Abstract: A mechanically scanned reflector antenna system that produces a compact swept diameter and overall height, which is ideally suited for use on the external surface of a high speed mobile platform where a low profile, lightweight antenna is needed. The antenna system includes a main reflector and a subreflector both formed from composite materials. A support assembly includes a pair of arms that cantilever the main reflector forwardly of a base portion of the support assembly such that a portion of the main reflector can be positioned below an upper surface of the base portion. This enables the vertical height of the swept arc of the main reflector to be reduced when the main reflector is rotated about its elevation axis. The assembly provides an even more compact system that can be enclosed within a smaller radome when the system is employed on an external surface of a high speed mobile platform.

Abstract: An apparatus and method for forming a cassegrain reflector antenna that allows an extended length feed horn to be employed without increasing an overall depth of the antenna. This enables the swept diameter of the antenna to be maintained at a minimum comparable to an antenna system using a standard length feed horn. The antenna system employs a hole at a vertex of the main reflector of the antenna system. The elongated feed horn is mounted at the vertex such that a major portion of its length projects outwardly form a rear surface of the main reflector. Antenna electronics components can be mounted on a neck of the feed horn or alternatively on a rear surface of the main reflector. Since the elongated feed horn does not increase the overall depth, and thus the swept arc of the antenna, the size of the radome needed to cover the antenna can be kept to a minimum size comparable to that required for reflector antennas employing conventional, standard length feed horns.

Abstract: An apparatus and method for mounting a rotatable reflector antenna system on an outer surface of an aircraft which minimizes a swept arc of a main reflector. This allows the effective frontal area of the main reflector to be reduced such that a radome with a smaller frontal area can be employed to cover the antenna system. The main reflector is rotated about an azimuth axis which is disposed forward of an axial center (i.e., vertex) of the main reflector. In one embodiment the azimuth axis is located in a plane extending between the outermost lateral edges of the main reflector, which define the aperture of the antenna. In another embodiment the azimuth axis is located forward of the outermost lateral edges of the main reflector. In further embodiments the azimuth axis of rotation is located in between a subreflector and a feed horn of the antenna, or in between the vertex of the main reflector and the subreflector.

Abstract: A multi-reflector antenna array capable of simultaneously transmitting and receiving communication signals at Ku-band frequencies is mounted on an exterior surface of an aircraft. The antenna array provides four cassegrain reflector antennas mechanically connected together in a group capable of being simultaneously mechanically scanned. A common support structure fixes the antennas with respect to each other. A drive mechanism and directional azimuth and elevation motors control the position of the array. The aerodynamic drag of the array is minimized using four antennas rather than a single large diameter antenna. Each antenna is positioned on a common horizontal centerline. Two centrally located antennas are positioned between two smaller diameter antennas. The antennas and positioning equipment are both mounted for rotation within a radome. A corporate power combiner/divider is provided to adjust both an amplitude and a phase of each antenna signal.

Abstract: An apparatus and method for mounting a reflector antenna system on an outer surface of an aircraft which minimizes a swept arc of a main reflector. This allows the effective frontal area of the main reflector to be reduced such that a radome with a smaller frontal area can be employed to cover the antenna system. The preferred embodiments make use of a platform which rotates the main reflector about an azimuthal axis which is disposed forwardly of an axial center of the main reflector. In one embodiment, the azimuthal axis is located in a plane extending between the outermost lateral edges of the main reflector. In another embodiment the azimuthal axis is located forwardly of the outermost lateral edges of the main reflector.

Abstract: An antenna exhibiting improved transmission and reception capabilities. The antenna does not make use of a solid support tube or solid support rods used by previous antennas to support a sub-reflector or other device above a main reflector of the antenna. Instead, the antenna employs the use of a low dielectric constant, perforated, support tube to support the sub-reflector, patch antenna, or other form of antenna element above the main reflector. The perforated support tube permits radio frequency signals to pass through the tube, thus decreasing signal degradation experienced due to reflection of the signal off the solid support tube or off the solid support rods.

Abstract: An apparatus and method for mounting a rotatable reflector antenna system on an outer surface of an aircraft which minimizes a swept arc of a main reflector. This allows the effective frontal area of the main reflector to be reduced such that a radome with a smaller frontal area can be employed to cover the antenna system. The main reflector is rotated about an azimuth axis which is disposed forward of an axial center (i.e., vertex) of the main reflector. In one embodiment the azimuth axis is located in a plane extending between the outermost lateral edges of the main reflector, which define the aperture of the antenna. In another embodiment the azimuth axis is located forward of the outermost lateral edges of the main reflector. In further embodiments the azimuth axis of rotation is located in between a subreflector and a feed horn of the antenna, or in between the vertex of the main reflector and the subreflector.

Abstract: A multi-reflector antenna array capable of simultaneously transmitting and receiving communication signals at Ku-band frequencies is mounted on an exterior surface of an aircraft. The antenna array provides four cassegrain reflector antennas mechanically connected together in a group capable of being simultaneously mechanically scanned. A common support structure fixes the antennas with respect to each other. A drive mechanism and directional azimuth and elevation motors control the position of the array. The aerodynamic drag of the array is minimized using four antennas rather than a single large diameter antenna. Each antenna is positioned on a common horizontal centerline. Two centrally located antennas are positioned between two smaller diameter antennas. The antennas and positioning equipment are both mounted for rotation within a radome. A corporate power combiner/divider is provided to adjust both an amplitude and a phase of each antenna signal.

Abstract: A reflector antenna adapted for use with a mobile platform, in particular with an aircraft. The reflector antenna includes an antenna aperture, a first signal processing subsystem located closely adjacent the antenna aperture exteriorly of the mobile platform, a two channel coaxial rotary joint for allowing rotation of the antenna aperture about an azimuthal axis, and a second antenna signal processing subsystem located within the interior of the mobile platform. A feedhorn of the antenna aperture is disposed within an opening at a coaxial center of a main reflector to allow a longer length feedhorn to be employed without physically interfering with a subreflector of the antenna aperture. The first antenna signal processing subsystem includes separate channels for processing vertically polarized RF energy and horizontally polarized RF energy.

Abstract: An antenna system includes a feedhorn, main reflector, sub-reflector, and frequency selective member. The sub-reflector includes an axially symmetrical reflecting surface. The frequency selective member includes an axially non-symmetrical reflecting surface. The frequency selective member transmits signals having a first frequency from the feedhorn to the sub-reflector. These signals are symmetrically reflected by the sub-reflector to the main reflector. The frequency selective member reflects signals having a second frequency from the main reflector to the feedhorn. These signals are reflected at a small conical angle by the frequency selective member to the feedhorn. In this way, the present transmit/receive system provides coincident transmit and receive signals with only conically scanned receive signals.

Abstract: A multi-reflector antenna array capable of simultaneously transmitting and receiving communication signals at Ku-band frequencies is mounted on an exterior surface of an aircraft. The antenna array provides four cassegrain reflector antennas mechanically connected together in a group capable of being simultaneously mechanically scanned. A common support structure fixes the antennas with respect to each other. A drive mechanism and directional azimuth and elevation motors control the position of the array. The aerodynamic drag of the array is minimized using four antennas rather than a single large diameter antenna. Each antenna is positioned on a common horizontal centerline. Two centrally located antennas are positioned between two smaller diameter antennas. The antennas and positioning equipment are both mounted for rotation within a radome. A corporate power combiner/divider is provided to adjust both an amplitude and a phase of each antenna signal.

Abstract: A multi-reflector antenna array capable of simultaneously transmitting and receiving communication signals at Ku-band frequencies is mounted on an exterior surface of an aircraft. The antenna array provides four cassegrain reflector antennas mechanically connected together in a group capable of being simultaneously mechanically scanned. A common support structure fixes the antennas with respect to each other. A drive mechanism and directional azimuth and elevation motors control the position of the array. The aerodynamic drag of the array is minimized using four antennas rather than a single large diameter antenna. Each antenna is positioned on a common horizontal centerline. Two centrally located antennas are positioned between two smaller diameter antennas. The antennas and positioning equipment are both mounted for rotation within a radome. A corporate power combiner/divider is provided to adjust both an amplitude and a phase of each antenna signal.

Abstract: An antenna system adapted to be mounted on an exterior surface of a mobile platform and having a reduced overall height to reduce aerodynamic drag caused by the antenna system. The antenna system includes a movable platform disposed concentrically within an annular stationary platform. The movable platform includes a slip ring assembly formed on its lower surface which is in physical contact with a brush assembly supported from a lower surface of the stationary platform. By locating the slip ring assembly and the brush assembly adjacent the lower surface of the movable platform, the overall height of the antenna is reduced. Reliability is also improved since contaminants are less likely to accumulate on the slip ring assembly due to its presence on the lower surface of the movable platform.

Abstract: An antenna system adapted to be mounted on an exterior surface of a mobile platform and having a reduced overall height to reduce aerodynamic drag caused by the antenna system. The antenna system includes a movable platform disposed concentrically within an annular stationary platform. The movable platform includes a slip ring assembly formed on its lower surface which is in physical contact with a brush assembly supported from a lower surface of the stationary platform. By locating the slip ring assembly and the brush assembly adjacent the lower surface of the movable platform, the overall height of the antenna is reduced. Reliability is also improved since contaminants are less likely to accumulate on the slip ring assembly due to its presence on the lower surface of the movable platform.

Abstract: An antenna exhibiting improved radio frequency transmission and reception capabilities. The antenna does not make use of a solid support tube or solid support rods used by previous antennas to support a sub-reflector or other device above a main reflector of the antenna. Instead, the antenna employs the use of a low dielectric constant, perforated, support tube to support the sub-reflector, patch antenna, or other form of antenna element above the main reflector. The perforated support tube permits radio frequency signals to pass through the tube, thus decreasing signal degradation experienced due to reflection of the signal off the solid support tube or off the solid support rods.

Abstract: A reflector antenna adapted for use with a mobile platform, in particular with an aircraft. The reflector antenna includes an antenna aperture, a first signal processing subsystem located closely adjacent the antenna aperture exteriorly of the mobile platform, a two channel coaxial rotary joint for allowing rotation of the antenna aperture about an azimuthal axis, and a second antenna signal processing subsystem located within the interior of the mobile platform. A feedhorn of the antenna aperture is disposed within an opening at a coaxial center of a main reflector to allow a longer length feedhorn to be employed without physically interfering with a subreflector of the antenna aperture. The first antenna signal processing subsystem includes separate channels for processing vertically polarized RF energy and horizontally polarized RF energy.

Abstract: An antenna system includes a feedhorn, main reflector, sub-reflector, and frequency selective member. The sub-reflector includes an axially symmetrical reflecting surface. The frequency selective member includes an axially non-symmetrical reflecting surface. The frequency selective member transmits signals having a first frequency from the feedhorn to the sub-reflector. These signals are symmetrically reflected by the sub-reflector to the main reflector. The frequency selective member reflects signals having a second frequency from the main reflector to the feedhorn. These signals are reflected at a small conical angle by the frequency selective member to the feedhorn. In this way, the present transmit/receive system provides coincident transmit and receive signals with only conically scanned receive signals.

Abstract: A reflector for use under a radome disposed on a mobile platform such as an aircraft for reflecting a portion of the electromagnetic energy radiated by an antenna disposed under the radome such that the reflected portion of energy impinges the radome at an angle normal thereto, thereby reducing or eliminating further reflections of the reflected portion of energy within the radome toward the mobile platform on which the radome is mounted. In one preferred embodiment the radome includes a base portion which is covered with a cover of radar absorbing material (RAM). In another embodiment the radome includes a curved base portion which is adapted to match the curvature of the surface of the mobile platform on which the reflector is mounted.

Abstract: A microwave reflector antenna comprises a rotary plate that rotates about an azimuth axis. At least one elevation cradle is attached to the rotary plate to provide an elevation axis and rotates about the azimuth axis with the rotation of the rotary plate. The at least one elevation cradle has a curved guide with a plurality of ball bearings to facilitate the rotation of the reflector about the elevation axis. A reflector travels along the at least one cradle as the reflector rotates about the elevation axis. The reflector rotates about the azimuth axis with the rotation of the at least one cradle. The rotation of the reflector about the azimuth axis and about the elevation axis define a swept volume of the reflector. The at least one cradle is positioned on the rotary plate so that the at least one cradle is within the swept volume of the reflector.

Abstract: A microwave reflector antenna for use on an aircraft. The microwave reflector antenna has a stationary plate that is attached to and stationary relative to the aircraft. A rotary plate rotates relative to the stationary plate about an azimuth axis. A rotary joint is attached to the rotary plate and has an axis of rotation that is aligned with the azimuth axis. A reflector is attached to the rotary plate adjacent the rotary joint so that the azimuth axis does not intersect the reflector. Individual ball bearings are positioned between the rotary plate and the stationary plate to allow the rotary plate to rotate about the azimuth axis. The stationary plate has gear teeth positioned along a peripheral side wall of the stationary plate. An azimuth motor is attached to the rotary plate and engaged with the gear teeth to selectively rotate the rotary plate about the azimuth axis.