456 IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 7, 2008 A Printed Log-Periodic Koch-Dipole Array (LPKDA)

Abstract—Koch-shaped dipoles are introduced for the first time in a wideband antenna design and evolve the traditional Euclidean log-periodic dipole array into the log-periodic Koch-dipole array (LPKDA). Antenna size can be reduced while maintaining its overall performance characteristics. Observations and character-istics of both antennas are discussed. Advantages and disadvan-tages of the proposed LPKDA are validated through a fabricated proof-of-concept prototype that exhibited approximately 12% size reduction with minimal degradation in the impedance and pattern bandwidths. This is the first application of Koch prefractal elements in a miniaturized wideband antenna design. Index Terms—Koch, log-periodic dipole antenna array, log-pe-riodic dipole array (LPDA), log-periodic Koch-dipole array (LPKDA), miniaturized antenna. I