EP0381037A1 - Antenna system - Google Patents

Antenna system Download PDF

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Publication number
EP0381037A1
EP0381037A1 EP90101435A EP90101435A EP0381037A1 EP 0381037 A1 EP0381037 A1 EP 0381037A1 EP 90101435 A EP90101435 A EP 90101435A EP 90101435 A EP90101435 A EP 90101435A EP 0381037 A1 EP0381037 A1 EP 0381037A1
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EP
European Patent Office
Prior art keywords
reflector
antenna system
auxiliary
operating wavelength
auxiliary reflector
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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.)
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EP90101435A
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German (de)
French (fr)
Inventor
Gebhard Vogt
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Siemens Schweiz AG
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Siemens Albis AG
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Publication of EP0381037A1 publication Critical patent/EP0381037A1/en
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    • 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
    • H01Q19/18—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 having two or more spaced reflecting surfaces
    • H01Q19/19—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 having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/195—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 having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein a reflecting surface acts also as a polarisation filter or a polarising device

Definitions

  • the invention relates to an antenna system with a main reflector and an at least approximately hyperbolic auxiliary reflector, in the focus of which a primary radiator for the transmission and reception of electromagnetic waves with linear polarization is arranged, and in which the auxiliary reflector is designed such that it the polarization plane of the electromagnetic waves rotates by 90 °.
  • Such antennas are shown, for example, in European Patent 0 021 866 and are mostly intended for target radar systems.
  • Target tracking radar systems which are used to track one or more targets, require fast frequency hops in the entire transmission frequency bandwidth in certain tracking phases. This results in high demands on the uniformity of the radiation characteristics of the antenna system in the range of the operating frequency, which is limited in particular by diffraction effects of the incident electromagnetic waves at the auxiliary reflector.
  • the invention consists in that the auxiliary reflector consists of an at least approximately hyperbolic-shaped metallic support body, the surface of which faces the main reflector is provided with a layer of a low-loss dielectric of such thickness that it is at least approximated electrically corresponds to a quarter of the operating wavelength, and on the surface facing the main reflector, a parallel line grid of conductive wires is preferably applied at a grid spacing which corresponds electrically to about a sixth of the operating wavelength, and that the main reflector is also a line reflector, which consists of a plurality of parallel arranged conductive wires, which are attached to a dielectric absorbent support body, preferably with a grid spacing of the wires about a twelfth of the operating wavelength.
  • the sensitivity to the spillover and diffraction effect on the auxiliary reflector is largely reduced and thus the bandwidth of the radiation characteristics of the antenna system is increased.
  • the use of absorbent material for the carrier body of the main reflector has the advantage that those of the incident electromagnetic waves are absorbed, those whose polarization plane is not parallel to the conductive wires.
  • the inventive choice of the grid spacing on the main reflector largely achieves frequency independence in the reflection behavior of the electromagnetic waves for the working bandwidth, the polarization plane of which coincide with the direction of the wires.
  • the grid spacing on the auxiliary reflector is selected according to the invention so that the most exact possible phase rotation of the shafts by 90 ° can be maintained over the entire working bandwidth.
  • the diameter of the wires at the auxiliary reflector is 0.2 mm at an operating wavelength in the cm range, and the diameter of the wires at the main parabolic reflector is 0.25 mm.
  • the dielectric on the auxiliary reflector consists of polytetrafluoroethylene, the thickness of which is 3.55 mm at an operating wavelength in the cm range. This ensures rotation of the polarization plane by 90 ° of the electromagnetic waves over the entire working range.
  • the conductive wires of the main parabolic reflector and the auxiliary reflector consist of copper.
  • the copper wires can advantageously be coated with a protective layer in order to avoid chemical reactions on their surface.
  • the auxiliary reflector is carried by a conical plastic construction attached to the tapering end surface of the main parabolic reflector.
  • This conical support structure offers the advantage that the auxiliary reflector is extremely stable in position. Furthermore, this construction also offers weather protection for the antenna system.
  • the material of the plastic construction is chosen such that the incident or radiated waves are not affected.
  • the primary radiator consists of four individual radiators combined to form an overall radiator.
  • the overall radiator is rotated with respect to its horizontal axis of symmetry so that its polarization plane is rotated by 90 ° with respect to the polarization plane of the incident waves.
  • the total emitter has good cross-polarization suppression, it is insensitive to the waves diffracted at the auxiliary reflector, the polarization direction of which is rotated by 90 ° with respect to the emitted wave.
  • the antenna system shown in FIG. 1 comprises a primary radiator 1, a main reflector 3 and an auxiliary reflector 2.
  • the main reflector 3 forms a stable unit with a carrier body 6.
  • the auxiliary reflector 2 is connected to the end faces of the main reflector 3 via a conical carrier body 4, as a result of which the auxiliary reflector is fixed in its position in an extremely stable manner.
  • the primary radiator 1 is arranged such that its center of radiation coincides with the real focal point of the at least approximately hyperbolic auxiliary reflector 2.
  • the main reflector 3, which is designed as a paraboloid cut-out, is arranged such that its focal point coincides with the virtual focal point of the auxiliary reflector 2.
  • the exact shape of the reflectors and the primary radiator 1 are coordinated with one another in such a way that an at least approximately flat phase front results in the aperture plane of the main reflector 3.
  • the main reflector 3 is intended for the reflection of linearly polarized waves.
  • the auxiliary reflector 2 rotates the waves incident on it in such a way that the reflected waves are rotated by 90 ° in their polarization plane.
  • the main reflector 3 consists of a dielectrically absorbing carrier body 31, on the inside of which a line grid of conductive wires 32 is attached.
  • the direction of the line grid on the main reflector 3 is arranged such that it corresponds to the direction of the plane of polarization of the wave, which is reflected by the auxiliary reflector 2.
  • the grid spacing D of the conductive wires 32 on the main reflector 3 is preferably one twelfth of the mean operating wavelength. This advantageously results in a favorable reflection behavior of those waves whose polarization plane is parallel to the line pattern of the main reflector 3.
  • the value for the grid spacing D is advantageously 1.2 mm.
  • Optimal reflection behavior of the main reflector 3 largely independent of the wavelength selected within the working bandwidth, results from the fact that the diameter of the conductive wires 32 at the main reflector 3 is 0.25 mm. Since the carrier body 31 of the main reflector 3 consists of an absorbing dielectric, the main reflector 3 acts like a polarization filter. In this case, those waves whose polarization plane deviates from the direction of the conductive wires 32 are absorbed.
  • the auxiliary reflector 2 shown in an enlarged representation in FIG. 3 consists of a carrier body 21 which has an approximate hyperbolic surface. This surface is coated with a low-loss dielectric 22, the electrical thickness of which preferably corresponds to approximately a quarter of the mean operating wavelength.
  • This dielectric 22 preferably consists of polytetrafluoroethylene, which is known under the trade names "Teflon" from Dupont.
  • a line grid of conductive, parallel-guided wires 23 is applied to the dielectric 22 and is arranged in such a grid spacing d of adjacent wires 23 that this is approximately electrical corresponds to a sixth of the operating wavelength. For an operating wavelength in the cm range, this distance d is preferably 2.55 mm.
  • the choice of the preferred grid spacing d of the conductive wires 23 prevents the virtual reflection plane from penetrating into the dielectric 22, thereby avoiding a deterioration in the efficiency of the antenna system.
  • Teflon is used as the dielectric 22
  • the thickness of the dielectric layer for an operating wavelength in the cm range advantageously results in a value of 3.55 mm.
  • the direction of the line grid 23 is rotated by 45 ° with respect to the direction of the polarization plane of the primary radiator 1. Due to the advantageous design of the auxiliary reflector 2, a constant rotation of the polarization plane by 90 ° of the electromagnetic waves is largely achieved over the entire transmission bandwidth.
  • the carrier body 21 is preferably made of an aluminum alloy.
  • the carrier body 31 of the main reflector 3 is also of lightweight construction, i. H. that the absorbent dielectric 31 consists of a honeycomb structure.
  • the tapered end faces of the main reflector 3 are connected to the carrier body 21 of the auxiliary reflector 2 via a conical plastic construction 4.
  • This plastic construction consists of a material that enables unimpeded penetration of the electromagnetic waves.
  • the primary radiator 1 As shown in FIG. 4, consists of four individual radiators A, B, C, D combined to form an overall radiator.
  • the primary radiator 1 is then in its axis of symmetry 5 by 90 ° with respect to the plane of polarization falling shaft rotated.
  • the primary radiator 1 is insensitive to the radiation incident through diffraction and spill-over effects on the auxiliary reflector 2. In this way, the frequency dependence of the radiation diagrams is reduced to a minimum value.

Abstract

The invention relates to an antenna system having a main reflector 3 and an at least approximately hyperbolic auxiliary reflector 2 which is designed such that it rotates the polarisation plane of the electromagnetic waves emitted by a primary emitter 1 through 90 DEG . The metallic supporting body 21 of the auxiliary reflector 2 has a layer consisting of a low-loss dielectric 22 on which there is fitted a parallel line grid of conductive wires 23 at a grid spacing d which electrically corresponds approximately to one sixth of the operating wavelength. This results in a phase rotation of the waves through 90 DEG which is as exact as possible over the complete operating bandwidth. The main reflector 3 consists of a dielectrically absorbent supporting body 31 on which there are fitted a large number of conductive wires 32, arranged parallel to one another, whose grid spacing D is selected such that it corresponds approximately to one twelfth of the operating wavelength. The design according to the invention advantageously results in the reflection characteristic for the electromagnetic waves being largely independent of frequency for the operating bandwidth of the antenna system. <IMAGE>

Description

Die Erfindung betrifft ein Antennensystem mit einem Hauptre­flektor und einem zumindest angenähert hyperbolischen Hilfsre­flektor, in dessen Brennpunkt ein Primärstrahler für das Senden und Empfangen von elektromagnetischen Wellen mit line­arer Polarisation angeordnet ist, und bei dem der Hilfsreflek­tor derart ausgebildet ist, daß er die Polarisationsebene der elektromagnetischen Wellen um 90° dreht. Solche Antennen sind beispielsweise in der europäischen Patenschrift 0 021 866 gezeigt und meist für Zielfolgeradaranlagen bestimmt.The invention relates to an antenna system with a main reflector and an at least approximately hyperbolic auxiliary reflector, in the focus of which a primary radiator for the transmission and reception of electromagnetic waves with linear polarization is arranged, and in which the auxiliary reflector is designed such that it the polarization plane of the electromagnetic waves rotates by 90 °. Such antennas are shown, for example, in European Patent 0 021 866 and are mostly intended for target radar systems.

Zielfolgeradaranlagen, die der Verfolgung eines oder mehrerer Ziele dienen, verlangen in bestimmten Verfolgungsphasen schnel­le Frequenzsprünge in der gesamten Sendefrequenzbandbreite. Da­raus ergeben sich hohe Ansprüche an die Gleichförmigkeit der Strahlungscharakteristik des Antennensystems im Bereich der Betriebsfrequenz, die insbesondere durch Beugungseffekte der einfallenden elektromagnetischen Wellen am Hilfsreflektor eingeschränkt wird.Target tracking radar systems, which are used to track one or more targets, require fast frequency hops in the entire transmission frequency bandwidth in certain tracking phases. This results in high demands on the uniformity of the radiation characteristics of the antenna system in the range of the operating frequency, which is limited in particular by diffraction effects of the incident electromagnetic waves at the auxiliary reflector.

Ausgehend von einem Antennensystem, der einleitend beschrie­benen Art, besteht die Erfindung darin, daß der Hilfsreflek­tor aus einem zumindest angenähert hyperbolisch geformten, me­tallischen Trägerkörper besteht, dessen dem Hauptreflektor zugewandte Oberfläche mit einer Schicht aus einem verlustarmen Dielektrikum solcher Dicke versehen ist, daß diese zumindest angenähert elektrisch einem Viertel der Betriebswellenlänge entspricht, und auf dessen dem Hauptreflektor zugewandten Oberfläche ein paralleles Linienraster aus leitenden Drähten vorzugwsweise in einem Rasterabstand aufgebracht ist, der elek­trisch etwa einem Sechstel der Betriebswellenlänge entspricht, und daß der Hauptreflektor ebenfalls ein Linienreflektor ist, der aus einer Vielzahl parallel angeordneter leitender Drähte besteht, die auf einem dielektrisch absorbierenden Trägerkörper angebracht sind, vorzugweise mit einem Rasterabstand der Drähte von etwa einem Zwölftel der Betriebswellenlänge.Starting from an antenna system of the type described in the introduction, the invention consists in that the auxiliary reflector consists of an at least approximately hyperbolic-shaped metallic support body, the surface of which faces the main reflector is provided with a layer of a low-loss dielectric of such thickness that it is at least approximated electrically corresponds to a quarter of the operating wavelength, and on the surface facing the main reflector, a parallel line grid of conductive wires is preferably applied at a grid spacing which corresponds electrically to about a sixth of the operating wavelength, and that the main reflector is also a line reflector, which consists of a plurality of parallel arranged conductive wires, which are attached to a dielectric absorbent support body, preferably with a grid spacing of the wires about a twelfth of the operating wavelength.

Aufgrund der besonderen Ausgestaltung des Antennensystems wird die Empfindlichkeit auf den Spillover und Beugungseffekt am Hilfsreflektor weitgehend reduziert und somit die Bandbreite der Strahlungscharakteristik des Antennensystems erhöht. Die Verwendung von absorbierenden Material für den Trägerkörper des Hauptreflektors den Vorteil, daß von den einfallenden elektro­magnetischen Wellen, diejenigen absorbiert werden, deren Pola­risationsebene nicht parallel zu den leitenden Drähten liegt. Außerdem wird wegen des geringen spezifischen Gewichtes des Dielektrikums im Vergleich zu einem Reflektor aus Vollmetall bei gleicher oder höherer Formstabilität dessen Gewicht nicht nachteilig erhöht. Durch die erfindungsgemaße Wahl der Raster­abstände am Hauptreflektor wird für die Arbeitsbandbreite weit­gehend eine Frequenzunabhängigkeit im Reflexionsverhalten der elektromagnetischen Wellen erreicht, deren Polarisationsebene mit der Richtung der Drähte übereinstimmen. Der Rasterabstand am Hilfsreflektor ist erfindungsgemäß so gewählt, daß eine möglichst exakte Phasendrehung der Wellen um 90° über die gesamte Arbeitsbandbreite beibehalten werden kann.Due to the special design of the antenna system, the sensitivity to the spillover and diffraction effect on the auxiliary reflector is largely reduced and thus the bandwidth of the radiation characteristics of the antenna system is increased. The use of absorbent material for the carrier body of the main reflector has the advantage that those of the incident electromagnetic waves are absorbed, those whose polarization plane is not parallel to the conductive wires. In addition, because of the low specific weight of the dielectric compared to a reflector made of full metal with the same or higher dimensional stability, its weight is not disadvantageously increased. The inventive choice of the grid spacing on the main reflector largely achieves frequency independence in the reflection behavior of the electromagnetic waves for the working bandwidth, the polarization plane of which coincide with the direction of the wires. The grid spacing on the auxiliary reflector is selected according to the invention so that the most exact possible phase rotation of the shafts by 90 ° can be maintained over the entire working bandwidth.

Um ein besonders günstiges Reflexions- und Phasenverhalten des Antennensystems zu erhalten, beträgt bei einer Betriebswellen­länge im cm - Bereich der Durchmesser der Drähte am Hilfsre­flektor 0,2 mm, der Durchmesser der Drähte am Hauptparabolre­flektor 0,25 mm.In order to obtain a particularly favorable reflection and phase behavior of the antenna system, the diameter of the wires at the auxiliary reflector is 0.2 mm at an operating wavelength in the cm range, and the diameter of the wires at the main parabolic reflector is 0.25 mm.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung besteht das Dielektrikum am Hilfsreflektor aus Polytetraflour­ethylen, dessen Dicke bei einer Betriebswellenlänge im cm - Be­reich 3,55 mm beträgt. Dadurch wird über die gesamte Arbeits­bandbreite eine Drehung der Polarisationsebene um 90° der elektromagnetischen Wellen sichergestellt.In a further advantageous embodiment of the invention, the dielectric on the auxiliary reflector consists of polytetrafluoroethylene, the thickness of which is 3.55 mm at an operating wavelength in the cm range. This ensures rotation of the polarization plane by 90 ° of the electromagnetic waves over the entire working range.

Günstige Reflexionseigenschaften bei geringem Aufwand werden dadurch erreicht, daß die leitenden Drähte des Hauptparabolre­flektors und des Hilfsreflektors aus Kupfer bestehen. Die Kup­ferdrähte können dabei vorteilhaft mit einer Schutzschicht überzogen sein, um chemische Reaktionen an deren Oberfläche zu vermeiden.Favorable reflection properties with little effort are achieved in that the conductive wires of the main parabolic reflector and the auxiliary reflector consist of copper. The copper wires can advantageously be coated with a protective layer in order to avoid chemical reactions on their surface.

Um eine stabile, aber auch leichte Bauweise des Antennensystems zu erhalten, ist der Hilfsreflektor von einer an der auslaufen­den Endfläche des Hauptparabolreflektors befestigten konusför­migen Kunststoffkonstruktion getragen. Diese konusförmige Trä­gerkonstruktion bietet den Vorteil, daß der Hilfsreflektor überaus stabil in seiner Lage befestigt ist. Desweiteren bietet diese Konstruktion auch einen Witterungsschutz für das Anten­nensystem. Das Material der Kunststoffkonstruktion ist dabei derart gewählt, daß die einfallenden bzw. abgestrahlten Wellen nicht beeinflußt werden.In order to obtain a stable but also lightweight construction of the antenna system, the auxiliary reflector is carried by a conical plastic construction attached to the tapering end surface of the main parabolic reflector. This conical support structure offers the advantage that the auxiliary reflector is extremely stable in position. Furthermore, this construction also offers weather protection for the antenna system. The material of the plastic construction is chosen such that the incident or radiated waves are not affected.

Wird das Antennensystem in einen Monopulsradarsystem mit Spie­gelunterdrückung verwendet, besteht der Primärstrahler aus vier zu einem Gesamtstrahler zusammengefügten Einzelstrahlern. Der Gesamtstrahler ist dabei hinsichtlich seiner horizontalen Syme­trieachse so gedreht, daß dessen Polarisationsebene gegenüber der Polarisationsebene der einfallenden Wellen um 90° gedreht ist. Besitzt der Gesamtstrahler eine gute Kreuzpolarisations­unterdrückung, ist er gegen die am Hilfsreflektor gebeugten Wellen, deren Polarisationsrichtung um 90° gegenüber der ausgestrahlten Welle gedreht ist, unempfindlich.If the antenna system is used in a monopulse radar system with mirror suppression, the primary radiator consists of four individual radiators combined to form an overall radiator. The overall radiator is rotated with respect to its horizontal axis of symmetry so that its polarization plane is rotated by 90 ° with respect to the polarization plane of the incident waves. If the total emitter has good cross-polarization suppression, it is insensitive to the waves diffracted at the auxiliary reflector, the polarization direction of which is rotated by 90 ° with respect to the emitted wave.

Anhand von Zeichnungen wird ein Antennensystem nach der Erfindung näher erläutert.

  • Die Figur 1 zeigt eine Seitenansicht des erfindungsgemäßen An­tennensystems.
  • Die Figur 2 zeigt einen Querschnitt durch das Antennensystem, das erfindungsgemäß ausgebildet ist.
  • In der Figur 3 ist ein Querschnitt des Hilfsreflektors nach Figur 1 in vergrößerter Darstellung wiedergegeben.
  • Figur 4 zeigt einen Primärstrahler bei einer Ausbildung als An­tennensystem für ein Monopulsradarsystem.
An antenna system according to the invention is explained in more detail with reference to drawings.
  • FIG. 1 shows a side view of the antenna system according to the invention.
  • FIG. 2 shows a cross section through the antenna system which is designed according to the invention.
  • FIG. 3 shows a cross section of the auxiliary reflector according to FIG. 1 in an enlarged view.
  • FIG. 4 shows a primary radiator designed as an antenna system for a monopulse radar system.

Das in Figur 1 dargestellte Antennensystem umfaßt einen Primär­strahler 1, einen Hauptreflektor 3 und einen Hilfsreflektor 2. Der Hauptreflektor 3 bildet mit einem Trägerkörper 6 eine sta­bile Einheit. Der Hilfsreflektor 2 ist über einen konusförmi­gen Trägerkörper 4 mit den Endflächen des Hauptreflektors 3 verbunden, wodurch der Hilfsreflektor überaus stabil in sei­ner Lage befestigt ist.The antenna system shown in FIG. 1 comprises a primary radiator 1, a main reflector 3 and an auxiliary reflector 2. The main reflector 3 forms a stable unit with a carrier body 6. The auxiliary reflector 2 is connected to the end faces of the main reflector 3 via a conical carrier body 4, as a result of which the auxiliary reflector is fixed in its position in an extremely stable manner.

Anhand von Figur 2 sind weitere Einzelheiten des Antennensy­stems erkennbar. Der Primärstrahler 1 ist derart angeordnet, daß dessen Strahlungsschwerpunkt mit dem reellen Brennpunkt des zumindest angenähert hyperbolischen Hilfsreflektors 2 zusammen­fällt. Der Hauptreflektor 3, der als Paraboloidausschnitt aus­gebildet ist, ist derart angeordnet, daß dessen Brennpunkt mit dem virtuellen Brennpunkt des Hilfsreflektors 2 zusammenfällt. Die exakte Formgebung der Reflektoren und des Primärstrahlers 1 sind derart aufeinander abgestimmt, daß sich in der Aperturebe­ne des Hauptreflektors 3 eine wenigstens annähernd ebene Pha­senfront ergibt. Der Hauptreflektor 3 ist für die Reflexion linear polarisierter Wellen bestimmt. Der Hilfsreflektor 2 dreht die auf ihn einfallenden Wellen derart, daß die reflek­tierten Wellen in ihrer Polarisationsebene um 90° gedreht sind. Beispielsweise derart, daß vertikal polarisierte Wellen in horizontal polarisierte gedreht werden. Der Hauptreflektor 3 besteht aus einem dielektrisch absorbierenden Trägerkörper 31, auf dessen Innenseite ein Linienraster aus leitenden Drähten 32 angebracht ist. Dabei ist die Richtung des Linienrasters am Hauptreflektor 3 so angeordnet, daß sie mit der Richtung der Polatisationsebene der Welle, die vom Hilfsreflektor 2 reflek­tiert wird, übereinstimmt. Der Rasterabstand D der leitenden Drähte 32 am Hauptreflektor 3 beträgt vorzugsweise ein Zwölf­tel der mittleren Betriebswellenlänge. Dadurch wird vorteil­haft ein günstiges Reflexionsverhalten jener Wellen erreicht, deren Polarisationsebene parallel zum Linienraster des Hauptre­flektors 3 legen. Für eine Betriebswellenlänge im cm - Bereich ergibt sich für den Rasterabstand D vorteilhaft ein Wert von 1,2 mm. Optimales Reflexionsverhalten des Hauptreflektors 3, weitgehend unabhängig von der innerhalb der Arbeitsbandbreite gewählten Wellenlänge ergibt sich dadurch, daß der Durchmesser der leitenden Drähte 32 am Hauptreflektor 3 0,25 mm beträgt. Da der Trägerkörper 31 des Hauptreflektors 3 aus einem absor­bierenden Dielektrikum besteht, wirkt der Hauptreflektor 3 wie ein Polarisationsfilter. Dabei werden jene Wellen, deren Pola­risationsebene von der Richtung der leitenden Drähte 32 ab­weicht, absorbiert.Further details of the antenna system can be seen from FIG. The primary radiator 1 is arranged such that its center of radiation coincides with the real focal point of the at least approximately hyperbolic auxiliary reflector 2. The main reflector 3, which is designed as a paraboloid cut-out, is arranged such that its focal point coincides with the virtual focal point of the auxiliary reflector 2. The exact shape of the reflectors and the primary radiator 1 are coordinated with one another in such a way that an at least approximately flat phase front results in the aperture plane of the main reflector 3. The main reflector 3 is intended for the reflection of linearly polarized waves. The auxiliary reflector 2 rotates the waves incident on it in such a way that the reflected waves are rotated by 90 ° in their polarization plane. For example, such that vertically polarized waves in horizontally polarized. The main reflector 3 consists of a dielectrically absorbing carrier body 31, on the inside of which a line grid of conductive wires 32 is attached. The direction of the line grid on the main reflector 3 is arranged such that it corresponds to the direction of the plane of polarization of the wave, which is reflected by the auxiliary reflector 2. The grid spacing D of the conductive wires 32 on the main reflector 3 is preferably one twelfth of the mean operating wavelength. This advantageously results in a favorable reflection behavior of those waves whose polarization plane is parallel to the line pattern of the main reflector 3. For an operating wavelength in the cm range, the value for the grid spacing D is advantageously 1.2 mm. Optimal reflection behavior of the main reflector 3, largely independent of the wavelength selected within the working bandwidth, results from the fact that the diameter of the conductive wires 32 at the main reflector 3 is 0.25 mm. Since the carrier body 31 of the main reflector 3 consists of an absorbing dielectric, the main reflector 3 acts like a polarization filter. In this case, those waves whose polarization plane deviates from the direction of the conductive wires 32 are absorbed.

Der in Figur 3 in vergrößerter Darstellung gezeigte Hilfsre­flektor 2 besteht aus einem Trägerkörper 21, der eine angenäh­erte hyperbolische Oberfläche aufweist. Diese Oberfläche ist mit einem verlustarmen Dielektrikum 22 beschichtet, dessen elektrische Dicke vorzugsweise etwa einem Viertel der mittleren Betriebswellenlänge entspricht. Dieses Dielektrikum 22 besteht vorzugsweise aus Polytetraflourethylen, das unter den Handels­namen "Teflon" der Firma Dupont bekannt ist. Auf dem Dielektri­kum 22 ist ein Linenraster aus leitenden, parrallelgeführten Drähten 23 aufgebracht und in einem solchen Rasterabstand d be­nachbarter Drähte 23 angeordnet, daß dieser elektrisch etwa einem Sechstel der Betriebswellenlänge entspricht. Für eine Betriebswellenlänge im cm - Bereich beträgt dieser Abstand d vorzugsweise 2,55 mm. Durch die Wahl des bevorzugten Rasterab­standes d der leitenden Drähte 23 wird ein Eindringen der vir­tuellen Reflexionsebene in das Dielektrikum 22 verhindert, wo­durch eine Verschlechterung des Wirkungsgrades des Antennensy­stems vermieden wird. Wird Teflon als Dielektrikum 22 verwen­det, ergibt für die Dicke der Dielektrikumsschicht für eine Be­triebswellenlänge im cm - Bereich, vorteilhaft ein Wert von 3,55 mm. Um die Polarisationsebene der elektromagnetischen Wel­len am Hilfsreflektor 2 um 90° zu drehen, ist die Richtung des Linienrasters 23 gegenüber der Richtung der Polarisationsebene des Primärstrahlers 1 um 45° gedreht. Durch die vorteilhafte Ausbildung des Hilfsreflektors 2 wird weitgehend eine konstante Drehung der Polarisationsebene um 90° der elektromagnetischen Wellen über die gesamte Sendebandbreite erreicht. Um ein gerin­ges Gewicht des Hilfsreflektors 2 zu erhalten, besteht der Trä­gerkörper 21 vorzugsweise aus einer Aluminiumlegierung.The auxiliary reflector 2 shown in an enlarged representation in FIG. 3 consists of a carrier body 21 which has an approximate hyperbolic surface. This surface is coated with a low-loss dielectric 22, the electrical thickness of which preferably corresponds to approximately a quarter of the mean operating wavelength. This dielectric 22 preferably consists of polytetrafluoroethylene, which is known under the trade names "Teflon" from Dupont. A line grid of conductive, parallel-guided wires 23 is applied to the dielectric 22 and is arranged in such a grid spacing d of adjacent wires 23 that this is approximately electrical corresponds to a sixth of the operating wavelength. For an operating wavelength in the cm range, this distance d is preferably 2.55 mm. The choice of the preferred grid spacing d of the conductive wires 23 prevents the virtual reflection plane from penetrating into the dielectric 22, thereby avoiding a deterioration in the efficiency of the antenna system. If Teflon is used as the dielectric 22, the thickness of the dielectric layer for an operating wavelength in the cm range advantageously results in a value of 3.55 mm. In order to rotate the polarization plane of the electromagnetic waves on the auxiliary reflector 2 by 90 °, the direction of the line grid 23 is rotated by 45 ° with respect to the direction of the polarization plane of the primary radiator 1. Due to the advantageous design of the auxiliary reflector 2, a constant rotation of the polarization plane by 90 ° of the electromagnetic waves is largely achieved over the entire transmission bandwidth. In order to keep the auxiliary reflector 2 light in weight, the carrier body 21 is preferably made of an aluminum alloy.

Der Trägerkörper 31 des Hauptreflektors 3 ist ebenfalls in Leichtbauweise ausgeführt, d. h. daß das absorbierende Dielek­trikum 31 aus einer wabenförmigen Konstruktion besteht.The carrier body 31 of the main reflector 3 is also of lightweight construction, i. H. that the absorbent dielectric 31 consists of a honeycomb structure.

Um den Hilfsreflektor 2 besonders stabil in seiner Lage zu be­festigen, sind die auslaufenden Endflächen des Hauptreflektors 3 über eine konusförmige Kunststoffkonstruktion 4 mit dem Trä­gerkörper 21 des Hilfsreflektors 2 verbunden. Diese Kunststoff­konstruktion besteht aus einem Material, das eine ungehinderte Durchdringung der elektromagnetischen Wellen ermöglicht.In order to fix the auxiliary reflector 2 in a particularly stable position, the tapered end faces of the main reflector 3 are connected to the carrier body 21 of the auxiliary reflector 2 via a conical plastic construction 4. This plastic construction consists of a material that enables unimpeded penetration of the electromagnetic waves.

Findet das Antennensystem in einem Monopulsradarsystem Anwen­dung, besteht der Primärstrahler 1, wie in Figur 4 dargestellt ist, aus vier zu einem Gesamtstrahler zusammengefügten Einzel­strahlern A,B,C,D. Der Primärstrahler 1 ist dann in seiner Sy­metrieachse 5 um 90° gegenüber der Polarisationsebene der ein­ fallenden Welle gedreht. Dadurch ist der Primärstrahler 1 ge­genüber der durch Beugung und Spill-over-Effekte am Hilfsre­flektor 2 einfallenden Strahlung unempfindlich. Auf diese Weise wird die Frequenzabhängigkeit der Strahlungsdiagramme auf einen minimalen Wert reduziert.If the antenna system is used in a monopulse radar system, the primary radiator 1, as shown in FIG. 4, consists of four individual radiators A, B, C, D combined to form an overall radiator. The primary radiator 1 is then in its axis of symmetry 5 by 90 ° with respect to the plane of polarization falling shaft rotated. As a result, the primary radiator 1 is insensitive to the radiation incident through diffraction and spill-over effects on the auxiliary reflector 2. In this way, the frequency dependence of the radiation diagrams is reduced to a minimum value.

Claims (7)

1. Antennensystem mit einem Hauptreflektor und einem zumindest angenähert hyperbolischen Hilfsreflektor, in dessen Brennpunkt ein Primärstrahler für das Senden und Empfangen von elektromag­netischen Wellen mit linearer Polarisation angeordnet ist, und bei dem der Hilfsreflektor derart ausgebildet ist, daß er die Polarisationsebene der elektromagnetischen Wellen um 90° dreht, dadurch gekennzeichnet, daß der Hilfs­reflektor (2) aus einem zumindest angenähert hyperbolisch ge­formten, metallischen Trägerkörper (21) besteht, dessen dem Hauptreflektor (3) zugewandte Oberfläche mit einer Schicht aus einem verlustarmen Dielektrikum (22) solcher Dicke versehen ist, daß diese zumindest angenähert elektrisch einem Viertel der Betriebswellenlänge entspricht, und auf dessen dem Hauptre­flektor zugewandten Oberfläche ein paralleles Linienraster aus leitenden Drähten (23) vorzugwsweise in einem Rasterabstand (D) aufgebracht ist, der elektrisch etwa einem Sechstel der Be­triebswellenlänge entspricht, und daß der Hauptreflektor (3) ebenfalls ein Linienreflektor ist, der aus einer Vielzahl parallel angeordneter leitender Drähte (32) besteht, die auf einem dielektrisch absorbierenden Trägerkörper (31) angebracht sind, vorzugweise mit einem Rasterabstand (D) der Drähte (32) von etwa einem Zwölftel der Betriebswellenlänge.1. Antenna system with a main reflector and an at least approximately hyperbolic auxiliary reflector, in the focal point of which a primary radiator for the transmission and reception of electromagnetic waves with linear polarization is arranged, and in which the auxiliary reflector is designed in such a way that it adjusts the polarization plane of the electromagnetic waves by 90 ° rotates, characterized in that the auxiliary reflector (2) consists of an at least approximately hyperbolic-shaped, metallic support body (21), the surface of which faces the main reflector (3) is provided with a layer of a low-loss dielectric (22) such that this corresponds at least approximately electrically to a quarter of the operating wavelength, and on the surface facing the main reflector a parallel line grid of conductive wires (23) is preferably applied at a grid spacing (D) which is electrically approximately one sixth of the operating wavelength e nn, and that the main reflector (3) is also a line reflector, which consists of a plurality of parallel arranged conductive wires (32) which are attached to a dielectric absorbing carrier body (31), preferably with a grid spacing (D) of the wires (32 ) of about one twelfth of the operating wavelength. 2. Antennensystem nach Anspruch 1, dadurch ge­kennzeichnet, daß bei einer Betriebswellenlänge im cm - Bereich, der Durchmesser der Drähte (23) des Hilfsre­flektors (2) 0,2 mm, der Durchmesser der Drähte (32) des Haupt­reflektors (3) 0,25 mm beträgt.2. Antenna system according to claim 1, characterized in that at an operating wavelength in the cm range, the diameter of the wires (23) of the auxiliary reflector (2) 0.2 mm, the diameter of the wires (32) of the main reflector (3) 0, Is 25 mm. 3. Antennensystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das Dielektrikum (22) des Hilfsreflektors (2) aus Polytetrafloure­thylen besteht.3. Antenna system according to one of the preceding claims, characterized in that the dielectric (22) of the auxiliary reflector (2) consists of polytetrafluoroethylene. 4. Antennensystem nach Anspruch 4, dadurch ge­kennzeichnet, daß bei Betriebswellenlänge im cm - Bereich die Schichtdicke des Dielektrikums (22) am Hilfsreflek­tor (3) 3,55 mm beträgt.4. Antenna system according to claim 4, characterized in that at the operating wavelength in the cm range, the layer thickness of the dielectric (22) on the auxiliary reflector (3) is 3.55 mm. 5. Antennensystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die leiten­den Drähte (32,23) des Haupt- und des Hilfsreflektors (3,2) aus Kupfer bestehen.5. Antenna system according to one of the preceding claims, characterized in that the conductive wires (32,23) of the main and auxiliary reflectors (3,2) consist of copper. 6. Antennensystem nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Hilfs­reflektor (2) über eine an der auslaufenden Endfläche des Hauptreflektors (3) befestigte, konusförmige Kunststoffkon­struktion (4) getragen ist.6. Antenna system according to one of the preceding claims, characterized in that the auxiliary reflector (2) on a tapered end surface of the main reflector (3) attached, conical plastic structure (4) is carried. 7. Antennensystem nach einem der vorhergehenden Ansprüche, daurch gekennzeichnet, daß bei einer Ausbildung als Antennensystem für ein Monopulsradarsystem der Primärstrahler (1) aus vier zu einem Gesamtstrahler zusammenge­fügten Einzelstrahlern besteht, und dieser Primärstrahler hin­sichtlich seiner Symetrieachse (5) um 90° gegenüber der Polari­sationsebene der einfallenden Welle gedreht ist.7. Antenna system according to one of the preceding claims, characterized in that in a training as an antenna system for a monopulse radar system, the primary radiator (1) consists of four individual radiators combined to form an overall radiator, and this primary radiator with respect to its axis of symmetry (5) by 90 ° with respect to the polarization plane the incident shaft is rotated.
EP90101435A 1989-01-31 1990-01-25 Antenna system Withdrawn EP0381037A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH31589 1989-01-31
CH315/89 1989-01-31

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EP0381037A1 true EP0381037A1 (en) 1990-08-08

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3235870A (en) * 1961-03-09 1966-02-15 Hazeltine Research Inc Double-reflector antenna with polarization-changing subreflector
CH634691A5 (en) * 1978-11-20 1983-02-15 Contraves Ag Radar reflector
EP0088681A1 (en) * 1982-03-02 1983-09-14 Thomson-Csf Dual-reflector antenna with incorporated polarizer
EP0101533A1 (en) * 1982-08-19 1984-02-29 Siemens-Albis Aktiengesellschaft Radar antenna

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161879A (en) * 1961-01-05 1964-12-15 Peter W Hannan Twistreflector
US3235870A (en) * 1961-03-09 1966-02-15 Hazeltine Research Inc Double-reflector antenna with polarization-changing subreflector
CH634691A5 (en) * 1978-11-20 1983-02-15 Contraves Ag Radar reflector
EP0088681A1 (en) * 1982-03-02 1983-09-14 Thomson-Csf Dual-reflector antenna with incorporated polarizer
EP0101533A1 (en) * 1982-08-19 1984-02-29 Siemens-Albis Aktiengesellschaft Radar antenna

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