A Comparison of Fractal and Non-Fractal End-Loaded Miniature Dipole Antennas

J.M. McGinthy, B.C. Kaanta, and S.R. Best (USA)


dipole antennas, end-loaded antennas, fractal antennas, electrically small antennas.


: End-loaded dipole antennas exhibit lower resonant frequencies than straight-wire dipole antennas that have the same overall length. End-loading is a well known and a relatively straight-forward technique for miniaturizing the overall size of an antenna at a fixed or given frequency. The typical design trade-offs that occur when miniaturizing an antenna are a reduction in resonant resistance and operating bandwidth. Here, we examine several different end-loading geometries, and compare their relative performance. These geometries include fractal and non-fractal configurations. In comparing different antenna geometries, we set the resonant frequency to be the same and we examine the antennas’ resonant resistance and impedance bandwidth. We show that the resonant impedance properties of the different end-loaded dipole antennas are consistent for a given resonant frequency, indicating that the dominant factor in establishing the antenna’s effective height is its overall length. We show that the antennas’ bandwidth properties vary to a greater degree and are more a function of the occupied and resulting effective volumes.

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