A dielectric filled ultra-wideband antenna for breast cancer detection

X-ray mammography, the most prevalent screening process for breast cancer, has limitations, thus generating interest in alternative detection methods One method of interest is microwave breast cancer detection which exploits the contrasts in dielectric properties between healthy and malignant tissue. Tissue sensing adaptive radar (TSAR) imaging has been proposed for microwave breast cancer detection (Fear, E.C. et al., IEEE Trans. Microwave Theory and Technique, 2003). This paper presents an antenna and its feeding structure for TSAR. The slotline bowtie hybrid (SBH) is selected as the basic design. The SBH has an integrated ultra-wideband balun to allow it to be easily connected via coaxial cable. The SBH is a hybrid of a slotline circuit board antenna and bowtie horn. A broad bandwidth match is achieved by widening the slot with a Vivaldi profile. The SBH achieves a flat main beam over the bandwidth by additionally employing triangular bowtie plates on the slot profile. A rolled edge at the bowtie aperture reduces edge diffraction. The introduction of an ambient dielectric in place of free space allows its size to be scaled down. Simulation results for the balun show that an acceptable insertion loss of less than 2 dB can be achieved, even when the balun is immersed in an ambient dielectric. Antenna simulations show that it meets the design objectives.