Simultaneous wireless information and power transfer (SWIPT) is an essential technology for future Internet of Things (IoT) networks. In this paper, the mutual coupling effect for SWIPT is presented by conducting simulations. In terms of energy harvesting, when mutual coupling exists with the spacing of antennas near half wavelength, the total received power can be as much as 5.10 μW, 1.47 times larger than the value without mutual coupling, showing that the received power of the half wave dipole antenna can be increased by exploiting mutual coupling. In addition, based on theoretical analysis, we attempt to generalize the mutual coupling effect for more than two dipole antennas. Analytical results show that the received power gain with mutual coupling can be more than 50%, compared to the uncoupled case. In terms of channel capacity in single-input multiple-out systems, the channel capacity is fluctuating as the interval of antenna is changed. Also, our results shows that the channel capacity that the coupled and uncoupled case are converged because the impact of mutual coupling decrease as the spacing of antennas is larger. ⓒ 2016 DGIST
Table Of Contents
Ⅰ. INTRODUCTION 1 -- 1.1 Internet of Things 1 -- 1.2 Simultaneous wireless information and power transfer 1 -- Ⅱ. MUTUAL COUPLING 3 -- 2.1 Mutual coupling effect 3 -- 2.2 In energy harvesting 8 -- 2.2.1 Equivalent circuits of dipole antenna 8 -- 2.2.2 Experiment setup 10 -- 2.2.3 Experiment results & discussion 12 -- 2.2.4 Generalization of mutual coupling for more than two dipole antennas 14 -- 2.3 In channel capacity 19 -- 2.3.1 SIMO system model 19 -- 2.3.2 Mutual coupling matrix 20 -- 2.3.3 Channel capacity with mutual coupling effect 22 -- Ⅲ. OPTIMIZATION 25 -- 3.1 Optimization modeling 25 -- 3.2 Lagrange multiplier method 27 -- 3.2.1 KKT conditions 27 -- 3.2.2 Method of undetermined coefficients 28 -- Ⅳ. CONCLUSION 30 -- References 31