Study on the properties of circular monopole antenna

Abstract
Wide band and miniaturization are both the hottest issues in the current researches on antennas. The circular monopole antenna is a kind of ultra-wideband antennas with simple feeding network. Detailed analyses are conducted to determinate the antenna's properties. The design method of the antenna is presented, and the influences on its impedance and radiation properties by varying the dimension parameters of the antenna are discussed. Through simulations and experiments, it is demonstrated that the antenna has a more than 10 times octave impedance bandwidth, good consistency of the horizon directivity diagram and the constant group delay. The results show that the circular monopole antenna has not only the ultra-wideband in frequency domain, but also the stable phase center, which makes the antenna suitable for the antennas in the time domain communication systems. Also, the antenna can easily cover the frequency range from 400 MHz to 4 GHz, which includes the usual bandwidth for RF devices such as RFID devices, GPS receivers, image transmission devices (all these RF devices are applied to various traffic control systems), so that the circular monopole antenna can be used as the antenna for the entire traffic control systems, which greatly reduces the complexity of the whole system