Given the proper conditions, antennas applied in medicine can offer improved quality of life to patients. However the human body proves hostile to typical, analytical antenna design techniques as it is composed entirely of frequency- and temperature-dependent lossy media. By combining optimization techniques with numerical methods, many of these challenges may be overcome. Particle swarm optimization (PSO) models the solution process after the natural movement of groups such as swarms of bees as they search for food sources. This meta-heuristic procedure has proven adept at overcoming many challenging problems in the electromagnetics literature. Therefore, this dissertation explores PSO and some of its variants in the solution of two biomedical antenna problems. Recent advances in biosensor technology have led to miniaturized devices that are suitable for in vivo operation. While these sensors hold great promise for medical treatment, they demand a wireless installation for maximum patient benefit, which in turn demands quite specific antenna requirements. The antennas must be composed of biocompatible materials, and must be very small (no more than a few square centimeters) to minimize invasiveness. Here PSO is applied to design a 22.5 mm × 22.5 mm × 2.5 mm implantable serpentine planar inverted-F antenna for dual-band MedRadio and ISM operation. Measurements reveal the accuracy of the models. Hyperthermia is the process of elevating a patient’s temperature for therapeutic gain. Since the ancient Egyptians, physicians have employed hyperthermia in the destruction of cancerous tumors. Modern implementations typically apply electromagnetic radiation at radio and microwave frequencies to induce local or regional heating. In this dissertation PSO is used to evaluate candidate antennas for inclusion in an array of antennas with the aim of local adjuvant hyperthermia for breast cancer treatment. The nearield of the array is then optimized to induce a uniform specific absorption rate throughout the breast.

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No description available.

Approved for public release; distribution is unlimited / The Numerical Electromagnetics Code (NEC) was used to evaluate the admittance, average power gain, and the electric near and far field of a monopole antenna mounted on a cubical box over a perfectly conducting ground plane. Two models of the box, employing surface patches and wire grids, were evaluated. The monopole was positioned at the center, the edge, and at a corner of the box's top surface. Admittance and average power gain of the antenna were calculated. NEC results were examined and compared with experimental data and with results from "PATCH", another independent electromagnetic modeling code. The near electric field was calculated for both models. Computer graphics techniques were presented for plotting NEC near field results using DISSPLA (Display Integrated Software System and Plotting Language), a commercial graphics package. Contour and 3-D amplitude, and phase plots of the near electric fields were presented. Radiation patterns were calculated to relate far field and near field behavior of the antenna. Surface patch and wire grid models are compared and conclusions were presented. / Naval Ocean Systems Center / http://archive.org/details/investigationofn00elli / O&MN, Direct Funding / Lieutenant, Hellenic Navy

<div>Recently, researchers have pointed their attention toward Method of Moments (MoM)-based approaches to model low frequency magnetic devices (i.e. transformers and inductors). This has been prompted by the use of population-based design (PBD) methods wherein the performance of large numbers (on the order of millions) of candidate designs must be evaluated. MoM is attractive for such problems due to the fact that only the magnetic material is discretized. In addition, for the case in which the magnetic material is linear, only a surface mesh is required. In this research, point-matching and Galerkin-based MoM formulations are utilized for the design of electric machinery. In the formulations considered, the model inputs are the free currents of machine windings and the bound currents of permanent magnets. The unknowns are the magnetizations within the magnetic material which are used to compute winding inductance, electromagnetic torque, and core loss. </div><div><br></div><div>The proposed Galerkin formulation has been utilized in the PBD of a surface-mount permanent magnet machine with favorable results. Specifically, it is shown that a machine's performance can be evaluated on a time scale expected of a practical design tool. This is achieved in part through judicious exploitation of the periodic structure and excitation of machines to reduce the size of the system matrix. It is shown how the exploitation of periodic structure may be extended to the point-matching formulation for use in nonlinear analyses. Finally, alternative hybrid approaches that combine surface and volume meshing are explored for the analysis of an internal permanent magnet machine. It is shown that such a combination holds promise as a tool for rapid evaluation of machine performance.</div>