Adaptive Uncoupled Termination for Coupled Arrays in MIMO Systems

On the Capacity of Densely Packed Arrays with Mutual Coupling and Correlated Noise

“…Although lossless multiport matching networks are practically difficult to implement, they provide a convenient theoretical construct that allows us to study the impact of small interelement spacing on the signal power collection capability and noise characteristics of MECSA. In practice, suboptimal matching strategies, such as the adaptive uncoupled matching presented in [19], may be used to mitigate the negative impact of impedance mismatch on the data throughput of the communications link. As will be demonstrated in Section 4, the capacity of a SIMO system can still be enhanced with mutual coupling even if no optimization of the multiport impedance network is assumed.…”

“…The effect of antenna heat losses on the channel capacity of the two-element MEA is illustrated by the capacity-versusspacing curves in Figure 4 for three cases of HL / 11 = 0, 0.01, and 0.1. The instantaneous capacity graphs for = 90 ∘ and = 0 ∘ are calculated from (19) and (20), respectively. As indicated by the = 90 ∘ graphs, capacity of the broadside MEA is only marginally influenced by the heat losses in the antenna system.…”

“…As indicated by the = 90 ∘ graphs, capacity of the broadside MEA is only marginally influenced by the heat losses in the antenna system. Comparing (19) and (13) shows that when HL / 11 ≪ 1, then BS,HL…”

“…In addition, ideal multiport matching networks are difficult to implement and practical MEAs are typically partially mismatched. This partial load mismatch results in a reduced signal power at the receiver loads [11,19,29]. The question of suboptimal loading and of the effect of changes in antenna current distribution will be treated in this section.…”

“…A spacing of 0.3 wavelengths has the advantage of smaller MEA physical size which is a remarkable result as it indicates that a moderate reduction of MEA physical size is possible without having to compromise the achievable channel capacity. We note that smaller MEA sizes may also be realized when a better matching technique, such as the adaptive termination to uncoupled loads [19], is used.…”