Showing papers on "Feed horn published in 1981"

Expandable panel and truss system/antenna/solar panel

Abstract: Disclosed is an expandable panel and truss structure capable of being stowed in a storage container (canister) for transportation into space and deployed to form structures such as antennas, solar panels or similar space or terrestial structures. The antenna formed comprises the panels stored as hinged pairs (sets) folded in accordian-like fashion together with the expandable trusses and other devices necessary for antenna space operation, such as attitude control and antenna feed. The panel sets are deployed from the canister to form a toroidal ring, circular in cross-section when deployed, for supporting the antenna lens and to form a feed support boom utilizing the canister as part of the antenna structure. The canister is connected to the ring and support boom in the deployed state by the expandable trusses. A fully automatic system is included for deploying the antenna and for holding the antenna structure in its deployed state. By adding a second (back) boom and reflector screen, a paraboloidal antenna is formed. In a second embodiment, utilizing the same storage and deployment principle but with panel sets which are triangular in cross-section, when deployed, either an offset (asymmetrical) paraboloidal or a feed horn type antenna structure is formed. In another embodiment of the invention, utilizing the same principle and with panel sets which are triangular in cross-section, when deployed, a solar panel array is formed. Also disclosed is a foldable truss geostationary platform and package for transfer into a geostationary orbit. Finally, an alternate mechanism is disclosed in the form of a pantograph for deploying panel sets to form a truss.

Two-axis antenna direction control system

Abstract: An antenna pointing control system primarily useful for aiming and controlling a communications satellite directional antenna. The invention makes use of a ground based pilot station which transmits an up-link signal to the satellite, including frequency differentiated communication signals and command and control signals. The command and control signals are referred to as the beacon or pilot signal. The pilot signal is a triangular frequency modulation waveform. The communications signals and the pilot signal are received by a common directional antenna on the satellite. A microwave network coupled to a multiple feed horn assembly of the antenna and responsive to the pilot signal produces pilot signal components including a sum signal and east-west and north-south error signals indicative of the corresponding angular errors between the desired antenna pointing direction and the direction from the satellite to the pilot station. Subsequent processing of the pilot signal components in a command and control receiver yields both command information and steering signals, the latter for controlling the antenna pointing direction with respect to the pilot station.

Feed horn for reflector antennae

Abstract: An improved feed horn for use with long f/D reflector antennae comprising an aperture having a plurality of protuberances orthogonally disposed around the periphery thereof, a conical section, a waveguide transition section and an impedance matching section.

Dip brazed corrugated feed horn

Abstract: A corrugated feed horn and its method of manufacture is disclosed for circularly polarized SHF (super high frequency) and EHF (extra high frequency) parabolic antennas operating in the 12-100 GHz range. A plurality of laminations are dip braze bonded, providing alternate fins and grooves in an inner conical configuration. Extremely thin fins are enabled without expensive parts or fabrication methods.

Focal axis resolver for offset reflector antennas

Abstract: Method and apparatus for determining the focal axis (26) of an asymmetrical antenna (14) such as an offset paraboloid reflector whose physical rim (15) is not coincident with the boundary of the electrical aperture but whose focal point is known. A transmitting feed horn array (34) consisting of at least two feed horn elements (36, 38) is positioned asymmetrically on either side of an estimated focal axis (40) which is generally inclined with respect to the boresight axis (12) of the antenna. The feed horn array (34) is aligned with the estimated focal axis (40) so that the phase centers (CP 1 , CP 2 ) of the two feed horn elements (36, 38) are located on a common line (42) running through the focal point (F) orthogonally with respect to the estimated focal axis. RF circuit means (44) are coupled to the feed horn elements for generating RF electric field components which are directed to the offset antenna (14) whereupon sum and difference radiation far field patterns (Σ, Δ) are generated and transmitted in a manner analogous to systems of the monopulse angle tracking type. The far field radiation patterns (Σ, Δ) are sensed by a far field detector (43) and the transmitting array (34) is rotated in discrete angular (β) incremental steps in at least one plane about an axis through the focal point whereupon the amplitude of the minimum value of the difference radiation pattern (Δ) as a function of angular rotation (β) is detected and measured with a determination being made of the angular orientation of the array where extreme magnitude of the minimum difference pattern signal strength occurs, which location is indicative of the focal axis (26) being determined. Alternatively, the relative phases (ψ 93 , ψ 66 ) of the sum and difference radiation patterns (Σ, Δ) are detected and measured as a function of angular rotation (β) and their difference value (|ψ 93 -ψ 66 |) determined. The maximum difference value provides an indication of the location of the focal axis (26) being determined.

Antenna arrangement for providing a frequency independent field distribution with a small feedhorn

Abstract: The present invention relates to an antenna arrangement which uses an imaging reflector (10) combined with a small feed or horn (14) which is capable of launching or receiving a spherical wavefront (18) to obtain a nearly frequency independent field distribution over a large antenna aperture. The antenna arrangement comprises a parabolic main reflector (10) disposed confocally with one focal point of a subreflector means (12) and a feed (14) disposed with the apex of the spherical wavefront at the other focal point of the subreflector means and the aperture of the feed centered on the image of the main reflector. If the rim of the feed aperture corresponds to an image of the edge of the main reflector, spill-over is substantially eliminated. Generally, any feed arrangement comprising a feed and subreflector means which transforms a spherical wavefront from the feed into a spherical wavefront emanating from the focal point of the parabolic main reflector can be used.

Dual polarized feed with feed horn

Abstract: The present invention relates to a dual polarized feed by which two linea polarized waves can be reliably separated. The two waves are conducted separately over high frequency coaxial cables, one of which extends axially and the other radially into the polarizer. Rotation of the planes of polarization is thus unnecessary and the two cables have a minimum influence on the illumination (irradiation) of the reflector.

An Ultra Low-Noise Schottky Mixer Receiver at 80–120 GHz

Abstract: An ultra low-noise mixer receiver has been developed at the Five College Radio Astronomy Observatory for astronomical observations from 80 to 120 GHz with the 13.7 m diameter millimeter telescope. The cryogenic front end consists of a feed horn, a ring filter and a waveguide mixer followed by a 1.4 GHz FET amplifier. The optimization of the mixer RF-impedance at 100 GHz has yielded single sideband (SSB) receiver noise temperatures of 1 24 K and 588 K at physical temperatures of 18 K and 295 K, respectively.

Bird-proof feed-horn windows for microwave radio system antennas

Abstract: Window units constructed from multiple dielectric plates offer means for combating bird damage to antenna feed horns on microwave radio systems. The need for such devices on Australian systems is increasing as routes are extended into the drier regions of the country. Measurements show that the antenna electrical characteristics are not appreciably altered by the new window units.

Wideband Constant Beamwidth Horn Antenna

Abstract: Work is reported on the development of a new wide band H-plane sectoral horn antenna which is not subject to the usual l/f variation of beamwidth with frequency. The upper frequency limit of wide band horn operation is dictated by the onset of TE30 mode in the horn feeder and throat. A compensating moding device in the feeder is optimised so that operation over greater than 3:1 bandwidths can be obtained.

Multimode diagonal feed horn

Abstract: In the past, conventional diagonal horns have been used for providing high gain and equalization of the beam widths in the E and H planes. However, a problem has existed in such horns in that cross-polarized lobes are present in the intercardinal lobes which deleteriously affect the horn's polarization purity. To overcome this, the diagonal horn technique is utilized in a multiflare pyramidal horn. Preferably, the pyramidal horn has two pyramidal sections each having a different flare angle. These flare angles are set so that the E and H fields will be tapered to improve equalization of the beam widths in the intercardinal planes to that in the E and H planes and to reduce the cross-polarized lobes in the intercardinal planes. The result is a compact diagonal horn having high gain without the polarization difficulties previously found in the intercardinal planes of such prior diagonal horns.

Numerical technique for shaping reflecting surfaces to synthesize antenna patterns

Abstract: Algorithms for shaping offset dual reflector antenna surfaces are presented which use small areas of optimally tilted conic sections reported by Y. Mizugutch for starting up a numerical synthesis of reflector surfaces. A new ray ratio squared method is described for the precise control of antenna aperture amplitude distributions.

Generation of Highly Contoured Beams by Shaping the Surface of an Offset-Fed Single Reflector

Abstract: The surface of an offset reflector illuminated by a single balanced feed is shaped so that the modified phase of the aperture field generates the desired contoured beam The deviations from the paraboloidal surface are so small that the amplitude distribution in the aperture plane remains essentially undistorted and only negligible cross polarization is generated

Dual-polarized fan-beam feed horn

Abstract: A simple dual-polarized feed horn that radiates fan-shaped primary patterns is described. The radiated patterns for the two orthogonal polarizations are essentially identical and are suitable for illuminating cut paraboloidal reflectors with f/D ratios of about 0.3. The horn is similar to conventional flared waveguide feed horns except that the corners have been modified to yield an octagonally shaped aperture. The horn has the added advantage of suppressed E -plane sidelobes, thus reducing spillover radiation.

An antenna pointing mechanism for large reflector antennas

Abstract: An antenna pointing mechanism for large reflector antennas on direct broadcasting communication satellites was built and tested After listing the requirements and constraints for this equipment the model is described, and performance figures are given Futhermore, results of the qualification level tests, including functional, vibrational, thermovacuum, and accelerated life tests are reported These tests were completed successfully

Design Optimization Procedures for Multi-Feed Satellite Shaped-Beam Antennas

Abstract: This paper describes a systematic procedure for the design of offset parabolic satellite frequency reuse antennas with multiple feeds. Launch vehicle size constraints and the coverage requirements determine the optimum reflector geometry and feed parameters. Then, the amplitudes and phases of the multiple feeds are optimized simultaneously at the two ends of the frequency band to satisfy coverage gain and isolation requirements. Sensitivity analysis of the coverage patterns to feed excitation variations is included in the overall design process.

Low Cross-Polar Radiation from Wide Flare-Angle Conical Corrugated Horns

Abstract: The prediction of the radiation pattern of conical corrugated horns is described using the spherical-mode expansion method. In particular, cross-polar patterns are obtained for several horns and excellent agreement with measured patterns is demonstrated. Three mechanisms of mode conversion are identified and one in particular investigated in detail. It is shown that mode conversion along the horn is not a significant effect and that the peak cross-polar radiation from a 30° corrugated horn lies below - 45 dB over more than a 10% bandwidth.