Frequency-selective surface (fss) structures

A frequency-selective surface (FSS) structure, comprising:

• a first FSS layer having a first conductive grid and a first plurality of conductive loops, wherein the first conductive grid and the first plurality of conductive loops are both located on a first plane;
• a second FSS layer having a second conductive grid and a second plurality of conductive loops, wherein the second conductive grid and the second plurality of conductive loops are both located on a second plane;
• and
• a thin substrate located between the first and second planes, wherein the first and second planes are spaced such that the first and second FSS layers are electromagnetically coupled to one another, and the FSS structure exhibits a multiple pole frequency response.

A tunable frequency-selective surface (FSS) structure, comprising:

• a first FSS layer having a first loop array;
• a second FSS layer having a second loop array;
• a thin substrate being located between the first and second FSS layers;
• and
• at least one bias network having a plurality of varactor diodes, wherein the first and second FSS layers are spaced such that the first and second loop arrays are electromagnetically coupled to one another, and the tunable FSS structure exhibits a frequency response that can be tuned with the bias network.

A tunable frequency-selective surface (FSS) structure, comprising:

• a first FSS layer having a first conductive grid;
• a second FSS layer having a second conductive grid;
• a thin substrate being located between the first and second FSS layers;
• and
• a plurality of varactor diodes connecting the first and second conductive grids together, wherein the first and second FSS layers are spaced such that the first and second conductive grids are electromagnetically coupled to one another, and the FSS structure exhibits a frequency response that can be tuned without a bias network.

An antenna arrangement, comprising:

• a frequency-selective surface (FSS) structure having a loop array, a conductive grid, and a thin substrate, the loop array is located on one side of the thin substrate and the conductive grid is located on another side of the thin substrate;
• an antenna array having a plurality of antenna elements;
• and
• a dielectric spacer located between the FSS structure and the antenna array, wherein the FSS structure is located over top of the antenna array such that electromagnetic waves incident upon or radiating from the antenna elements are filtered by the FSS structure.