The Electromagnetic Interaction with Tissue of a Circular Patch Antenna, Comprising a Concentric Ring and a Radially Slotted Groundplane

TitleThe Electromagnetic Interaction with Tissue of a Circular Patch Antenna, Comprising a Concentric Ring and a Radially Slotted Groundplane
Publication TypeConference Paper
Year of Publication2008
AuthorsCurto, S, Bao, XL, Ammann, MJ
Conference NameProgress In Electromagnetics Research Symposium
Pagination372
Conference Start Date24/03/2008
Conference LocationHangzhou, China
Abstract

The study of a novel compact circular patch with a concentric ring and radial slots in the ground plane for a hyperthermia applicator at the 434 MHz ISM band shows that it exhibits an enhanced E-feld coupling into simulated human tissue models. In RF-hyperthermia
applicators, reducing the size of the applicator for the treatment of tumours located at curved sites of the body and the effcient delivery of electromagnetic energy are priority considerations. Designed for a small size and a low cost alternative to large resonant loops, square patches, dielectric loaded horns or dipole arrays, the lightweight antenna can be deployed in close proximity to a patient undergoing a clinical course of superficial hyperthermia treatment. Arbitrary near-feld loading of an antenna by various tissue types requires that its input impedance be suffciently insensitive to in-band resonant detuning, that it have matched bandwidth to a high powered source and that the felds in the tissue can be targeted to selected areas in the patient. The antenna has been modelled using CST's MWS and reported here are E-fields, input impedances, surface currents and specific absorption rates. The antenna's design and properties are discussed for performance in very close proximity to human tissue models. For contrast, the free-space behaviour illustrates the tissue loading effect on the antenna. The resonant modes on the compact patch are analyzed to evaluate the coupling of fields into the tissue. As tissue
layer thicknesses vary around the body and between patients, a range of skin, fat and muscle thicknesses are used to estimate appropriate distances between the antenna applicator and the patient.

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