A comparison of planar monopole antennas for UWB applications

In this paper, a number of planar monopole antennas are first investigated to maximize the bandwidth with a fixed area of the radiator. This is done by changing the feed gap (the spacing between the radiator and the ground) as well as the length and width of the ground plane with the aid of a simulation package. A comparison of these antennas along with two different feed lines (microstrip and co-planar waveguide) is then made. Furthermore, a rectangular conducting reflector is placed below the antennas to obtain unidirectional radiation pattern which is required by some applications. It is shown that the optimised antennas with relatively small dimensions can achieve a very broad bandwidth for both feed-lines with the ability to produce uni-directional radiation pattern for applications such as ground penetrating radars and detection. Some measurements results are obtained and they confirm the validity of the simulations.