US3815136A - Coaxial tracking signal coupler for antenna feed horn - Google Patents

Coaxial tracking signal coupler for antenna feed horn Download PDF

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Publication number
US3815136A
US3815136A US00287708A US28770872A US3815136A US 3815136 A US3815136 A US 3815136A US 00287708 A US00287708 A US 00287708A US 28770872 A US28770872 A US 28770872A US 3815136 A US3815136 A US 3815136A
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United States
Prior art keywords
horn
coupler
waveguide
antenna
coaxial
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Expired - Lifetime
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US00287708A
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English (en)
Inventor
J Rootsey
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SPACE SYSTEMS/LORAL Inc A CORP OF DELAWARE
Space Systems Loral LLC
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Philco Ford Corp
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Priority to US00287708A priority Critical patent/US3815136A/en
Priority to JP48101756A priority patent/JPS5232959B2/ja
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Assigned to SPACE SYSTEMS/LORAL, INC., A CORP. OF DELAWARE reassignment SPACE SYSTEMS/LORAL, INC., A CORP. OF DELAWARE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FORD AEROSPACE CORPORATION, A CORP. OF DELAWARE
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/146—Systems for determining direction or deviation from predetermined direction by comparing linear polarisation components
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/04—Multimode antennas

Definitions

  • ABSTRACT Tracking signals are extracted from the antenna feed horn by means of a two-stage coaxial coupler.
  • the first stage consists of irises located on the horn end of a coaxial spear that extract signals in the first order circular transverse electric mode.
  • the second stage consists of a probe located at the waveguide end of the coaxial spear that extracts TEM energy derived from signals in the first order transverse magnetic mode. Only one coupling stage is-required for tracking circularly polarized signals, while both are required for tracking linearly polarized signals. In either case, fundamental mode transverse electric energy is passed without significant coupling or obstruction.
  • a sub-reflector is located at the antenna focus and the feed horn, located in a hole at the center of the parabolic reflector, illuminates the subreflector which in turn illuminates the parabolic reflector.
  • a very large horizontal horn has a flat reflecting surface, tilted at a 45? angle with respect to the horn axis, located at the large end.
  • the small end of the horn terminates in the waveguide transmission line.
  • the horn can be rotated about its long axis and its-vertical beam center line to provide scanning or pointing.
  • Such antennas are optimized for operation in a communications frequency band to provide reliable low-noise communication. Tracking is accomplished within this band and the satellite being tracked is ordinarily supplied with a beacon transmitter emitting at the tracking frequency for easy viewing.
  • the beacon frequency is sufficiently off-set from any communications frequencies to avoid interference.
  • the communications antenna feed is surrounded by four tracking feed antenna horns, two each for azimuth and elevation data.
  • Such a system is cumbersome and, since the communications feed is at the reflector focus, the tracking feeds must be compromised in terms of location and size. Ithas become standard practice to use a single feed horn and to extract the desired tracking signals from the waveguide transmission line.
  • One successful prior art system is described in the article titled The Autotrack System published in the Bell System Technical Journal 42 1283-1307. (July, 1963).
  • the extraction of tracking signals is ordinarily by way of coupling irises inthe waveguide walls, or other externally mounted pick off elements, These elements are complex and must be located with great precision.
  • the iris location, size, and coupling bandwidth must be compromised with respect to minimizing influence on the communications channel.
  • a doubly tapered conducting coaxial element into the throat of the antenna feed horn where it joins the wave guide transmission line.
  • the taper pointing toward the horn serves as a mode control section that will convert any TM, energy in the horn to TEM energy.
  • the taperedsection pointing down the waveguide terminates in a coaxial probe.
  • the coaxial probe extracts TEM energy from the coaxial section, thereby coupling out transverse magnetic signal energy from the horn.
  • This energy contains antenna pointing error signal information whenever the field vector is in the plane ofthe pointing error. While such a device operates well on circularly polarized signals, it will not respond equally to all directions of linearly polarized signals.
  • the horn end of the coaxial element may also contain longitudinal slots or coupling irises that will be excited by rotary transverse electric signal energy (TE in the throat of the horn. All TE energy propagating into the horn will be reflected at the point of cut-ofl' and will set up a standing wave pattern. By placing the longitudinal slots at the field maximum, strong coupling to the circular electric mode occurs. For broadband operation a discrete step is added to the horn wall to define the cutoff point over the frequency band of operation.
  • TE rotary transverse electric signal energy
  • This device also operates well on circularly polarized signals, but will not respond equally to all directions of linearly polarized signals.
  • the limitations referred to in the two preceding paragraphs are avoided because the TE output is complementary in directional response to the TM output.
  • the resulting output is nearly constant for all directions of linearly as well as circularly polarized signals.
  • FIG. 1 is a showing, in partial cross-section, of a coaxial tracking coupler located in the throat of an antenna feed horn;
  • FIG. 2 is a graph showing the receiving antenna mode response as a function of angle of arrival of incident signal
  • FIG. 3 is a cross section of a tracking coupler which has provision for coupling to the TM input mode
  • FIG. 4 is a cross section of a tracking coupler which has provision for coupling to the TE input mode
  • FIG. 5 is a block diagram of a system using either the tracking coupler of FIG. 3, or the tracking coupler of FIG. 4;
  • FIG. 6 is a block diagram of a system using both tracking couplers simultaneously as would be required for tracking a linearly polarized signal.
  • FIG. 1 shows a cross section of a'feed horn used to excite a large parabolic antenna.
  • the horn l is simply a flared section extending from round or square waveguide 2.
  • the horn dimensions are selected to provide the desired parabolic reflector illumination as is well known in the prior art.
  • the surface of the horn may be corrugated to aid in mode control if desired.
  • the waveguide coupling to the horn is dimensioned to provide for operation at the TIE fundamental mode at the lowest frequency of operation. For the systems of interest this will usually be within 40 percent of the highest beacon or tracking frequency. Thus the waveguide will not support the higher order modes at the beacon frequency.
  • Coupler 3 is mounted inside the throat of the horn as shown.
  • lts basic form is a tapered section of a conducting cylinder accurately centered with respect to the waveguide axis.
  • This device is mounted by means of metal or low loss dielectric standoffs not shown in this view. These standoffs may be dimensioned and shaped to minimize r-f losses as is well known in the art.
  • Coupling irises 41 see also FIG. 4, are the TE coupler and excite an inner coaxial line in the TEM mode.
  • a small diameter coaxial cable '7 brings energy from the slot area to the exterior of the waveguide wall.
  • Probe is the TM coupler and, as illustrated in FIG.
  • coupler 3 is connected to the center conductor of .a length of small diameter coaxial cable 6 that brings energy from the probe outside the waveguide wall where it is available for the tracking receiver.
  • the horn end of coupler 3 includes a tapered section extending into the horn. This section serves to convert received signal energy in the TM mode to the TEM mode of coaxial line operation. While waveguide 2 will not support this mode, the coaxial line composed of inner conductor 3 and outer conductor 2 will propagate the TEM mode.
  • the portion of coupler 3 acting on the wave approaching the horn to waveguide transition serves as a mode filter that tends to reject all modes except TE and TEM.
  • the TE signals pass on down waveguide 2 but the TEM energy is matched by the taper to probe 5 which then conducts it out via coaxial cable 6.
  • the source of the beacon signal is precisely on boresight (the antenna accurately pointed at the source) all energy will propagate down the horn l. and waveguide 2 in the fundamental TE mode, and there will be no TM. or TE excitation and no signal will be coupled out of coaxial cables 6 or 7. If, however, the source is located slightly off boresight, it will still propagate down waveguide 2 but it will also introduce a TlVl TE or combined component into the horn dependent upon its polarization. This component will appear at cables 6 or 7 (or both) and will have a phase relative to the TE signal dependent upon the direction of departure of the source from boresight.
  • FIG. 2 shows the relative performance of the TE and TM components as a function of boresight error.
  • the TE component shows a broad maximum about the 0 or boresight angle. This constitutes a conventional plot of antenna beamwidth.
  • the TM and TE. components go through a very deep null on boresight and rise to about 6 dB below the main beam value at relatively slight angular departure from boresight.
  • the foregoing assumes that the beacon signal is completely circularly polarized. Any departure from this condition will result in variations in the TM and TE components as a function of the direction of departure from boresight.
  • FIG. 3 shows the details of coaxial probe 5. Coupler 3 is shown in cross section at the waveguide end. Probe 5 is connected by way of matching section 8 to the coaxial cable exiting the waveguide section as element 6. The probe assembly can be secured mechanically by filling the interior of the coaxial line with low loss dielectric material. The coaxial line 6 passes through the standoff 9 which may be a vane or rod of conducting or dielectric material.
  • FIG. 1 shows the horn end of coupler 3 containing four coupling irises 1 arranged in orthogonally disposed pairs. Since the drawing is a cross section of coupler 3, only two irises appear. Energy from these irises is coupled to the exterior of the waveguide by means of coaxial cable '7. The irises 4 will be excited only by TE energy. Since this mode will only propagate a limited distance down horn 11, step 10 is provided. The outer diameter of step 10 is made such that the horn will propagate TE energy, while the inner diameter of the step is beyond cutoff. Thus the step acts as a mode filter passing TE and TM energy but blocking TE energy.
  • the irises 4 are located so that they will couple to the T13 field and, since this electric field is concentric with the horn, will be excited thereby. Iris energy is coupled by way of conventional coupling tabs 11 to coaxial line 12, which couples the TE energy out by way of cable 7.
  • the inner conductor of coaxial line 12 is connected to the inner conductor of coaxial cable '7. Since the irises are excited in a circumferential manner in respect to the coupler, the fields must be reconfigured with respect to coaxial line 12 to excite it. This may be accomplished by slightly displacing opposing iris faces or by including tabs Ell. These tabs are fixed to one iris face and extend toward the center conductor of line 112. Each iris will have one tab and the tabs can be trimmed or adjusted to equalize the individual iris coupling.
  • the output from coaxial cable 7 will represent the TE input and will be available whenever the polarization is orthogonal to the plane of the pointing error.
  • FIG. 5 is a block diagram showing how either coupler may be connected into a tracking receiver for singlestage, circular polarization operation.
  • the horn 1 and waveguide 2 feed a wideband low noise amplifier 13 and normally provides the communications signals to the receiver circuits.
  • Tracking coupler 3 provides the TM signal by way of cable 6 or, alternatively, the TE signal by way of cable '7 to a phase lock tracking receiver M.
  • the tracking receiver obtains its reference signal from the low noise amplifier by way of coupler 15.
  • the tracking receiver 14 produces an output that contains sense information in terms of the phase difference of the two inputs to indicate the direction of departure from boresight, and the magnitude of the output indicates the amount of departure from boresight.
  • These signals are then used in known manner to operate conventional antenna control servomechanisms 26 to minimize the boresight error.
  • the mechanical linkage between antenna control servomechanisms 2t and horn 1 is represented by dashed line 22.
  • FIG. 6 is a block diagram showing how both stages of the coupler including the probe and irises of FIGS. 3 and 41 respectively might be connected to a tracking receiver for dual stage linear polarization operation.
  • the iris coupling to the TE component is fed by way of cable 7 through a phase adjuster 16 and into one input port of a .hybrid coupler 18.
  • the probe coupled TM component is fed by way of cable 6 to the other input port of coupler 118 through an amplitude adjuster 17.
  • the phase adjuster control 16 compensates electrically for the physical separation between probe 5 and irises 4.
  • the amplitude adjuster 17 equalizes the two signals.
  • the signals are combined in the 90 hybrid coupler 18 for application to tracking receiver 14. From this point the operation is as was described for FIG. 5.
  • the coaxial probe can take other forms such as a ball or disk, and conventional broadbanding techniques may be applied.
  • the coupler and waveguide components while being shown as circular in cross section, could be square or hexagonal. These elements could incorporate ridges for further control of transmission modes.
  • the TE coupling slots could be excited by conducting loops, and the slots, rather than being rectangular, could be other shapes such as elliptical or dumbell.
  • the means of propagating the TE signal to the slots could be accomplished by dielectric loading rather than a stepped horn. It is intended that the invention be limited only by the following claims:
  • An antenna system comprising: a beam steering system, a feed horn, a waveguide transmission line connectedto said feed horn, a coaxial coupler mounted at the juncture of said waveguide and said horn, said coupler containing elements responsive to non-axial horn signal components, said horn and waveguide being adapted to operate on TE, signal energy, said nonaxial components comprising a TE component when the departure from the axis is perpendicular to the polarization of said signal and a TM component when the departure from the axis is parallel to the polarization of said signal, said coupler including a plurality of longitudinal irises responsive to said TE, signal, said" communications and beacon signals from a satellite,
  • said antenna includes means responsive to said beacon signals which, through the agency of antenna control servomechanisms, orient said antenna to track said satellite, said antenna including a horn section and a waveguide feed section, the improvement comprising: a coaxial coupler mounted at the juncture of said horn and said waveguide, said coaxial coupler including means extending into the throat of said horn section for converting TM horn signal components to TEM signal components, and means connected to said cou- Dler for extractin T .7.
  • said antenna comprising a horn section to receive both said signals and a waveguide section coupled to said horn section for transmitting received signals to signal utilization means, a coaxial coupler mounted within said horn and waveguide sections at the juncture thereof, one portion of said coaxial coupler extending coaxially into the throat of said horn and another portion of said coaxial coupler extending coaxially into said wave guide, the transverse external dimensions of said coupler being sufficiently small compared to the internal transverse dimensions of said waveguide that no substantial interference with transmission of the TE fundamental mode from said horn to said waveguide occurs at any communication frequency, said coaxial coupler including means in the horn thereof for converting TM horn signal components of said beacon signals into TEM signal components, coaxial line means connected to said coaxial coupler and extending through a wall of said antenna, said coaxial line means providing a TEM output separate from the TE output of said antenna, and means in the horn portion

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Waveguide Switches, Polarizers, And Phase Shifters (AREA)
  • Details Of Aerials (AREA)
  • Waveguide Aerials (AREA)
US00287708A 1972-09-11 1972-09-11 Coaxial tracking signal coupler for antenna feed horn Expired - Lifetime US3815136A (en)

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JP48101756A JPS5232959B2 (nl) 1972-09-11 1973-09-11

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955202A (en) * 1975-04-15 1976-05-04 Macrowave Development Laboratories, Inc. Circularly polarized wave launcher
EP0113901A2 (de) * 1982-12-22 1984-07-25 Siemens Aktiengesellschaft Wellentypenweiche
EP0128970A1 (de) * 1983-06-18 1984-12-27 ANT Nachrichtentechnik GmbH Viertornetzwerk für Mikrowellenantennen mit Monopulsnachführung
FR2613534A1 (fr) * 1987-03-31 1988-10-07 Toshiba Kk Gyrotron
EP0443526A1 (en) * 1990-02-20 1991-08-28 Andrew A.G. A microwave coupling arrangement
US5255003A (en) * 1987-10-02 1993-10-19 Antenna Downlink, Inc. Multiple-frequency microwave feed assembly
US20020167452A1 (en) * 2001-05-11 2002-11-14 Alps Electric Co., Ltd. Primary radiator having excellent assembly workability
US20060125706A1 (en) * 2004-12-14 2006-06-15 Eric Amyotte High performance multimode horn for communications and tracking
DE102008048582A1 (de) * 2008-09-23 2010-03-25 Endress + Hauser Gmbh + Co. Kg Mit Mikrowellen arbeitendes Füllstandsmessgerät
US10218076B1 (en) * 2018-09-10 2019-02-26 The Florida International University Board Of Trustees Hexagonal waveguide based circularly polarized horn antennas

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6333206U (nl) * 1986-08-21 1988-03-03

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259899A (en) * 1963-12-24 1966-07-05 Bell Telephone Labor Inc Nondegenerate multimode tracking system
US3566309A (en) * 1969-02-24 1971-02-23 Hughes Aircraft Co Dual frequency band,polarization diverse tracking feed system for a horn antenna
US3568204A (en) * 1969-04-29 1971-03-02 Sylvania Electric Prod Multimode antenna feed system having a plurality of tracking elements mounted symmetrically about the inner walls and at the aperture end of a scalar horn
US3665481A (en) * 1970-05-12 1972-05-23 Nasa Multi-purpose antenna employing dish reflector with plural coaxial horn feeds

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259899A (en) * 1963-12-24 1966-07-05 Bell Telephone Labor Inc Nondegenerate multimode tracking system
US3566309A (en) * 1969-02-24 1971-02-23 Hughes Aircraft Co Dual frequency band,polarization diverse tracking feed system for a horn antenna
US3568204A (en) * 1969-04-29 1971-03-02 Sylvania Electric Prod Multimode antenna feed system having a plurality of tracking elements mounted symmetrically about the inner walls and at the aperture end of a scalar horn
US3665481A (en) * 1970-05-12 1972-05-23 Nasa Multi-purpose antenna employing dish reflector with plural coaxial horn feeds

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955202A (en) * 1975-04-15 1976-05-04 Macrowave Development Laboratories, Inc. Circularly polarized wave launcher
EP0113901A2 (de) * 1982-12-22 1984-07-25 Siemens Aktiengesellschaft Wellentypenweiche
EP0113901A3 (en) * 1982-12-22 1986-03-26 Siemens Aktiengesellschaft Mode filter
EP0128970A1 (de) * 1983-06-18 1984-12-27 ANT Nachrichtentechnik GmbH Viertornetzwerk für Mikrowellenantennen mit Monopulsnachführung
US4630059A (en) * 1983-06-18 1986-12-16 Ant Nachrichtentechnik Gmbh Four-port network coupling arrangement for microwave antennas employing monopulse tracking
US4926093A (en) * 1987-03-31 1990-05-15 Kabushiki Kaisha Toshiba Gyrotron device
FR2613534A1 (fr) * 1987-03-31 1988-10-07 Toshiba Kk Gyrotron
US5255003A (en) * 1987-10-02 1993-10-19 Antenna Downlink, Inc. Multiple-frequency microwave feed assembly
EP0443526A1 (en) * 1990-02-20 1991-08-28 Andrew A.G. A microwave coupling arrangement
AU634858B2 (en) * 1990-02-20 1993-03-04 Andrew Corporation A microwave coupling arrangement
US20020167452A1 (en) * 2001-05-11 2002-11-14 Alps Electric Co., Ltd. Primary radiator having excellent assembly workability
US6717553B2 (en) * 2001-05-11 2004-04-06 Alps Electric Co., Ltd. Primary radiator having excellent assembly workability
US20060125706A1 (en) * 2004-12-14 2006-06-15 Eric Amyotte High performance multimode horn for communications and tracking
DE102008048582A1 (de) * 2008-09-23 2010-03-25 Endress + Hauser Gmbh + Co. Kg Mit Mikrowellen arbeitendes Füllstandsmessgerät
US10218076B1 (en) * 2018-09-10 2019-02-26 The Florida International University Board Of Trustees Hexagonal waveguide based circularly polarized horn antennas

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Publication number Publication date
JPS4966053A (nl) 1974-06-26
JPS5232959B2 (nl) 1977-08-25

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Owner name: SPACE SYSTEMS/LORAL, INC., 3825 FABIAN WAY, PALO A

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Effective date: 19910215