EP0203193A1 - Conception d'antenne a rapport eleve de gain/surface/produit - Google Patents

Conception d'antenne a rapport eleve de gain/surface/produit

Info

Publication number
EP0203193A1
EP0203193A1 EP19860900687 EP86900687A EP0203193A1 EP 0203193 A1 EP0203193 A1 EP 0203193A1 EP 19860900687 EP19860900687 EP 19860900687 EP 86900687 A EP86900687 A EP 86900687A EP 0203193 A1 EP0203193 A1 EP 0203193A1
Authority
EP
European Patent Office
Prior art keywords
signal
antenna
plane
distribution
gain
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Withdrawn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
EP19860900687
Other languages
German (de)
English (en)
Inventor
James D. Thompson
Gregory S. Czuba
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.)
Raytheon Co
Original Assignee
Hughes Aircraft 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 Hughes Aircraft Co filed Critical Hughes Aircraft Co
Publication of EP0203193A1 publication Critical patent/EP0203193A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H01Q19/13—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 single radiating element, e.g. a dipole, a slot, a waveguide termination
    • 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
    • H01Q13/025—Multimode horn antennas; Horns using higher mode of propagation

Definitions

  • the present invention generally relates to sector beam antennas, and more particularly, to a method and apparatus for obtaining a high gain-area-product and a substantially uniform gain coverage over a regional area by utilizing both the main and side lobes of the electromagnetic signal emitted from a dual mode antenna feed element.
  • Parabolic reflector antennas for communication satellites are normally used to provide a sector beam, viz. gain coverage over an angular region of the surface of Earth.
  • Reflector antennas for most other applications e.g., Earth stations, terrestrial relays, etc.
  • the energy distribution at the antenna reflector conventionally is dimensioned so as to include only a portion of the main lobe of the aperture distribution pattern (Fourier transform) emitted from the feed element.
  • the aperture distribution pattern Frier transform
  • a Potter horn feed 2 element uses a dual mode to modify the electric plane distribution to look like the magnetic plane distribution. See "A New Horn Antenna with Suppressed Sidelobes and Equal Beamwidths," P.D. Potter, The Micro ⁇ wave Journal, June 1963, pp. 71-78, for the principles of
  • GAP gain-area-product
  • Another common solution is to provide a single antenna system with a multiple feed array shaped roughly in proportion to the region intended to .be covered.
  • the electromagnetic signal energy is apportioned among the feed elements.
  • the reflector then projects a set of overlapping beams in order to attempt to achieve full coverage of the regional area with approximately the same gain factor over the entire area.
  • These systems are complex, using computerized assistance to select the optimum arrangement of amplitudes and phases needed to coordinate the excitations. Such systems often have high power demands difficult to achieve given the current limits of space technology.
  • An additional object of the present invention is to provide a sector beam antenna compatible with the practical considerations involved in current satellite configurations and launch vehicle compatibilities.
  • the present invention in a broad aspect, is a method and apparatus for obtaining a substantially uniform gain in an electromagnetic signal projected over a large regional area.
  • An electromagnetic beam is projected by emitting a signal pattern from a dual mode antenna feed using two modes to form the magnetic plane (H-plane) amplitude distribution, such that the H-plane amplitude distribu ⁇ tion looks like that of the plane containing the electric field vector (the E-plane).
  • the radiation pattern from the antenna feed including side lobes, is reflected toward the regional area to be covered by the beam.
  • Proper selection of the specific number of side lobes of the feed horn primary radiation patterns in both the H-plane and the E-plane to be reflected along with the main lobe provides a beam of substantially uniform gain and a high gain-area-product.
  • a dual mode feed horn is used to emit the primary radiation pattern.
  • Two modes are used to form the H-plane amplitude distribution in order to make the H-plane amplitude distribution look like that of the E-plane uniform amplitude distribution obtained in single mode emission from the horn.
  • An offset parabolic antenna reflector is used to form the secondary beam pattern which is projected toward the regional area to be covered.
  • the method and apparatus When applied to satellite communications using only a single feed element and reflector, the method and apparatus provides a higher gain-area-product with substantially uniform coverage over large geographic regions than is currently obtained. Hence, a stronger and more uniform beam over the coverage area is achieved while reducing the complexity and the power requirements of the system needed to obtain those features using current technology.
  • FIGURE 1 is a schematic elevation view of the present invention showing the electromagnetic dis ⁇ tribution as well as signal patterns before and after reflection.
  • FIGURE 1(a) is a graphical representation of a circularly symmetric electromagnetic signal distribution across an ideal antenna aperture
  • FIGURE 1(b) is a graphical representation of the signal pattern of a beam obtained from an ideal antenna focusing device from the pattern of Figure 1(a);
  • FIGURE 2(a) is a graphical representation of a circularly symmetric electromagnetic signal distribution across a finite antenna aperture as contemplated by the present invention
  • FIGURE 2(b) is a graphical representation of the signal pattern of a beam obtained from a finite antenna focusing device from the pattern of Figure 2(a);
  • FIGURE 3(a) is a graphical representation of the results of an analytical study showing the aperture distribution function contained on a circular antenna aperture versus the scaling factor K for a normalized aperture radius condition in a circularly symmetrical distribution of the form 2J.(r)/r;
  • FIGURE 3(b) is a graphical representation of the results of the analytical study as defined in Figure 3(a) showing antenna efficiency vs. K;
  • FIGURE 3(c) is a graphical representation of the results of the analytical study as defined in Figure 3(a) showing gain-area-product vs. K;
  • FIGURE 4 is a schematic drawing of the antenna feed/reflector geometry of the preferred embodiment of the present invention as shown in Figure 1;
  • FIGURE 5 is a graphical representation of the gain line product vs. K for the E-plane distribution pattern obtained from an arrangement of the embodiment as shown in Figure 4;
  • FIGURE 6 is a graphical representation of the gain line product vs. K for the H-plane distribution pattern obtained from an arrangement of the embodiment as shown in Figure 4;
  • FIGURE 7 is a computer simulated representation of the signal coverage pattern obtained with the embodiment as shown in Figure 4.
  • the general arrangement of the feed horn and reflector schematically is shown in Figure 4. Note the arbitrary association of the E-plane of the feed horn 2 with the x dimension and the H-plane with the y dimen- sion.
  • the primary pattern selected to be seen by the reflector 4 is represented at 6 in Figure 1.
  • the resultant secondary pattern of the projected beam is shown at 8, closely approximating the ideal sector beam as shown in Figures 1(a) and (b) .
  • the E-plane distri- bution is chosen to be a uniform amplitude distribution function 3 across the antenna aperture feed horn 2.
  • the fundamental cosine function of the H-plane is modified by the addition of one or more of its odd number harmonics.
  • the H-plane primary and secondary signal patterns will be substantially similar to those as shown in Figure 1 for the E-plane distribution.
  • an ideal circular sector beam is formed when a circularly symmetric distribution of the form 2J (r)/r is put on a circular aperture of infinite extent.
  • r is the radial coordinate
  • J,(r) is a Bessel function of order 1.
  • This aperture distribution and the resulting beam distribution are shown in Figures la and lb, respectively.
  • An infinite aperture has no meaning in a practical sense; however, i-t has been found that truncated versions of this same aperture distribution on a finite aperture will result in beam shapes which closely approximate the ideal sector beam.
  • a truncated aperture distribution and the resulting beam distribution are shown in Figures 2a and 2b, respectively.
  • the approximation to the ideal sector beam improves as the aperture grows radially to encompass more of the distribution function before truncation occurs.
  • GAP gain-area product
  • the voltage pattern g ( M ) is given by the Hankel transform normally associated with circular apertures. This function was normalized to yield a value of 1 at (°r ⁇ ) equal to 0. The normalized power pattern is merely the square of the voltage pattern and these were scaled to yield relative gain patterns.
  • gain-area-product is the area of 2 coverage (pi ⁇ Q ) times the absolute gain at ⁇ , where ⁇ is the angle at which GAP is maximized. No explicit mathematical expression exists for determining ⁇ .
  • GAP at ⁇ o ⁇ was determined by ⁇ an iterative search procedure. In this manner, the GAP was determined as a function of K (the index proportional to the amount of the distribution function contained on the aperture), and the results are shown in Figure 3.
  • Figure 3a shows the aperture distribution function versus K
  • Figure 3b shows the on-axis antenna efficiency versus K
  • Figure 3c shows GAP versus K.
  • the gain-area-product increases as K increases; however, several local minimums can be seen in Figure 3c. These minimums occur at the zero crossings of the distribution function, and are particularly deep for positive going zero crossings. Note that traditional antenna design would suggest operating at a value of K where the antenna efficiency is maximized. This occurs when K equals 2.8, and the value of GAP at this point is
  • the reflector may grow to unacceptable size.
  • a beam covering the contiguous 48 states could be generated at 12 GHz with a reflector diameter of about 96 inches.
  • This reflector size would yield a GAP in excess of 25,000 deg 2 . yet would still be physically compatible with today's satellite configurations and launch vehicle envelopes.
  • the above analysis was repeated for a rectangular reflector operating with a rectangular feed horn. This feature permits the analysis and application of the results to be separated in the vertical and horizontal dimensions.
  • the GAP is formed by the product of the GLP (gain-line-product) in the X dimension and the GLP in the Y dimension.
  • Figure 5 shows the available GLP for the E-plane as a function of Kx, the index proportional to the number of sidelobes on the reflector in the E-plane.
  • Figure 5 indicates a generally increasing GLP with Kx.
  • Figure 6 shows the available GLP in the H-plane (using two modes) as a function of Ky. These results can be used to design an antenna for coverage of the area of interest.
  • Figure 6 indicates that the best H-plane GLP (150.1) can be obtained with Ky equal to 3.5.
  • Kx equal to 5.35 with
  • gain-area-product is about 25,000 deg .
  • the reflector 4 is an offset parabolic square, 76.16 inches per side, having a focal length of 65.96 inches.
  • the feed 2 is a rectangular, dual mode type horn, 6.78 inches long in the H-plane and 10.36 inches long in the E-plane.
  • a horizontally polarized radiation pattern is emitted at 12 GHz having a mode content of 3.96% E Q3 and 96.04% TE Q ..
  • the resulting simulated coverage pattern is shown in Figure 7 for a satellite antenna of this design in a stationary orbit at 100 degrees west longitude.
  • 2 gain-area-product for the 30 dB contour is 25,000 deg ; two gain depressions inside the east and west edges

Landscapes

  • Aerials With Secondary Devices (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

Une antenne à rapport élevé de gain/surface/produit, doté d'un élément sensible à double mode de fonctionnement, est conçue pour offrir une répartition plus ou moins uniforme de gain sur une zone angulaire. Le dessin primaire (6) émis au niveau de l'alimentation de l'antenne (2) est modifié pour rapprocher la répartition du plan H de celle du plan E (3). Le lobe principal et les lobes latéraux du dessin primaire sont projetés sur le réflecteur (4) pour créer un dessin secondaire (8) qui se rapproche d'un faisceau de secteur idéal.
EP19860900687 1984-11-19 1985-11-12 Conception d'antenne a rapport eleve de gain/surface/produit Withdrawn EP0203193A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US67273984A 1984-11-19 1984-11-19
US672739 1984-11-19

Publications (1)

Publication Number Publication Date
EP0203193A1 true EP0203193A1 (fr) 1986-12-03

Family

ID=24699804

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860900687 Withdrawn EP0203193A1 (fr) 1984-11-19 1985-11-12 Conception d'antenne a rapport eleve de gain/surface/produit

Country Status (3)

Country Link
EP (1) EP0203193A1 (fr)
JP (1) JPS62501326A (fr)
WO (1) WO1986003344A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0219321A1 (fr) * 1985-10-10 1987-04-22 British Aerospace Public Limited Company Système d'antenne
GB2243489A (en) * 1990-02-19 1991-10-30 British Telecomm Antenna

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1516046B1 (de) * 1966-03-09 1975-10-09 Telefunken Patent Anordnung zum gleichzeitigen Erzeugen mehrerer vorgegebener elektromagnetischer Wellentypen
CA890032A (en) * 1970-08-10 1972-01-04 Wu Chuang-Jy Microwave horn-paraboloidal antenna
US4091387A (en) * 1977-05-05 1978-05-23 Rca Corporation Beam forming network
FR2418551A1 (fr) * 1978-02-24 1979-09-21 Thomson Csf Source hyperfrequence multimode et antenne comportant une telle source

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8603344A1 *

Also Published As

Publication number Publication date
WO1986003344A1 (fr) 1986-06-05
JPS62501326A (ja) 1987-05-21

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Inventor name: THOMPSON, JAMES, D.