US2316151A - Electromagnetic horn - Google Patents

Electromagnetic horn Download PDF

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Publication number
US2316151A
US2316151A US249910A US24991039A US2316151A US 2316151 A US2316151 A US 2316151A US 249910 A US249910 A US 249910A US 24991039 A US24991039 A US 24991039A US 2316151 A US2316151 A US 2316151A
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United States
Prior art keywords
horn
waves
wave
throat
exciting
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Expired - Lifetime
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US249910A
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English (en)
Inventor
Barrow Wilmer Lanier
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Research Corp
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Research Corp
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Publication date
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Priority to US249910A priority Critical patent/US2316151A/en
Priority to GB32811/39A priority patent/GB534066A/en
Priority to FR862785D priority patent/FR862785A/fr
Priority to US422402A priority patent/US2467578A/en
Application granted granted Critical
Publication of US2316151A publication Critical patent/US2316151A/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
    • 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

Definitions

  • the present invention relates to electromagnetic horns. r
  • any horn will transmit or receive any wave
  • an object of the present invention is to assure the production near the mouth of the horn of a wave of a desired type, such as the Hm or H1,o wave.
  • a plurality of diflzerent types of horn waves may be generated, depending upon the configuration of the exciting means in the throat of the horn, or upon the nature of thewaves delivered there by a hollow-pipe transmission system, and also upon the flare angle 60 and the cut-ofl length pc from the apex tothe throat, or small or reflecting end, or the back of the horn. Special cases may arise wherein several wave-types may be used simultaneously;
  • a .further object is to exclude waves of other types than those desired.
  • Another object is to provide a horn having a predetermined performance.
  • a further object is to provide quantitative curves to facilitate the design of such horns.
  • FIG. 1 is a perspective, partly broken away, of a sectoral electromagnetic horn embodying the invention, and fed by a hollow-pipe line;
  • Fig. 4 is a diagrammatic'perspective of a sectoral horn, disposed in Cartesian and cylindrical systems of co-ordinates, and carrying symbols useful in describing the invention
  • Fig. 5 is a plot of two curves showing the relation between the flare angle or: and the cut-oil length p0 of the horn from the apex to the throat, the cut-oil length po being of the wave length A;
  • Figs. 6 and 7 are plots of further curves to be described more fully hereinafter.
  • Figs. 8 and 9 are views similar to Figs. 1 and 4, respectively, of a conical horn.
  • a horn it of rectangular cross section, flaring smoothly and continuously from the throat to a mouth or aperture or. large end of the horn, at its front.
  • the principal or central axis of, the horn extends between the smaller and larger ends of the horn.
  • a hollowpipe transmission system comprising an elongated hollow pipe or tube body portion or section. i8 that'is connected to the throat of the horn so as to extend over any desired distance from the horn, to the left, as viewed in Figs. 1 to 4.
  • the horn may be constituted of aformed sheet of conducting material, like. metal, such as cop per or aluminum, or it may b constituted of other material if its inner wall is otherwise rendered a conductor of the saidwaves.
  • the hollowpipe body portion It, to which the horn lt is connected,' may be of any desired material, conducting or dielectric, or it may otherwise be provided with an inner conducting wall. It may contain air or other gas, or it may be evacuated. If the body portion 18 is constituted of a metal pipe, the flared-out continuation may constitute a conducting extension of the body portion 18.
  • the pipe portion i 8 from which it flares out.
  • dielectric supports and insulators are not required in represented in terms to sides of varying flare, such as exponential or hyperbolic.
  • the horn of the present invention may be useo for transmission or reception of ultra-hilgh-irequency electromagnetic waves.
  • transmission In transmission,
  • electromagnetic energy transmitted through the interior of the pipe or tube II from a projecting metal exciting or absorbing antenna rod or other energy-translating apparatus II, is delivered to the throat of the horn and propagated through the interior of the horn to the mouth'as horn waves.” At the mouth, substantially all of this energy is radiated. into free space as ordinary radio waves.
  • the horn thus constitutes a directive electromagnetic radiator.
  • the rod II is shown in Fig. 1 disposed approximately centrally in the hollow pipe i8, substantially at right angles to the axis of the horn, but it may be disposed unsymmetrically in the horn, to give a modified directive pattern for the radiant energy.
  • Sending apparatus may be connected to a coaxial-line system I0, i2, or to a. parallel-wire system, or to any other desired connecting system.
  • the conductor 12 may be extended into the bell of the horn or the tube i8,
  • Diflerent types of horn waves may be separately excited and propagated within the hom, or absorbed by the hom, by properly arranging the exciting rod or rods in or out of the throat of the horn, both as to the position of, and the current in, the rod or rods.
  • One of the most important modes or wave types is the lowest-order transversely polarized horn wave I-Io,1, with the electric vector mainly parallel everywhere to the vertical direction, obtained with an exciting rod I4 transverse to the axi and in the vertical plane.
  • Another important mode or wave type is the Hm wave. These two wave types are probably the best for sending a single I beam of radiant energy and are the waves most naturally adopted for receiving.
  • the use oisectoral horns is particularly advantageous in certain kindsof applications where the shape of the beam plays an essential role in the operation.
  • the orientation of the exciting rod perpendicular to this axis offer certain features, among them the important feature of a radiated linearly polarized space wave.
  • the rectangular shape furthermore, permits independent control of the width of the radiated beam in the horizontal and vertical planes.
  • Beams transmitted from directive antenna systerns are usually accompanied by small amounts of radiation in directions other than those intended. These small amounts of radiation are referred'to as secondary lobes.
  • Beam radiated rom sectoral horns may be remarkably free from In the blind-landing of airplanes, for example, it is-desirable, not only that the beam be very sharp, but also that it be peculiarly free from secondary lobes.
  • a smooth straight-line intersection is formed between two overlapping beams; systems of this type are commonly referred to as "equal-signal" systems.
  • Horn radiators can provide such smooth overlapping beams without waviness or spurious components that would aflect the straightness of this path of intersection. No other types of antenna have been found to produce so smooth beams with such small secondary lobes. Patterns of this character are useful also in other applications, such as direction-finding and obstacle-detection.
  • the horn i6 is shown excited by means of a hollow-pipe transmission line It, connected to the throat of the horn, with the translating apparatus positioned in the pipe It, at the rear of the throat of the horn;
  • the antenna then first excites waves in the hollow pipe, which are transmitted times desirable, however, as explained in my application, Serial No. 240,545, filed November 15, 1938, that the translating apparatus be positioned directly in the throat of the horn, as illustrated in Fig. 2, in order directly to excite the horn itself, without the use of a hollow-pipe transmission line.
  • the horn has smaller physical diergy-translating means directly in the throat of the horn, is applicable to longer waves. Substantially the same radiation pattern may be produced with either arrangement.
  • the invention is not, of course, limited to the use of an exciting or absorbing rod l4.
  • Other radiating or absorbing means such as a vacuum tube, may also be employed, as described, for example, in the said application, Serial No. 240,545, filed November 15, 1938.
  • Serial No. 240,545 optimum conditions may be obtained by adjusting a piston (not shown) at the back or throat of the horn, thus to resonate or tune the throat of the horn, thereby rendering the throat of the horn more responsive to a particular frequency or a narrow band of frequencies than to other fre quencies, and also in other ways.
  • the throat of the horn is disposed along a vertical cylindrical surface having a radius oand with its axis coincident with the Y axis.
  • the non-parallel sides, each 01 length pi-po, are symmetrically disposed in planes perpendicular to the xz plane, forming with the XY plane a dihedral angle equal-to etc/2,.
  • the horn is regarded as having a forward direction in the and bottom and the two side walls, respectively.
  • hornfthe H waves For most applications of the hornfthe H waves are employed, particularly the two waves of lowest order, 110.1 and Hip.
  • the reason for this choice is that the configuration of the field of these waves inside the horn is such as to produce positive direction of the x axis.
  • the horizontal length of the mouth or aperture of the-horn is assumed to have a value b. and the corresponding length of the throat to have a value Do.
  • the symbols illustrated in Fig. 4 have, therefore, the following meaning:
  • #0 represents the flare angle of the ,horn illustrated in Fig. 1;
  • a represents the corresponding vertical dimension, at right angles to the horizontal dimension, or the distance between the opposite vertically disposed'sideso! the horn, at the mouth of the horn. This vertical dimension is parallel to the lines 01 electric intensity of the waves propagated within the horn:
  • pi represents the radial length 01 the horn, meassubstantially single-lobelbeams of linear polarization in theradiated waves. Both waves have constant phase on cylindrical surfaces about'the axis within the horn.
  • a desired wave such as either-an Her orpHro wave, and also, in cases,
  • the desired wave only. shall exist in the horn, when used for transmitting; or so that the horn shall be responsive to the desired wave, such as either the Hai or H wave, or the desired wave alone, when used for receiving.
  • the Ho,1 wave may be excited by the currentcarrying antenna rod It in the throat disposed parallel to the Y axis of Fig. 4, as shown in Fig. 2,
  • 'po represents the cut-oil length, from the said apex to the free end of the throat of the horn.
  • E-waves having a radial component of electric intensity. but no radial component of magnetic intensity, in the horn
  • H-waves -
  • the H1,o type of wave may be excited by the current-carrying antenna rod i4 disposed centrally inthe throat parallel to the XZ plane, as illustrated in Fig. 3, or by feeding an Hm wave into the throat froma rectangular hollow pipe.
  • the electric lines of force lie along arcs concentric with the Y axis between the two flared sides; they have a uniform distribution along the arcs, but a half-sinusoidal distribution in the direction of the Y axis. lines lie in planes passing through the Y axis.
  • the attenuation oi each wave is relatively large near theapex oi the horn it, which may be termed the attenuation region. but is progressively smaller at greater radial distances :from the apex, which may be termed the transmission region.
  • the attenuation region obviously involves small values of p, and the transmission region large values of p, and the boundary between the two regions is not definite.
  • the attenuation region extends from the apex outward over .progressively shorter portions of the horn For small flare angles o6, therefore, the attenuation region extends overlarge distances from the apex.
  • the attenuation region shrinks and is confined substantially to the throat.
  • the radial distance, from the apex radially outward, to which the region 01 relatively higli attenuation extends, is progressively greater for waves 01' higher order than for waves of lower order.
  • the horn provides for eflective elimination oithe angle 8c, and for a givenwave-length A, there- M fore, a particular value for the cut-ofilength pc from the apex of the horn to the exciting antenna It may be adopted that will permit the Hm wave to form and travel freelythrough the horn to be radiatedinto space from its mouth substantially tin-attenuated, but that will afiect almost complete attenuation or filtration of higher-order waves H Hos, etc. during propagation from the exciting antenna toward the mouth.
  • Horns for the production of single-lobe smooth beams should have their cut-oil lengths po not too different from their optimum value.
  • a proper value of pi to be associated with this optimum cut-oil length c- may be chosen in accordance with the design of application, Serial No. 249,005, abovementioned.
  • the relation between the flare angle gin and the optimum cut-01f length p0, measured in terms of the wave-length 7 ⁇ , for the high-attenuation region, for the Ho,1 and the Has waves, is illustrated in Fig. 5.
  • the flare angle o is the exciting antenna II should be disposed approximately at adistance higher-order waves.
  • the horn is excited for the Ho,1 wave by a small antenna ll in its throat.
  • the higher-order waves, or spatial harmonics, H0,m are produced, which tend to propagate in the radial direction of the horn.
  • the field distribution, along an arc of the horn is nonsinusoidal, because of the presence of these H0,m waves, and is so configured that the boundary conditions at the surface of the antenna H are satisfied.
  • the magnitude of the fields of the higher-order waves are less than the magnitude of the field oi the Ho,: wave at the throat of the horn.
  • the radiated energy is formed into a rather broad beam 'along the principal axis, and there is an irregular back-radiation curve.
  • the beam is quite sharp.
  • the flare angle is made even greater, the beam becomes distorted by the appearance of secondary lobes, which push out into the principal lobe, broadening the beam as shown in Fig. 3G.
  • the secondary lobes are nearly as large as the principal lobe and the beam has been spread into a fan-shaped pattern with almost uniform radiation over an 80 sector.
  • FIG. 7 shows that a sinusoidal variation of electric intensity across the mouth of the horn corresponds to a radiation pattern having a single principal lobe and secondary lobes of insignificant amplitudes.
  • Non-sinusoidai distributions occuring with flare angles 4w greater than 60, correspond to irregular radiation patterns.
  • the irregular shape involving the strong secondary lobes, may be attributed to the harmonic components of the distribution across the mouth of the horn. Even if the distribution had remained sinusoidal, however, there would have been a broadening of the main lobe for increasing fiare angles o greater than about 50, because, as the waves travel outward in the radial direction in the horn, a horn of large flare angle 4m can not concentrate the waves mainly in a single direction, even inside the horn.
  • the vertical horn dimension a in this case, therefore, be achieved by adjusting r the vertical horn dimension a.
  • the Hm wave will travel freely in the radial direction through the horn when a is greater than M2, but for free transmission of the Hat wave, a must be greater than 3M2, and soon for higher-order waves. To eliminate the higher-order waves, therefore, the dimension a should be slightly greater than M2, but less than 3M2.
  • the exciting system may be constructed with even symmetry about the waves should i tion is caused solely by decreasing the energy density as the area of the vertical cylindrical surface, coaxial with the Y axis, increases with horizontal plane equidistant between the two upper and lower sides of the horn, as viewed in Fig. 4.
  • the attenuation constant a may be defined as the logarithmic rate of decrease of magnitude in the direction of propagation, along the X axis,
  • phase constant p may be defined I as the logarithmic change of phase along the said X axis. It is known that, for the H0,m wave,
  • J represents the Bessel function of the first w kind
  • the attenuation region is that portion of the horn in which the phase constant p is very small compared to the value 21r/A for a wave in free space; and the transmission region is that portion of the horn in which the phase constant 6 is sub-v stantially equal to 21r/ Fig. 6 is a plot of curves, for the H0,m wave,
  • the transverse dimension Do, or the position of the exciting or absorbing means M in the horn should be substantially between of all waves of higher order.
  • the hollow pipe I! should be connected to the horn l6, at the point deter-. mined by the equation approximately, or a little more or less. To pass the Hon wave, this distance should be approximately that is, the length of the horn will be at least long enough to pass substantially the Ho.: wave. The higher-order waves will thus stantially eliminated.
  • the transverse dimension at the throat or the position of the energy-translating means should be substantially equal to or slightly greater than the critical transverse dimension of a hollow pipe of circular cross-section for the corresponding type of wave.
  • the critical transverse dimension of a hollow pipe of circular cross-section for the corresponding type of wave.
  • the transverse dimension at the throat or at the position of the energy-translating means may be determined from the critical relation to! hollow-pipe waves in a hollow pipe of the same cross-section.
  • An electromagnetic horn of substantially sectoral shape adapted for the propagation therein of Hum waves or wave-length x having a radial component or magnetic intensity but no radial component of electric intensity in the horn, where m is a positive integer, the horn being provided with a pair of oppositely disposed flaring sides substantially parallel, and a pair of oppositely disposed sides substantially normal, to the lines of electric intensity of the said waves within the horn, and exciting or absorbing means positioned in the throat of the horn where the transverse dimension of the throat, between the flaring sides oi the horn, is between substantially A A m and (m+2) 9.
  • An electromagnetic system having, in combination, an electromagnetic horn adapted for the propagation therein of waves of a predetermined wave-length and having a small throat end and a large mouth end, and means for producing waves of the said wave length of a predetermined order and excluding waves of higher order comprising absorbing or exciting means positioned in the throat where the transverse dimension of the throat is substantially equal to or only slightly greater than the critical transverse dimension of ahollow pipe that will pass waves 01' the said wave-length.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)
  • Aerials With Secondary Devices (AREA)
  • Waveguide Aerials (AREA)
US249910A 1939-01-09 1939-01-09 Electromagnetic horn Expired - Lifetime US2316151A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US249910A US2316151A (en) 1939-01-09 1939-01-09 Electromagnetic horn
GB32811/39A GB534066A (en) 1939-01-09 1939-12-22 Horns for the transmission and reception of ultra-short electromagnetic waves
FR862785D FR862785A (fr) 1939-01-09 1940-01-08 Dispositifs rayonnants pour la propagation d'ondes électro-magnétiques
US422402A US2467578A (en) 1939-01-09 1941-12-10 Electromagnetic horn

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US249910A US2316151A (en) 1939-01-09 1939-01-09 Electromagnetic horn

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GB (1) GB534066A (fr)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2433074A (en) * 1943-07-02 1947-12-23 Raytheon Mfg Co High-frequency coupling device
US2467578A (en) * 1939-01-09 1949-04-19 Research Corp Electromagnetic horn
US2501335A (en) * 1947-12-27 1950-03-21 Westinghouse Electric Corp Coaxial line to wave guide matching section
US2552334A (en) * 1945-03-02 1951-05-08 Rca Corp Electron discharge device and associated circuit
US2598475A (en) * 1945-12-17 1952-05-27 Raytheon Mfg Co Antenna system
US2624803A (en) * 1946-01-17 1953-01-06 Robert A Howard Device for measuring radiofrequency power
US2656535A (en) * 1945-08-06 1953-10-20 Leland K Neher Nonreflecting background for testing microwave equipment
US2683251A (en) * 1942-08-13 1954-07-06 Gen Electric High-frequency electromagnetic wave transmission system
US2688732A (en) * 1949-05-05 1954-09-07 Bell Telephone Labor Inc Wave guide
US2721263A (en) * 1945-11-13 1955-10-18 Roy C Spencer Curved throat scan horn for the transmission of electromagnetic energy
US2755465A (en) * 1949-10-07 1956-07-17 Marconi Wireless Telegraph Co Aerials
US2791770A (en) * 1946-04-08 1957-05-07 Jacob R Risser Tapered electromagnetic horn
US2851686A (en) * 1956-06-28 1958-09-09 Dev Engineering Corp Electromagnetic horn antennas
US2962677A (en) * 1945-10-04 1960-11-29 Bell Telephone Labor Inc Wave guide joint
US3031661A (en) * 1956-10-31 1962-04-24 Bendix Corp Microwave antenna feed for circular polarization
US4053894A (en) * 1974-03-21 1977-10-11 Siemens Aktiengesellschaft Radio signal switching system employing dielectric rod antennas
US4861124A (en) * 1987-05-13 1989-08-29 Sanders Associates, Inc. Dual-section spatial modulation transmitter
US8581794B1 (en) * 2010-03-04 2013-11-12 Qualcomm Incorporated Circular antenna array systems
US20160006129A1 (en) * 2014-07-07 2016-01-07 Google Inc. Horn Lens Antenna
US20200014096A1 (en) * 2018-07-03 2020-01-09 Wistron Corporation Antenna Waveguide and Antenna Module Thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58176896A (ja) * 1982-04-10 1983-10-17 豊田合成株式会社 マイクロ波加熱装置

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2467578A (en) * 1939-01-09 1949-04-19 Research Corp Electromagnetic horn
US2683251A (en) * 1942-08-13 1954-07-06 Gen Electric High-frequency electromagnetic wave transmission system
US2433074A (en) * 1943-07-02 1947-12-23 Raytheon Mfg Co High-frequency coupling device
US2552334A (en) * 1945-03-02 1951-05-08 Rca Corp Electron discharge device and associated circuit
US2656535A (en) * 1945-08-06 1953-10-20 Leland K Neher Nonreflecting background for testing microwave equipment
US2962677A (en) * 1945-10-04 1960-11-29 Bell Telephone Labor Inc Wave guide joint
US2721263A (en) * 1945-11-13 1955-10-18 Roy C Spencer Curved throat scan horn for the transmission of electromagnetic energy
US2598475A (en) * 1945-12-17 1952-05-27 Raytheon Mfg Co Antenna system
US2624803A (en) * 1946-01-17 1953-01-06 Robert A Howard Device for measuring radiofrequency power
US2791770A (en) * 1946-04-08 1957-05-07 Jacob R Risser Tapered electromagnetic horn
US2501335A (en) * 1947-12-27 1950-03-21 Westinghouse Electric Corp Coaxial line to wave guide matching section
US2688732A (en) * 1949-05-05 1954-09-07 Bell Telephone Labor Inc Wave guide
US2755465A (en) * 1949-10-07 1956-07-17 Marconi Wireless Telegraph Co Aerials
US2851686A (en) * 1956-06-28 1958-09-09 Dev Engineering Corp Electromagnetic horn antennas
US3031661A (en) * 1956-10-31 1962-04-24 Bendix Corp Microwave antenna feed for circular polarization
US4053894A (en) * 1974-03-21 1977-10-11 Siemens Aktiengesellschaft Radio signal switching system employing dielectric rod antennas
US4861124A (en) * 1987-05-13 1989-08-29 Sanders Associates, Inc. Dual-section spatial modulation transmitter
US8581794B1 (en) * 2010-03-04 2013-11-12 Qualcomm Incorporated Circular antenna array systems
US20160006129A1 (en) * 2014-07-07 2016-01-07 Google Inc. Horn Lens Antenna
US9722316B2 (en) * 2014-07-07 2017-08-01 Google Inc. Horn lens antenna
US20200014096A1 (en) * 2018-07-03 2020-01-09 Wistron Corporation Antenna Waveguide and Antenna Module Thereof
US10615487B2 (en) * 2018-07-03 2020-04-07 Wistron Corporation Antenna waveguide and antenna module thereof

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GB534066A (en) 1941-02-26
FR862785A (fr) 1941-03-14

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