Properties of an electromagnetically coupled small antenna with a superconducting thin-film radiator

This paper describes the structure and properties of a 900-MHz-band small antenna with a superconducting thin-film radiator operated by electromagnetic coupling. The radiation efficiency of the antenna with a /spl lambda//38 radiator reached 74% at 79 K. The loss in this antenna comprised mismatching loss and radiator loss caused by the surface resistance of the superconducting thin film. A simulation model with a meander-line radiator and a parallel line is also proposed. This model makes it possible to design a superconducting thin-film radiator which can be fabricated on a dielectric substrate by using the moment method without taking account of the dielectric substrate.