RESPONSE OF RADIO-FREQUENCY SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES TO ELECTROMAGNETIC-INTERFERENCE

A number of applications of high-temperature superconductor radio freq uency superconducting quantum interference devices (rf SQUIDs) require a certain immunity of these sensors against electromagnetic interfere nce (EMI). We have investigated effects of electromagnetic radiation i n the high-frequency and ultrahigh-frequency range on various types of rf SQUIDs. It has been found that EMI of sufficient field strength re duces the voltage versus flux transfer function, and thus increases th e flux noise of the SQUIDs. SQUIDs with a wire wound tank circuit coil have been found to be more sensitive to EMI than SQUIDs integrated in to a superconducting microstrip resonator. (C) 1995 American Institute of Physics.