Abstract: A feed structure (105) for a horn antenna (100). The feed structure can include a first waveguide (110) and a second waveguide (115) having a first portion at least partially disposed within the first waveguide. The second waveguide also can include a second portion intersecting a first wall (240) of the first waveguide. The first wall can include a first frequency selective surface (244) at an intersection (280) of the first wall and the second portion of the second waveguide. The first waveguide can be operatively coupled to a first horn section (130) and the second portion can be operatively coupled to a second horn section (135).

Abstract: An antenna (100) for microwave radiation including a first horn (135) which includes a plurality of corrugations (150). At least one of the corrugations (150) is formed of a frequency selective surface (FSS) (138). The FSS has a plurality of FSS elements (305) coupled to at least one substrate (310). The substrate (310) can define a first propagation medium such that an RF signal having a first wavelength in the first propagation medium can pass through the FSS (300). The FSS (300) is coupled to a second propagation medium such that in the second propagation medium the RF signal has a second wavelength which is at least twice as long as a physical distance between centers of adjacent FSS elements (305).

Abstract: Method for dynamically optimizing radome (110) performance. The method can include the steps of sensing (405) at least one parameter defining a performance characteristic of the radome (110). At least one electrical characteristic of the radome (110) can responsively be varied to dynamically modify the performance characteristic. For example, the electrical characteristic can be varied by application of an energetic stimulus (440) to the radome (110).

Abstract: A method for dynamically modifying electrical characteristics of a radome (110). The method can interpose a radome (110) in the path of a radio frequency signal (140). At least one electrical characteristic of the radome (110) can be selectively varied by applying an energetic stimulus to dynamically modify a performance characteristic of the radome (110). Electrical characteristic can include a permittivity, a permeability, a loss tangent, and/or a reflectivity. The energetic stimulus can include an electric stimulus, a photonic stimulus, a magnetic stimulus, and/or a thermal stimulus.

Abstract: A waveguide (100) including at least one outer surface (105, 110, 115, 120) defining a waveguide cavity (140) and at least one inner surface (130, 135) positioned within the waveguide cavity (140). The inner surface (130, 135) includes a frequency selective surface (FSS) having a plurality of FSS elements (145) coupled to at least one substrate. The substrate defines a first propagation medium such that an RF signal having a first wavelength in the first propagation medium can pass through the FSS (130, 135). The FSS (130, 135) is coupled to a second propagation medium such that in the second propagation medium the RF signal has a second wavelength which is at least twice as long as a physical distance between centers of adjacent FSS elements (145). The second wavelength can be different than the first wavelength.