Abstract: A dual frequency antenna and radome system, including a dual frequency antenna system for operation at a first, higher frequency band and at a second lower frequency band. The antenna system includes a first antenna operable at the first frequency band and a second antenna operable at the second frequency band. The first and second antenna systems are orthogonally polarized. A radome is tuned for dual frequency operation, and includes a dielectric wall having a thickness equal to one-half wavelength at a frequency in the first frequency band. The radome further includes a grid of monopole elements formed on a surface of the dielectric wall orthogonal to the first antenna to tune the radome to efficient operation at the second frequency band.

Abstract: The disclosed common aperture seeker antenna includes a parabolic array of crossed dipoles. This array is substantially reflective for radiated electrical signals in one band, and substantially transmissive for radiated electrical signals outside of that band. A monopulse (four-element) waveguide feed is rigidly positioned on the concave side of the parabolic array at the focal point thereof. The parabolic reflector antenna operates in the one band to provide a high gain active system for accurate tracking of targets. A planar spiral antenna is rigidly positioned on the convex side of the parabolic array in axial alignment with the parabolic reflector antenna. This wideband antenna operates over a multioctave frequency band below that of the one band to provide a low gain system for passive tracking of targets. The two antenna systems coexist in such a manner that each utilizes the available aperture to its fullest extent.

Abstract: A high accuracy broadband antenna system is disclosed. This system is a dual mode system which includes a parabolic reflector dish having a dielectric substrate and a conductive material coating on the substrate; an antenna feed positioned at the focus of the paraboloid and directed at the reflector dish for providing a narrow beam monopulse radiation pattern; and a circuit for coupling energy to and/or from the antenna feed. The conductive material coating on the reflector dish substrate defines a plurality of conductive spiral arms for providing a wide beam monopulse radiation pattern; and the antenna system further includes structure defining a cavity for backing the conductive spiral arms and a circuit for coupling energy to and/or from the conductive spiral arms, whereby the parabolic reflector dish is operable as a primary antenna providing a wide beam radiation pattern.