A transceiver for direct phase measurement magnetic induction tomography

Magnetic Induction Tomography (MIT) is a technique for imaging the electromagnetic properties of materials. Excitation coils are used to induce eddy currents within the sample volume which are then sensed by receiver coils. The technique has attracted interest for biomedical application due to the non-contacting nature of the measurements, which may provide advantages over electrode based impedance tomography in certain applications. The paper describes a transceiver designed for use in a prototype biomedical MIT system operating with a single excitation frequency of 10 MHz. To improve channel isolation and phase stability during signal distribution, the received signals undergo heterodyne downconversion to 10 kHz, filtering and limiting at the transceiver. Direct phase measurement between the downconverted reference and received signals is then undertaken to measure the signal perturbation due to the induced conduction eddy currents.