Miniaturized superconducting metamaterials for radio frequencies

Abstract

We have developed a low-loss, ultrasmall radio frequency (rf) metamaterial operating at ∼76 MHz. This miniaturized medium is made up of planar spiral elements with diameter as small as ∼λ/658 (λ is the free space wavelength), fashioned from Nb thin films on quartz substrates. The transmission data are examined below and above the superconducting transition temperature of Nb for both a single spiral and a one dimensional array. The validity of the design is tested through numerical simulations and good agreement is found. We discuss how superconductors enable such a compact design in the rf with high loaded-quality factor (in excess of 5000), which is in fact difficult to realize with ordinary metals.