FR2685979A1 - ANTENNA SYSTEM. - Google Patents

Abstract

Antenna installation for simultaneous communication with a geostationary satellite and a polar-orbiting satellite, characterized by a concentric stack of circularly polarized discoidal or circular microstrip or ribbon waveguide radiator elements (resonators; 3, 6, 12) which are fixed on a metallic reflective surface (14) arranged horizontally by means of a metallic, symmetrical and cylindrical central body (8 to 12), the diameter of the resonators (12, 6, 3) calculated from the metal reflective surface (14) arranged downwards, decreasing from bottom to top, the upper resonator having the form of a circular or discoidal radiator element with disturbed symmetry and by means of a coaxial pipe guided eccentrically through the body central (8 to 10) fed in such a way that two excited fundamental modes (1.1) orthogonal in the phase quadrature are formed, and the other resonators (6, 12) are formed as elements circular radiators and are excited by a supply network (13) printed between the lower resonator and the flat reflecting surface (14) and by means of four supply wires (71 to 74) in higher mode (2.1 or 3.1).

Description

ANTENNA SYSTEM

  The invention relates to an antenna system for

  simultaneous communication with a geostation satellite-

  and a polar orbiting satellite. The object of the invention is to design an antenna system which can communicate by means of a single system without monitoring on frequency bands very close to each other simultaneously as well with a satellite.

  geostationary than with any revolution satellite

  that according to the invention, this is obtained thanks to an antenna system for the simultaneous communication with a satellite

  geostationary and with a polar polar orbit satellite charac-

  tererized by a concentric stack of radiator elements (resonators) with ribbed waveguides or discordant or circular microstrips, with circular polarization which are fixed on a metallic reflecting surface and arranged horizontally by means of a metallic central body, symmetrical and cylindrical, the diameter of the resonators calculated from the metal reflecting surface arranged downwards, decreasing from the bottom upwards, the upper resonator having the shape of a circular or discoid radiator element with disturbed symmetry and

  being fed by an eccentric guided coaxial pipe-

  through the central body to form two excited orthogonal fundamental modes in phase quadrature, and the other resonators being formed as elements

  circular radiators and energized by a supply network

  tion printed between the lower resonator and the planar reflecting surface and by four supply wires

superior mode.

  In advantageous variants which are the subject of

  subclaims, N 2 2 emitters circular radiators

  are provided, the central body being designed as an N-stage rotating element allowing the internal bores of the circular radiator element to be filled with precision, the radiator element with ribbon waveguide or

  with lower circular microstrip and the feeding system

  Hybrid tion securely connected to it in a ribbon or microstrip waveguide version uses the same substrate, instead of a circular or cylindrical symmetry of the resonators or of the central body, an axial symmetry is provided. octagonal or another axial order symmetry for the mode 2 1 or order symmetry

  disturbed for the mode radiator element 1 1.

  In the antenna installation according to the invention, two antenna systems are provided, in this case an antenna system arranged and mounted more vertically, which comprises a ribbon waveguide antenna (or several superimposed antennas of this type) circular or polarized

  circularly, designated in English as

  tion of "Patch" and which radiates in fundamental mode and produces for moving satellites, for example in the global positioning system (GPS) the necessary semicircular characteristic, and an antenna system assigned to it which comprises at least one circular antenna (or also several superimposed circular antennas) which radiates in a higher mode The higher modes produce characteristics of radiation with a zero position in the zenithal direction which turns out

  optimal for communication with geosta-

European territory.

  The antennas excited by the higher modes are designed according to the principle of antennas or devices

  microstrip or annular ribbon waveguide radiation

  area which when using two or more radiator elements fixed to a central body with two or more axially symmetrical stages In this case, this central body has the effect of not influencing the properties of symmetry as a result of the realization of a supply line for

the upper antenna.

  Thanks to the stepped central body, a better adaptation of the second guide radiator element is obtained

  of circular ribbon waves (or umpteenth radiating elements

  teurs), i.e. the lowest radiating ribbon waveguide element when the supply point is

  optimally selected for the first radiating element

  waveguide circular ribbon.

  Suitably, the diameter of each central body stage is equal to the inside diameter of the corresponding circular radiator element in order to avoid coupling of the circular radiator elements through the air gap and

  thus simplifying the optimization of adaptation (experimenta-

  the). Thanks to the described combination of orthogonal modes, we obtain for a symmetrical arrangement with respect to the axis

  advantageously a particularly satisfactory decoupling

  making the two antenna systems superimposed.

  Thanks to the installation of antennas according to the invention, it is possible to decouple satisfactorily two channels, one of which is assigned to a geostationary satellite and the other is assigned to a satellite moving according to

any orbit.

  Since the installation of antennas according to the invention is intended for the application on the roof of

  automotive or similar environment, the installation

  tion of antennas according to the invention is of particular design

  smoothly compact and housed in a radome formed

  advantageously aerodynamically and of low height.

  The invention will now be described on the basis of a preferred embodiment with reference to the accompanying drawing in which: FIG. 1A is a view from below and FIG. 1B is a view in median section of a way

  advantageous realization of an installation

  antenna lation coated with a radome according to the invention; Figure 2 is a perspective representation

  detailed of the pre-

  féré shown in Figures l A and 1 B of the antenna installation without radome;

  Figure 3 is a three-dimensional representation

  basic functions as well as current distribution diagrams

  in top view of a circulating resonator

  cular for three different modes of operation Figure 4 is an elevation section of a radiation pattern measured for the global positioning system (GPS) with an azimuth angle + = O '; Figures 5 and 6 are an elevational section of a radiation pattern measured for an antenna

  INMARSAT-standard-C with an azi- angle

  mutal + = O 'for a SAT-COM channel of 1.5375 G Hz or 1.635 G Hz; as well as figures 7 and 8 are conical sections of a radiation pattern measured for an INMARSAT-standard-C antenna with elevation angles 900 4 = 200 and 450 for SAT-COM channels of 1.5375 G Hz and

1.635 G Hz.

  Figures 1 A, l B and 2 show a view of

  underside in median section or a perspective view

  tive exploded in detail of a preferred embodiment of an antenna installation according to the invention in the form of a combined GPS / INMARSAT arrangement As it appears in FIGS. 1B and 2, the antenna installation comprises three overlapping circular waveguide elements 3, 6 and 12 with circular polarization for three neighboring frequency bands close to one another In this case, the GPS frequency of 1.575 G Hz of the waveguide radiator element with circular ribbon 3 is located between the two INMARSAT frequency bands from 1.535 to 1.545 G Hz and 1.625 to 1.645 G Hz of the two guide radiator elements

  of circular ribbon waves 6 and 12.

  The GPS radiator element 3 is as it appears in FIG. 2, arranged as an upper radiator element and it is excited in basic mode 1 1 The GPS radiator element 3 is produced from a substrate with a thickness of approximately 5 mm with a high dielectric constant (E = 6) thus making it possible to obtain a characteristic of

radiation as wide as possible.

  The two superimposed circular ribbon waveguide elements 6 and 12 superimposed while however being arranged under the GPS radiator element 3 operate for example in 2: 1 mode. The two radiator elements 6 and

  12 consist of a polyolefin substrate with a consistency

  considerably lower dielectric aunt (E = 2.3) and they are supplied by means of a hybrid element 13 Thanks to a central body constituted by three parts 8 to 10 in the embodiment shown, a pipe is conducted

  coaxial 5, 11 by means of which a condenser is supplied

  tor 2 of the GPS radiator element 3 mounted in series and provided on the upper side of this GPS radiator element 3 This capacitor 2 is used to condense the inductivity of the supply line at the level of the GPS radiator element 3 and to

  simultaneously improve the antenna adaptation A pola-

  circular rization is produced by a disturbance of the circular symmetry of the GPS radiator element 3 in the form of two countersinks 3, and 32 in the outer periphery of the circular radiator element 3 The two countersinks 31 and

  32 in the radiator element 3 are formed diametrically

  trally opposite to each other with azimuth angles of

450 and 245.

  The two INMARSAT 6 and 12 radiator elements are supplied via the hybrid system 13 which is executed using ribbon waveguide or microstrip technology, in four places 61 to 64 via capacitors 41 to 44 or in four places 12, up to 124 of the radiator element 12 Thanks to the hybrid system 13, modes 2 1 are excited offset from 450 in azimuth with a phase difference of 90, which allows

  to produce an almost indefinite radiation characteristic

  pendant from the azimuth, and practically polarized circular-

  ment To improve symmetry, as shown in FIG. 2, each mode 2 1 is supplied at two diametrically opposite points 61, 63 and 62, 64 or 121, 123

and 122, 124.

  The hybrid system 13 is bonded with the resonator dielectric of the lower radiator element 12 so that said hybrid system 13 and the radiator element 12 use the same substrate. Thanks to this measurement, it is possible for example

  compared to a hybrid system designed using technical

  that guide to 3 pads save a level of substrate and therefore reduce the overall height of

antenna installation.

  The undesirable electrodynamic coupling of the hybrid system 13 and the radiator element 12 is kept to a minimum due to the fact that the substrate thickness of the plate of the hybrid system 13 is small compared to that of the lower radiator element 12 (Part of the asymmetry on the azimuthal characteristics

  shown in Figures 7 and 8 is attributable to these coupla-

  ges). As shown in Figures l B and 2, the wires 71 to 74 are connected in corresponding bores

  61 to 64 or 12, to 124 in the two sockets made of syn-

  aesthetic 15 provided in the two radiator elements 6 and 12 with four capacitors 41 to 44 or with coaxial sockets

  16, and 16 provided on the upper side of the radiating element

  upper tor 6 The coaxial sockets 16, to 163 are fixed to a base or plate 14 on which, thanks to a threaded bolt 1, the entire antenna installation 3, 6, 12/13 is put in place and by means of fasteners not shown in detail through bores 140 of the plate 14 is fixed a radome 20 covering the entire antenna installation, as shown in Figure 1 B. The two modes, in l occurrence the fundamental mode 1.1 and mode 2 1 of the radiator element GPS 3 or of the two radiator elements INMARSAT 6 and 12 are orthogonal with respect to each other, that is to say that the GPS channel East

  decoupled from the two INMARSAT channels Thanks to this, a reception

  GPS meter will not be overloaded even when transmitting INMARSAT antennas and the characteristics of two antenna systems 3 and 6, 12 do not influence each other even in the case

  o the corresponding frequency bands overlap.

  Figure 3 is a three-dimensional representation of the basic functions of the three different modes 1 1, 2 1 and 3.1 as well as the corresponding current distributions of a circular resonator respectively. In addition, Figure 3 shows for orientation the polar coordinates cp and p . Figures 4 and 8 show the measured radiation patterns of the embodiment shown in Figures l A, 1 B and 2 of an antenna installation according to the invention with the respective average frequencies Here, the antenna installation is mounted in the center of a metal plate of approximate dimensions of 1.4 mx 1.5 m which can constitute a car roof The vertical here is the polar axis e = OO of a coordinate system

polar e, A.

  Figure 4 shows in detail and in elevation a radiation diagram measured for GPS with + = Q O and a circular polarization to the right and left of the GPS channel of

1.575 G Hz.

  FIG. 5 represents a radiation diagram in elevation in section for standard C with 1 = O 'with a

  circular polarization to the left and right of the SAT- channel

COM with 1.5375 G Hz.

  Figure 6 shows a section in additional elevation

  ment of a radiation scheme for standard C for + = O 'with a circular polarization to the right and left of the

SAT-COM channel with 1.635 G Hz.

  Figure 7 reproduces the conical sections of a radiation scheme measured for standard C for 90 e = and 45 for a circular polarization to the right of

SAT-COM channel with 1.5375 G Hz.

  Figure 8 shows other conical sections of a radiation scheme measured for standard C for 90 e = and 45 for a circular polarization to the right of

SAT-COM channel with 1.635 G Hz.

Claims (4)

  1 Antenna installation for simultaneous communication with a geostationary satellite and with a polar orbiting satellite characterized by a concentric stack of radiator elements with ribbon or microstrip, discordant or circular waveguides, with circular polarization (resonators; 3, 6, 12) which are fixed on a metallic reflecting surface (14) and arranged horizontally by means of a central body (8 to 12) metallic, symmetrical and cylindrical, the diameter of the resonators (12, 6, 3) calculated from the downwardly reflecting metallic surface (14), decreasing from bottom to top,   the upper resonator having the form of a radiating element   circular or disco tor with disturbed symmetry and being fed by a coaxial pipe guided eccentrically through the central body (8 to 10) so as to form two   excited fundamental modes (1 1) orthogonal in the quadra-   phase ture, and the other resonators (6, 12) being formed as elements   circular radiators and energized by a supply network   tion (13) printed between the lower resonator and the planar reflecting surface (14) and by four wires   power supply (71 to 74) in higher mode (2 1 or 3 1).   2 antenna installation according to claim 1,   characterized in that N 2 2 radiator transmitters circulating   res are provided, the central body being designed as a rotating N-stage element and in that the internal bores of the circular radiator element are filled with precisely.   3 antenna installation according to claim 1, characterized in that the radiator element waveguide ribbons or microband circular lower (12) and the   hybrid power system (13) firmly connected to it   Ci in execution with ribbons or microstrip waveguide use the same substrate.   4 antenna installation according to claim 1, characterized in that instead of a circular or cylindrical symmetry of the resonators (3, 6, 12) or of the central body (8 to 10), an axial symmetry is provided octagonal or another axial symmetry of order eight for the case of mode (2 1) or a symmetry of order four disturbed for   the mode radiator element (1 1).