Fractal-Shaped Koch-Ring Microstrip Patch

Design of small antennas that can be integrated with the circuitry inside handheld electronic devices is an emerging research topic in the field of mobile communication. Use of circular-shaped rings is a viable solution proposed to design miniature antennas. In this paper, a novel shape is proposed for printed antennas by incorporating the Koch fractal with circular rings. The proposed Fractal-Shaped Koch-ring antennas exhibit miniature properties. The miniaturization factors of the circular ring microstrip patch antenna (MPA) and Koch-ring MPAs of first and second iterations were analyzed and their characteristics were compared in terms of the resonant-frequency at the fundamental mode, input impedance at the resonance frequency, bandwidth, radiation efficiency and the radiation pattern. Numerical and experimental results show that a fractal-shaped Koch-ring MPA resonates at a lower frequency than classical circular rings. Based on these findings, a stacked MPA with Koch-rings was designed to make the antenna miniature with high efficiency and a high directivity along the broadside radiation.