Affiliated with the
Communication & Space
Sciences Laboratory

Fractal Antenna Engineering

Fractal Tree Elements

Photograph of a Prototype Tri-band Fractal
Tree Monopole Antenna


..: References :..

1-) Radiation Characteristics of Thin-Wire Ternary Fractal Trees
by D.H. Werner, A. Rubio Bretones and B.R. Long
Electronics Letters, Volume 35, Issue 8, pp. 609 - 610, 15 April 1999.

ABSTRACT: The multiband electromagnetic behaviour of thin-wire structures based on a ternary tree fractal geometry are investigated. As an example, experimental and numerical results are presented for the particular case of a three-band monopole structure, which show the expected self-similar behaviour at those bands. Some interesting properties are observed for these ternary tree fractial structures that are not evident in their Sierpinski monopole counterparts.

2-) Dense 3-D Fractal Tree Structures as Miniature End-Loaded Dipole Antennas
by Joshua S. Petko and D. H. Werner
2002 IEEE International Symposium on Antennas and Propagation, San Antonio, Texas, June 16-21.

3-) Reconfigurable Miniature Three Dimensional Fractal Tree Antennas
by Joshua S. Petko and D. H. Werner
2003 IEEE International Symposium on Antennas and Propagation, Columbus, Ohio, June 22-27.

4-) Miniature Reconfigurable Three Dimensional Fractal Tree Antennas
by Joshua S. Petko and Douglas H. Werner
IEEE Transactions on Antennas and Propagation, Vol. 52, Issue 8, pp. 1945 - 1956, August 2004.

ABSTRACT: This paper introduces a design methodology for miniature multiband as well as reconfigurable (i.e., tunable) antennas that exploits the self-similar branching structure of three-dimensional (3-D) fractal trees. Several fundamental relationships, useful for design purposes, are established between the geometrical structure of the fractal tree antenna and its corresponding radiation characteristics. In particular, it will be shown that the density and elevation angle of the branches play a key role in the effective design of miniature 3-D fractal tree antennas. Several design examples are considered where fractal trees are used as end-loads in order to miniaturize conventional dipole or monopole antennas. Multiband and reconfigurable versions of these miniature antennas are also proposed, where either reactive LC traps or RF switches are strategically placed throughout the branches and/or along the trunk of the trees. Included among these designs is a miniature reconfigurable dipole antenna that achieves a 57% size reduction for the center frequency of the lowest intended band of operation and has a tunable bandwidth of nearly 70%.

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