Introduction to Electromagnetic Compatibility

Noninvasive brain stimulation with transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) is valuable in research and has potential therapeutic applications in cognitive neuroscience, neurophysiology, psychiatry, and neurology. TMS allows neurostimulation and neuromodulation, while tDCS is a purely neuromodulatory application. TMS and tDCS allow diagnostic and interventional neurophysiology applications, and focal neuropharmacology delivery. However, the physics and basic mechanisms of action remain incompletely explored. Following an overview of the history and current applications of noninvasive brain stimulation, we review stimulation device design principles, the electromagnetic and physical foundations of the techniques, and the current knowledge about the electrophysiologic basis of the effects. Finally, we discuss potential biomedical and electrical engineering developments that could lead to more effective stimulation devices, better suited for the specif...

https://www.annualreviews.org/doi/pdf/10.1146/annurev.bioeng.9.061206.133100

Noninvasive human brain stimulation.

Antenna Theory And Design

Electric field depth-focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs.

Ultra Wideband Signals and Systems in Communication Engineering

The problem of the radiated emission from apertures in metallic enclosures has been theoretically and experimentally investigated. In particular, the tangential electric field in the aperture has been evaluated by two methods: the first is helpful during the design stage and the second during the prototype development stage of electronic equipment shielded by a metallic box. The first method is a rigorous approach and uses the equivalence principle that leads to an integral equation then solved by the method of moments. The second is an approximate technique. This technique is based on simple, cheap, and quick measurements of the normal components of the magnetic field across the aperture. Numerical simulation in good agreement with experimental results is shown. >

Theoretical and experimental evaluation of the electromagnetic radiation from apertures in shielded enclosure

The paper investigates the possibility of reverberating a shielded room by means of source mode stirring. The transmitting antenna position and orientation are randomly changed inside a sub-volume of the chamber. In general, antenna displacement can be achieved by a proper design of an array of antennas, where one or more antennas are activated at different time instants. This technique eliminates mechanical rotating paddles inside the chamber, and offers the advantage of a continuous wave (CW) operation with respect to the frequency stirring method. The preliminary experimental and simulated results encourage further investigation of the proposed technique.

Source stirring mode for reverberation chambers

We present a 3-D model for the simulation of a realistic clinical situation during magnetic stimulation. The electromagnetic problem is solved by reconstructing the inhomogeneous head tissues from magnetic resonance images and associating relative values of conductivity to each tissue. Application of Maxwell's equations in the integral form leads to an equivalent 3-D electrical network, whose solution gives the current density distribution in the brain. The high spatial resolution and rigorous electromagnetic approach make this model an accurate and useful tool for stimulator design and for estimating the efficiency and safety of this clinical methodology.

An accurate 3-D model for magnetic stimulation of the brain cortex.

The feasibility of an electromagnetic sensor to assist the autonomous walking of visually impaired and blind users is demonstrated in this paper. It is known that the people affected by visual diseases usually walk assisted by some supports, among which the white cane is the most common. Our idea consists in applying a microwave radar on the traditional white cane making aware the user about the presence of an obstacle in a wider and safer range. Compared to the already existing electronic travel aids devices, the proposed system exhibits better performance, noise tolerance, and reduced dimensions. In the following, the latest developments of this research activity are presented, with special concern for the miniaturization of circuit board and antennas. A laboratory prototype has been designed and realized and the first test results of obstacle detection are hereby shown to demonstrate the effectiveness of the system.

An Electromagnetic Sensor Prototype to Assist Visually Impaired and Blind People in Autonomous Walking

This paper presents two test benches for the characterization of a plasma column used as a radiating element. In particular, the main parameters to be quantified are the efficiency of the plasma antenna, the turn-on time of the column, and the conductivity of the plasma. The first two parameters are evaluated by measuring the field radiated by the plasma antenna compared with that of an equivalent copper antenna. For the conductivity, a reflectometric technique is used, wherein the plasma column is inserted inside a waveguide. The accuracy of the method is limited by the ill-conditioned relationship between the reflection coefficient and the plasma conductivity; nevertheless, it is sufficient to subdivide the range of the conductivity values into three regions (i.e., low, medium, and high conductivities) to determine the best operating conditions of the antenna.

Graziano Cerri

Papers

Theoretical and experimental evaluation of the electromagnetic radiation from apertures in shielded enclosure

Source stirring mode for reverberation chambers

An accurate 3-D model for magnetic stimulation of the brain cortex.

An Electromagnetic Sensor Prototype to Assist Visually Impaired and Blind People in Autonomous Walking

Measurement of the Properties of a Plasma Column Used as a Radiating Element