On the path to superconductor broadband receivers

We review progress in developing software-defined radio communication systems through using superconductive rf and digital technologies. Both the outstanding sensitivity and high spurious-free dynamic range (SFDR) of the state-of-the-arts superconductor analog-to-digital converters (ADC) enable broadband receiving systems with direct signal digitizing and subsequent digital extraction of sub-bands. To raise the overall system performance up to the outstanding performance of superconductor ADC, one can use an active superconductor electrically-small antenna (ESA) instead of standard passive antenna with a low-noise amplifier, both providing lower performance as compared to the ADC. The attainable characteristics and design issues of the superconductor active ESAs are reviewed and discussed.