US3750183A - Multimode antenna system - Google Patents

Multimode antenna system Download PDF

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Publication number
US3750183A
US3750183A US00208060A US3750183DA US3750183A US 3750183 A US3750183 A US 3750183A US 00208060 A US00208060 A US 00208060A US 3750183D A US3750183D A US 3750183DA US 3750183 A US3750183 A US 3750183A
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Prior art keywords
section
waveguide
input
sections
junction
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Expired - Lifetime
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US00208060A
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English (en)
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S Drabowitch
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Thales SA
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Thomson CSF SA
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    • 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
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/04—Multimode antennas

Definitions

  • a waveguide structure designed to operate as a wideband multimode antenna, has an elongate main wave- [22] 1971 guide section centered on an axis and terminating at a [21] A pL No.1 208,060 radiating aperture, an intermediate waveguide section of lesser width joined to that main section, and a pair of still narrower input sections feeding the intermediate [30] Foreign Application Priority Data section, these input sections being cophasally or anti- Dec.
  • Multimode antennas are radiating devices which are based upon simultaneous radiation of different guided propagation modes which are generated by devices known as moders and whose amplitudes and phases are controlled. Under these conditions, the resulting radiant-energy distribution or beam pattern is determined by the superimposition of the fundamental and harmonic guided-propagation modes.
  • moders which are constituted by waveguides and embody discontinuities designed to generate higher modes from the fundamental mode injected at the input ot the structure.
  • 3,308,469 discloses moders of this kind in which one or more waveguides known as excitation waveguides, each filtering its fundamental propagation mode, terminate in the input of a main waveguide which has a definite length and'whose open end in principle constitutes the radiating opening.
  • This main waveguide is designed to propagate various higher modes and the harmonic modes are generated in principle at the planes of the discontinuities at which the excitation waveguides terminate.
  • FIG. 1 of the accompanying drawing illustrates such a moder which can now be considered as conventional.
  • the main waveguide l of length L, communicates with two excitation waveguides 2 and 3, the latter terminating in the main waveguide at the plane 2 known as the discontinuity plane.
  • the excitation waveguides 2 and 3 are supplied with the fundamental mode whereas harmonic modes are generated at this discontinuity plane; the harmonic modes, together with the fundamental mode, are propagated through the principal waveguide 1, whose dimensions are chosen accordingly, up to the opening or aperture plane Z L where they are radiated.
  • the moder of FIG. 1 has been illustrated purely schematically and may be supplemented with, for example, mode filters for eliminating unwanted modes, matching devices associated with the excitation waveguides, and also other discontinuities intentionally introduced in order to modify the ratio of the generated modes.
  • the fundamental and harmonic modes generated in accordance with the foregoing are propagated through the main waveguide at different phase velocities up to the radiating aperture at location 2 L.
  • the result is that the precise phase combination required at the radiating aperture is strictly achieved only at a single frequency.
  • the modes utilized are not too close to cut-off it can be shown that very stable energy distribution can be obtained through frequency bands having a width on the order of 10 percent.
  • the object of the present invention is to provide, in a moder of the class described in the aforementioned patent, a novel structure which operates over a substantially wider passband than has been obtained with selective moders of prior-art design.
  • An antenna system comprises a waveguide strucutre with at least two stepped junctions, or discontinuities, between an excitation stage, including a plurality of input waveguide sections, an intermediate waveguide section, and a main waveguide section terminating in a radiating aperture.
  • the intermediate waveguide section has a crosssection which is smaller than that of the main waveguide section but larger than that of each input waveguide section and, in fact, of the several input waveguide sections combined.
  • the main waveguide section may be centered on an axis and may have a circular cross-section, with the stepped junctions lying in planes transverse to that axis.
  • the input and intermediate waveguide sections in the embodiment described hereinafter, are of rectangular cross-section similar to corresponding waveguides in the antenna system of my prior U.S. Pat. No. 3,308,469.
  • the length of the main waveguide section should be calculated to produce substantial in-phase relationship at the radiating aperture between the energy propagating at the fundamental mode from the input stage and energy propagating at a higher mode, generated at the last junction, for a minimum transmissible frequency giving rise to this higher mode.
  • FIG. 1, already referred to, is a perspective view of a prior-art moder according to my U.S. Pat. No. 3,308,469;
  • FIG. 2 is a similar schematic view of a moder in accordance with the invention.
  • FIG. 3 is a schematic axial sectional view of a simplified type-E moder embodying my invention.
  • FIG. 4 is a similar view of another embodiment of the invention.
  • the widening of the passband of a moder depends upon the phase velocity of the modes propagating within its structure, and upon its length which is determined in such a fashion that the modes are in phase in the plane of the radiating aperture.
  • FIG. 2 schematically illustrates my improved waveguide strucutre in wich the main waveguide 1 is pre ceded by a conventional moder of the kind disclosed in my above-identified patent.
  • the composite unit 4 is a flat E-type moder whose excitation or input sections 5 and 6 are both supplied in the fundamental mode (TE cophasally or in antiphase depending upon the parity of the modes which it is desired to generate in an intermediate section waveguide 8,'the dimensions of the latter section having been chosen accordingly.
  • Another horn-type waveguide 9 is shown as well, with its discontinuity plane 10.
  • These multimode excitation assemblies terminate in the main waveguide 1 whose input plane 11 constitutes a discontinuity plane or stepped junction.
  • the modes generated at the discontinuity planes such as 7 and 11 combine in phase and amplitude to produce the resultant in-phase modes at the radiating aperture.
  • the novel structure thus has two axially spaced discontinuities located in the junction planes between the several differently sized waveguide sections.
  • FIG. 3 illustrates another multimode structure embodying my invention which has the characteristics set out hereinbefore and is simplified for the sake of easier explanation of its operation.
  • This schematic view illustrates a longitudinal section of an E-type moder but the explanation which follows applies equally to an H-type moder also coming within the scope of the invention.
  • This moder structure in accordance with the invention comprises excitation stage 5, 6 between the input plane 12 and the plane of a first discontinuity 13. Between the plane 13 and the plane 14 of a second discontinuity, there is an intermediate waveguide section 15. Beyond the plane M, the main waveguide section 16 extends up to the plane 17 of the radiating aperture of the system.
  • these TE and TEM modes propagate at their own phase velocities and if they are to be in phase at the end of the main waveguide through which they propagate, then the length L of the latter must satisfy the condition where A and A are the wavelengths of the two modes in question.
  • the higher mixed mode TEM is cut off in the intermediate waveguide and does not start to propagate until beyond the second discontinuity 14.
  • the system then operates like a conventional moder with only one discontinuity.
  • the higher mixed mode is generated at the first discontinuity 13, propagates through the intermediate waveguide and thus excites the main waveguide 16.
  • a function of the higher mode TEM is generated which combines in amplitude phase with the mode generated by the first discontinuity.
  • equation (I) The two mode functions which combine at the second discontinuity are out of phase and, in accordance with equation (I), the length of the main waveguide is such that this equation is satisfied. Under these conditions, the wave components will attain a cophasal relationship at the plane of the radiating aperture where, for this length of waveguide, the desired distribution is achieved. In fact, in accordance with the frequency at which the system is operated, equation (I) is satisfied by the introduction ofan equivalent length L, as if the resultant TEM mode were generated in a plane located between the two discontinuity planes l3 and 14.
  • the plane of generation of the resultant mode is that of the second discontinuity, but as the operating frequency increases, this plane of generation of the higher mode tends to move further away from the plane of the second discontinuity l4 and to move towards the plane of the first discontinuity 13.
  • the equivalent length L of the structure in accordance with the invention thus increases with the frequency, the physical length ot the main waveguide being chosen for the lowest frequency in the range.
  • FIG. 4 illustrates a further multimode antenna structure which constitutes a generalization of the embodiment hereinbefore described.
  • this flat E-typc moder structure the two discontinuity planes 13 and 14 are still present but this time there terminate at the plane of the second discontinuity i. e., at the entrance end of main waveguide section 16, two supplementary excitation waveguides 18, 19 designed to generate odd modes, e.g. TEM
  • This kind of arrangement makes it possible to carry out range measurements in a monopulse system by the exploration of difference channels. The operation of this kind of system is similar to that already described. At the low frequencies in the band in question, the higher mode disappears at the first discontinuity 13 and is only propagated beyond the level of the second discontinuity 14.
  • the system behaves as if the resultant mode produced in the principal waveguide had been generated at a plane moving from the second discontinuity 14 to the first in the tapering intermediate waveguide 20 of progressively increasing cross-section and a function of the higher mode is generated at the plane of the first discontinuity 13.
  • I provide shield means to produce theoretically perfect decoupling between the supplementary waveguides 18, 19 and the composite waveguide 22 for the excitation of the even modes.
  • This shield means consists of metal plates 23 24 disposed transversely to the electric field of the fundamental mode.
  • FIGS. 3 and 4 the intermediate waveguide section 15 or 20 is shown to be coaxial with main waveguide section 16 whereas the input waveguide sections 5, 6 or .22a, 22b are symmetrically disposed with reference to their axis.
  • Sections 22a, 22b of FIG. 4 are seen to open into a further waveguide section 220 ahead of section 20, with formation of an additional stepped junction or discontinuity at 22d.
  • the number of discontinuities used is a function ofthe width of the desired passband.
  • the number of cascaded discontinuities is in no way limitative and may be increased without departing from the principles of the invention.
  • An antenna system comprising a waveguide structure with a main waveguide section terminating at a radiating aperture, an intermediate waveguide section coupled to said main waveguide section at an end thereof remote from said aperture, said intermediate waveguide section having a cross-section smaller than that of said main waveguide section, and a plurality of input waveguide sections of still smaller cross-section coupled to said intermediate waveguide section at an end thereof remote from said main waveguide section, said input and intermediate waveguide sections forming a stepped first junction, said intermediate and main waveguide sections forming a stepped second junction; and a source of wave energy of a frequency transmissible by said waveguide structure connected to said input waveguide sections for simultaneously exciting same with a common fundamental mode of propagation.
  • main waveguide section is centered on an axis, said first and second junctions lying in planes transverse to said axis.
  • main waveguide section has a length calculated to produce substantial in-phase relationship at said radiating aperture between energy propagating at said fundamental mode and energy propagating at a higher mode, generated at said second junction, for minimum transmissible frequencies giving rise to said higher mode.

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  • Waveguide Aerials (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
US00208060A 1970-12-22 1971-12-15 Multimode antenna system Expired - Lifetime US3750183A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7046249A FR2118848B1 (no) 1970-12-22 1970-12-22

Publications (1)

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US3750183A true US3750183A (en) 1973-07-31

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US (1) US3750183A (no)
FR (1) FR2118848B1 (no)
GB (1) GB1359830A (no)
IT (1) IT945571B (no)
NL (1) NL160995C (no)
SE (1) SE375410B (no)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764775A (en) * 1985-04-01 1988-08-16 Hercules Defense Electronics Systems, Inc. Multi-mode feed horn
WO1992011555A1 (en) * 1990-12-20 1992-07-09 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical device
WO1992011554A2 (en) * 1990-12-20 1992-07-09 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Intensity dividing device
US5410625A (en) * 1990-12-20 1995-04-25 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical device for beam splitting and recombining
US5428698A (en) * 1990-12-20 1995-06-27 The Secretary Of State For Defense In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Signal routing device
WO2001011713A1 (de) * 1999-08-10 2001-02-15 Marconi Communications Gmbh Hohlleiterübergang
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2477785A1 (fr) * 1980-03-07 1981-09-11 Thomson Csf Source hyperfrequence multimode et antenne comportant une telle source
FR2498820A1 (fr) * 1981-01-23 1982-07-30 Thomson Csf Source hyperfrequence bi-bande et antenne comportant une telle source
FR2641133B1 (no) * 1988-12-26 1991-05-17 Alcatel Espace

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373431A (en) * 1964-11-02 1968-03-12 James E. Webb Low-noise single aperture multimode monopulse antenna feed system
US3530483A (en) * 1967-07-13 1970-09-22 Csf Multimode monopulse horn antenna
US3566309A (en) * 1969-02-24 1971-02-23 Hughes Aircraft Co Dual frequency band,polarization diverse tracking feed system for a horn antenna
US3573838A (en) * 1968-10-28 1971-04-06 Hughes Aircraft Co Broadband multimode horn antenna

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3305870A (en) * 1963-08-12 1967-02-21 James E Webb Dual mode horn antenna
FR1537063A (fr) * 1967-07-10 1968-09-02 Labo Cent Telecommunicat Perfectionnements aux cornets multimodes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373431A (en) * 1964-11-02 1968-03-12 James E. Webb Low-noise single aperture multimode monopulse antenna feed system
US3530483A (en) * 1967-07-13 1970-09-22 Csf Multimode monopulse horn antenna
US3573838A (en) * 1968-10-28 1971-04-06 Hughes Aircraft Co Broadband multimode horn antenna
US3566309A (en) * 1969-02-24 1971-02-23 Hughes Aircraft Co Dual frequency band,polarization diverse tracking feed system for a horn antenna

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764775A (en) * 1985-04-01 1988-08-16 Hercules Defense Electronics Systems, Inc. Multi-mode feed horn
WO1992011555A1 (en) * 1990-12-20 1992-07-09 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical device
WO1992011554A2 (en) * 1990-12-20 1992-07-09 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Intensity dividing device
WO1992011554A3 (en) * 1990-12-20 1992-08-06 Secr Defence Brit Intensity dividing device
US5379354A (en) * 1990-12-20 1995-01-03 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom And Northern Ireland Intensity dividing multimode wave guide device for producing intensity distribution maxima
US5396570A (en) * 1990-12-20 1995-03-07 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical device for beam splitting, mixing and recombination functions
US5410625A (en) * 1990-12-20 1995-04-25 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical device for beam splitting and recombining
US5428698A (en) * 1990-12-20 1995-06-27 The Secretary Of State For Defense In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Signal routing device
US5475776A (en) * 1990-12-20 1995-12-12 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Optical mixing device
WO2001011713A1 (de) * 1999-08-10 2001-02-15 Marconi Communications Gmbh Hohlleiterübergang
US6661305B1 (en) 1999-08-10 2003-12-09 Marconi Communications Gmbh Wave guide adapter
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna

Also Published As

Publication number Publication date
DE2163881B2 (de) 1975-12-11
SE375410B (no) 1975-04-14
GB1359830A (en) 1974-07-10
NL160995B (nl) 1979-07-16
IT945571B (it) 1973-05-10
DE2163881A1 (de) 1972-06-29
FR2118848B1 (no) 1974-03-22
NL7117456A (no) 1972-06-26
NL160995C (nl) 1979-12-17
FR2118848A1 (no) 1972-08-04

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