EP0421757A2 - Antenne à micro-ondes - Google Patents

Antenne à micro-ondes Download PDF

Info

Publication number
EP0421757A2
EP0421757A2 EP90310821A EP90310821A EP0421757A2 EP 0421757 A2 EP0421757 A2 EP 0421757A2 EP 90310821 A EP90310821 A EP 90310821A EP 90310821 A EP90310821 A EP 90310821A EP 0421757 A2 EP0421757 A2 EP 0421757A2
Authority
EP
European Patent Office
Prior art keywords
diameter
channels
antenna
radiating aperture
antenna according
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.)
Withdrawn
Application number
EP90310821A
Other languages
German (de)
English (en)
Other versions
EP0421757A3 (en
Inventor
Hari Jairam
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Electronics Ltd
Original Assignee
GEC Marconi Ltd
Marconi Co Ltd
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 GEC Marconi Ltd, Marconi Co Ltd filed Critical GEC Marconi Ltd
Publication of EP0421757A2 publication Critical patent/EP0421757A2/fr
Publication of EP0421757A3 publication Critical patent/EP0421757A3/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/06—Waveguide mouths
    • H01Q13/065—Waveguide mouths provided with a flange or a choke
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/02—Waveguide horns
    • H01Q13/0241—Waveguide horns radiating a circularly polarised wave
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/02—Waveguide horns
    • H01Q13/0266—Waveguide horns provided with a flange or a choke

Definitions

  • This invention relates to a microwave antenna particularly but not exclusively for use on an aircraft performing ground surveillance by radar.
  • the antenna should have limited elevation beam width but wide azimuth beam width since the antenna would normally be mounted underneath the aircraft and directed ahead, perhaps with a small declination.
  • Linearly polarized circular horn antennas are known to give a maximum 3dB beamwidth in the E and H planes of approximately 70 degrees when operating near the cut-off frequency of the circular waveguide feed. While such a beamwidth would be satisfactory in many applications, if this figure is calculated for the low frequency end of a broad band system, of say 8 to 18 GHz, the beamwidth at the upper end would be unacceptably low, say below degrees.
  • An object of the present invention is to provide a broadband microwave antenna having a wide beam throughout the band.
  • a microwave antenna comprises a cylindrical radiator the radiating aperture of which slopes back on both sides of a diameter, and a ridge conductor extending across the radiating aperture along this diameter, the arrangement being such as to widen the radiation characteristic in a transverse axial plane lying transverse to the diameter, in respect of an E-field component parallel to the diameter.
  • further conductors extending across the radiating aperture parallel to the diameter and in an axial plane containing the diameter, the further conductors being spaced from the ridge conductor by one quarter wavelength successively, at approximately the mid-band operating frequency of the antenna.
  • the sloping faces of the radiating aperture preferably contain an angle of 60 degrees.
  • a plurality of capacitive studs project from opposite internal surfaces of the radiating aperture towards the axial plane containing the diameter, the studs being spaced apart and of extent such as to widen the radiation characteristic in the transverse axial plane, in respect of an E-field component perpendicular to the diameter.
  • the antenna preferably comprises an annular choke member closely surrounding the cylindrical radiator, the choke member comprising a plurality of annular concentric channels open to the front of the antenna and centred on the axis of the cylindrical radiator, each of the channels providing a short-circuited quarter-wave stub and the depth of the channels being graded to correspond with the range of operative frequencies, the innermost channel being the shallowest.
  • the radiating aperture consists of a cylindrical member 1 having a mounting flange 3 on the rear end and bevelled faces on the front end, the bevelled faces having an included angle of 60 degrees.
  • 'Front' and 'rear' here are in relation to the direction of transmission.
  • the signal transmitted is circularly polarized and the flange 3 is fixed to a polarizer (not shown) which converts a plane (ie linearly) polarized signal into a circularly polarized signal.
  • Broadening of the beam in the plane of Figure 1, ie the azimuth plane, is achieved by, in effect, splitting the beam into two in respect of a vertically polarized E-field component by means of a conductor 5, a metal post 0.5mm diameter, extending along the apex, ie the ridge, of the bevelled faces of the aperture.
  • the ridge coincides with a diameter 6 of the cylinder 1.
  • the conductor 5 is parallel to the vertical component of the polarized signal and thus forms a boundary to each sloping face of the aperture.
  • the resulting two beams are thus diverged significantly and they jointly constitute a beam of azimuth width in the region of 95 degrees as indicated at 7.
  • the effect of bevelling the front end of the radiating aperture is to alter the phase distribution across the aperture.
  • the phase at the azimuth sides 13 now lags the phase at the ridge diameter. This occurs because the phase velocity in the waveguide is greater than the velocity in free space. Hence energy at the centre will be advanced in phase when compared to that at the edges. This lagging phase shift causes the beam to widen.
  • the overall effect is the same as dielectric at the sides of the waveguide (see Figure 2).
  • Two further conductors 9 and 11 extend across the radiating aperture in the same plane as the conductor 5 but spaced from it by one quarter wavelength successively at centre frequency of 13GHz.
  • the conductors form an impedance transformer in the matching of the radiating aperture to free space.
  • the conductors 5, 9 and 11 could be an integral part of the radiating cylinder 1, machined out of a solid piece with it.
  • the above described beam widening effects are in respect of the vertical component of the circularly polarized signal.
  • the horizontal E-field component extending transverse to the conductors 5, 9 and 11 is substantially unaffected by these conductors. Beam widening in respect of the horizontal component is achieved by, in effect, narrowing the aperture.
  • Capacitive studs 15, which may be of screw form for ease of adjustment or of pre-set length, are fitted to extend from the internal wall of the radiating aperture. There are three on each side of the ridge arranged as mirror images. The extent of each stud into the aperture must be less than one quarter wavelength at the highest band frequencies and preferably at 19GHz. Above 19GHz the studs become inductive and have no effect on the beam. 3 millimetres is found to be satisfactory. The studs of each set of 3 are mutually spaced at one quarter wavelength at 19GHz.
  • the studs effectively narrow the aperture in the azimuth plane and thus broaden the beam.
  • axial ridges 17 in known manner.
  • the tapered ends of these ridges taper over a distance of one quarter wavelength at 18GHz, the upper frequency.
  • a significant amount of radiated energy would spill over the edge of the radiating aperture and increase the side lobes of the radiation pattern relative to the main lobe.
  • Such spillover energy is considerably suppressed by a novel form of choke which is fitted around the radiating aperture 1 as shown in Figure 1.
  • the choke is an annular member 19 shown in Figure 1 and partially in Figure 3.
  • This choke ring is of course metallic and consists of a thick 'disc' in the front face of which 7 annular concentric channels 21 are formed. The depth of these channels increases linearly with the radius in such manner that it is one quarter wavelength at 186Hz in the innermost channel and at 8GHz in the outermost channel.
  • the innermost channel is one quarter wavelength deep, the remainder are increasingly deeper and thus increasingly capacitive.
  • the signal phase is thus advanced progressively from centre to outside. Any 'spillover' energy thus tends to be driven into the main beam.
  • the outermost channel is one quarter wavelength deep and the inner, shallower, ones are progressively inductive.
  • the signal phase is thus retarded progressively towards the centre, again therefore tending to drive 'spillover' energy into the main beam.
  • Figure 1 it can be seen that the gradation of channel depth is achieved by a plane front face and a conical contour to the bottoms of the channels.
  • An alternative form of the choke ring is shown in Figure 4 in which design the bottoms of the channels lie on a plane and the front face of the channels lies on a conical contour.
  • the same effect of graded frequency impedances is achieved but there is a slight difference in the effect on the form of the main lobe.
  • the effect is to increase the gain of the main lobe while the Figure 4 design tends to widen it by approximately 7.5 degrees at high frequencies. This occurs because the current is allowed to flow at the sides initially and then 'choked' by the quarter wave stubs.
  • the choke ring of Figure 4 represents the best option for constant wide beam performance. Both designs however, achieve considerable suppression of the side lobes.
  • the choke ring is a close fit on the radiating aperture and is fixed in position as shown in Figure 1 so as just to expose the lowermost slopes of the bevelled surfaces.
  • the result of the above design is to produce an antenna operative over 8 to 18GHz with a VSWR of only 2:1, an azimuth 3dB beam width of 95 degrees plus/minus 7.5 degrees over the band, an average gain of 3.5dB and sidelobes better than 25dB down on the main lobe over the band.

Landscapes

  • Waveguide Aerials (AREA)
EP19900310821 1989-10-04 1990-10-03 Microwave antenna Withdrawn EP0421757A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898922377A GB8922377D0 (en) 1989-10-04 1989-10-04 Microwave antenna
GB8922377 1989-10-04

Publications (2)

Publication Number Publication Date
EP0421757A2 true EP0421757A2 (fr) 1991-04-10
EP0421757A3 EP0421757A3 (en) 1991-11-21

Family

ID=10664051

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900310821 Withdrawn EP0421757A3 (en) 1989-10-04 1990-10-03 Microwave antenna

Country Status (2)

Country Link
EP (1) EP0421757A3 (fr)
GB (2) GB8922377D0 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1037305A2 (fr) * 1999-03-16 2000-09-20 TRW Inc. Antenne cornet pour deux fréquences avec une structure piège à deux profondeurs pour égalisation de diagrammes de rayonnement dans les plans E et H
EP1372217A3 (fr) * 2002-06-12 2004-03-17 The Boeing Company Antennes à faisceaux très étroits à minimisation de champs
JP2012253411A (ja) * 2011-05-31 2012-12-20 Mitsubishi Electric Corp ホーンアンテナ
WO2013154658A1 (fr) * 2012-04-12 2013-10-17 Raytheon Company Antenne d'interrogateur à cornet miniature avec combineur interne de somme/différence

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434146A (en) * 1966-08-03 1969-03-18 Us Army Low profile open-ended waveguide antenna with dielectric disc lens
US3553707A (en) * 1967-05-25 1971-01-05 Andrew Corp Wide-beam horn feed for parabolic antennas
JPS5424561A (en) * 1977-07-26 1979-02-23 Oki Electric Ind Co Ltd Electromagnetic horn

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4119951A (en) * 1977-02-16 1978-10-10 Gilles Garon Microwave intrusion sensing units and antenna therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434146A (en) * 1966-08-03 1969-03-18 Us Army Low profile open-ended waveguide antenna with dielectric disc lens
US3553707A (en) * 1967-05-25 1971-01-05 Andrew Corp Wide-beam horn feed for parabolic antennas
JPS5424561A (en) * 1977-07-26 1979-02-23 Oki Electric Ind Co Ltd Electromagnetic horn

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ELECTRONICS LETTERS, vol. 17, no. 21, October 1981, pages 777-779; W. DAVIES et al.: "Bird-proof feed-horn windows for microwave radio systems antennas" *
ELECTRONICS LETTERS, vol. 9, no. 25, 13th December 1973, pages 596-597; J. COWAN: "Dual-band reflector-feed element for frequency-reuse applications" *
PATENT ABSTRACTS OF JAPAN, vol. 3, no. 47 (E-105), 20th April 1979; & JP-A-54 24 561 (OKI DENKI KOGYO K.K.) 23-02-1979 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1037305A2 (fr) * 1999-03-16 2000-09-20 TRW Inc. Antenne cornet pour deux fréquences avec une structure piège à deux profondeurs pour égalisation de diagrammes de rayonnement dans les plans E et H
EP1037305A3 (fr) * 1999-03-16 2002-10-02 TRW Inc. Antenne cornet pour deux fréquences avec une structure piège à deux profondeurs pour égalisation de diagrammes de rayonnement dans les plans E et H
EP1372217A3 (fr) * 2002-06-12 2004-03-17 The Boeing Company Antennes à faisceaux très étroits à minimisation de champs
JP2012253411A (ja) * 2011-05-31 2012-12-20 Mitsubishi Electric Corp ホーンアンテナ
WO2013154658A1 (fr) * 2012-04-12 2013-10-17 Raytheon Company Antenne d'interrogateur à cornet miniature avec combineur interne de somme/différence
US9035842B2 (en) 2012-04-12 2015-05-19 Raytheon Company Miniature horn interrogator antenna with internal sum/difference combiner

Also Published As

Publication number Publication date
EP0421757A3 (en) 1991-11-21
GB2236626A (en) 1991-04-10
GB2236626B (en) 1994-04-06
GB9021481D0 (en) 1990-11-14
GB8922377D0 (en) 1990-06-20

Similar Documents

Publication Publication Date Title
US4873534A (en) Hybrid mode feed horn having funnel-shaped horn flange with grooved conical inner surface
US3969730A (en) Cross slot omnidirectional antenna
US5486839A (en) Conical corrugated microwave feed horn
US5757323A (en) Antenna arrangements
US4658258A (en) Taperd horn antenna with annular choke channel
AU633458B1 (en) Asymmmetrically flared notch radiator
KR100453030B1 (ko) 광대역인쇄네트워크안테나
US5194876A (en) Dual polarization slotted antenna
EP0136818A1 (fr) Antenne cornet à deux modes fonctionnant sur deux bandes de fréquences
GB2476787A (en) Microwave antenna
US4309710A (en) Multi-lobe antenna having a disc-shaped Luneberg lens
AU2012331250B2 (en) Reflector antenna including dual band splashplate support
JP3010052B2 (ja) 非対称双円錐ホーンアンテナ
EP0066455B1 (fr) Antennes micro-ondes du type réflecteur à source conique tapissée d'absorbant
US5200757A (en) Microwave antennas having both wide elevation beamwidth and a wide azimuth beamwidth over a wide frequency bandwidth
US5859615A (en) Omnidirectional isotropic antenna
JPH0121641B2 (fr)
US4301457A (en) Antenna employing curved parasitic end-fire directors
US5068671A (en) Orthogonally polarized quadraphase electromagnetic radiator
EP0421757A2 (fr) Antenne à micro-ondes
US4423422A (en) Diagonal-conical horn-reflector antenna
EP0174068A1 (fr) Antenne à microbandes
US3631502A (en) Corrugated horn antenna
US5239311A (en) Flat slot array antenna
US5142290A (en) Wideband shaped beam antenna

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR IT

17P Request for examination filed

Effective date: 19920513

17Q First examination report despatched

Effective date: 19940414

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19940825