Contents I. Introduction
The Intrinsic properties of fractal geometries are conducive to the miniaturization of antenna designs and realization of antenna multiband characteristics. Since the fractal structures are generated by a recursive process, they can produce a very long length or a wide surface area in a limited space. Consequently, fractal structures can give rise to miniaturized wideband antennas having radiation patterns and input impedance characteristics similar to the larger antennas. In 1951, Mandelbort proposed the fractal geometries [1], which were extensively used in various science and engineering fields. They were also applied for the design and realization of frequency-independent and multiband antennas. Multiplication of an antenna size by a factor generally decreases the operating frequency of the antenna by the same factor. If an antenna is much smaller than the wavelength of the operating frequency, its efficiency deteriorates drastically since its radiation resistance decreases and the reactive energy stored in its near field increases [2]. These two factors make the matching of a small antenna to its feeding network difficult. Consequently, fractal antennas are a viable candidate for their miniaturization [3]. Antenna geometries and dimensions are the main factors determining their operating frequencies [4]. It is shown that if the angular variations define the antenna geometry, then its performance is independent of frequency because no particular size may be attributable to it [5]. Therefore, the antenna has an effectively infinite bandwidth. The spiral and helical antennas may be considered as examples of frequency-independent antennas. The self-similarity properties of log-periodic antennas also make them frequency-independent [6].
