Multiple Element Antenna Efficiency and its Impact on Diversity and Capacity

• Published in: IEEE transactions on antennas and propagation Vol. 60; no. 2; pp. 529 - 539
• Main Authors: Yun, J. X., Vaughan, R. G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2012; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna correlation; Antenna measurements; Antennas; capacity; Computational efficiency; Computing time; Correlation; diversity gain; Diversity reception; Efficiency; Equivalence; Finite element methods; Gain; Integrated circuit modeling; MEA total efficiency; multiple element antenna (MEA); Mutual coupling; Ports; Signal to noise ratio
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2011.2173444

A desirable characteristic of a multiple element antenna (MEA) is to be compact, but a smaller size tends to lead to higher ohmic and mutual coupling losses. A metric for the efficiency of the MEA would help clarify the tradeoffs between compactness and performance. In a MIMO/diversity antenna, the total efficiency seen at each port directly affects the signal-to-noise ratio (SNR) in the diversity branch. The SNR after diversity combining governs the performance of the diversity antenna system. In this paper, MEA efficiencies is therefore discussed and formulated in the context of mutual coupling and diversity combining. The impact of MEA efficiency on the diversity gain and the information theoretical capacity is also formulated and demonstrated using measurements of example MEAs. With these formulations, an equivalent number of idealized (lossless, uncorrelated, uncoupled, equal power) branches can be found for an MEA, and this defines the diversity order and the capacity order of the MEA. With this metric, the performance of different MEAs can be compared.