Abstract: The hybrid antenna includes a spiral antenna, e.g. a log spiral antenna, and a patch array layer adjacent to the spiral antenna and including a passive periodic patch array of conductive patch elements. A conductive ground plane may be adjacent to the patch array layer, and a dielectric layer may be between the conductive ground plane and the patch array. The spiral antenna may include an upper antenna arm, a lower antenna arm and a dielectric sheet therebetween. Each of the upper and lower antenna arms may be a printed planar conductive trace that is wider at a distal end thereof with respect to a center of the log spiral antenna. The patch or periodic array layer operates in conjunction with the ground plane to couple energy into the spiral antenna and thereby improve low frequency antenna efficiency while maintaining electrically small dimensions.

Abstract: A radome uses traditional continuous heating wires mixed with detuned dipoles between heating wires and can be placed at any chosen distance from an array antenna or FSS. The continuous heating wires add a reactive component to the incident field phase, which is effectively cancelled out by the detuned dipoles which provide a capacitive component. The orthogonal components of the incident field are transmitted with very small losses over a wide number of scan angles. These heating and detuned dipoles can be printed on low loss dielectric materials. In addition, the printed elements of this radome can be scaled to operate over a chosen frequency band.

Abstract: Multi-layer frequency selective panel includes a group of frequency selective surfaces arranged in a stack. A first frequency selective surface includes a first group of slot elements, and a second frequency selective surface includes a second group of slot elements. The first frequency selective surface and the second frequency selective surface are formed of a conductive metal layer. The first frequency selective surface and the second frequency selective surface are positioned a predetermined distance apart in parallel planes. The second frequency selective surface is disposed in an evanescent field region of the first frequency selective surface.

Abstract: The hybrid antenna includes a spiral antenna, e.g. a log spiral antenna, and a patch array layer adjacent to the spiral antenna and including a passive periodic patch array of conductive patch elements. A conductive ground plane may be adjacent to the patch array layer, and a dielectric layer may be between the conductive ground plane and the patch array. The spiral antenna may include an upper antenna arm, a lower antenna arm and a dielectric sheet therebetween. Each of the upper and lower antenna arms may be a printed planar conductive trace that is wider at a distal end thereof with respect to a center of the log spiral antenna. The patch or periodic array layer operates in conjunction with the ground plane to couple energy into the spiral antenna and thereby improve low frequency antenna efficiency while maintaining electrically small dimensions.

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.

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: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.

Abstract: To reduce sidelobes in the radiation pattern of a phased array dipole antenna, a plurality of parasitic antenna elements are provided adjacent to the array of dipole elements of the antenna. The driven elements of the dipole array and associated director elements are formed as patterned conductor elements on one surface of a thin dielectric substrate. Feed elements for the driven dipole array also comprise patterned conductor elements formed on an opposite surface of the substrate. The feed elements have a geometry and mutually overlapping projection relationship with the conductors of the driven dipole elements, so as to form a matched impedance transmission line through the dielectric substrate with the patterned dipole elements. The parasitic elements are formed on additional dielectric substrates spaced apart from and parallel to the thin dielectric substrate upon which the driven dipole array is formed.