Surface Wave and Back Radiation Suppression in Microwave Breast Screening

The challenges in antenna design for microwave-based breast screening systems identify two distinct needs: 1) to minimize the surface-wave propagation at the interface between the substrate and the tissue, and 2) to address the back-radiation. These surface waves become more noticeable within the substrate, particularly when a confining ground plane is present, and yet the ground plane is pivotal for achieving unidirectionality and shielding against environmental radiation. This paper introduces a simplified human breast model and offers a quantitative analysis of existing surface waves. We then propose a 16-antenna array of cavity-backed patch antennas with parasitic elements, designed for operation in the 3.1–5.1 GHz range. Each antenna element is optimized to function seamlessly alongside the breast tissue. Full-wave simulations illustrate that the proposed antenna array achieves superior unidirectionality and diminished mutual coupling levels when compared to its predecessor. We further outline the cost-effective fabrication method that employs the SYLGARD(TM) 184 silicone elastomer PDMS kit. The measurements from the fabricated antenna elements are consistent with the results of the full-wave simulations.