A Vivaldi Antenna Palm Tree Class with Koch Square Fractal Slot Edge for Near-Field Microwave Biomedical Imaging Applications

This article presents the modeling of an antipodal Vivaldi antenna (AVA), Palm Tree Class, with radiating fractal slot edge (FSE), in the form of a Koch Square Fractal (SK), labeled as SK-FSE-AVA. The surface currents of the proposed antenna are analyzed, as well as the return loss, directivity, squint, side lobe level (SLL), and Main Lobe (ML) gain. Improvement on directivity is observed when compared to an AVA, with 8.41 dB of gain in the main lobe at 4 GHz, SLL of 11.70 dB, and the squint of 0.10°. SK-FSE-AVA has 9.23 dB of gain in the main lobe at 4 GHz, SLL of –13.50 dB, and the squint of 0.2°. This antenna could be used in ultra-wideband (UWB) systems for applications on Near-Field Microwave Imaging (NMI). To show the feasibility of this application, a 3D numerical simulation of a model containing lung tissue with a malignant tumor is presented, using the proposed antenna and the respective imaging results.