Control of radar cross sections of electrically small high temperature superconducting antenna elements using a magnetic field

The radar cross sections (RCS) of small circular loops made from YBCO high temperature superconductor are calculated as a function of applied magnetic field strength. It is shown that the RCS is reduced as the magnetic field increases, and that the effect is more pronounced as radiation resistance decreases. Two factors contributing to the RCS reductions are identified, firstly an increase in surface resistance with magnetic field, and secondly a detuning effect caused by a change in the loop input reactance. It is suggested that antennas might be made from superconductor as a means of controlling their RCS, rather than for improved efficiency