A Compact Fractal Dielectric Resonator Antenna for the Microwave Imaging of Skin Cancer

This manuscript presents a miniaturized Ultra-Wideband (UWB) fractal geometry and Dielectric Resonator based Antenna. This antenna is specifically designed for skin cancer detection through a radar-based monostatic microwave imaging (RBMMI) method. The proposed antenna consists of an ‘Inverted-U’-shaped alumina dielectric resonator positioned on a Rogers substrate. Its structure includes a defected ground surface design (DGS) inspired by a fractal-modified Incan cross pattern and a microstrip feed-line with integrated slots. The overall dimension of the antenna is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$30 \times 22 \times 6.87 ~\text{mm}^{3}$</tex> and it supports a wide impedance bandwidth ranging from 4.9-16.195 GHz. To demonstrate its effectiveness in microwave imaging (MI) for skin tumor detection, a model of bio-phantom is developed using CST software, enabling reconstruction of a 2D dielectric image of the targeted skin area. The S-parameters are collected using the antenna as a sensor for both the case of tumor and no tumor inside the phantom. The collected data is then processed using the Coherent-Factor Delay Multiply and Sum (CF-DMAS) algorithm. This results in a 2D image that accurately pinpoints the tumor's location. Furthermore, the antenna is demonstrated to be safe for human exposure, with Specific Absorption Rate (SAR) values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.0564 ~\mathrm{W} / \text{kg}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.0346 ~\mathrm{W} / \text{kg}$</tex> at 7 GHz and 12 GHz respectively, based on 1 gram of tissue