Power deposition and focusing in a lossy cylinder by a concentric phased array

Abstract

We present an analysis of phased array applicators for heating of torso, limbs, and neck. A homogeneous cylindrical model is adopted for the calculations. Four-, eight-, and 16-horn apertures are considered. Focusing of power is demonstrated for an operation frequency of 915 MHz in a cylindrical phantom of radius 5.2 cm, with a conductivity of 1.28 S/m and a relative permittivity of 51. Experimental verification is shown for the case with four-horn applicators. We thus demonstrate that by controlling the relative phases and amplitudes of the aperture sources, it is possible to focus electromagnetic power at desired locations such as tumors. LUMORI

Quantitative evaluation of arrays of Lucite cone applicators in flat layered phantoms using Gaussian-beam-predicted and thermographically measured SAR distributions

“…The Gaussian beam (GB) model has been described extensively elsewhere (Bach Andersen 1987, Lumori 1988, Lumori et al 1990a. The LCA source parameters for the model, the half-power half-width (S) and the phase curvature of the wave front (R), in both the Eand H -principal planes were derived from E-field measurements: S E = 3.9 cm, R E = ∞, S H = 5.0 cm and R H = 35 cm (Rietveld et al 1998) and are based on single antenna measurements without use of water as an intermedium.…”

Gaussian Beam Modeling of Sar Enhancement in Paraxial and Non-Paraxial Regions of Biological Tissues

“…The letter included 13 copies of his journal publications in one year, with the following note: "The tank is a bit low." He continued, "A good journal paper would be to apply the focal theory from our work [2,16,17] to the Gaussian Beam Model." A recent review of the letter prompted the author to write this paper in memory of Professor J. R. Wait who could have been a Worthy Co-author of this paper.…”

“…1. Next, we determine SAR enhancement (focus) via an analytical formulation, based on [2,16,17]: Consider an array of N -element applicators driven coherently [2,4,5,7] to achieve focus at a tumor site. From (7), for an x-polarized electric field E x (y, z), the field contribution due to the nth element (n = 1, 2, 3, .…”