Abstract: A parabolic reflector antenna having a truncated parabolic surface such that the edges of the parabolic reflector form a rectangular side edge configuration. The parabolic reflector antenna is comprised of a truncated parabolic reflector, and at least one truncation wall projecting outwardly from the truncated side edges of the parabolic reflector. In addition, an antenna feed would be located at the focus of the parabolic reflector. As a result, the use of truncation walls does not increase the axial extent of the parabolic reflector. The truncation walls do not extend beyond the outer corners of the parabolic reflector. Furthermore, the additional use of truncation walls does not increase the overall size of the antenna or the size of the radome required to house the antenna. The use of one or more truncation walls advantageously increases or decreases the antenna sidelobe levels on either side of the reflector antenna.

Abstract: A phase scanned array of antenna elements, preferably, an array consisting of three, short, helical, radiating elements. Each antenna element is connected to a corresponding transmit/receive switch, which in turn is connected to a low-noise amplifier on the receive side of the switch. The antenna system includes receive path phase shifters which are connected to the low noise amplifiers. In a preferred embodiment, two receive path phase shifters are connected to two outer low noise amplifiers, which are in turn connected to the two outer antenna elements. The receive path phase shifters shift the phase of signals received from the two outer antenna elements. In the transmit path, two of the three transmit/receive switches are connected directly to transmit path phase shifters. According to another preferred embodiment, each of the transmit path phase shifters are connected to an outer antenna element through a corresponding transmit/receive switch.

Abstract: A ridged feed horn antenna for use in broadband satellite communications. This multi-ridged feed horn operates in a receive band of 10-13 GHz and a transmit band of 14-15 GHz. The ridged feed horn antenna comprises excitation conductors which excite the field between each of the ridges in the feed horn antenna. The excitation conductors are connected to each of the ridges. A waveguide, terminated at the back of the horn antenna, enables the ridges to guide the energy from their respective excitation conductors toward the mouth of the feed horn antenna. A planar balun and matching circuit, located at the back of the horn antenna, may be used to feed each of the excitation conductors. Furthermore, the cross-section of each excitation conductor is chosen so as to optimize horn antenna performance. Each excitation conductor extends outwardly from the back of the horn and is parallel to the longitudinal axes of the horn waveguide.

Abstract: An antenna array of parabolic rectangular reflectors for use in satellite communications. The antenna comprises two parabolic reflectors disposed contiguously on a common outer surface. The common surface forms a continuous antenna aperture. The parabolic reflectors have rectangular side edges which permit the adjacent edges of the parabolic reflectors to be spaced closely. The mouth of each parabolic reflector is focussed on a separate feed. The focus of the feed is not located at the center of the reflector but rather offset. The antenna feeds and the reflector foci are displaced toward the center of the array such that the spacing between the antenna feeds is less than half the length of the antenna. The present invention provides the displacement of each reflector focal point and each antenna feed toward the center of the array.

Abstract: Systems and devices for mechanically rotating the polarisation of a signal emanating from or being received by an antenna system. The rotation of the polarisation is achieved by mechanically rotating the feed using a non-metallic drive cord or belt connected to a motor which is displaced outside or behind the radiating aperture. For a linear array of multiple antenna elements, each feed for each antenna element is rotated simultaneously and by an equal amount through the use of a drive system common to all the feeds. The drive system is coupled to each feed and to a drive motor. When the motor is activated, the drive system simultaneously rotates each feed by a given amount. By rotating the feed, the polarisation of the signal is correspondingly rotated and compensation for polarisation loss is provided.

Abstract: Quad ridged horn antennas which may be individually disposed at the focal point of a parabolic reflector, or in an antenna array of parabolic reflectors. In the field of satellite communications, focus-fed parabolic reflectors are required to be compact yet provide broadband signal services. As such, the antenna horn feed structure must be very compact and provide equally broadband services. In order to provide uniform excitation of a parabolic reflector antenna, the antenna must have equal beamwidths in the E plane and the H plane. The quad ridged horn antenna of the invention equalizes these beamwidths through of a conductive ring around the mouth of the horn antenna. Matching the E plane and the H plane beam widths results in uniform excitation of a parabolic reflector. The conductive ring is advantageously effective for exciting a reflector or an array of reflectors in two closely spaced bands, such as the Ku band.

Abstract: An antenna system consisting of parabolic rectangular reflectors disposed contiguously in a linear array. The use of parabolic rectangular reflectors permits the reflectors to form a larger common rectangular aperture without gaps in illumination. The contiguous array of parabolic rectangular reflectors permits a lower profile which is ideal for use on an aircraft. Each parabolic rectangular reflector has its own feed system and each of the feeds are excited in phase. The combined radiation patterns of the parabolic reflectors produces a beam with a narrow width. This narrow beamwidth permits the system to communicate with one source while filtering out signals coming from other sources. In one embodiment, the antenna system may be mechanically steered in order to communicate with a transmitter and/or receiver whose relative position is continuously varying with respect to the antenna system.

Abstract: The present invention provides a dichroic surface with a pointed resonator cross grid pattern that offers enhanced bandwidth and a sharper response between frequency bands. The dichroic surface is fabricated as a self-adhesive decal, conforming the dichroic surface to the surface of the reflector antenna.

Abstract: A drive mechanism for an antenna array mounted on a moving vehicle. The antenna array is mounted on a disc having two motors which, cooperatively, rotate the disc and rotate a number of antenna elements mounted on the disc. By rotating the antenna elements, the main lobe of the array may be scanned towards a satellite in the elevation plane. To track a moving source from a moving vehicle, one of the motors rotates the disc as a whole, thereby scanning the beam in the azimuth plane. Each antenna element is at an angle to the vertical so that, by rotating the disc to face the direction of the signal source, such as a satellite, a better signal can be obtained.

Abstract: An antenna assembly comprising a radiating element which passively receives a signal fed by a vertically-stacked pair of asymmetrically-shaped, conductive cone elements mounted below the radiating element. The cone elements are centrally fed by a coaxial cable input at a common junction formed the apex of each cone element. This antenna assembly provides a low-profile antenna to transmit and receive radio frequency (RF) energy with high gain and desirable antenna patterns for data transmission in an in-building, wireless local area network. The antenna assembly can be mounted in a standard ceiling or wall-mounted enclosure, with the low-profile antenna extending beneath the surface of a conductive enclosure cover that serves as the ground plane for the antenna element. This configuration achieves high antenna gain with a downtilt-beam, omnidirectional radiation pattern, which is highly desirable in an in-building wireless local area network (WLAN) application.

Abstract: An antenna assembly comprising a radiating element which passively receives a signal fed by a vertically-stacked pair of asymmetrically-shaped, conductive cone elements mounted below the radiating element. The cone elements are centrally fed by a coaxial cable input at a common junction formed the apex of each cone element. This antenna assembly provides a low-profile antenna to transmit and receive radio frequency (RF) energy with high gain and desirable antenna patterns for data transmission in an in-building, wireless local area network. The antenna assembly can be mounted in a standard ceiling or wall-mounted enclosure, with the low-profile antenna extending beneath the surface of a conductive enclosure cover that serves as the ground plane for the antenna element. This configuration achieves high antenna gain with a downtilt-beam, omnidirectional radiation pattern, which is highly desirable in an in-building wireless local area network (WLAN) application.

Abstract: An antenna comprising at least one dipole, the dipole comprising a pair of arms drooping relative to a plane orthogonal to a central axis, end portions of the arms being bent back toward the central axis. In one form of the invention the arms are bent back toward the central axis in at least one plane which is parallel to the central axis, and in another form of the invention the dipole arms are bent in the same rotational direction out of a pland which includes the central axis.

Abstract: An aircraft mounted antenna system comprising a plurality of linear blade antenna arrays mounted on an upper portion of an aircraft fuselage. The blade arrays are symmetrically placed on the fuselage about a plane vertically bisecting the upper portion of the fuselage. The placement of the blade arrays is such that large scanning angle gain losses are minimized as the blade arrays on one side of the fuselage hand off the satellite tracking, acquisition, and communication to the blade arrays on the other side of the fuselage as the scanning angle increases.

Abstract: An improved top fed quadrafilar helical antenna that provides circular polarization with near uniform gain over the upper hemisphere. The antenna comprises a pair of crossed printed circuit boards with two feed lines and two horizontal arms per board and four piecewise linear conductors. Each arm is connected to a feed line and to the end of a conductor that is piecewise linearly attached to the edges of the crossed printed circuit boards.

Abstract: A dual band, dual polarized antenna comprising an array of resonators in a plane for radiating at a first frequency, a ring resonator in a plane, the array of resonators being contained within a projection of the boundary of the ring resonator, the ring resonator for radiating at a second frequency which is lower than the first frequency, apparatus for exciting the array of resonators to cause them to radiate at the first frequency with dual polarizations simultaneously, and apparatus for exciting the ring resonator to cause it to radiate at the second frequency with dual polarizations simultaneously.

Abstract: A helical antenna comprised of a helical conductor having one end adapted to be connected to a feedline, a conductive surface contained within but spaced from the helical conductor, the distance of the conductive surface from the helical conductor being predetermined so as to vary the radiation loss from the helical conductor during electromagnetic emission therefrom.

Abstract: An antenna radiator comprising a rectangular conductive cap disposed over a top of a dielectric, the cap having an extension over a side of the dielectric, apparatus for feeding energy to the radiator adjacent an end of the extension remote from the cap, and a ground plane spaced from and parallel to the cap, below the dielectric.

Abstract: This invention relates to a radiating element, such as a microstrip antenna, having a low input impedance and being capable of allowing high RF power to be supplied to the radiating element. The radiating element incorporates impedance transformation capabilities by providing a dielectric member with an electrically conductive ground plane formed on one side of the dielectric member. A metal patch element is formed on the other side of the dielectric member and spaced from the ground plane by the dielectric member. The patch element is capable of radiating RF energy when coupled to a source of RF input energy applied thereto. An impedance transforming section is selectively located within the perimeter of the patch element to give a desired input impedance at a feedpoint of the impedance transformation section.

Abstract: A device is provided for use in a helical antenna having an antenna element wound about the periphery of a dielectric support post, the post being in the form of a tube or cylinder. The device has an electrically conductive member electrically connected to one end of said antenna element. The conductive member is of any appropriate shape or configuration and is operable to increase the loading on the antenna whereby standing waves on the antenna element are reduced and a more uniform electrical current is produced along the antenna element.