Ultimate impedance matching of HTS microstrip antennas

In this paper, we report the phenomenon of the perfect impedance matching o f high-T-c superconducting (HTS) antennas near the critical temperature (T- c). Two HTS antennas and two gold antennas with and without matching geomet ry are constructed in order to investigate the variation of impedance match ing with temperature. We observe an ultimate impedance matching irrespectiv e of the matching geometry of HTS antennas around the T-c unlike the normal conducting antennas. At the temperature of 88 K the return loss rapidly dr ops down below -60 dB and the characteristic impedance approaches almost 50 Omega at the resonant frequency of 11.824 GHz. These can be attributed to the kinetic inductance which abruptly increases around the critical tempera ture. (C) 2001 Elsevier Science B.V. All rights reserved.