A matching technique that may be used with electrically small antennas uses one or more digital circuit blocks connected in a feedback arrangement configured to tune the transfer function response between the antenna and an output port of the system. Each circuit block may include an analog-to-digital converter (ADC), a digital filter, and a digital-to-analog converter (DAC). As such, tuning the transfer function may be achieved by sensing a voltage or current at various circuit nodes using one or more ADCs, filtering the measurements in response-shaping digital filters, and using one or more DACs to drive other circuit nodes in a manner that elicits a desired circuit response. Techniques are provided for allowing a matched antenna to adapt to a changing environment about the antenna. In one illustrative embodiment, the digital circuit blocks may be provided as digital non-Foster circuit blocks.