DE1466052A1 - Antenna system for use in spacecraft or the like. - Google Patents

Description

Dlpl, lng Dipl. Ooc. DUb-T- 12, NOV. 1365

! •! • tone 11139

Compagnie Francaise Thomson-Houston,

Paris 8, Boulevard Haussmann 175 (France)

"Antenna system for use in spacecraft or the like."

French priority from Ij5. November 1964 from the French Patent Application No. 99 ^ 959

The invention provides an improved multipurpose antenna system, that is capable of “simultaneous radio signals from different sources with different directional and directional signals other features to send »The invention was developed for use in spacecraft, in particular Satellites, for telecommunications systems and will accordingly

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explained herein with particular reference to this area of application. It is clear, however, that the invention can be used for other areas of application in the area of point connections.

Connections to satellites and other types of spacecraft create difficult problems that mainly due to the considerable number of different P connectors that were created have to be and on the transmission of signals of various characteristics with regard to the carrier frequency, polarization and direction, also with the extremely limited space and the limited capacity of the load carrier of the vehicle is related. Today's satellites generally require the simultaneous Provision of three different types of radio links:

1) A main link for sending and receiving information,

2) a telemetry connection for the transmission of measurements, carried out on board the satellite, and

J>) a remote control connection for receiving control signals to operate various relays, which controls the operation of the satellite devices. Different radio frequency bands are assigned to each of the above links by international agreement.

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Some of the radio links in the links above can be sent (and received) directionally while others must be sent (and received) in multiple directions. This is how it will be the main or information link mentioned above in general put into operation only after the satellite has been placed in its prescribed orbit and has continued to stabilize itself in orbit so that it is constantly on the same side |

returns to earth. In these conditions it is profound advantageous to send the information signals via a directional antenna, such as a /xii-.ls tr ahler, pointing perpendicular to the earth as this is a considerable gain in radiation efficiency allowed.

On the other hand, other types of information, such as the remote measurement and control signals mentioned above, the as connecting links (2) and (;>) were mentioned, not useful to be sent through a directional antenna, as these signals must be able to begin sending before the Satellite is stabilized and while it is still whirling around arbitrarily in space.

The above illustrates a situation wherein a spacecraft antenna system both die.gerichtete as well as the multi-directional transmission and reception of various Ig Signa

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must take over »It is clear * that other locations in which a requirement of the same kind generally occurs can certainly occur.

So far, to the best of the applicants' knowledge and belief, no efforts have been made to establish a uniform or to create an integrated multi-purpose antenna system, that would be able to simultaneously direct one signal and emit another signal in multiple directions. It is therefore a primary object of the invention to fill this gap to fill and such an integrated multi-purpose antenna system to accomplish.

The usual antenna arrangement commonly used in satellites for simultaneous transmission of directional and multiple Directional radio waves simply consist of two different antenna assemblies, one one Directional antenna and the other a multi-directional antenna that are not functionally related to each other stand. Thus, the directional antenna can comprise a single axial conductor emerging from an end surface of the satellite skin protrudes and cooperates with this end surface as a ground plane to form a common ground plane directional antenna system to accomplish. The multi-directional antenna device that concurrently with such Directional antenna used often comprises a pair of crossed dipoles called a turnstile abstractor

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represent * In such a system, the two Radiating systems can be arranged quite far apart if they do not perform their functions mutually should disturb and this requires that the turnstile dipoles protrude from the sides of the satellite housing. The resulting arrangement is unfavorable because it has a Part of the valuable space required for accommodating solar elements and other external devices I

is available on the outer surface of the satellite skin, the wiring is complicated and more Has disadvantages, which will be explained later.

It is an object of the present invention to provide an integrated antenna unit that includes two radiators includes that are capable of - energy of different Sources emit and which has different directional and other characteristics, these emitters are functionally interconnected in such a way that an abstraction acts as a basic level or a counterweight for serves the other, thereby giving the desired directional characteristics.

Another objective is to make such a compound To create antenna unit, in which the functional context. between the two radiators is such that both radiators can be attached close to each other

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(and indeed must), thereby reducing overall dimensions, easing wiring, and other "benefits." be created that are particularly cheap in a spacecraft. Another goal is that To facilitate "shaping" the radiation feature pattern of the directional radiator of the composite antenna.

Further features and advantages of the invention result from the following description of several exemplary embodiments shown in the accompanying schematic drawings.

Fig. 1 is a perspective view of a satellite with separate directional and multi-directional antennas in accordance with a typical The arrangement is state-of-the-art,

Figure 2 is a similar view of a satellite installed with the improved, unitary directional, multi-directional antenna system is equipped according to the invention,

Figure 3 is a simplified view showing the basic concept which is used in the invention and is a basic embodiment thereof.

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Pig. H is a fragmentary view of the system shown in Fig. 2 in section on a diametrical plane of the satellite, showing, inter alia, the feed devices for the antenna elements;

Figure 5 is a schematic view of the improved one Satellites after directional stabilization

in orbit around the earth, being partially '

an advantageous directional beam pattern is shown as achieved with the improved antenna system can be, in this view the linear dimensions of the satellite of course are largely exaggerated, but directional relationships essentially are retained,

Fig. 6 illustrates one type of balun which |

can be used according to the invention.

In the typical prior art arrangement, as shown in FIG. 1, an artificial satellite is included a body 2 of generally cylindrical shape provided with a directional antenna consisting of a single axial There is radiating element 4, which protrudes from the center of a flat end wall 6 of the body perpendicular thereto and

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the body is also provided with a multi-directional antenna of the so-called turnstile type. This turnstile antenna arrangement has two dipole elements 8 and 8 'in a crossed relationship, each dipole being a half-wave ^{resonance conductor whose opposite legs or rods 8 A and 8 B and 8 1} A and 8 ¹ B protrude from diametrically opposite points on the cylindrical side surface of the body 2 . In the operation of such a conventional spacecraft antenna system, the axial radiating element 4 is excited with very high frequency or ultra-high frequency energy in relation to the metal skin of the body 2 which represents the satellite mass or the artificial earth. The axial radiating element 4 works together with the base plane, which is represented by the end face 6 of the satellite body, in order to radiate the applied energy around the axial direction, which is shown as Z, with a relatively high directional characteristic.

So, after the satellite is brought into orbit and stabilized in its position, like the one in usually happens so that the direction Z of the axial radiating element 4 is perpendicular to the earth, the axial antenna 4 can be used with high efficiency to transmit information signals to the earth.

The turnstile arrangement is crossed with both of them

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Dipoles 8 and 8 'excited in phase quadrature with very high frequency or ultra-high frequency energy from another source with a different frequency from the source, which is used to excite the axial radiating element 4. In accordance with the known turnstile principle, the dipole arrangement 8-8 has a radiation pattern which is roughly circular in the plane of the turnstile and is therefore very well suited for multi-directional connections. Furthermore, the energy radiated polarized from the hub in a plane which is perpendicular to the plane of polarization of the energy radiated from the directional antenna 4, the turnstile antenna 8 - 8 ^f, accordingly, can be used for exchanging information between the ground and the satellite before that the latter on his Ural career; has been brought and stabilized in its position, for the transmission of control signals and telemetry information to and from the satellite, It should be ^{noted that after the satellite has stabilized in its orbit, the multi-directional antenna 8 - 8 1} continues to exchange these last mentioned Signals is used simultaneously with the operation of the directional antenna 4.

The usual antenna system, which is described with reference to ♦.

/ described * owns; a number of disadvantages, the correct positioning of the turnstile antenna

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elements 8-8 'requires unfavorable through-holes the slack of the satellite body. The valuable surface area available around the body to Housing solar battery elements and other devices there is considerably reduced while the overall radial dimensioning of the satellite is undesirably enlarged by the protruding turnstile dipoles. The electrical circuit connections between the various antenna elements and internal electronic devices are difficult to wire because of the distant points at which the antenna elements are connected to the body and because of the tight space and the overcrowding with furnishing elements inside the satellite body. Likewise, unfavorable capacitance effects are created by the side surface of the body 2, which affects the operating efficiency interfere with the antenna device.

In the satellite antenna system according to the present invention Invention, as shown in Fig. 2, the disadvantages mentioned above are eliminated. As shown, is the antenna system according to the invention, which in general denoted by Io 1st, arranged in the form of an integrated unitary group that completely is arranged beyond an end face of the satellite body. This group Io is on a tubular Mounted carrier 12, axially from the center of the \

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End face 6 protrudes and has a directional beam element 14 which protrudes axially from the carrier 12 and a Multi-directional arrangement that the pair crossed, folded Dipole elements 18 and 18 *, which protrude laterally from the other end of the tubular support.

Before describing the construction of the improved antenna arrangement in detail with reference to FIG. 4, the basic principle of the invention, which makes such an arrangement feasible%, explains

Fig. 3 schematically illustrates a composite antenna unit according to the invention, which basically consists of an axial radiating element 14 and a folded dipole element 18 which is arranged perpendicular to the element 14 and in, near its lower or excitation end N. The folded dipole element 18, such as it is well known per se, can be viewed as a wavelength conductor folded as shown to have an unbroken upper leg 2ο extending a quarter wavelength to either side of a center point M and another leg 22 parallel to and in close proximity to the leg 2o, which is interrupted at its center to create the pair of connecting terminals. Radio energy of frequency f is fed to the supply terminals PQ in such a way that the

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Current values at terminals P and Q are in phase opposition, as shown by the * indication "180 °". The total power distribution along the folded dipole conductor then assumes such a shape that the net current at the midpoint M of the unbroken leg of the folded dipole is zero.

An essential idea of the invention arises from the presence of this current node at the center M of the folded dipole · Because of the absence of current, it is possible to connect the center M of the dipole element with the same earth conductor, in this case the satellite body 2 « such as the earth conductor used for the axial radiating element 14 and supplying power to this latter element via the end terminals MN at a frequency fg different from fi.

With the arrangement produced in this way, it is clear that the upper leg 18 of the folded dipole serves as a ground plane serves for the axial directional emitter 14, whereby the need is eliminated, the end face 6 of the Satellite body to use to perform this function, as in the usual antenna system according to Fig. 1 was required. At the same time, the folded dipole element 18 can be used to generate energy with a to emit different frequencies and with a different

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from the fcf & rfeie ', through the

; k 'Üe both beam -

e- l (ürid of course Enfcfarfgs- ^ l & eWfce fei ^ foaeifckfe ώτιά regardless of unarians l

In the Grütidänfeennensyatem; as shown in Fig. 3,

is clear; that whoever has individual g'e'faitete Öipolstrahler 18 |

Correct% hschäi4; eh aüfwlist insofar as it is a maximum at Straiilühg in the plain; the perpendicular to his Hauptabmessüng lies. This property can, to a certain extent,

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.sjenschaft can in certain Applicable forms of the invention be important in which it is desired to have different information at the same time to send in different directions. However, the main aspect of the invention is how already explained earlier, with the case in which the folded dipole radiator, which belongs to the axial radiator, has a multi-directional rather than a directional characteristic. To do this, it's easy necessary to supplement the Qrundsystem of Fig. 3, in which another folded dipole element 18 'is added which is perpendicular to the element 18, as shown in Fig. 2, with the additional, folded , Dipole is fed from the same energy source as the first dipole element 18, but in phase quadrature thus to provide a modified form of turnstile assembly that has a multi-directional flow pattern.

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This preferred aspect of the invention will then be described in detail with reference to FIGS.

As shown in Fig. 4, the axial radiating element 14 of the combined antenna system is through an axial opening guided in a plug 24 made of insulating material, which is located in the outer end of a tubular support 12, and is connected to the central conductor of my coaxial P line 26. The line 26 is through the tubular support 14 and is inside the satellite housing with a first Ssnde-receiving device of any conventional type, indicated generally at 28.

Only one folded dipole element 18 of the double turnstile arrangement is shown in FIG. 4, it being understood that the associated element 18 'lies in a plane which is perpendicular to the plane of the drawing and that the general arrangement is similar to that of element 18. For reasons to be given later, the two sides 18A and 18B of the folded dipole 18 (and the dipole 18 ¹ ) are preferably positioned symmetrically with respect to each other to the axis of the system at an angle in directions on the satellite body, as shown. The upper branches 2o A and 2o B of the two sides of the element 18 have their inner ends jio A and 3o B at diametrically opposite points

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of the upper edge of the tubular support 12 is soldered, whereby it is mechanically held and electrically connected to provide the grounded center point indicated as "M" in FIG. The lower branches 22 A * and 22 B are mechanically in the with their inner ends tubular carrier 14 held, but electrically insulated from it, in which they by insulation insert pieces 32 A 52 B are guided, the In diametrically opposite Openings of the tubular carrier are arranged. These inner ends of the branches 22 A and 22 B are within the Carrier 12 with the symmetrical terminals 42 of a Symmetrieruinwandlers or balun 34 connected and in the like Manner, the inner ends of the lower branches of the element 18 ', not shown in Fig. 4, with the corresponding end clamps 42 'of another balun 34 * connected. The asymmetrical end terminals 44, 44 'of the baluns 54 and 34' are with the central Conductors of corresponding coaxial lines 36 and 36 * connected, whose central conductor is combined by a line 38 with a second transceiver device 4o and are connected. As explained earlier, the inner terminals of the lower branches, such as 22 A and 22 B of each folded dipole, these terminals having the lead cycles labeled P and Q in FIG must be fed in a phase-shifted ratio of 180 °. This result will best achieved by using symmetry glides

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J4 J4 and ^f, as shown more particularly by so-called Posaunenart In Fig x 6; the opaxial lines 36 and 36 *, which ^{feed the corresponding folded dipoles 18 and 18 f} , differ from one another by approximately a quarter wavelength in their electrical waves, shown schematically by a phase shifting element 35 in the line 34 *. As ready indicated earlier, a OeeaatstrahlungsiBUSter, which is in and of substantially the same intensity in all Scheltelpunkten β te Ilen as a Vie lfachr conduit arrangement constitutes have the folded dipoles 18 and 18 ·, when fed eo in Phasenquadra- ψ door.

As shown at yj , the outer conductors of all coarial lines are connected to the common earth, which is represented by the envelope of the satellite.

In FIG. 6, it is shown that a balun J54 or 54 ^f, which can be used gemäßs of the invention, to feed to one or the other of the folded dipole has a line 46, which has an electrical length which is approximately one half wavelength of the supply energy and is connected to the symmetrical end clusters at their ends. The unbalanced end terminal 44 is connected by a line 48 to one of the balanced end terminals.

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U66052 ft

When the fire was used for the eleventh time, the signal got drunk, the axial radiator 14 is fed from the probe * 2θ, 'too Hegafcortz, “In 3tandardfirequena” artd for satellite information connection lines. The turnstile 19-13 * receives 4o bits of any of a two frequencies from the 3ender, an Is 149 Hogahertz band as the «standard for 3atelllten-

and the other in 1 ^ 6-1 ^ 8 Mti »· *

hertaband that * trnfl * »eYerblndune * n exhibited 1st. me corresponding garbage lengths οίηά X ^ · 2.o3 ■ and Λ 2 ^s * j

2.19 a · de combined length a ioden of the folded Dipole) ld odor 10 * is then at a vert L between the Half-length values of the two signals selected, which the rotary

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cross arrangement can be initiated «ie L a - ^ V / A ₁ ^ 2 or I.056 m, in order to be able to combine both frequencies, the Broadcast in all directions. It should be pointed out to £ 3 that the folded dipole turnstile arrangement is a has relative broadband characteristics, so that effective radiation is achieved for both frequency ranges.

The above value L * »I.056 m represents approximately the overall transverse dimension of the improved antenna unit. An additional advantage of the invention results from the fact that the folded dipoles provide an unexpectedly suitable direction for pretending or" deforming ¹¹ the radiation pattern of the axial antenna ·

In Fig. 5, satellite 2 is on after stabilization its orbit, so that the axial antenna 14

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is directed vertically erdw'irt3. Dag Strahlongsrauater of the antenna 14, v; ia Juroh changes the 3rvmd3tene, which is represented by the unbroken legs (denoted in Fig. 3.-Bit 2o) of the folded dipoles 13 and 13 *, i3t shown as the main apex βinschilessend the in dashed lines at L * L DA33 ^ft is shown, wherein it clear 1st, the two forms, the separately as L 'and L''are shown, actually a vertical cross-section through a garneirsaasen Drehfestk: Jrper uai the vertical Z represent; obei? this body next: he, d as the tip L bezeicr.net vriri. It is also clear that the ray pattern comprises smaller lobes or ears, which have been omitted from FIG. 5 for greater clarity. The geometrical shape of an aolohen StrahlungsiBUster can be characterized by two angles, such as the VfinkeHK and 3, which together define both the angular deflection of the bisector axes (such as Ii) of the main field intensity from the vertical and the angular width of the tip L. In particular, 2 is the Angle between the tip 3isector:; and the normal Z, and <^ is the angle between the normal and the generatrix (such as Z) of a cone approximately tangent to the inner surface of the solid tip3 L · Ss is desirable in many satellite link programs to have an alignment beam pattern from the satellite create which has a general shape as shown in Fig. 5, ie with a tip of relatively

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narrow width (that is, with a size Ί (£ - / ,,) relatively small) and it is inclined with respect to a vertical line, since a cone which lies approximately tangential to the outer surface of the solid tip L is essentially tangential to the surface of the earth, as displayed at A and B. Such a radiation pattern comprises a "deaf area" which is defined by the inner cone CD of substantial extent and leads to a high concentration of received energy, which is in the remaining useful area between the inner and outer. Cones CD and AB remain, thereby reducing Ir. the power requirement of the satellite transmitter is possible.

The values required for the angles et and Q are in order to generate such a pattern, of course, depend on the mean height of the satellite. Technique as shown in Fig. 1 as Type shown were the paraneters, which could be adjusted by controlling the angle dk - ^ d ü and thereby created a radiation pattern of the desired type (for given values of height and radiated frequency) two ar. the number; the length of the axial antenna and you Distance from the base plane, which was represented by the end face 6. Kit was not inside the limited control options that were available in this way feasible, an optional shape for a particular Satellite altitude and a specific signal frequency

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reach. The antenna system according to the invention provides an additional parameter, whereby the "shaping" of the radiation pattern of the directional antenna of the satellite is considerably facilitated. This additional parameter is the inclination of the sides of the dipole elements 18 and 18 ', ie the angle "fi formed by one of the two side legs, such as 18 A or 18 B of each dipole, with _{respect to the fc} axial direction of the antenna 14. Es shows that the

- additional Qrad of freedom that goes into the construction of the antenna system is introduced by this additional parameter Y, taken together with the parameters H (length of the axial radiator 14) and h (height of the dipole group above the satellite end surface) es möglloh maoht that desired directional radiation characteristics in practical all important cases.

In the practical application mentioned here, it was found that essentially optimal telecommunication conditions are achieved if the angles <K and B in Fig.5 could be made equal to 45 ° and 54 ° (the angular width of the main radiation lobe is then approximately 2 (54 - 45) = 18 °). The mean altitude of the satellite, as it resulted from the chosen orbit, was determined to be approximately 780 kilometers. The fixed frequency for the information signals to be transmitted from the directional antenna 14 was 400

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$ 146605

Megahertz as stated above. Ba is calculated that The high directional characteristics that meet the above values of <* and Ö hai, with the following Parameterveh achieved

H = 59o mm} h «14o mmj Q a ? 8 °.

The combined length of any pole elements, as before determined, is 1.06 mm.

With the aforementioned directional pattern, as by the above given values of 0 \ and S, it is calculated that the concentration of the steeled energy in the already (dashed in FIG. 5) is such that a gain of about 5 db compared to what is achieved with an isotropic directional pattern, i.e. with approximately the same radiation intensity compared to the entire cone between the tangents is given at A and B to the earth's surface. This allows a corresponding reduction in the power supply to the * Radio systems inside the satellite.

From the above description it is clear that the integrated multi-purpose antenna system according to the invention b ^ - has lucid advantages. As a result of the tight functional Interaction between the two independently fed radiation subsets that comprise the system, such as a directional axial radiator and a multi-directional

, the latter partly being the

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level for the former, can, the two subgroups structurally can be combined into a compact unit that can be easily put into a small support structure, such as such as a satellite can be mounted and wired. At the same time, this integration of the two radiation components, by which the invention is characterized, nothing away from the main function of the system, which is to radiate point energy from various sources, each of which has its particular frequency, polarization and Has directional characteristics. Indeed, the special kind of interaction between the two radiators brings an additional one Parameter or a Qrad of the freedom which can be used to determine the radiation characteristics of the directional source improve in the manner described.

It is clear that various modifications can be made in the details of the embodiments as the case may be ! Requirements of a particular field of application for which the invention is to be used. As mentioned earlier, In certain areas of application, it may be desirable for both the radiation components to have directional features each in a different particular direction, and in such cases the multi-directional turnstile radiator may have be replaced by a single directional emitter, or with a directional group of spaced radiators, such as folded dipoles, which, for example, are arranged in an end-fire arrangement

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are built. Various other possibilities will be readily apparent to those skilled in the art.

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Claims (6)

U66052 patent claims: 1. Multiple antenna system, characterized in that it comprises a first radiating element (14), a second radiating element (18), one point (M) of which is grounded and located in the vicinity of the first element so as to form an earth plane therefor, wherein the first element in connection with the earth plane (18) has a first predetermined beam characteristic and the second element has a different and different beam characteristic, a means of drawing radio frequency energy from a first source between a point of the first element (14) and earth introduce radiation in accordance with the first characteristic, and means for supplying radio frequency energy from another source to a point of said second element at the same time for radiating in accordance with the said other characteristic, whereby energy from both sources (4o), (42) and can be radiated independently with the different characteristics. 2. Antenna system according to claim 1, characterized in that the first radiating element (14) in context with the earth plane (18) has a directional characteristic, while the second element (18 A, 18 B) has a substantially has characteristics that radiate in all directions. -24- 909848/0126 BATH ORIGINAL Ί466052 IS 3. Antenna system according to claims 1 or 2, characterized in that the first radiating element (14) has an axial conductor (26) which is fed at one end and the second radiating element has a folded dipole (18) whose center (m) is grounded and lies in a plane generally perpendicular to said axial conductor (26), the earthed Center point (M) near the feeding end of the axial Conductor lies and means (PQ) are provided to take energy f from said second source (42) in a l8o ° phase-shifted relationship over those in close proximity To lead ends of the folded dipole 4. Sin antenna system according to claim 2, characterized in that the «rat · radiating element (14) has an axial Has conductor (26) which is fed at one end and the second radiator (13) consists of two folded dipoles (ISA, 18 B) whose centers (M) are grounded and which lie in a cross relation in a plane which is generally perpendicular to the axial conductor (26) and with the grounded centers of it near the Feed end (42, 42 ') of the axial conductor (26), wherein Means are provided in the energy of the said Source about the closely spaced To supply the ends of a folded dipole in 180 ° phase reversal ratio and to supply means, including energy from the second source 116er al · tightly packed loads BATH ORIGINAL -as 100841/0126 14ÖÖ052 of the other folded dipole in 180 ° phase-shifted relation and in phase quadrature relation to the Feeding the energy to the said first dipole » 5. An antenna system according to claims 4 or 5, characterized in that energy from said second source (42) to said or each folded dipole via a symmetry device (} 4) which is arranged to have a 13o ° phase shift between the symmetrical end terminals thereof brings in, which are connected to the supply terminals (42) of the dipole. 6. Antenna system according to any one of the claims 3 to 5, characterized in that the sides of the or of the folded dipoles are bent at a predetermined inclination angle to the plane perpendicular to the axial conductor (26) in a direction from the axial Head (26) is away. 7, antenna system according to any one of the claims 1 to 6, characterized in that e «is arranged on board a spacecraft, e.g. a satellite. 3t! "Tenrfachantenntnsyet · *, characterized in that the essentials are as described herein as written uafc ·! · Note on and wi · Xn Pi«, 2, Fig, 3 or Pig 4, 4 and 6 of the accompanying drawings. 00 9 8 48/0128 BAD ORIGINAL • Sun ·