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Traditional high-value monostatic imaging systems employ frequency-diverse pulses to form images from small synthetic apertures. In contrast, RF tomography utilizes a network of spatially diverse sensors to trade geometric diversity for bandwidth, permitting images to be formed with narrowband waveforms. Such a system could use inexpensive sensors with minimal ADC requirements, provide multiple viewpoints...
During magnetic resonance imaging (MRI), an implanted lead present in a patient's body scatters the radiofrquency (RF) field used for magnetic resonance. The resultant RF field can achieve very high values in the vicinity of the implant structure. The conduction currents flowing in tissue can cause dangerous resistive heating. Therefore scattering by implanted devices is an important safety issue...
The interest in the exploitation of wireless sensor networks in dissipative media (other than the free space) is nowadays growing in importance, thanks to the identification of ever newer fields of applications. This paper introduces an efficient design methodology for an easy definition of the characteristics of mobile sensors inserted in pipes filled with fluids. The proposed procedure takes into...
We present an overview of our work in instantaneous frequency measurement systems employing optical mixing and DC detection which are capable of measuring both the frequency and power of an RF over ultrahigh bandwidths from DC to 40 GHz. We particularly focus on all optical systems employing four wave mixing in highly nonlinear fibers.
The effect of skin tissue on the scattering of the MRI RF field by deep brain stimulation (DBS) leads is analyzed. RF induced heating occurs in the tissue surrounding the electrodes at the end of such a medical lead. The electric field and the induced temperature rise are found by solving the wave and heat equations. Spatial plots of the solutions are obtained. The presence of skin tissue also affects...
High-power electromagnetic (HPEM) technology, and the associated effects it can have on modern electronics, is of interest for a variety of non-lethal applications, such as ending dangerous car pursuits and access denial to suspect vehicles. In this paper, we present concepts for using HPEM pulses as a means to remotely stop the engines of cars, describe potential technologies and systems, discuss...
Belowground imaging using RF Tomography is challenged by strong direct-path coupling between sensors. In this work, a direct-path mitigation procedure is introduced, consisting of two steps. First, the Tx and Rx dipoles are rotated in along particular directions that maximizes the signal with respect to the direct-path contribution. Then, the remaining contribution is removed by using a hybrid analog/digital...
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