US3851281A - Impedance matched waveguide device - Google Patents

Impedance matched waveguide device Download PDF

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Publication number
US3851281A
US3851281A US00369028A US36902873A US3851281A US 3851281 A US3851281 A US 3851281A US 00369028 A US00369028 A US 00369028A US 36902873 A US36902873 A US 36902873A US 3851281 A US3851281 A US 3851281A
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US
United States
Prior art keywords
impedance
dielectric
waveguide
energy
frequencies
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US00369028A
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English (en)
Inventor
J Hanfling
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Raytheon Co
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Raytheon Co
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 Raytheon Co filed Critical Raytheon Co
Priority to US00369028A priority Critical patent/US3851281A/en
Priority to CA198,921A priority patent/CA1003916A/en
Priority to IT51097/74A priority patent/IT1011460B/it
Priority to GB2384474A priority patent/GB1444328A/en
Priority to DE19742426173 priority patent/DE2426173A1/de
Priority to JP6327774A priority patent/JPS5539927B2/ja
Priority to NL7407550A priority patent/NL7407550A/xx
Priority to FR7419316A priority patent/FR2232842B1/fr
Priority to BE145203A priority patent/BE816068A/fr
Application granted granted Critical
Publication of US3851281A publication Critical patent/US3851281A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/44—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
    • H01Q3/46—Active lenses or reflecting arrays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/08—Coupling devices of the waveguide type for linking dissimilar lines or devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/30—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array
    • H01Q3/34—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means
    • H01Q3/36—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means with variable phase-shifters
    • H01Q3/38—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array by electrical means with variable phase-shifters the phase-shifters being digital

Definitions

  • ABSTRACT A waveguide device is disclosed for matching, over a wide band of frequencies, the impedance of free space to the impedance of ferrite phase shifters disposed within the antenna element of a phased array antenna and for preventing higher order modes from propagating through such device.
  • the device is comprised of a series of resonant circuits, including a waveguide structure, a first one of such circuits including the impedance of free space and a last'one thereof including the impedance'of the ferrite phase shifter, adjacent ones of such resonant circuits being inductively coupled.
  • the resonant circuits are tuned to a nominal operating frequency of the antenna, thereby inductively coupling the energy in a band of frequencies about such operating frequency through the device.
  • waveguide structure is dimensioned so that its cutoff frequency for the dominant mode is higher than the highest frequency in the band of frequencies, thereby preventing the higher order modes from passing through the device.
  • This invention relates generally to waveguide devices and more particularly to phased array antenna elements wherein such devices are used to match the impedance of free space to the impedance of a ferrite phase shifter disposed within such antenna element.
  • a collimated beam of radio frequency energy may be formed and steered by controlling the phase of the energy radiated from each one of a plurality of antenna elements in an array thereof.
  • One technique used to provide such impedance matching has been to dispose a stepped quarter-wave matching transformer within the waveguide feeding each antenna element. The use of such quarter-wave matching transformer, while adequate in many applications, has been found to be inadequate when it is required that the antenna be physically compact, yet operate over a relatively wide frequency band.
  • One technique used to increase the useful bandwidth 7 of an antenna has been to use a circular waveguide antenna element with a cutoff frequency lower than the frequency of the dominant mode of the energy passing therethrough.
  • a series of dielectric discs within such a waveguide are disposed to increase the separation between the dominant mode cutoff frequency and the cutoff frequency of the higher order modes. While such technique has been found to increase the useful bandwidth of the antenna, no impedance matching between free space and the phase shifter is thereby provided to improve the radiating efficiency of the antenna over a broad band of frequencies.
  • a device comprising a series of adjacent resonant circuits including a waveguide structure,-a first one of such circuits including the impedance of free space and the last one of such circuits including the impedance of a load, adjacent ones of such resonant circuits being inductively coupled.
  • the waveguide structure is so dimensioned that its cutoff frequency for the dominant mode. of radio frequency energy to be propagated therethrough is higher than the frequency of the radio frequency energy actually applied.
  • FIG. 1 is a simplified sketch of a radar system using an array of antenna elements, each one thereof being connected to a ferrite phase shifter element, to radiate a collimated beam of radio frequency energy and to receive echo signals from targets illuminated by such radiated energy;
  • FIG. 2 is a cross-section of the impedance matchingdevice of an antenna element of the type shown in FIG. 1 with the cover thereof removed;
  • FIGS. 3A and 3B are diagrams useful in the understanding of the invention.
  • phased array antenna 10 includes a number of fixed antenna elements 11, each such element having associated therewith driver circuitry 13.
  • the antenna elements 11 and associated driver circuitry 13 may be mounted in any conventional manner (not shown in detail) to form a space-fed planar array antenna. Appropriate connections are made, as indicated, between each current circuitry 13 and the ferrite phase shifters included within antenna element 11' (shown in FIG. 2) to control such antenna element 11 in accordance with digital control signals supplied by beam steering computer 15.
  • such an arrangement permits radio frequency energy from a feed horn 17 to be collimated in a beam and directed as'desired and echo signals returning to the individual antenna elements ll of the antenna array 10 to befocused on the feed horn 17.
  • the feed horn 17 is connected in any convenient manner, as by waveguide (not numbered) to a transmitter/receiver 19.
  • the operation of the transmitter/receiver 19 and the beam steering computer 15 is controlled by a conventional synchronizer 21.
  • an exemplary one of the antenna elements 11 includes a section of rectangular waveguide 23 with the ends (not numbered) thereof matched to free space by impedance matching devices 25, 25, the details of which will be described later.
  • the exemplary antenna element 1 1 has disposed within the rectangular waveguide 23 three serially arranged ferrimagnetic toroids 26a, 26b, 26c (FIG. 2) (sometimes referred to as ferrite phase shifters 26a-c) to operate in response to a three bit control signal supplied by beam steering computer 15.
  • ferrimagnetic toroids 26a, 26b, 26c FIG. 2
  • the number of toroids may be changed without departing from any inventive concepts.
  • a different bit of a three bit control signal is applied to a different one of three identical current drivers, collectively referred to herein as current driver 13.
  • a different one of the current drivers is coupled to a different one of the ferrimagnetic toroids 26a to via current drive cables 28a to c.
  • the toroids 26a to 260 are separated from each other and from impedance matching element 25 in a conventional manner by insulating spacers 30a to c, as shown.
  • spacers 30a-c are magnesium titanite dielectric spacers.
  • a conventional support structure, not shown, fastens toroid 26c within waveguide 23.
  • lmpedance matching devices 25, 25' are used to efficiently match, over a wide band of frequencies, the impedance of free space to the impedance of the ferrite phase shifters 26a-c disposed within rectangular waveguide 23.
  • lmpedance matching device 25 here includes a circular waveguide structure 27 having disposed therein two dielectric slabs 32, 34, here discs made of Beryllia. The dielectric slabs 32, 34 are spaced from each other and from the ferrimagnetic toroid. Dielectric slab 32 is fastened on a shoulder 33 within circular waveguide 27 by a suitable epoxy, not shown.
  • the impedance matching device 25 is coupled to the rectangular waveguide 23 by coupling device 37.
  • Coupling device 37 is of conducting material and is circular in shape, having a rectangular slot, 4], formed therein to provide coupling between the rectangular and circular waveguides.
  • the coupling device 37 is welded to waveguides 27 and 23.
  • the coupling device 37, together with epoxy, not shown, is used to hold slab 34 within circular waveguide 27.
  • the slot within such coupling device 37 also provides an air space between slab 34 and spacer 30a.
  • An air-filled cavity 36 is formed between the dielectric slabs 32, 34.
  • the circular waveguide structure 27 has a cutoff frequency higher than the highest frequency in a desired band of frequencies about the frequency of the dominant mode of the radio frequency energy to be passed through the antenna element, that is, higher than the highest frequency in a desired band of frequencies about the nominal operating frequency of the antenna (FIG. 1).v
  • Impedance matching device 25 may be viewed as a series of resonant circuits 38 to 40, a first one thereof, 38, being coupled to free space and a last one thereof, 40, being coupled to the ferrite phase shifters 26a-c. Further, the ferrite phase shifters 26a-c may be viewed as being a load for the impedance matching device 25.
  • the impedance of such load is represented in FIG. 38 by the term Z Likewise, the impedance of free space is represented in FIG.
  • Dielectric slabs 32 and 34 may be viewed as providing a dielectric medium within the circular waveguide structure 27 which is different from the dielectric medium provided by the air-filled cavity 36. Therefore, the impedance of the dielectric medium associated with dielectric slabs 32, 34 may be represented by a capacitor, C,, for the desired band of frequencies. Because the circular waveguide has a cutoff frequency higher than the highest frequency in the band of frequencies, the impedance of the dielectric medium associated with the portion of the cavity 36 adjacent slab 32 may be represented as an inductor, L, for such band of frequencies.
  • the impedance of dielectric slab 34 may also be represented by capacitor C and the portion of the circular waveguide structure 27 defining air-filled cavity 36 adjacent slab 34 may also be represented by an inductor L Further, the separation between dielectric slabs 32 and 34 is here such that the resonant circuits 38, 40 are inductively coupled, the coefficient of mutual inductance being represented by M.
  • Ferrite phase shifter 26a is coupled to impedance matching device 25 by inductive coupling within air-filled slot 41, as shown in FIG. 3A.
  • This slot 41 is a section of rectangular waveguide having a cutoff frequency higher than the highest frequency of the band of frequencies and, therefore, is represented in FIG.
  • the resonant circuits 38 and 40 may each be tuned to the nominal operating frequency of the antenna, thereby coupling, by mutual coupling between the resonant circuits 38, 40, the energy at such frequency through the impedance matching device 25. (Because of the mutual inductive coupling between the resonant circuits 38 and 40, matching device 25 may be considered as a double-tuned circuit.) Further, the Q of resonant circuits 38 and 40 determines the band of frequencies about the nominal frequency which will readily inductively couple through the impedance matching device.
  • the Q is selected so that the frequencies associated with the higher order modes will not be within the band of frequencies and hence will not readily couple through the device by the mechanism of inductive coupling.
  • Such higher order frequency modes will also be prevented from passing through the impedance matching device 25 because the circular waveguide structure 27 and rectangular waveguide structure 37 in such matching device 25 have cutoff frequencies higher than the highest frequency of the band of frequencies about the nominal operating frequency of the antenna.
  • Matching device 25' operates in an equivalent manner to matching device 25.
  • Matching device 25' here is coupled to rectangular waveguide structure 23.
  • Such rectangular waveguide structure 23 has associated therein, as shown, a pair of dielectric slabs 44, 46, here rectangular in shape.
  • Such slabs 44, 46 are separated from each other by an air-filled cavity 48.
  • Dielectric slab 44 is separated from toroid 26c by an air-filled cavity 49.
  • the dielectric slabs 44, 46 are separated from each other by means of integrally formed spacer sections 52, 54.
  • the spacer sections 52, 54 and the slabs 44, 46 are a dielectric material, here Rexolite.
  • the rectangular waveguide defining such cavity 48 (including spacer sections 52, 54) has a cutoff frequency higher than the highest frequency within the band of frequencies passing through the structure. Therefore, a first resonant circuit, coupled to free space, includes dielectric slab 46 (which provides the required capacitance) together with both cavity 48 and spacer sections 52, 54 (which provide the required induct
  • last resonant circuit, coupled to ferrite phase shifters 26a-c (via a cavity 49) includes dielectric slab 44 (which provides the required capacitance) together with both cavity 48 and spacer sections 52, 54 (which provide the required inductance).
  • the thickness of the dielectric slabs 32 and 34 may be determined in the following manner.
  • a planar wave of radio frequency energy is made incident to the face of the antenna element 11.
  • the VSWR is measured for each one of a series of different dielectric slabs 32, each one having a different thickness.
  • the slab having the optimum thickness is that which produces a VSWR measurement indicating that a resonance occurs.
  • a similar procedure is used for determining the optimum thickness of slab 34; however, the energy is introduced into the antenna element through the ferrite phase shifter end thereof.
  • the spacing between the two dielectric slabs 32 and 34 (or dielectric slabs 42, 46) and therefore the amount of inductive coupling, M, between the two resonant circuits 38, 40 is also determined by VSWR measurement. It is noted that such measurements are 7 made over the band of frequencies about the nominal operating frequency and also over a variety of scan angles to determine the optimum spacing. It is also noted that the Q of circuit 40 may be adjusted by the spacing between the ferrite phase shifters and dielectric slab 34.
  • a system for transmission of radio frequency energy within a band of frequencies from a source of such energy to a load, the impedance of the source being different from the impedance of the load apparatus for matching the impedance of such source and such load and for preventing modes higher than the dominant mode of such energy from passing between such source and such load, such apparatus comprising:
  • a second one of such circuits including the load, a separate one of the dielectric mediums and a portion of such waveguide, the center frequency of each one of such resonant circuits corresponding to the frequency of the dominant mode and the bandwidth of said resonant circuits corresponding to the band of frequencies of radio frequency energy to be passed between such source and such load;
  • the dielectric medium in the first one of such circuits provides a different propagation time delay to the passed radio frequency energy from the propagation time delay provided to such passed energy by the dielectric medium in the second one of such circuits.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Waveguide Switches, Polarizers, And Phase Shifters (AREA)
  • Waveguide Aerials (AREA)
US00369028A 1973-06-11 1973-06-11 Impedance matched waveguide device Expired - Lifetime US3851281A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00369028A US3851281A (en) 1973-06-11 1973-06-11 Impedance matched waveguide device
CA198,921A CA1003916A (en) 1973-06-11 1974-05-03 Waveguide impedance matching device
IT51097/74A IT1011460B (it) 1973-06-11 1974-05-17 Dispositivo di guida d onda
DE19742426173 DE2426173A1 (de) 1973-06-11 1974-05-29 Anordnung zum koppeln von hochfrequenzenergie mittels eines hohlleiters
GB2384474A GB1444328A (en) 1973-06-11 1974-05-29 Waveguide device
JP6327774A JPS5539927B2 (fr) 1973-06-11 1974-06-04
NL7407550A NL7407550A (fr) 1973-06-11 1974-06-05
FR7419316A FR2232842B1 (fr) 1973-06-11 1974-06-05
BE145203A BE816068A (fr) 1973-06-11 1974-06-07 Guide d'ondes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00369028A US3851281A (en) 1973-06-11 1973-06-11 Impedance matched waveguide device

Publications (1)

Publication Number Publication Date
US3851281A true US3851281A (en) 1974-11-26

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US00369028A Expired - Lifetime US3851281A (en) 1973-06-11 1973-06-11 Impedance matched waveguide device

Country Status (9)

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US (1) US3851281A (fr)
JP (1) JPS5539927B2 (fr)
BE (1) BE816068A (fr)
CA (1) CA1003916A (fr)
DE (1) DE2426173A1 (fr)
FR (1) FR2232842B1 (fr)
GB (1) GB1444328A (fr)
IT (1) IT1011460B (fr)
NL (1) NL7407550A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4445099A (en) * 1981-11-20 1984-04-24 Rca Corporation Digital gyromagnetic phase shifter
FR2604307A1 (fr) * 1986-09-19 1988-03-25 Spinner Georg Piece de transformation pour relier des guides d'ondes de sections differentes

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2076546B (en) * 1980-05-20 1983-11-23 Philips Electronic Associated Rf impedance determination
FR2738398B1 (fr) * 1988-04-08 1997-11-28 Thomson Csf Radant Panneau dephaseur a diodes et son application a une lentille hyperfrequence et une antenne a balayage electronique

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623120A (en) * 1950-04-20 1952-12-23 Bell Telephone Labor Inc Microwave filter
US2930008A (en) * 1955-07-07 1960-03-22 Gen Electric Co Ltd Waveguide arrangements including windows for passing electromagnetic waves
US3603899A (en) * 1969-04-18 1971-09-07 Bell Telephone Labor Inc High q microwave cavity
US3621483A (en) * 1966-06-10 1971-11-16 Int Standard Electric Corp Waveguide filter
US3680012A (en) * 1969-02-17 1972-07-25 Thomson Csf Microwave band-pass filter having constant bandwidth as filter is tuned

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1312506A (en) * 1970-06-08 1973-04-04 Standard Telephones Cables Ltd Waveguide antenna

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623120A (en) * 1950-04-20 1952-12-23 Bell Telephone Labor Inc Microwave filter
US2930008A (en) * 1955-07-07 1960-03-22 Gen Electric Co Ltd Waveguide arrangements including windows for passing electromagnetic waves
US3621483A (en) * 1966-06-10 1971-11-16 Int Standard Electric Corp Waveguide filter
US3680012A (en) * 1969-02-17 1972-07-25 Thomson Csf Microwave band-pass filter having constant bandwidth as filter is tuned
US3603899A (en) * 1969-04-18 1971-09-07 Bell Telephone Labor Inc High q microwave cavity

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4445099A (en) * 1981-11-20 1984-04-24 Rca Corporation Digital gyromagnetic phase shifter
FR2604307A1 (fr) * 1986-09-19 1988-03-25 Spinner Georg Piece de transformation pour relier des guides d'ondes de sections differentes
US4786883A (en) * 1986-09-19 1988-11-22 Georg Spinner Transformation device for connecting waveguides

Also Published As

Publication number Publication date
FR2232842B1 (fr) 1979-02-16
FR2232842A1 (fr) 1975-01-03
JPS5023751A (fr) 1975-03-14
GB1444328A (en) 1976-07-28
JPS5539927B2 (fr) 1980-10-15
IT1011460B (it) 1977-01-20
DE2426173A1 (de) 1975-01-02
NL7407550A (fr) 1974-12-13
CA1003916A (en) 1977-01-18
BE816068A (fr) 1974-09-30

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