Optimization of Antenna Array Structures in Mobile Handsets

A study of the capacity of multiple-element antenna systems is presented with particular emphasis on the effects of mutual coupling between the antenna elements. As the total size of the array is often fixed and limited, the correlation of fading as well as the mutual coupling of two elements separated in index by some value$l$increases. In this paper, at first with the assumption that the length of the linear array of antenna elements and the number of antenna elements at the receiver are fixed, the capacity with coding, without coding, and the symbol error rate (SER) of space-time coding are investigated. The results obtained show that for the mean signal to noise ratio at the receiver of$rho = 20$dB, the linear array of three antenna elements is the optimum choice if the total length of the array is in the range of$0.3lambda$–$0.86lambda$, while in the case of channel state information (CSI), this range is$0.25lambda$–$0.6lambda$. The effects of the signal-to-noise ratio (SNR) and number of the base station antenna elements on the capacity of the fixed-length linear arrays are also discussed. Next, it is assumed that the number of antenna elements at the transmitter and receiver are equal. Simulation results show the number of antenna elements for maximizing the capacity.