An Ultra-wideband Monopole Antenna of Small Size

Abstract

Ultra-wideband antennas with omni-directional coverage have an increasing demand for the applications of e.g. wireless communication services. Most of these applications require an antenna of compact size and low profile. Compared with spheroidal, biconical, spiral or discone types of antennas which have been used for ultra wideband (UWB) systems, planar monopole antennas [1-3] have many advantages such as wide impedance bandwidth, omni-directional radiation pattern, compact and simple structure, low cost and ease of fabrication. However, a traditional monopole antenna usually has the dimension of about quarter wavelength at the low frequency band in order to radiate efficiently [1].