Showing papers on "Feed horn published in 1996"

Plural frequency antenna feed

Abstract: Apparatus and method for providing an antenna feed (10) operative at different microwave frequency bands employ a circular waveguide (14) interconnecting an orthomode transducer (20) to a feed horn (16) thereby providing a feed (10) suitable for illuminating the reflector (54) of an antenna (12). The orthomode transducer provides for a coupling of waves in the first frequency band with both vertical and horizontally polarized waves. Included within the feed is a coupler assembly (26) of waves of the second frequency band operative via a sidewall of the circular waveguide. The coupler assembly includes plural identical coupling sections (28) each having a rectangular waveguide section contiguous and parallel to the circular waveguide with a row of apertures for coupling power into and out of the circular waveguide. Pairs of the coupling sections are disposed in orthogonal planes so as to introduce two linearly polarized waves which are perpendicular to each other. A slab (48) of dielectric material is placed in each of the coupling sections to match the phase velocity of waves in the coupling sections to waves in the circular waveguide at the second frequency band while mismatching the phase velocities at the first frequency band. The dispersion of the waveguides provides for interaction with electromagnetic waves in the second frequency band while inhibiting such interaction at the first frequency band.

Radio communication system using portable mobile terminal

Abstract: A radio communication system comprises a transmitting antenna for transmitting radio signals. Each radio signal is transmitted via one of a plurality of beams of different maximum radiated directions. The system also comprises a transmitting section for adding to a radio signal, transmitted via an i-th beam among the plurality of beams, beam identification information that identifies on which i-th beam of said plurality of beams said radio signal is being transmitted. The system further comprises a receiving antenna for receiving the radio signals transmitted by the plurality of beams and a receiver for selectively receiving a signal transmitted by a specific beam according to a predetermined estimation standard. Alternatively, the system may comprise a first radio station and a second radio station. The first radio station may include a transmitting antenna for transmitting signals with beam identification numbers and a receiving antenna for receiving signals from other radio stations. The second radio station may include a receiving antenna capable of receiving signals transmitted by the first transmitting antenna and a receiver for selectively receiving a signal transmitted by a specific beam according to a predetermined estimation standard. The second radio station may also include a transmitting antenna that forms a wide-angle beam to transmit the specific beam.

A system and method for achieving extended radio coverage and additional capacity using extended frequency bands

Abstract: The present invention provides increased geographical coverage and system capacity for mobile/portable radio transceivers using adjacent and typically separate radio communication frequency bands. A radio that transceives in just one frequency band is adapted to provide a configurable duplexing arrangement to permit communications in extended frequency bands. Duplexing circuitry is connected between the radio antenna and the radio transmitter and receiver. Depending upon the mode of operation of the radio transceiver, switches are selectively operated for variously configuring the antenna, duplexer circuitry, receiver, and transmitter to permit communications in a first or a second set of transmit/receive frequency bands. In one preferred example embodiment, only a single duplexer is employed connected to the antenna and transceiving circuitry through plural switches.

Durable, lightweight, radar lens antenna

Abstract: A radar lens 14 is made from a conventional Fresnel lens 10, but replaces the conventional curved surface 32 with a stepped approximation thereto 22, 24, 26, preferably of three steps. The thickness of the stepped lens 14, at each step, is a half-wavelength or a multiple half-wavelength of the radar operating frequency in the medium of the lens 14. The half-wavelength or multiple half-wavelength separation of the steps 22, 24, 26 causes reflections from the front 16 and rear 18 surfaces to cancel, thereby minimizing the (undesirable) standing wave between the lens 14 and the feed horn or feed horns 46, 48, 50. This avoids the necessity of reducing the standing wave by presenting the curved or stepped side 18 forward. The planar side 16 of the lens 14 (unlike the stepped side 18) doesn't need to be protected from road debris. The lens 14 can therefore be molded as an integral unit of a radome, desirable in the automotive setting. This lens 14 is also thin enough (and, therefore, light enough) that it can be moved side-to-side very rapidly, preferably by a combination of cams 42, 52 and springs 44, 54. This allows a very fast scan, albeit over a limited field of view. Gimballing 56 the lens 14 and feed horns 46, 48, 50 together provides a slower scan, but gives an unlimited field of regard. Combining the two gives a fast scan and unlimited field of regard, desirable in the missile setting.

Cooperative diversity antenna switching on transmitter and receiver side

Abstract: The pair of radio communication apparatuses of this invention on a transmitter side and a receiver side conduct data transmission and receiving through radio communication by a space diversity method where a plurality of antennas are switched therebetween, wherein the radio communication apparatus on the transmitter side includes a transmission circuit for conducting data transmission and a transmitting antenna switch circuit for selecting a transmitting antenna among a plurality of transmitting antennas for transmitting radio waves and connecting the selected transmitting antenna to the transmission circuit, and the radio communication apparatus on the receiver side includes a receiving circuit for conducting data receiving and a receiving antenna switch circuit for selecting a receiving antenna among a plurality of receiving antennas on the receiver side the radio waves and connecting the selected receiving antenna to the receiving circuit.

Diversity radio communication system

Abstract: The pair of radio communication apparatuses of this invention on a transmitter side and a receiver side conduct data transmission and receiving through radio communication by a space diversity method where a plurality of antennas are switched therebetween, wherein the radio communication apparatus on the transmitter side includes a transmission circuit for conducting data transmission and a transmitting antenna switch circuit for selecting a transmitting antenna among a plurality of transmitting antennas for transmitting radio waves and connecting the selected transmitting antenna to the transmission circuit, and the radio communication apparatus on the receiver side includes a receiving circuit for conducting data receiving and a receiving antenna switch circuit for selecting a receiving antenna among a plurality of receiving antennas on the receiver side the radio waves and connecting the selected receiving antenna to the receiving circuit.

Integrated transmitter/receiver apparatus (monolithic integration capabilities)

Abstract: A radio transceiver having a receive mode and transmit mode is disclosed. The transceiver makes use of an application controller to control the operation of the transmitter and receiver portions of the transceiver. The application controller enables the control of a voltage source connected to the transmitter portion to vary the amplification gain of the transmitter section. The output of the transmitter and the input of the receiver are connected directly to the antenna circuit without the use of a duplexer. An oscillator circuit provides a transmission carrier during transmission and is used to convert signal frequency during reception of a signal. The controller can switch between the transmitting and receiving functions by activating and de-activating either one of the transmitter and receiver sections of the radio transceiver.

Communication and tracking antenna systems for satellites

Abstract: A communication and tracking antenna is formed by embedding a tracking patch array in a shaped dual gridded reflector. The reflector includes first and second reflector grids that have orthogonally arranged grid lines and are respectively fed by feed horns. The patch array is positioned so that the first reflector grid is between the patch array and the first feed horn. The first reflector grid thus serves as a filter to remove unwanted polarization components and enhance the quality of both the tracking radiation and the radiation that is reflected from the second reflector grid. In other embodiments, a tracking array is positioned adjacent a reflector's perimeter.

Different methods of PO analysis in a dual reflector antenna with a shaped main reflector

Abstract: The shaped reflector has emerged as a vital technology in the field of satellite antennas. The dual offset Gregorian geometry considered, using an ellipsoidal subreflector fed by a spherical source feed, is shown. In a Cassegrainian system, a hyperboloid is used as the subreflector. By choosing an optimum tilt angle between the main reflector and the subreflector axes, the cross-polarization in a dual offset reflector can be minimized. Thus, by shaping the main reflector a shaped beam with superior cross-polar performance can be realized. The surface profile of the shaped reflector is synthesized using an accurate analysis embedded inside an optimization. This accurate analysis is usually based on physical optics (PO). Ideally a dual reflector analysis using PO on both the subreflector and the main reflector is necessary to synthesize the main reflector shape. This can be very time consuming and unnecessary especially if only the main reflector shape is synthesized. Two other simplified techniques which can be used more efficiently during the main reflector synthesis, are presented. A brief overview of the different analysis techniques are also presented.

Feed-horn with helical antenna element and converter including the same

Abstract: The feed-horn with helical antenna element of this invention comprises (1) a waveguide made of conductive cylinder having a step inside, the inner diameter in the vicinity of the opening face of the waveguide is larger than that of the base of the waveguide, and (2) a helical antenna element disposed at the base axial center of the waveguide. Introduction of the step-formed inside to the waveguide makes it possible to obtain excellent characteristics both of cross polarization and impedance.

Mobile radio reception with antenna diversity

Abstract: The radio receiver system contains a radio receiver (11) and a diversity box (12). Four antennas (3a to 3d) are connected with the amplifiers (4a to 4d) in the box, and the amplified signals are each fed to one of four contacts of a four stage antenna switch (5). The central contact of the switch is connected with a tuner (7) of the radio receiver (12) through the high frequency line (6), and the IF signal from the tuner goes to the evaluating unit (13) in the radio receiver (11). When there is a loss of quality in signal received, a signal goes to the logic unit (14) so that the switch (5) can change to another antenna.

Parabolic antenna capable of adjusting the elevation angle of a feed horn

Abstract: A parabolic antenna provided with a reflector and an arm comprises a housing fixed to a free end of the arm, a case enclosing a low noise blockdown converter ("LNB"), a feed horn protruding from a front side of the LNB case and a driving and a driven gears for adjusting an elevation angle of the feed horn. The LNB case has a pair of hinge pins. The housing has a pair of supporting members which are spaced from each other and provided with a pair of apertures into which the hinge pins of the LNB case are snugly fitted, respectively. The driven gear is engaged on one of the hinge pins of the LNB case and the driving gear is engaged on an input shaft. The input shaft rotatably passes through one of the supporting members, the driving gear and the driven gear being meshed with each other and, in turn, rotated with the input shaft, thereby allowing the elevation angle of the feed horn can be adjusted by rotating the input shaft.

Antenna feedhorn with protective window

Abstract: A feed structure for an antenna, comprising a feed horn having an input end and an output end, a collar threadably engaged to the output end of the feed horn and a protective window interposed between the feed horn and the collar. The collar forms an aperture exposing said window.

EMCP microstrip antennas as feed for satellite receiver

Abstract: Horn antennas with peripheral chokes are used as feeds for reflector antennas in satellite TV receivers for C-band operation. A microstrip antenna (MSA) is proposed which can replace the existing horn feed. The advantages of this feed are compact size, reduced cost, reduced volume and weight, integration of the required electronics on the same substrate and small aperture blockage. Although MSAs are known for their narrow bandwidth, the use of a stacked patch allows a wider bandwidth. Double layer stacked circular microstrip antennas with different radii have been proposed for use as reflector feeds for satellite communications in the C-band (3.7-4.2 GHz) as well as extended C-band (3.5-4.5 GHz).

Offset-paraboloid geometry: relations for practical use

Abstract: Offset-paraboloidal reflector antennas are used for satellite-communication systems, because they provide low sidelobes and high eficiency. The analysis of the radiation characteristics for the reflector antenna have been studied, with the geometric parameters related to focal length. But we sometimes need to convert the geometrical parameters of the offset-paraboloidal reflector to dimensions relative to the plane of the rim, especially during manufacture. The focal length and geometric parameters are also formulated from the easily measured parameters of the reflector, such as length, width, and depth.

Antenna system parabolic reflector, flat plate shroud and radome

Abstract: In a parabolic reflector system for directing or receiving radiation from or to a radiation feed, having a parabolic reflector surface defining a parabolic reflector axis, a parabolic reflector focus and a radiation aperture, wherein the parabolic reflector has a flat plate shroud attached thereto at the aperture thereof and a radome covering the shroud aperture.

Wide flare-angle horn antenna with means for radiating low levels of crosspolarisation in two widely separated frequency bands

Abstract: Preliminary results for a horn antenna with good crosspolar performance in two discrete frequency bands in addition to desirable VSWR characteristics are presented. The horn combines two different design concepts. It uses corrugations to control the crosspolarisation in the lower frequency band when the corrugation depth is approximately /spl lambda//4, and in the upper frequency band when the corrugation depth tends towards /spl lambda//2, crosspolarisation is reduced by controlling the aperture distribution with the addition of the necessary magnitude and phase of the TM/sub 11/ mode controlled by a mode transducer in the input waveguide.

Design and Development of VSAT Antenna Feed .

Abstract: The paper deals with the design and development of a dual polarised corrugated conical horn employed as a feed for parabolic reflector antennas used in very small aperture terminal applications. The VSAT antenna feed is designed, fabricated and tested to operate over a band from 3.7 GHz to 6.5GHz with good pattern symmetry, low side lobes and low cross-polarisation.

A new field theory approach for design of circular corrugated horn with axial slots

Abstract: Presents results of a theoretical investigation of circular corrugated horns with axial slots. A new field theory approach for calculation of the generalized scattering matrices of separate modules, which are obtained by dividing the circular horn into simple regions, is proposed. The problem is solved by the integral equation method. The numerical results obtained have been compared with known data. It is shown that the approach is highly efficient in its computer resources usage.

Multichannel satellite television receiver

Abstract: The satellite television receiver consists of a parabolic antenna (12) connected to a twin channel receiver (10). A television (18) can be connected conventionally by cable (14). Alternatively, a radio transmitter is fitted in the satellite receiver to transmit (16) radio waves to a receiver (24) which then sends a signal to a second television (20). A conventional infrared remote control (26) is used to operate the system.

Space antennas: design, analysis and measurement challenges

Abstract: Modern technological demands necessitates utilization of sophisticated antenna configurations as an integral part of future satellite communications and scientific payloads. A typical configuration consists of multi offset reflector antennas illuminated by feed arrays operating at various frequency bands. Additionally, it is desired to use large reflector antennas providing improved link performances and high resolutions for various applications. An overview of representative recent advances in large antenna design, analysis and measurements are presented. Examples of recent developments of mesh deployable and inflatable reflector antennas are given.

Dual-grid dual-band shaped reflector antennas for AsiaSat-2

Abstract: Dual-grid, shaped surface, offset reflector antennas provide both the C-Band and Ku-Band shaped beam coverage and frequency re-use for AsiaSat-2 satellite communication service, without the use of complex multiple feed arrays and beam forming networks. The AsiaSat-2 commercial communication satellite utilizes this type of dual band polarization diverse flight antenna and is currently in preparation for shipment to the launch site from the Lockheed Martin Astro Space, East Windsor, New Jersey facility. This satellite, operating in the fixed satellite services C and Ku bands with beams covering virtually all of Asia, parts of Europe and Australia, has both the highest EIRP and total power radiated levels of any commercial satellite yet developed for this region. This system provides twenty-four 55 Watt C-Band channels and nine 115 Watt Ku-Band channels. This satellite system will provide a complete range of telecommunications, from private and PSTN voice and data networks to both analog and compressed digital television services for general distribution to cable head ends and community TVRO's, for example, for extensive direct-to-home reception. This shaped reflector antenna system employs a single rectangular trifurcated feed horn at C-Band and a circular corrugated feed horn at Ku-band for reflector illumination with the advantages of reduced size, weight, insertion loss and cost when compared to more complex array shaped beam antennas. Software based on physical optics optimization techniques was incorporated to develop shaped, gridded reflector surfaces that generated the proper aperture amplitude and phase distribution to produce the desired beam shape. Reflector feed and system design trades are presented. Test results showing excellent correlation between the measured and predicted co-polarized and cross-polarized performance of the flight antennas integrated on the spacecraft at the Lockheed Martin compact antenna range in Princeton, New Jersey are highlighted.

S/X-band beam waveguide for the Onsala radio telescope

Abstract: The antenna of the Onsala radio telescope is a Cassegrain antenna with a parabolic main reflector of 19.810 m diameter and a hyperbolic subreflector of 1.83 m diameter. The focal length is 8.990 m. The secondary focus is located at the apex of the paraboloid. This antenna was built primarily for radio astronomical research, but is temporarily reconfigured for geodetic VLBI by placing a S/X-band feed system in the secondary focal zone of the Cassegrain antenna. However, the old feed system can no longer be used because the secondary focus of the Cassegrain will be permanently occupied by a millimeter wave imaging array. In the present report we study a new beam waveguide feed system which will not interfere mechanically with the imaging array and which can be removed when the latter is to be operated. The new feed system consists of a S/X-band corrugated conical horn illuminating a dual-offset-reflector beam waveguide structure. One reflector deflects the received beam away from the secondary focus and the rest of the feed system is located beside this region. There will be access to it through a hole in the main reflector surface. The present paper describes the Gaussian beam synthesis and the results of PO analysis of the complete four reflector system. The present study included also an investigation of single reflector feed solutions.

xed-Tune erconductor-

Abstract: A fixed-tuned superconductor-iqsulator-super- conductor (SIS) receiver has been designed to operate in the 250-350-GHz frequency hand. This receiver has a douhle- side-band noise temperature of between 35 and 45 K, or about 3hv/k~, over its entire operating band. Extensive characterization of the receiver has been carried out using techniques developed for submillimeter waves. The" input noise, side-band ratio, 1 dB compression point, optimum LO drive level, and vector near-field beam profile have all been measured experimentally. The measurement techniques and results are presented and discussed. Fig. 1 is a detailed drawing of the central portion of the mixer block. The dimensions are essentially 70% of the corresponding dimensions of the 200 GHz mixer block from which the 300 GHz design is derived. The reduced height waveguide section (0.80 x 0.19 mm) is created by mechanical stamping. This shorted waveguide section, which forms the fixed backshort tuner of the mixer, measures 0.26 mm in depth. This mechanical layout, together with the low-pass IF filters, produces a driving point impedance of about 35 R at the waveguide feed point over the required operating bandwidth The mixer block is fitted with an electroformed corrugated feed horn section that includes a transition from reduced height guide to corrugated guide. The semiflare angle of the horn is 8.5". The fused quartz mixer chip, measuring 0.355 x 0.090 x 4 mm, is clamped between the horn section and the mixer block back piece in a suspended microstrip line configuration, parallel to the E-plane of the waveguide. The chip is contacted on both the IF connector side and the ground side by gold plated beryllium copper wire, 0.125 mm in diameter. Since the contact pads on the chip are overlaid with a thin gold layer, no indium is needed to maintain the mechanical contact. Two grooves are milled on each side of the block along the H-plane of the waveguide. They allow a pair of magnetic pole pieces to come into close proximity of the SIS junction. '

Wide band horn (ridged horn) calibration by the three antenna method

Abstract: The gain of the double ridged horn for frequency of 1 to 18 GHz has been precisely calibrated by the three antenna method in an anechoic chamber. The error in the calibration is estimated as /spl plusmn/0.15 dB or less.

Analysis of a broadband choke horn and a dipole-disk with ring as feeds for the Arecibo tri-reflector system

Abstract: This study shows that a newly published compact broadband choke horn is an almost ideal feed for the Arecibo tri-reflector system over a relative bandwidth of 1.8. At frequencies below 500 MHz a lighter dipole-disk feed with beam forming ring may instead be used.

A compact L band feed for a multi-frequency cassegrain radio telescope

Abstract: A compact L band antenna feed system is needed for use on 25m cassegrain radio telescopes. A horn fed lens antenna has been designed using CAD, and a scale model constructed. A mounting and positioning system has been devised for the full-size feed system. Results oftests on the model have been encouraging, and the initial computer model has been improved.

Corner reflector antenna fed by slotted cylinder

Abstract: The radiation pattern of a corner reflector fed by a circular conducting cylinder with an axial slot is examined. An integral equation for the TE case is derived using Green's second identity. The method of moments is then employed to obtain a numerical solution for the integral equation. In order to study the effect of the slotted cylinder feed, radiation patterns corresponding to a line source feed are also calculated. The comparison between radiation patterns of corner reflector antenna fed by a line source and their correspondence with a slotted circular cylinder feed showed that the later can give a narrower beam width, which increases the antenna gain.

Performance of a novel dual-band horn antenna @ 20/30GHz

Abstract: The design for a narrow angle feed horn radiating low levels of cross polarisation in two widely separated frequency bands is presented. The horn uses corrugations to control the cross polarisation in the lower frequency band and a synthesised aperture distribution controlled by a TM 11 mode transducer in the input waveguide to reduce cross polarisation in the upper frequency band. Provisional theoretical radiation patterns and VSWR characteristics are included to indicate antenna performance.