US2663016A - Microwave antenna - Google Patents

Microwave antenna Download PDF

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Publication number
US2663016A
US2663016A US135482A US13548249A US2663016A US 2663016 A US2663016 A US 2663016A US 135482 A US135482 A US 135482A US 13548249 A US13548249 A US 13548249A US 2663016 A US2663016 A US 2663016A
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Prior art keywords
radiators
antenna
radiator
plane
paraboloids
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US135482A
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English (en)
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Coligny Guerric De Pillot De
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Individual
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/007—Antennas or antenna systems providing at least two radiating patterns using two or more primary active elements in the focal region of a focusing device
    • 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
    • H01Q19/10—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 reflecting surfaces
    • H01Q19/12—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 reflecting surfaces wherein the surfaces are concave
    • H01Q19/15—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 reflecting surfaces wherein the surfaces are concave the primary radiating source being a line source, e.g. leaky waveguide antennas

Definitions

  • FIG. 1 MICROWAVE ANTENNA
  • This invention relates to transmitting systems for projecting a plurality of divergent radio beams and more particularly for projecting divergent radio beams by means of a plurality of radiators used conjointly with a single reflector.
  • One of the objects of the invention is to provide a new arrangement which permits the transmission, by means of a plurality of non-directional radiators which cooperating with a single reflector, of a plurality of differentiated divergent radio beams of substantially the same pattern.
  • Another object of the invention is to provide a new arrangement permitting the transmission, by means of a plurality of non-directional radiators cooperating with a single reflector, of a plurality of homothetic beams all having the same angle but having different radiation pattern ranges which are proportional to certain readily controlled and predetermined factors as set forth hereinafter.
  • Still another object of the invention is to provide a new cosecant squared antenna.
  • antennae employing a sta tionary grating type of reflector have been developed, an essential feature of which is that they utilize a focal line, i. e. a locus of points having the particular property that, for certain regions of said focal line and with an approximation neglecting the values of second order, the sharpness of focusing produced by the reflector is not affected, whatever the exact location of the radiating source along the focal line may be.
  • a focal line i. e. a locus of points having the particular property that, for certain regions of said focal line and with an approximation neglecting the values of second order, the sharpness of focusing produced by the reflector is not affected, whatever the exact location of the radiating source along the focal line may be.
  • the present invention relates to means for differentiating electromagnetic beams according to their angular elevation, which are fixed with respect to a stationary grating antenna.
  • the reflectors utilized in the instant invention are the same as set forth in the copending application wherein they are termed stationary grating antennae, and which are constituted by a plurality of narrow strips of conducting material each generally disposed along a curve traced upon a given paraboloid of a family of paraboloids, said curves being defined with reference to a small movement undergone by the aforesaid paraboloids and being called in kinematics stationary characteristic line.
  • the antennae of the type set forth above may be rotative antennae.
  • a stationary grating reflector is associated with a number of electromagnetic sources which may differ from each other by some particular feature other than the carrier frequency, these sources being fixed with respect to the stationary grating reflector and being, moreover, located along its focal line.
  • the total beam radiated by the antenna comprises a number of pencil beams, each being associated with a given primary source and differing from the other pencil beams by the particular characteristic feature differentiating its source from the sources giving rise to the other pencil beams.
  • pencil beams having the same angle but different pattern ranges may be obtained in accordance with the characteristics of the power feed of the primary sources, and the juxtaposition of said pencil beams gives a total pattern of any arbitrary shape.
  • Fig. 1 is a plot of the trace in a meridian plane of a few members of a family of paraboloids of revolution having a common focus and axis of revolution, but drawn to different scales.
  • Fi 1 indicates the location on each of those paraboloids of the characteristic line associated with small oscillatory motions of the paraboloids in the plane of the figure about a center of motion located at a short distance from the axis of revolution of the paraboloids.
  • the strip refiecting elements, of an antenna according to the invention, conforming to such paraboloids, are shown fragmentarily in Fig. 1 at the positions of the characteristic lines on those paraboloids.
  • Fig. 2 is a perspective view of an antenna according to the invention.
  • Fig. 3 is a diagram illustrating the antenna of Fig. 2 in relation to the beam patterns laid down thereby.
  • Fig. 4 is a diagram similar to that of Fig. 3 illustrating the provision of additional beams of the same pattern by the addition offurther radiators on the focal line of the grating reflector.
  • Figs. 5 and 6 are diagrams illustrating particular forms of construction for the plural primary radiation sources. 7 4
  • Fig. 7 is a diagram similar to that of Fig. 3, but illustrating a cosecant squared antenna pattern resulting from a plurality of beams, all of which have the same angular pattern but which are of different power;
  • Fig. 8 illustrates a form of feed suitable for use in the antenna ofFig. '7.
  • I, 2, 3, 4, 5 and 6 are the traces in a meridian plane (the plane of the figure) of a plurality of paraboloids of revolution having a common focus 1,. a common axis 8 lying in the meridian plane of the figure and vertexes 9, I0, II, I2, I3, I4 the successive distances between which are equal to wherein K is an integer and A is the wavelength chosen for the primary radiator.
  • the primary radiator is diagrammatically shown at I5, and may be considered to possess an oscillatory arcuate motion of small amplitude with respect to the parab oloids, this motion carrying the radiator through the common focus 'I and having a center of motion in the. plane of Fig.
  • the radiator is considered to. be stationary and if the paraboloids are considered instead to have an oscillatory circular motion in. the plane of the figure about H as a center, each of the paraboloids will develop an envelope for its v'arious positions assumed during this motion, and each paraboloid will interest its envelope along a line which is the stationary characteristic line of that paraboloid for that motion.
  • the position of the portion of each moving paraboloidal surface in the vicinity of its characteristic line is stationary, within an approximation neglecting terms of the second order, and the stationary characteristic line of each paraboloid may be determined by dropping perpendiculars from the axis I? to the surface of the paraboloid in question.
  • the different stationary characteristic lines are the curves which are traced upon the paraboloids and which are formed by the intersections of these latter with the equilateral hyperbolic cylinders generated parallel to the axis I1 and which cut the plane of Figure 1 along the equilateral hyperbolae 2
  • the stationary grating antenna comprises a plurality of narrow metal strips disposed one on each paraboloid and conforming to a portion of the surface thereof along the stationary characteristic line of such paraboloid. All of the strips are supported on a framework and are enclosed between two. parallel planes on opposite sides of the Fig. 1 plane, equidistant from the plane of Figure 1 and parallel to the plane of Figure l', to form thereby the lateral limits of the antenna.
  • the stationary characteristic lines 2 I26 cut the lateral planes above mentioned, both above and below the plane of Figure 1, at the points which are aligned along the curves 30, 30'.
  • the metallic strips comprising the antenna are represented in Figure 1 at 3
  • Each strip is restricted to a narrow width on either side of the characteristic line along which it lies, i. e. to a narrow width in the dimension of the meridian plane of Fig. 1.
  • This width may be of the order of 10 to' 20 millimeters, for example in the case of an antenna intended to operate on a wave length of 10 to 15 centimeters.
  • a large number of reflecting strips are employed, for example at least or more.
  • the stationary grating antenna described herein has the property that the emitted beams from radiator I5 has a pattern angle and a pattern range after reflection from the strips, whichis independent of the position of the radiator along the portion I8
  • This portion of circle I6 is the focal line of the antenna.
  • FIG. 2 there is shown in perspective an antenna according to the present invention.
  • 41 designates a framework of non-conducting material, for example wood, which supports, by means of the cross pieces 48 the mounting members for the metal strips, which mounting members 99, 50, 51 and 52, 53, 54 are likewise made of wood.
  • Central mountings 59 and 53 are formed in the profile of strophoid 20, in the re-
  • the lateral mounting members 49 and 5I have the profile of curve 39 and the lateral mounting members 52 and 54 have the profile of curve 39.
  • a plurality of microwave radiators 31, 38 and 39 adapted to radiate energy of the same carrier frequency, are supported from the framework 61 by means of a structure 49 to lie at spaced points
  • the radiators may be positioned equiangularly along the circular arc IS, in which case the lobes or beam to which they give rise will be equiangularly inclined.
  • the radiators 37-39 may be fed from a common source of microwave energy such as a magnetron 40'.
  • a radio beacon having a wave length of centimeters for example, comprises a framework 55 supporting a plurality of metal strips 56 which are disposed in accordance with the explanation hereinabove given in connection wih Fig. 1 to provide a reflector and a series of microwave radiators 58, 59, 69 disposed along the circular focal line 57 of the array of reflecting strips 56, this focal line corresponding to the focal line I6 of Fig. 1.
  • radiators are schematically illustrated in Figure 3, and are further shown in greater detail in Figure 5.
  • 'Framework55 may be rotated about the shaft 35 which is fixed on base 62.
  • the reflector is schematically shown at B3 in Figure 4.
  • 64 denotes the plane of symmetry of the antenna which contains focal lne 51 and radiators 58, 59 and 99.
  • Radiator 58 provides beam 68, radiator 59 beam 69, radiator 69 beam I9 etc.
  • the spacing of the radiators along the focal line isso disposed as to have a certain'predetermined angular spacing between the two axes of successive beams. This angular spacing between two successive beams is equal to the angular spacing between the two successive radiators along the circular focal line, as viewed from the center of the circle.
  • the radiators are represented on Fig. 5, as open end rectangular wave guide radiators 58, 59, 69 which are aligned along the circular focal line 51.
  • Wave guides 65, 66 and 61 are provided with T-R boxes I5, I9, 'I'I operated by their keep alive electrodes I8, I9, 89.
  • the keep alive electrodes may be operated in such a manner that the nth radiator, starting from the one, 58, giving the pencil beam 68 closest to the horizontal position is fed one pulse out of n
  • nth radiator starting from the one, 58, giving the pencil beam 68 closest to the horizontal position is fed one pulse out of n
  • radiator 58 radiates all the pulses, radiator 59 one pulse out of two, radiator 69 one pulse out of three and so on.
  • an aircraft located at M can not only determine the bearing of the radio beacon, by comparing the instant when the radio beam of plane 99 are received in the aircraft with the instant when the same plane passes through the north direction 8I and which instant will be indicated in some conventional manner, but the aircraft can also determine'its angular elevation by measuring the frequency of recurrence of the pulses received. With this information the aircraft bearing and angular elevation are known and if the altitude is, moreover, supplied by some other device, the aircrafts exact geographical location is known.
  • Figures 7 and 8 refer to antennae having any desired predetermined outline of polar graph of their amplitudes. panoramic search radar antennae it is desirable to obtain such a graph, in the vertical search plane, that the echoes of objects situated at any distance, but located at a similar altitude, be comparable. It is thus desirable to have an antenna of a so-called cosec type, i. e. for a direction situated in the vertical plane and making an angle A with the horizontal line, it is desirable to obtain a power density pattern proportional to cosec A, or a field intensity pattern proportional to cosec )t.
  • cosec type i. e. for a direction situated in the vertical plane and making an angle A with the horizontal line
  • the reflector is schematically illustrated at 94 in Figure 7.
  • 95 indicates the plane of symmetry of the antenna and contains focal line 9! and radiators 98, 99 and I90.
  • Radiator 98 provides beam I98 which makes an angle M with the horizontal, and which has an intensity proportional to cosecant M.
  • Radiator 99 provides beam I99 which makes an angle M with the horizontal and which has an intensity proportional to cosecant M.
  • Radiator I99 provides beam I I0 making an angle A2 and having an intensity proportional to cosecant Az.
  • the penci1 beam associated with each radiator will have an intensity proportional to cosec and since the total beam is formed by the adjacent component pencil beams, the total beam will have for each direction making an angle A with the horizontal direction an intensity proportional to .cosec A, It is also possible to give to the polar graph of the whole pattern any desired predetermined out line.
  • An antenna adapted to lay down a plurality of radio frequency energy beams of similar directivity properties and having coplanar axes angularly inclined to each other, said antenna comprising a plurality of radiators capable of emitting radiation of the same carrier frequency,
  • said radiators being located at spaced points along frequency, said surfaces having in a common 1 meridian plane of said paraboloids a small extension on either side of the intersections with said paraboloids respectively of the perpendiculars to said paraboloids drawn from the center of said circle.
  • An antenna adapted -to lay down a plurality .of .angularly inclined radio frequency energy beams of substantially the same directiv-ity proplerties, said antenna comprising a plurality of radiators adapted to radiate energy of the :same
  • radiatorsat spaced locations along the arc.,of a circle means to support said radiatorsat spaced locations along the arc.,of a circle, a plurality of metallic reflector elements each having a surface conforming substantiallyto :a portion of a paraboloid of revolution, the paraboloids to which said surfaces conform being membersof afamily of paraboloids having acornmoh focus on said circle a d a axi o re o ut on in n. th l ne of toidoiro e.
  • tho ort s o aid a ebo oid being s ed rom ac the by int g a mu i l s o e hal the v en h co espond g to a f e ency.
  • the vertices .of said paraboloids being spaced from each other sub.- stantially by integral multiples of one-half the w ve n t cor po in t s i requen y. mo n supp ng s d lement wit their urfaces substantially lyingin the surfaces of their es ec e pa b i s.
  • An antenna according to claim 2 including a source of radio frequency energy and a plurality of transmission lines coupling said source to said radiators, said transmission lines including attenuation elements, whereby the intensity of said beam varies from beam to beam.
  • An antenna according to claim 3 including a source of pulsed energy, transmission lines coupling said source to, said radiators, and means short-circuiting said transmission lines at varying rates.

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US135482A 1948-12-29 1949-12-28 Microwave antenna Expired - Lifetime US2663016A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112483A (en) * 1957-07-26 1963-11-26 Electronique Soc Nouv Wide angle scanning reflector
US3881178A (en) * 1973-04-03 1975-04-29 Hazeltine Corp Antenna system for radiating multiple planar beams
US5309167A (en) * 1989-10-31 1994-05-03 Thomson-Lgt Laboratoire General Des Telecommunications Multifocal receiving antenna with a single aiming direction for several satellites

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2039812A (en) * 1929-12-03 1936-05-05 Telefunken Gmbh Signaling system
US2217321A (en) * 1935-06-01 1940-10-08 Telefunken Gmbh Beam antenna
US2367764A (en) * 1942-01-30 1945-01-23 Rca Corp Frequency modulation detection system
US2408435A (en) * 1941-03-01 1946-10-01 Bell Telephone Labor Inc Pipe antenna and prism
US2426992A (en) * 1942-05-27 1947-09-09 Sperry Gyroscope Co Inc Glide path transmitter
US2435988A (en) * 1943-11-22 1948-02-17 Sperry Corp Aircraft landing system
US2530580A (en) * 1946-10-30 1950-11-21 Rca Corp Multichannel signaling system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2039812A (en) * 1929-12-03 1936-05-05 Telefunken Gmbh Signaling system
US2217321A (en) * 1935-06-01 1940-10-08 Telefunken Gmbh Beam antenna
US2408435A (en) * 1941-03-01 1946-10-01 Bell Telephone Labor Inc Pipe antenna and prism
US2367764A (en) * 1942-01-30 1945-01-23 Rca Corp Frequency modulation detection system
US2426992A (en) * 1942-05-27 1947-09-09 Sperry Gyroscope Co Inc Glide path transmitter
US2435988A (en) * 1943-11-22 1948-02-17 Sperry Corp Aircraft landing system
US2530580A (en) * 1946-10-30 1950-11-21 Rca Corp Multichannel signaling system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112483A (en) * 1957-07-26 1963-11-26 Electronique Soc Nouv Wide angle scanning reflector
US3881178A (en) * 1973-04-03 1975-04-29 Hazeltine Corp Antenna system for radiating multiple planar beams
US5309167A (en) * 1989-10-31 1994-05-03 Thomson-Lgt Laboratoire General Des Telecommunications Multifocal receiving antenna with a single aiming direction for several satellites

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NL146717B (nl)
NL83707C (enrdf_load_stackoverflow)

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