Broad Flat-Top Adjustable Filter With Metamaterial

A flat-top filter with adjustable, broad, and robust tunneling band is proposed, where the barrier is composed of multiple layers including a medium with adjustable permeability (MAP) and metamaterial. Using a frustrated total internal reflection structure composed of glass-MAP-metamaterial-MAP-glass, the flat-top tunneling band can be realized and shifted to other frequency bands by adjusting the permeability of MAP to satisfy permeability and incident angle match conditions. In addition, our filter has a more robust flat-top tunneling band compared with other flat-top filters when the thickness of every layer changes. At last, the effect of metamaterial loss is considered.