  We demonstrate a low-dissipation dielectric metamaterial with tunable
properties based on the Josephson effect. Superconducting wires loaded with
regularly spaced Josephson junctions ($I_c \approx 0.25$ $\mu$A) spanning a
K-band waveguide and aligned with the microwave electric fields create a
superconducting dielectric metamaterial. Applied dc current tunes the cutoff
frequency and effective permittivity of this unique electric metamaterial. The
results are in agreement with an analytical model for microwave transmission
through the artificial dielectric medium.
