On the impact of the mutual impedance of an antenna array on power and achievable rate

In this paper, we consider antennas arrays with small mutual resistance, and assess the impact of neglecting both the small mutual resistance and the mutual reactance, on the radiated power and on the achievable rates. This extends our earlier results on antenna arrays with zero mutual resistance, which show that when those antenna arrays are excited by practical radio frequency amplifiers modeled as linear sources, the radiated power depends on the mutual reactance and that there is a gap between capacity and the achievable rate when neglecting the mutual reactance. In this investigation, we consider a Uniform Linear Array (ULA) consisting of λ/2-dipoles spaced by λ/2, and compare it to a ULA consisting of hypothetical isotropic radiators spaced by λ/2. Numerical results are given for the ergodic rates in an independent and identically distributed channel in the up- and downlink, with a base station transmitting to a single antenna mobile. Furthermore, the investigation is extended to a more realistic channel model based on QuaDRiGa.