Electrically and Optically Controlled Wideband Matching of Radio-Absorbing Composites to the Ambient Space

Abstract

Microwave radio-absorbing metastructures are proposed that possess controlled broadband matching to the ambient space by virtue of an array of varactor-loaded chiral and annular elements in which magnetic resonance are excited. Experimentally in a rectangular waveguide and numerically in free space, it is shown that the tuning of the magnetic resonance frequency leads to a shift in the matching frequency region. The electric control of the magnetic resonance and, accordingly, the matching (25% relative tuning) is achieved by the variation in the reverse bias voltage at the varactor, and the optical control is achieved by directing a red laser pointer to a photodiode connected to the varactor in the photodiode mode.