WO1995001661A1 - Ensemble d'alimentation d'ondes ultracourtes a frequences multiples - Google Patents

Ensemble d'alimentation d'ondes ultracourtes a frequences multiples Download PDF

Info

Publication number
WO1995001661A1
WO1995001661A1 PCT/US1994/007094 US9407094W WO9501661A1 WO 1995001661 A1 WO1995001661 A1 WO 1995001661A1 US 9407094 W US9407094 W US 9407094W WO 9501661 A1 WO9501661 A1 WO 9501661A1
Authority
WO
WIPO (PCT)
Prior art keywords
cavity
band
feed assembly
frequency
probe
Prior art date
Application number
PCT/US1994/007094
Other languages
English (en)
Inventor
Gerry B. Blachley
Original Assignee
Antenna Down Link, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Antenna Down Link, Inc. filed Critical Antenna Down Link, Inc.
Publication of WO1995001661A1 publication Critical patent/WO1995001661A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/06—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens
    • H01Q19/08—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using refracting or diffracting devices, e.g. lens for modifying the radiation pattern of a radiating horn in which it is located
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/24—Polarising devices; Polarisation filters 
    • H01Q15/242—Polarisation converters
    • H01Q15/244—Polarisation converters converting a linear polarised wave into a circular polarised wave
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
    • H01Q5/45—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements using two or more feeds in association with a common reflecting, diffracting or refracting device
    • H01Q5/47—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements using two or more feeds in association with a common reflecting, diffracting or refracting device with a coaxial arrangement of the feeds

Definitions

  • This invention relates generally to antenna feed assemblies and, more particularly, to antenna feed assemblies adapted to detect incident electromagnetic signals in two or more distinct frequency bands, simultaneously.
  • Each of these receiving stations requires an antenna capable of detecting signals at levels in the range of -120 dbm to -30 dbm, while rejecting terrestrial interference, and capable of polarization control. It is desirable for maximum utility that a single feed assembly exhibit the capability of operating simultaneously in two different frequency bands, e.g., the C band of 3.7 to 4.2 GHz and the Ku band of 11.7 to 12.2 GHz or the optional Ku band of 10.95 to 11.7 GHz. Simultaneous operation in yet a third frequency band, e.g., the S band of 2.544 to 2.655 GHz, also is desirable in many applications. A separate probe ordinarily must be provided for detecting signals in each band.
  • This invention relates generally to microwave feed assemblies and, more particularly, to microwave feed assemblies that are adapted to detect signals in multiple distinct frequency bands.
  • One attempt at a coaxial C- and Ku-band receiver antenna employs a plurality of wires surrounding a Ku-band assembly to bypass it as an obstruction and introduce the received signal into a C-band polarizer behind the Ku-band assembly.
  • a common servo motor rotates both the Ku-band and C-band probes, to controllably adjust their polarities.
  • the electromagnetic signals detected by antenna feed assemblies of this kind ordinarily are linearly- polarized.
  • the probes for detecting these signals typically have polarities that are controllably adjusted into alignment with the polarities of the incident signals.
  • the incident electromagnetic signals are circularly polarized.
  • These same probes can detect such circularly polarized signals, but one half of the power, or 3 db, automatically is lost.
  • a quarter-wave plate is used to convert the circularly polarized signals into linearly-polarized signals, for more efficient detection by the probe.
  • the feed assembly includes first and second antenna assemblies having aligned longitudinal axes.
  • the first antenna assembly includes a feed assembly body having a boundary wall that defines a first waveguide cavity, with a first aperture at a forward end of the cavity, and with a first probe mounted in a rearward portion of the cavity, for receiving electromagnetic energy in a first band of frequencies.
  • the second antenna assembly includes a second probe for receiving electromagnetic energy in a second band of frequencies, higher than the first band, along with a second signal conductor extending through a portion of the first waveguide cavity, for conducting energy received by the second probe to the exterior of the feed assembly body.
  • means are provided for mounting the second antenna assembly coaxially within the first waveguide cavity, forwardly of the first probe and spaced from the boundary wall that defines the cavity. The cavity thereby provides a continuous, uninterrupted signal path, around the second antenna assembly, for conveying incident electromagnetic signals from the first aperture to the first probe.
  • the boundary wall that defines the first waveguide cavity includes a circular, rear end wall and a cylindrical side wall such that the first waveguide cavity has a cylindrical shape.
  • the second antenna assembly includes a circular, rear end wall and a cylindrical side wall that define a second cylindrical waveguide cavity, in which is located the second probe.
  • a dielectric spacer located radially between the cylindrical side walls of the first and second antenna assemblies positions the second antenna assembly coaxially in the first waveguide cavity.
  • the feed assembly further includes means for rotating both the first probe and the second probe about the axial longitudinal axes of the first and second antenna assemblies, to change their respective polarities.
  • a portion of the means for rotating the second probe extends through a portion of the first waveguide cavity, without adversely interfering with signal detection by the first probe.
  • a slip joint is provided between the second probe and the second signal conductor, which is fixed relative to the feed assembly body.
  • the feed assembly further includes a third antenna assembly having a third probe for receiving electromagnetic energy in a third preselected band of frequencies, lower than the first band of frequencies, along with means mounting the third probe within the first waveguide cavity, adjacent to the second antenna assembly.
  • the third probe can include a single wire having an axial portion projecting forwardly within the first waveguide cavity, generally parallel with the coaxial longitudinal axis of the first and second antenna assemblies.
  • a signal conductor carries the detected signals from the third probe to the exterior of the feed assembly body either radially outwardly through the cylindrical wall of the first waveguide cavity or rearwardly along the cylindrical wall to the rear wall of the first waveguide cavity.
  • the radial portion of the third signal conductor preferably is positioned parallel with, and axially forwardly of, that second conductor.
  • the feed assembly further includes a dielectric cover for the first waveguide cavity, which seals the cavity from debris and other contamination.
  • the cover includes a dielectric plate having a resilient lip sized to provide a snap-fit over the forward end of the cavity.
  • the rearward side of the plate includes a dielectric block configured to project rearwardly into the waveguide cavity, symmetrically relative to the cavity's longitudinal axis. This block is configured to function as a quarter-wave plate, to convert incident circularly polarized electromagnetic signals into linearly polarized electromagnetic signals having a predetermined polarization axis, for detection by the probe.
  • the entire dielectric cover conveniently can be injection molded as a single piece of polystyrene or polycarbonate.
  • the dielectric block can include two portions, located on opposite sides of the second antenna assembly. If the incident electromagnetic signals in only the second band of frequencies are circularly polarized, then the dielectric block can be sized and configured to project rearwardly into the second waveguide cavity.
  • multiple dielectric blocks can be sized and configured to project rearwardly into both the first waveguide cavity and the second waveguide cavity.
  • FIG. 1 is a perspective view of a first embodiment of a dual-frequency feed assembly in accordance with the invention.
  • FIG. 2 is a sectional view of the feed assembly of FIG 1.
  • FIG. 3 is an enlarged side elevational view of the probe and probe holder portion of the feed assembly of FIG. 1.
  • FIG. 4 is a front elevational view of the feed assembly of FIG. 1.
  • FIG. 5 is a side sectional view of a second embodiment of a dual-frequency feed assembly in accordance with the invention, this embodiment including an external gear drive system.
  • FIG. 6 is a fragmentary side sectional view of a third embodiment of a dual-frequency feed assembly in accordance with the invention.
  • FIG. 7 is a fragmentary side sectional view of a fourth embodiment of a dual-frequency feed assembly in accordance with the invention.
  • FIG. 8 is a graphical representation of the relative power/angle characteristic of a feed assembly having standard cavity and probe.
  • FIG. 9 is a graphical representation similar to FIG. 8, but for the feed assembly of the invention.
  • FIG. 10 is a front elevational view of a fifth embodiment of a feed assembly in accordance with the invention, this embodiment detecting electromagnetic signals in three distinct frequency bands.
  • FIG. 11 is a fragmentary side sectional view of the feed assembly of FIG. 10, taken substantially in the direction of the arrows ll-ll in FIG. 10.
  • FIG. 12 is a front elevational view of a sixth embodiment of a feed assembly in accordance with the invention, this embodiment likewise detecting electromagnetic signals in three distinct frequency bands.
  • FIG. 13 is a side sectional view of the feed assembly of FIG. 12, taken substantially in the direction of the arrows 13-13 in FIG. 12.
  • FIG. 14 is a side view of a dielectric cover suitable for use in sealing the waveguide cavities of the dual-frequency feed assembly of FIG. 1, the cover incorporating a quarter-wave plate for converting circularly polarized C-band signals into linearly polarized signals.
  • FIG. 15 is a rear view of the dielectric cover of FIG. 14.
  • FIG. 16 is a fragmentary sectional view of the feed assembly of FIG. 1, with the dielectric cover of FIG. 14 positioned over the first waveguide cavity.
  • FIG. 17 is a side view of an alternative embodiment of a dielectric cover, this cover incorporating a quarter-wave plate for converting circularly polarized Ku-band signals into linearly polarized signals.
  • FIG. 18 is a rear view of the dielectric cover of FIG. 17. DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • a dual frequency feedhorn and polarizer assembly generally designated 10, may be seen ready to be installed in a reflector dish for receiving satellite communication signals.
  • the assembly 10 includes a circular feedhorn 11 having a pair of outer annular rings 12 and 13, which encircle a C-band aperture defined by an annular tube 14.
  • a Ku- band feed assembly 15 Coaxially located within the tube 14 is a Ku- band feed assembly 15 that includes a sleeve 16 defining a Ku-band aperture and a rotatable probe 20 dimensioned to detect polarized signals in the plane of polarization of the probe 20.
  • the sleeve 16 is part of a cup-shaped member 25 seen in FIG. 2, having a central aperture through with the probe 20 extends.
  • a rear part of the probe 20 is insulatingly mounted on a coaxial probe support 26 at the rear of the cup-shaped member 25.
  • the probe support 26 includes a side slot, unshown in the drawings, through which a coaxial or centerline feed conductor 30 passes between the probe 20 and a Ku-band waveguide adapter 31 mounted on the rear face of the feed body 11 and providing a Ku-band waveguide termination.
  • the centerline feed conductor 30 extends into the waveguide adapter 31 to couple microwave energy detected by the Ku-band probe 20 to an external waveguide for transmission to a low-noise amplifier, which is unshown in the drawings but normally associated with feed assemblies, to amplify the detected signals.
  • the centerline feed conductor 30 enters the cavity behind the probe 20 via the slot described above and extends to the rear or bottom of the support 26 and there forms a U bend to a coaxial position at 17 (FIG. 2) extending toward the Ku-band aperture and joining the probe 20.
  • the probe 20 itself is secured to the probe support member 26 and is free to rotate with the aperture defining sleeve 16.
  • the sleeve 16 is held in a spring grip of an insulating extension 27A of a harp 32, best seen in FIG. 3.
  • a similar ring-shaped extension 27B of the harp 32 encircles the support member 26.
  • the harp 32 encircles a C-band probe 33 of FIG. 3, which is located behind the Ku-band feed assembly 15 and therefore is not visible in FIG. 1 but is clearly shown in FIGS. 2 and 3.
  • the C-band probe 33 and harp 32 are coupled via a shaft 34 and thermally-insulating bearing block 35, with its extension 35A to a servo motor 36 illustrated in FIG. 2 by a dashed line labeled DRIVE.
  • the C-band probe 33 extends part way through the shaft 34 which itself extends through the termination of a C-band waveguide section 40 that includes a 90-degree bend 41 and a flange 42.
  • the flange 42 is adapted to be coupled to additional waveguide sections to the low-noise amplifier.
  • the Ku-band probe 20 and the C-band probe 33 are both mechanically secured to the harp 32 and therefore are both capable of simultaneous movement under the control of the servo drive 36.
  • Both the Ku-band and the C-band feed assemblies have centerline feeds to their respective probes 20 and 33, and the centerline feeds extend through respective waveguide sections 31 and 40 to couple Ku-band and C-band energy to their respective waveguides.
  • the Ku-band feed assembly 15 is located behind the C-band aperture, at a distance approximately 1/3 of the distance D from the aperture to the rear wall or bottom of the cup-like portion of the feedhorn which defines a C-band cavity.
  • the Ku-band feed assembly 15 has hardly noticeable detrimental effects upon signals received by the C-band probe 33.
  • the C- band probe 33 being located to the rear of the Ku-band probe 20, does not interfere with Ku-band signal detection.
  • the sleeve 16 of the Ku-band assembly 15 is dimensioned so that its diameter has a ratio to the diameter of the first or C-band cavity on the order of 0.3.
  • the nominal inside dimension of the C-band cavity was 2.4 inches and the diameter of the sleeve was 0.8 inch or 0.33 ⁇ g (C-band). When enlarged to 0.85 inch and 0.90 inch, the C-band performance was degraded.
  • the minimum diameter of the Ku-band assembly is dictated by the required diameter of the Ku-band cavity, namely 0.74 inch or ⁇ g (Ku band) , the waveguide wavelength.
  • the length L of the Ku-band assembly 15 is dictated by several considerations. It must allow the coaxial conductor 30 to be aligned at the rear with the probe 20. This requires an L shape or modified U shape for the conductor 30. We have found that an overall length L of the Ku-band assembly 15 of 1.6 inches provides a structurally and electrically effective design.
  • the coaxial conductor 30 for the Ku- band probe 20 may extend from the Ku-band assembly 15 outwardly through the C-band cavity where it is located in the order of 0.6 ⁇ g, the waveguide wavelength at the mid band of the lower frequency, e.g., 3.9 GHz for C-band.
  • FIG. 8 illustrates a state-of-the-art single probe feed assembly as shown in the small sketch in FIG. 8. It shows a definite bell-shaped curve with noticeable side lobes. The peak at -2db is located on the axis and the - 12db points are located approximately 60-degrees off axis. Optimum performance requires precise directional positioning of the feed relative to the dish.
  • curve A of FIG. 9 shows the C-band characteristic of a coaxial assembly as illustrated in FIGS. 1-4.
  • that of FIG. 9 is relatively insensitive to directional errors as much as 40 degrees.
  • the average response between these angles is on the order of -5db.
  • the -lOdb points are at ⁇ 72 degrees, in contrast with the typical characteristic of FIG. 8.
  • a feed assembly 110 has an outer ring 112, an inner ring 113, and a lower or C-band aperture 114 in which the higher or Ku-band assembly 15 is located, similar to the assemblies of FIGS. 1-4.
  • the assembly 15 and probe 20 are coaxially mounted in the aperture 114 by a microwave energy transparent spider 117 on a ring 118.
  • the periphery of a front flange portion of the spider 117 constitutes a ring gear that engages the spur gear 119 on a shaft 126 of servo motor 36.
  • the servo motor 36 is located on the rear face of the feed assembly 110 and out of the received energy path. The servo motor 36 may easily be protected from the weather by a cover, unshown in the drawing.
  • signals received by the Ku-band probe 20 are fed by the coaxial line 30 from the waveguide termination 31, which, similar to the embodiments of FIGS. 1-4, is available at an integral flange coupling 31A at the rear of the feed assembly, ready for engagement with the next section of the waveguide.
  • operation of the servo motor 36, driving shaft 126, and spur gear 119 allows rotation of a sleeve 116 that carries the probe 20.
  • Unshown in FIG. 5 is the C-band or lower frequency probe and its own drive and waveguide.
  • the rear of the feed assembly 110 of FIG. 5 is designed to receive on a rear step 120 the identical waveguide structure as illustrated in FIG. 2.
  • the assembly of FIG. 5 may be operated as a single frequency adjustable polarization feed employing the same casting for the assembly as used in the embodiment of FIGS. 1-4, only adding the spider 117, the ring 118, the shaft 126, and the spur gear 119 to the standard servo motor 36.
  • the two probes have independently controlled polarization in the embodiment of FIG. 5.
  • a third embodiment of the invention appears in the fragmentary diametrical sectional view of FIG. 6.
  • a horn assembly 210 is basically of the same design as shown in FIG. 2, with certain exceptions described below.
  • the high frequency or Ku-band assembly 15 is mounted within the C-band aperture 40, but in this case by a washer 216 and by an axial support 217 that carries on it a low frequency or C-band probe 233.
  • a portion of the support 217 extends outside of a rear wall 237 to engage the drive 36.
  • the outermost end of the support 217 is secured as by soldering to the Ku-band assembly 15.
  • the probe 20 feeds a coaxial line 231, which extends forwardly through the washer 216 and then rearwardly through the horn body 211.
  • FIG. 7 A fourth embodiment of the invention is illustrated in FIG. 7. This embodiment employs certain of the characteristics of the previous embodiments, in particular, the front drive of the embodiment of FIG. 5, the forward coaxial line of the Ku-band assembly of the embodiment of FIG. 6, and the dual independent drive capability of the embodiment of FIG. 5.
  • the basic horn structure 210 is of the type disclosed in FIG. 6, which includes the aperture 40 for the low frequency or C-band assembly and a 180-degree slot 301 in a spider 311 through which the fixed coaxial feed 231 extends to the front and then through an opening 302 in the feedhorn to the rear, where it joins a waveguide transition, unshown in FIG. 7 but similar to the waveguide termination 31 of FIGS. 2 and 3.
  • the high frequency or Ku-band assembly 15 is insulatingly mounted with the probe 20 in a rear plug 303, in signal-conducting contact with the center conductor of the coaxial line 231.
  • the plug 303 constitutes the rear of the probe holder, equivalent to probe support 26 of FIG. 1, and it engages the spider 311 to rotate the probe 20 as the spur gear 119 on the shaft 126 is driven by the servo motor 236.
  • the low frequency or C-band probe 33 is driven directly by the drive motor 36.
  • the two probes 20 and 33 have their polarization independently controllable by their respective drive motors 236 and 36.
  • coaxially mounted high- and low-band probes are provided. They are simultaneously controlled in polarization by a single servo motor, or they may be independently controlled by independent servo motors.
  • the high-band assembly is positioned coaxial with, and within, the cavity of the low-band assembly, spaced from the boundary wall that defines the low-band cavity but sized such that the low-band cavity provides a continuous, uninterrupted signal path around the high-band assembly, for conveying incident electromagnetic signals to the low- band probe at the rear of the low-band cavity.
  • efficient signal recovery is possible at both frequencies, and precise polarization control is possible without unwanted interference at the two bands.
  • the structure is relatively simple and reliable as well.
  • FIGS. 10 and 11 depict a fifth embodiment of a feed assembly in accordance with the invention.
  • This embodiment is similar to the embodiment of FIGS. 1-4, except that it further includes an S-band probe 401 for detecting incident electromagnetic signals in yet another frequency band, i.e., S band, which extends from 2.544 to 2.655 GHz.
  • S band yet another frequency band
  • Components included in the embodiment of FIGS. 10 and 11 that are common to the embodiment of FIGS. 1-4 are identified by the same reference numerals. For simplicity, the structure associated with the C-band probe and the structure associated with rotation of the C-band and Ku-band probes are omitted from the drawings.
  • the S-band probe 401 includes a single wire extending longitudinally within the C-band cavity, immediately adjacent to the Ku-band assembly 15. This probe conveniently is the exposed center conductor at the remote end of an S-band coaxial cable or signal conductor 403.
  • the signal conductor 403 extends radially outwardly from the probe 401 through the C-band cavity and beyond to a standard coaxial cable connector 405 secured to the outermost annular ring 12 of the circular feedhorn 11.
  • the signal conductor extends through holes formed in the annular tube 14 and the two annular rings 12 and 13.
  • a set screw 407 is threadedly received in a threaded bore formed in a lateral extension 409 of the tube 14, to tighten against the signal conductor 403 and thereby secure the signal conductor and probe in place.
  • the S-band probe 401 and S-band signal conductor 403 preferably are aligned circumferently with the signal conductor 30 associated with Ku-band assembly 15.
  • the S-band conductor 401 is arranged to be parallel with, and axially forward of, the radial portion of the Ku-band conductor 30. This relative orientation for the two conductors 401 and 30 provides minimal degradation of the electromagnetic signal detected by the C-band probe (not shown) at the rear of the C-band cavity.
  • the Ku-band conductor 30 extends radially from the Ku-band assembly 15 through the C-band cavity and through a hole in the tube 14 to reach a waveguide adapter 31 as was the case in the embodiment of FIGS. 1-4.
  • a rubber plug 413 preferably is positioned between the two conductors 401 and 30, in alignment with the two threaded bores and to provide adequate isolation between the two conductor.
  • FIGS. 12 and 13 depict a sixth embodiment of a feed assembly in accordance with the invention, this embodiment being similar functionally to the embodiment of FIGS. 10 and 11 in that it further includes an S-band probe 501 for detecting incident electromagnetic signals in the S-band of frequencies.
  • S-band probe 501 for detecting incident electromagnetic signals in the S-band of frequencies.
  • Components of this embodiment that correspond to components in previously-described embodiments are identified by corresponding reference numerals.
  • the structure associated with the C-band probe and the structure associated with rotation of the C-band probe and Ku-band probe are omitted from FIGS. 12 and 13.
  • the S-band probe 501 includes a single wire extending longitudinally within the C-band cavity, immediately adjacent to the Ku-band assembly 15, for detecting incident S-band signals.
  • the probe 501 is a single wire that is the exposed center conductor at the remote end of an S-band coaxial cable or signal conductor 503.
  • the signal conductor 503 includes a short radial portion 505 extending from the probe 501 radially outwardly to the wall defined by the annular tube 14, and further includes a longitudinal portion 507 extending rearwardly within the C-band cavity, immediately adjacent to the cavity wall.
  • a signal conductor 513 for the Ku-band assembly 15 likewise extends longitudinally rearwardly within the C-band cavity, immediately adjacent to the longitudinal portion of the S- band conductor.
  • the S-band probe 501 and signal conductor 503 and the Ku-band assembly 15 and signal conductor 513 provide minimal disruption of the incident C- band electromagnetic signals being detected by the C-band probe (not shown) .
  • the S-band and Ku-band conductors need not both exit the C- band cavity in the same location, i.e., both in the cylindrical side wall (as in FIGS. 10 and 11) or both in the circular rear wall (as in FIGS. 12 and 13) . Rather, the two conductors instead can exit the C-band cavity in separate locations.
  • the S-band conductor could exit through the side wall while the Ku-band conductor exits through the rear wall, or conversely the S-band conductor could exit through the rear wall while the Ku-band conductor exits through the side wall.
  • the S-band and Ku-band conductors both are located in generally the same circumferential position within the C-band cavity.
  • the feed assemblies described above all are adapted to detect incident C-band and Ku-band electromagnetic signals that are linearly polarized. Although the feed assemblies also are effective in detecting incident circularly polarized signals, one-half of the power, or 3-db, automatically is lost. In the past, quarter-wave plates have been used to convert circularly polarized signals into linearly polarized signals, to recapture at least a portion of that otherwise lost power.
  • FIGS. 14-16 depict a dielectric cover 601 suitable for placement over the forward end of the C-band waveguide cavity 14 of the feed assembly 10 shown in FIG. 1.
  • This dielectric cover seals the interior of the C-band cavity, as well as the entire Ku-band feed assembly 15, from external debris and other contamination.
  • the dielectric cover includes a disc-shaped plate 603 with a peripheral resilient flange 605 sized to snap-fit over the forward end of the C-band cavity.
  • the dielectric cover further includes two solid blocks 607a and 607b sized and positioned to project rearwardly into the C-band cavity, on opposite sides of the Ku-band assembly. These blocks are configured as quarter-wave plates, to delay one component of the incident circularly polarized signal by one-quarter wavelength, or 90°. These blocks convert the incident signal into a linearly polarized signal suitable for efficient detection by the C-band probe 33 (FIG. 2) . Steps are provided in the radially outward sides of the blocks, to accommodate corresponding steps in the C-band cavity
  • the dielectric cover 601 conveniently can be injection molded as a single piece of a material such as polystyrene or polycarbonate. Several vent holes 609 are distributed uniformly around the cover's periphery, which function to equalize the air pressure within the C-band cavity.
  • the disc-shaped plate 603 preferably has a slight dome shape, for improved rigidity and positioning of the quarter wave plates 607a and 607b.
  • FIGS. 17 and 18 depict an alternative dielectric cover 611, suitable for use with the feed assembly 10 of FIG. 1, this cover including an integral quarter-wave plate 613 sized and positioned to convert incident circularly polarized Ku-band signals into linearly polarized signals, for efficient detection by the Ku-band probe 20 (FIG. 1) .
  • the dielectric cover snap-fits onto the C-band cavity wall 14, in the same fashion as the dielectric cover 601 of FIG. 14.
  • the cover 611 has substantially no effect on incident C-band signals.
  • a dielectric cover incorporating both a two-part C-band quarter-wave plate and a one-part Ku-band quarter-wave plate could alternatively be provided, for use with a feed assembly receiving circularly polarized signals in both the C-band and the Ku-band.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Waveguide Aerials (AREA)

Abstract

Ensemble d'alimentation à fréquences multiples destiné à un système d'antenne comprenant deux cavités coaxiales dans lequel une petite cavité haute fréquence est montée de manière coaxiale dans une plus grande cavité basse fréquence. Une sonde tournante individuelle est montée dans chaque cavité. La petite cavité est montée dans la grande cavité au moyen de plusieurs structures telles qu'un croisillon de forme annulaire, un élément d'espacement se présentant sous forme d'une rondelle plate, ou un éventail s'étendant vers l'arrière dans la grande cavité. Dans toutes les formes de réalisation, un trajet de parcours du signal continu et non interrompu est prévu dans la cavité basse fréquence, autour de la cavité haute fréquence, pour acheminer les signaux électromagnétiques incidents jusqu'à la sonde basse fréquence qui est montée à l'arrière de la cavité basse fréquence. Dans d'autres formes de réalisation l'ensemble d'alimentation est conçu pour détecter les signaux électromagnétiques incidents dans une troisième bande de fréquences, inférieure à la bande basse fréquence, à l'aide d'une troisième sonde située dans la cavité basse fréquence juste à côté de la cavité haute fréquence. Cette troisième sonde est de préférence alignée de manière circonférencielle sur un conducteur pour conduire le signal haute fréquence détecté depuis la sonde haute fréquence jusqu'à l'extérieur de l'ensemble d'alimentation. Dans une autre forme de réalisation de cette invention, un couvercle diélectrique destiné à la cavité basse fréquence comprend un ou plusieurs blocs diélectriques solidaires par construction qui fonctionnent comme lames quart d'onde pour transformer les signaux électromagnétiques incidents à polarisation circulaire situés dans l'une des bandes ou bien dans les deux bandes basse fréquence et haute fréquence, en signaux à polarisation linéaire, qui peuvent être efficacement détectés par les sondes correspondantes.
PCT/US1994/007094 1993-06-29 1994-06-23 Ensemble d'alimentation d'ondes ultracourtes a frequences multiples WO1995001661A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US8483093A 1993-06-29 1993-06-29
US08/084,830 1993-06-29

Publications (1)

Publication Number Publication Date
WO1995001661A1 true WO1995001661A1 (fr) 1995-01-12

Family

ID=22187481

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/007094 WO1995001661A1 (fr) 1993-06-29 1994-06-23 Ensemble d'alimentation d'ondes ultracourtes a frequences multiples

Country Status (1)

Country Link
WO (1) WO1995001661A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3561946A1 (fr) * 2018-04-27 2019-10-30 Nokia Shanghai Bell Co., Ltd. Polarisateur double bande

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3701160A (en) * 1970-06-25 1972-10-24 Int Standard Corp Radar monopulse antennas with converting polarization
US4544900A (en) * 1981-11-18 1985-10-01 Chaparral Communications, Inc. Polarized signal receiver system
US5103237A (en) * 1988-10-05 1992-04-07 Chaparral Communications Dual band signal receiver
DE4116095A1 (de) * 1991-05-17 1992-11-19 Uwe Heynen Allwetterschutz fuer den polarisierer einer parabolantenne
EP0527569A1 (fr) * 1991-07-29 1993-02-17 Gec-Marconi Limited Antenne hyperfréquence

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3701160A (en) * 1970-06-25 1972-10-24 Int Standard Corp Radar monopulse antennas with converting polarization
US4544900A (en) * 1981-11-18 1985-10-01 Chaparral Communications, Inc. Polarized signal receiver system
US5103237A (en) * 1988-10-05 1992-04-07 Chaparral Communications Dual band signal receiver
DE4116095A1 (de) * 1991-05-17 1992-11-19 Uwe Heynen Allwetterschutz fuer den polarisierer einer parabolantenne
EP0527569A1 (fr) * 1991-07-29 1993-02-17 Gec-Marconi Limited Antenne hyperfréquence

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3561946A1 (fr) * 2018-04-27 2019-10-30 Nokia Shanghai Bell Co., Ltd. Polarisateur double bande
US11695191B2 (en) 2018-04-27 2023-07-04 Nokia Shanghai Bell Co., Ltd Dual-band polariser

Similar Documents

Publication Publication Date Title
CA2202843C (fr) Antenne a liaison d'alimentation
US4903037A (en) Dual frequency microwave feed assembly
CA2423489C (fr) Source primaire de poursuite coaxiale multimode a double bande
EP0612120B1 (fr) Antenne à tige diélectrique
US6005528A (en) Dual band feed with integrated mode transducer
US4414516A (en) Polarized signal receiver system
US5929820A (en) Scanning cup-dipole antenna with fixed dipole and tilting cup
US5134420A (en) Bicone antenna with hemispherical beam
EP0485467A4 (en) Improved feeds for dual frequency feed assembly
US5461394A (en) Dual band signal receiver
EP0627128A1 (fr) Structures de source primaire double mode/double bande
US4821046A (en) Dual band feed system
US5005023A (en) Dual band integrated LNB feedhorn system
US5103237A (en) Dual band signal receiver
WO2009072781A1 (fr) Système d'antenne à ellipse déplacée axialement utilisant une source hélicoïdale pour polarisation double
US6577283B2 (en) Dual frequency coaxial feed with suppressed sidelobes and equal beamwidths
US20240154356A1 (en) Waveguide window/seal
US5255003A (en) Multiple-frequency microwave feed assembly
WO1995001661A1 (fr) Ensemble d'alimentation d'ondes ultracourtes a frequences multiples
US5440319A (en) Integrated microwave antenna/downconverter
US4819005A (en) Concentric waveguides for a dual-band feed system
KR20030085358A (ko) 다중 주파수 밴드 위성통신 안테나
US5463358A (en) Multiple channel microwave rotary polarizer
EP0677212B1 (fr) Systeme d'antenne en helice
JPH1197924A (ja) アンテナ装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA