including human body scattering along with ray-optical multipath radio channel simulations. Results show that an array configuration with modules on opposite sides of the mobile phone chassis is clearly the best both at median and outage levels when spherical coverage is concerned. However, according to our evaluation of the total array gain in outdoor and indoor small-cell scenarios, an array of antenna elements on each side of two corners of mobile phone chassis performs equally robust because the array can capture energy from most directions despite near-field interaction with the human body. The results illustrate the importance of having a link gain metric in addition to an antenna gain metric, to be able to compare and rank array performances.