Multi-band horn antenna using frequency selective surfaces

An antenna for microwave radiation comprising:

• a first horn;
• and
• at least a second horn positioned within said first horn, said second horn comprising at least one frequency selective surface having a plurality of frequency selective surface elements coupled to at least one substrate, said substrate defining a first propagation medium such that an RF signal having a first wavelength in said first propagation medium can pass through said frequency selective surface;
• wherein said frequency selective surface is coupled to a second propagation medium such that in said second propagation medium said RF signal has a second wavelength which is at least twice as long as a physical distance between centers of adjacent ones of said frequency selective surface elements.

A waveguide horn antenna comprising,

• a tapered hollow metallic conductor;
• and
• a frequency selective surface comprising a substrate and an array of elements defining at least one wall of said horn, said frequency selective surface positioned for confining and guiding a propagating electromagnetic wave;
• said substrate having at least one of a permeability and a permittivity greater than about three.

A waveguide comprising:

• at least one outer surface defining a waveguide cavity;
• and
• at least one inner surface positioned within said waveguide cavity arranged parallel to said outer surface, said inner surface comprising a frequency selective surface (FSS) having a plurality of frequency selective surface elements coupled to at least one substrate;
• wherein an RF signal having a first wavelength passes through said frequency selective surface and is incident on said at least one outer surface, and an RF signal having a second wavelength does not pass through said inner surface, wherein said inner surface defines a wall of a second waveguide structure.