Fractal antennas: a novel antenna miniaturization technique, and applications

• Published in: IEEE antennas & propagation magazine Vol. 44; no. 1; pp. 20 - 36
• Main Authors: Gianvittorio, J.P., Rahmat-Samii, Y.
• Format: Magazine Article
• Language: English
• Published: New York, NY IEEE 01.02.2002; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antennas; Applied sciences; Clouds; Contours; Exact sciences and technology; Focusing; Fractal analysis; Fractal antennas; Fractal geometry; Fractals; Geometry; Linear antenna arrays; Manufacturing; Mathematical models; Patch antennas; Phased arrays; Radiocommunications; Shape; Solid modeling; Telecommunications; Telecommunications and information theory; Wire; Mutual coupling; Wire antenna; Linear antenna; Fractal; Microstrip antennas; Printed antenna; Miniaturization; Phased array antenna; Dipole antenna; Loop antenna; Electromagnetic coupling
• ISSN: 1045-9243; 1558-4143
• DOI: 10.1109/74.997888

Fractal geometry involves a recursive generating methodology that results in contours with infinitely intricate fine structures. This geometry, which has been used to model complex objects found in nature such as clouds and coastlines, has space-filling properties that can be utilized to miniaturize antennas. These contours are able to add more electrical length in less volume. In this article, we look at miniaturizing wire and patch antennas using fractals. Fractals are profoundly intricate shapes that are easy to define. It is seen that even though the mathematical foundations call for an infinitely complex structure, the complexity that is not discernible for the particular application can be truncated. For antennas, this means that we can reap the rewards of miniaturizing an antenna using fractals without paying the price of having to manufacture an infinitely complex radiator. In fact, it is shown that the required number of generating iterations, each of which adds a layer of intricacy, is only a few. A primer on the mathematical bases of fractal geometry is also given, focusing especially on the mathematical properties that apply to the analysis of antennas. Also presented is an application of these miniaturized antennas to phased arrays. It is shown how these fractal antennas can be used in tightly packed linear arrays, resulting in phased arrays that can scan to wider angles while avoiding grating lobes.