Wireless energy transmission using electrically small antennas

This paper presents a concept for rectifying low ambient radiation sources to supply autonomous measurement systems such as microsystems. In addition to an analytic computation and nonlinear simulation of the rectifier circuit with advanced design system (ADS), a circuit was built and the efficiency factor of the RF-harvesting system was measured. Matching the impedance is done by using an electrically small loop-antenna. A resonance circuit transformation with a high quality factor in front of a Schottky-diode works as a passive voltage transformer with a gain of 30 at 300 MHz. The measurements are in excellent agreement with calculations and simulations.