Nonlinear microwave response of a superconducting YBa2Cu3O7-δ microstrip transmission line with a constriction

Microwave power losses IL(P-in) introduced by a superconducting YBa2Cu3O7-delta film microstrip transmission line with a constriction have been investigated experimentally in the temperature range 78-90 K. For microwave current flow with amplitude greater than the critical value I-c(rf) losses growing rapidly with increasing input microwave power arise in the line. Hysteresis of the functions IL(P-in) is observed when the microwave power is increased and then decreased. Calculations show that the losses in the line are due to the formation of resistive transverse domains, whose temperature is above the critical value, in the region of the constriction. It is shown that a small constriction consisting of a HTSC film in a microwave transmission line can be regarded as a concentrated nonlinear resistive element, which can be used as basis for building a microwave power limiter. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3075938]