Resonant metallic rings with irregular contours for spiral antennas miniaturization

This paper addresses the miniaturization of Archimedean spiral antennas by using stacked resonant metallic rings. Such rings are electromagnetically coupled to spiral antennas and play a key role in the reduction of the antennas diameter. A methodology for selecting very compact resonant rings based on fractal geometry is reported. The fabrication of spiral antennas incorporating the selected fractal rings uses flexible substrate and ink-jet printing technology.