The advent of high- superconducting materials has presented new opportunities for improving antenna performance. Many antenna workers are not familiar with the current findings on superconductors. Considered here are electrically small antennas, and matching of them, and millimeter-wavelength antennas. Not included are SQUID devices that incorporate a loop or other antenna. These are primarily of interest as very low-frequency magnetic field sensors.
7.2 Superconductivity Concepts for Antenna Engineers
There are many excellent books on superconductivity; only a basic overview is given here. An excellent treatise on all aspects of high- and low-temperature superconductivity, including a thorough mathematical treatment, is provided by Tinkham (1996). A physical understanding, with a minimum of mathematics, is provided by Ginzburg and Andryushin (2004). And there are many others. Lancaster (1997) has written a useful book on HTS applications including antennas. Table 7.1 shows a brief chronology up through the fullerenes. It is interesting to note the first step toward HTS: in 1975, Sleight, Gibson, and Bierstedt discovered superconductivity in a barium lead bismuth metallic oxide at . This significant increase in , for a ceramic material, ...