Design optimization of transmitting antennas for weakly coupled magnetic induction communication systems

Abstract

This work focuses on the design of transmitting coils in weakly coupled magnetic induction communication systems. We propose several optimization methods that reduce the active, reactive and apparent power consumption of the coil. These problems are formulated as minimization problems, in which the power consumed by the transmitting coil is minimized, under the constraint of providing a required magnetic field at the receiver location. We develop efficient numeric and analytic methods to solve the resulting problems, which are of high dimension, and in certain cases non-convex. For the objective of minimal reactive power an analytic solution for the optimal current distribution in flat disc transmitting coils is provided. This problem is extended to general three-dimensional coils, for which we develop an expression for the optimal current distribution. Considering the objective of minimal apparent power, a method is developed to reduce the computational complexity of the problem by transforming it to an equivalent problem of lower dimension, allowing a quick and accurate numeric solution. These results are verified experimentally by testing a number of coil geometries. The results obtained allow reduced power consumption and increased performances in magnetic induction communication systems. Specifically, for wideband systems, an optimal design of the transmitter coil reduces the peak instantaneous power provided by the transmitter circuitry, and thus reduces its size, complexity and cost.

Human activity recognition using magnetic induction-based motion signals and deep recurrent neural networks

“…The MI coils have a small radiation resistance, which means that the energy propagated to the far-field is negligible. As a result, multipath fading is not an issue, and the MI system can offer a much better quality of service (QoS) compared to Bluetooth-type systems 33,44,45 . The non-propagating magnetic field produced by the coils falls off proportional to r −3 instead of r −1 for radiating fields at a transmission distance r. Although the rapid decay limits the coverage range, it can be favorable in short-range applications such as WBANs 46 .…”

“…It allows the signal to remain in a 'bubble' around the coil, which provides a personalized space for the user. It also minimizes the leakage outside the targeted coverage range, reduces interference, increases security, and enables bandwidth reuse 44,47 . One of the main notable advantages of the MI system is that it works well in lossy dielectric media, such as the human body 48 .…”

A mechanically based magneto-inductive transmitter with electrically modulated reluctance

“…Conventionally, coiled loops or solenoids are used to generate a magnetic moment. Work has been done to optimize the design of coiled loops and solenoids for MI communications [ 11 ]. Very recently, however, interest has been shown in producing a magnetic moment with a spinning magnet [ 12 ]–[ 13 ].…”