Time-Modulation as a Vehicle for Bypassing the Gain-Bandwidth bound of Small LTI Antennas

Abstract

The Chu bound, developed under the assumptions of passivity, linearity, and time-invariance sets a lower limit on the quality factor of a small antenna. This with the gain properties of the antenna dictates its maximal attainable gain-bandwidth product of an antenna. By revoking the LTI assumption of the properties e.g., by allowing time variation of the antenna properties, better performance may be achieved. In the following presentation we specifically discuss the effect of time-modulation of the antenna structure on the gain-bandwidth product of a system of three coupled antennas. It is shown that time-modulation may give better results beyond that obtained for the corresponding LTI antenna system.