Microwave radiation and sensing of Josephson junction with the log-periodic toothed trapezoid antenna of high T/sub c/ superconducting films

• Published in: IEEE transactions on applied superconductivity 1999-06, Vol.9 (2), p.3074-3076
• Main Authors: Kwang-Yong Kang, Insang Song, Yeon Su Ha, Seok-Kil Han, Gun Yong Sung, I-Hun Song, Gwangseo Park
• Format: Article
• Language: English
• Subjects: Antenna measurements; Frequency measurement; Josephson junctions; Microwave measurements; Power measurement; Receiving antennas; Superconducting microwave devices; Superconducting thin films; Temperature sensors; Waveguide junctions
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.783678

Using high temperature superconducting thin films, we designed and fabricated Josephson junctions associated with a log-periodic toothed trapezoid antenna. Microwave self-radiation from the Josephson junction was measured by using both a superheterodyne receiver at the center frequency of 22 GHz and an external waveguide system. In the case of junction incorporated with an antenna structure, there was a significant increase of power by an order of magnitude with respect to a junction without antenna. Under the 22 GHz irradiation, we observed distinctive Shapiro steps in the I-V measurement, which allowed as estimating the received power of the junction. The received power of the junction with an antenna exhibited as a large increase as that of a self-radiation. Our results indicate that a Josephson junction with an antenna is very effective for the microwave coupling between Josephson junction and free space. The combined device can be used either for a high power microwave source or for a high sensitive sensor.