Breast cancer affects many women and early detection aids in fast and effective treatment. Mammography, which is currently the most popular method of breast screening has some limitations and microwave imaging offers an attractive alternative. The objective of this paper is to design a simple and cost effective single layer aperture coupled microstrip patch antenna for breast cancer detection. The radiation characteristics and the performance of the proposed design are compared with double layer patch antenna. The result of this study shows that the designed antenna has excellent performance across the required frequency range. This single layer patch antenna offers better radiation coverage to the breast and provides efficiency of 62.6% (wide slot) and 62.2% (narrow slot) than double layer stacked patch antenna.