Enhancement of the Focusing Properties of a Passive Radiometry Imaging System: A Theoretical Electromagnetic Study
ABSTRACT A non-invasive imaging system, consisting of an ellipsoidal conductive cavity and radiometric receivers, designed and constructed in our laboratory the past few years is restudied. A means for further improvement of the ellipsoidal reflector's focusing properties thus its performance is herein investigated. The main differentiating factor of our new approach is that the receiving antenna is more realistically modelled and also covered by two layers of different dielectric properties. The present paper provides details on the electromagnetic theoretical analysis of the problem and presents numerical results for the electric field distribution inside the head model, using two main operating frequencies, namely 0.5GHz and 1.5GHz for four distinct cases. The focusing optimization of the system in terms of spatial accuracy and penetration depth is assessed while the method and results are also separately validated.
SourceAvailable from: Melpomeni I. Giamalaki[Show abstract] [Hide abstract]
ABSTRACT: A Green's function based methodology has been developed and implemented with the view to optimize the focusing properties and thus the performance of a Microwave Radiometry Imaging System (MiRaIS). The system consists of an ellipsoidal conductive wall cavity and a sensitive radiometric receiver and its operation principal is based on the convergence of the radiation from one focal point, where the subject or phantom is placed, on the other, where the receiver antenna is positioned. A two-layered cylinder is used to model the human head with the semi-analytical Green's function technique. The imaging configuration is enhanced by different matching structures of various materials which are placed on the surface of both the human head model and the antenna inside the ellipsoidal. Numerical code executions have been realized and the results for the electric field distribution inside the head are presented for materials of various dielectric properties and for left handed materials at two different frequencies (0.5GHz and 1.0GHz). Increased sensitivity of the system focusing properties is observed using particular matching structures.Progress In Electromagnetics Research 01/2009; 90:385-407. DOI:10.2528/PIER09010803 · 5.30 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: A non-invasive imaging system, consisting of an ellipsoidal conductive cavity and radiometric receivers, designed and constructed in our laboratory the past few years is restudied. In order to enhance the system's focusing properties thus its performance, the head is covered by a dielectric matching layer while the receiving antenna is more realistically modelled and also covered by two layers of dielectric properties similar to those of the head. The electric field distribution inside the head is calculated for two frequencies and for matching layers of different dielectric properties and thicknesses, through a theoretical electromagnetic analysis using a Green's function technique. Sensitivity of the system focusing properties is observed when the head or the source center is moved away from the system's geometrical focal areas.Journal of Instrumentation 05/2009; 4(05):P05011. DOI:10.1088/1748-0221/4/05/P05011 · 1.53 Impact Factor