Design of Monopole Antenna Based on Fractal Geometry

This paper presents a circular disc monopole antenna based on fractal geometry. The antenna is designed to be applied in UWB systems. So it is essential to ensure that the bandwidth of the antenna ranges from 3.1？GHz to 10.6？GHz, that is, IEEE 802.15.3a. However, the proposed antenna has achieved working in the required bandwidth. Compared to the antennas illustrated in most similar literatures, the proposed antenna has a much smaller size, which makes the antenna possible to be integrated with portable devices. Firstly, the antenna was designed through CST Microwave Studio. Then, the antenna was fabricated according to the simulated results. At last, the comparison between the simulated results and measured results was carried out which demonstrated good consistency. 1. Introduction With the development of society, UWB systems are becoming increasingly important in our life. Given the fact that antennas play a vital role in the whole systems, design of appropriate antennas attracts lots of interest from researchers and engineers. There are several different methods utilized to devise the required antennas. The circular disc monopole antenna is of great popularity for its wide bandwidth characteristic. The antenna presented in [1] utilizing multicircular blades has an ultrawide bandwidth. Likewise, the antenna reported in [2–7] also has potential to be used in UWB systems. Nevertheless, the dimensions of these antennas are sometimes too large to be used in practice. So, in order to make an improvement to this drawback, we make the combination of conventional circular disc monopole antenna with fractal theory. As well known, fractal theory including various different shapes like Sierpinski gasket, Sierpinski carpet, and Descartes circle may have different impacts on the performance of an antenna. In this paper, the Descartes circle theorem [8] is used in the design of circular disc monopole antenna for the sake of realizing outstanding properties. The concept of multicircular blades is also taken into consideration. Based on the theorems mentioned above, it is predictable that the proposed antenna has a wide bandwidth from approximately 2.9？GHz to 13.5？GHz, which satisfies the requirement of UWB systems. Meanwhile, the radiation patterns of the antenna almost remain stable in the operating bandwidth and are similar to those of the conventional cylindrical monopole antenna. More importantly, a compact configuration is obtained through this method, which makes the antenna capable of being used in practice more conveniently. 2. Antenna Design In this paper,