Microwave receivers using SQUIDs and Josephson junction arrays

Performance of various microwave receiving devices, using the Josephson junctions closed with superconducting loops and/or united in arrays, is discussed. These composite nonlinear elements enable us to eliminate problem of their matching with the signal source, to increase the saturation power and to come close to ultimate limits of the device noise performance. For internally-pumped devices, connection of several junctions in a closed-loop (ring) array turns out to be most effective, with coherent junction self-oscillations. For externally-pumped devices, the use of low-inductance (non-hysteretic) SQUIDs is of the greatest interest, enabling one to avoid the difference in junction dynamics due to parameter random spread.