Effect of Mutual Coupling on Multiple Antenna Channel

Abstract

Abstract-The influence mechanism of mutual coupling (MC) on multiple antennas system are studied. Some new exact expressions of receiving signal vector, signal power and spatial correlation coefficient are derived, which includes the effect of MC. The capacity of multiple-input multiple-output (MIMO) channel with MC in different conditions is also discussed. Analysis and simulation results show that the modification of signal parameters cased by MC is related to the MC matrix, which is decided by antenna self-impendence, mutual impendence and load impedance.Index Terms-Mutual coupling (MC), MIMO channel, antenna pattern, channel capacity. I. INTRODUCTIONMultiple-input multiple-output (MIMO) technology can significantly improve the channel capacity of wireless systems under rich propagation environment. However, the advantage of MIMO system over signal antenna system depends on the channel characteristics such as spatial correlation. Since antenna's feathers are inherently included in the communication link, mutual coupling not only affects the antenna efficiency but also the system performance [1].Ref. [2] proved that the distance between antennas and the operation frequency difference are the main affect factors of mutual coupling. Wang in [3] presented an iterative autocalibration method to estimate unknown mutual coupling for a uniform circular array. In [4], the network theory was used to derive the channel transfer matrix, which includes the coupling effects on spatial correlation between different antennas. Lu and Hui [5] also proved that MC among antennas would limit the increase of capacity due to spatial proximity. In [6], the effects of MC on MIMO channel capacity under different coupling assumptions were analyzed and compared. [7] presented a comparison between the measured mutual coupling effect on the ergodic channel capacity of a MIMO system in a Rayleigh channel and in Rician channel at Long Term Evolution (LTE) radio band. A method to reduce MC among MIMO antennas by inserting parasitic elements is proposed in [8], and the 1-D EBG and SRR structures were experimentally shown to be very effective in suppressing mutual coupling [9].In this paper, we will study the MC effect on multiple antennas system and derive some new expressions of receiving signal vector and power, channel correlation and capacity. Firstly, we construct an equivalent channel model Manuscript received May 10, 2016; revised July 13, 2016. The authors are with the Jiangsu Key Laboratory of Internet of Things and Control Technologies, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China. Zhu Qiuming is also with China Airborne Missile Academy, Luoyang 471009, China (e-mail: zhuqiuming@nuaa.edu.cn).with MC in both the transmitting and receiving arrays and give the receiving signal model including coupling in Section II. On this basis, the signal power and spatial correlation between multiple receiving antennas including MC will be given, and the effect of MC on channel capacity will also be studied in combining...

Subarray Design with Two Rectangular Elements for Massive MIMO System Development

“…Mutual coupling is an electromagnetic interaction and the influence of surface currents on each element of the antenna array [12]. Mutual coupling effects can cause changes in antenna parameters such as radiation pattern, return loss, directivity, low side lobe level (SLL), gain, impedance matching and transmit power [13], [14], [15], [16]. Several ways to reduce the effect of mutual coupling is to use a metamaterial structures [17], exponential corrugated truncated (ECT) structures [11], defected ground structures (DGS) [18].…”