Novel ultra-wideband directional antennas for microwave breast cancer detection

This paper presents two novel designs of elliptical ultra-wideband (UWB) antennas with voltage standing wave ratios (VSWRs) less than 1.96 and return loss lower than -10 dB across a broad frequency range of 3 GHz to 20 GHz. The directive gains of one design range from 7.4 dBi to 8.81 dBi, while for the other, they range from 7.15 dBi to 9.08 dBi. The key feature of these two designs is the careful engineering of the ground planes and the major and minor axes of the elliptical patches, which permits the operational bandwidth to span over an UWB range. As a result, directional beam patterns can be achieved even for low-profile, miniaturized designs. These antennas may find useful applications in microwave breast imaging due to their desirable directional properties and compact sizes.