Analysis and Measurement of a Time-Varying Matching Scheme for Pulse-Based Receivers With High-$Q$ Sources

Abstract

A time-varying matching scheme designed for pulse- based high-quality factor ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> ) receiving systems is introduced and analyzed. The proposed technique takes advantage of the time-domain characteristics of the short-duration pulses in a way that the matching network is optimized for absorbing energy from the pulse within its duration, and is reconfigured after the pulse so that the captured energy is efficiently delivered to the load. Particularly, this paper extends the authors' earlier work by providing a comprehensive analysis of the capability of the proposed design in achieving exceptional voltage gain and width compression. Measurements in the VHF range are provided to show the performance of the proposed design versus the conventional ones. The proposed technique is applied to the matching design for electrically small antennas, which achieves output signals with ten times narrower pulsewidths compared to original pulses, 3-4 times larger amplitudes, and 0.3-3-dB energy gains compared to conventional matching designs. New results also demonstrate the effects of timing/synchronization, which show that accurate synchronization (with typical error smaller than 10% of the original pulsewidth) is required to maintain large output amplitude (e.g., higher than 90% of the maximum achievable level). The proposed technique is particularly suitable for receiving systems using common modulation schemes including pulse amplitude modulation and on-off keying.