User Effects on the Circular Polarization of 5G Mobile Terminal Antennas

User effects on a circularly polarized phased array for 5G mobile applications for frequencies around 28 GHz are studied in this communication. Two figures of merit are defined: the total scan pattern and coverage efficiency of the circular polarization (CP). The user effects on the performance of a CP phased array are studied via two defined parameters. The investigations are carried out in talk mode (with a hand and a head) and in data mode (with a homogeneous whole-body phantom). The scattering properties of the proposed phantom are verified via the measurement of an antenna with known radiation parameters and a human. The CP coverage efficiency is relatively less affected by biological tissues than by the conventional coverage efficiency, although the absolute value of the CP coverage efficiency depends on a specific design. When user effects are introduced, the axial ratio bandwidth becomes approximately 0.8 to 1.3 GHz narrower. To realize the optimal CP performance and reduce the user effects of the CP coverage efficiency, a CP array at the bottom short edge of the ground plane should be chosen in the talk mode, while the top short edge location should be chosen in the data mode.