Contents I. Introduction
Wideband antennas find multiple applications in many different fields, including communication, medicine, agri-tech, and microwave image processing as a non-invasive technique [1]–[6]. Planar antennas allow to obtain good radiation properties and high compactness. They can be designed considering different technologies, such as microstrip, substrate integrated waveguide (SIW), and 3D printing [3]–[10]. Microstrips antennas are characterized by fabrication easiness, low-cost, and low profile. These qualities attracted research interest during the last decades. Vivaldi antennas are widely employed thanks to their large bandwidth and good gain. Moreover, they can be designed in microstrip technology, obtaining also light-weight and low-profile antennas [9]–[13].
