EP0122391B1 - Broadband microwave radiator - Google Patents

Broadband microwave radiator Download PDF

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Publication number
EP0122391B1
EP0122391B1 EP84101496A EP84101496A EP0122391B1 EP 0122391 B1 EP0122391 B1 EP 0122391B1 EP 84101496 A EP84101496 A EP 84101496A EP 84101496 A EP84101496 A EP 84101496A EP 0122391 B1 EP0122391 B1 EP 0122391B1
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Prior art keywords
waveguide
microwave radiator
coaxial
cylinders
metal plate
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EP84101496A
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German (de)
French (fr)
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EP0122391A1 (en
Inventor
Eberhard Dr.-Ing. Schuegraf
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Siemens AG
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Siemens AG
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    • 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
    • H01Q13/0258—Orthomode horns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
    • H01P1/161—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion sustaining two independent orthogonal modes, e.g. orthomode transducer

Definitions

  • the invention relates to a broadband microwave radiator for two polarizations for illuminating a rotationally symmetrical parabolic reflector with a waveguide of square or round cross section, the one bottom surface facing away from the parabolic reflector is closed with a metal plate and offset against one another in the direction of the waveguide axis and in the circumferential direction below arranged at an angle of 90 ° to one another, two feed lines, preferably in the form of coaxial lines, are connected.
  • Such an arrangement is known from CH-A 350 335.
  • the main problem lies in adapting the existing, strongly frequency-dependent jump in wave resistance to broadband at the transition point from the open waveguide end to the free space.
  • the square waveguide has the characteristic line impedance for the adaptation
  • the invention has for its object to provide a simply constructed, very broadband microwave radiator, which radiates two perpendicular linear polarizations each from a separate antenna output with high mutual decoupling and small reflection and the open, abrupt waveguide end is broadband adapted as well as possible.
  • This object is achieved according to the invention in such a way that on the inner wall of the waveguide, after the opening forming the aperture, a first group of four cylinders which are offset by 90 ° in the circumferential direction and are opposite one another in pairs and form a double capacity, and a second group of four cylinders, each offset in the direction of the waveguide axis by a predetermined distance, each cylinder being made of dielectric material with small losses.
  • the microwave radiator 1 shows an antenna arrangement with a microwave radiator 1 (primary radiator) and a rotationally symmetrical parabolic reflector illuminated by the latter with a flat crown plate 15 in the middle.
  • the primary radiator is held by a support 13 which extends through an opening 14 in the parabolic reflector 12.
  • the microwave radiator 1 is designed as a waveguide with a square cross section, which is shown in detail in FIG. 2.
  • the waveguide in the microwave radiator is closed off with a metal plate on the bottom surface facing away from the parabolic reflector.
  • the two mutually perpendicular H 1O polarizations are coupled in and out with a coaxial line 3, 5 which, offset from one another in the direction of the waveguide axis, penetrates two adjacent side walls each in the middle of the waveguide side and their extended inner conductor 4, 6 as a coaxial probe protrudes about 0.3 a deep into the waveguide.
  • a is the inside length of the square base of the waveguide.
  • the coaxial probe 4 near the opening excites the vertically polarized H 10 wave with its vertical E field. In addition, this probe generates a longitudinal electrical field, which results in an E 11 interference field in the square waveguide.
  • the length L E "of the square waveguide section from the confluence of the near-opening probe 3 to the aperture, it is dimensioned such that its aperiodic E 11 attenuation is sufficiently large according to the requirement, in particular at the critical upper band limit f Ob ( ⁇ ob ), the condition is sufficient: where ⁇ KE11 a ⁇ 2.
  • a short circuit is arranged at a distance of approximately a / 2 behind the two coaxial probes 4, 6. This is formed for the probe 4 close to the opening by a vertical transverse plate 7 which is approximately 0.25 a wide and which practically does not interfere with the coaxial probe remote from the opening.
  • the short circuit for the coaxial probe 6 remote from the opening is the metal plate 2, which closes the square waveguide at the rear.
  • the distance between this metal plate 2 and the rear edge of the transverse plate 7 must be less than ⁇ Hob / 2 at the highest operating frequency f ob .
  • Parallel capacitances are provided in the area of the aperture, preferably by ⁇ H / 8 in front of the aperture in the square waveguide, for broadband adaptation of the strongly frequency-dependent wave resistance jump at the transition point from the open waveguide end to free space, where ⁇ H is assigned to an average frequency of the frequency band.
  • These capacitances are each broken down into two partial capacitances and consist of cylinders made of dielectric material with small losses, which are opposite each other on the four inner walls in the middle of the inside of the waveguide and are arranged offset in the direction of the waveguide axis.
  • the cylinders 8, 8 ' are attached to the underside, the cylinders 9, 9' to the top, the cylinders 10, 10 'to the left and the cylinders 11, 11' to the right .
  • the distance between two partial capacitances or the cylinders realizing them is selected such that it is approximately ⁇ Hob / 4 at the upper band limit.
  • the two partial capacities almost cancel each other out.
  • their electrical distance 1 / ⁇ Hu is much smaller than at the higher frequency f ob , whereby not only the frequency difference from f Ob to f " the decisive factor is the significantly larger wavelength difference in the waveguide.
  • both capacitances add up at the 'lower frequency f u almost, and the resulting capacitance acts locally in the middle between the partial capacities.
  • the amount of the resulting capacitance decreases in a desired manner from the lower frequency limit f u to the upper frequency limit f ob .
  • Frequency response, amount and location of the resulting capacity can be influenced in a defined manner via the distance, size and location of the individual capacities.
  • the dielectric disturbance of a cover can also be compensated, which is preferably arranged approximately in the aperture plane for the weatherproof closure of the radiator.
  • the excitation of interference wave types on the dielectric cylinders is prevented in that each individual capacitance is designed symmetrically, that is to say it is formed in each case from two halves on both mutually opposite waveguide walls.
  • the measures according to the invention for adapting the wave resistance jump at the transition point from the open waveguide end into the free space can of course also be used for waveguides whose aperture, in contrast to the precisely abrupt end, has a e.g. has funnel-shaped approach.

Abstract

1. A wide-band microwave radiator for two polarizations, for illuminating a rotation-symmetrical parabolic reflector (12), comprising a wave-guide (1) of square or round cross-section whose first base surface faces away from the parabolic reflector (12) and is terminated by a metal plate (2) connected to two supply lines, preferably in the form of coaxial lines (3, 5), mutually offset in the direction of the waveguide axis and together forming an angle of 90 degrees in the peripheral direction, characterized in that the inner wall of the waveguide, following the opening which forms the aperture, has arranged thereon a first group of four cylinders (8, 9, 10, 11) which are mutually offset by 90 degrees in the peripheral direction, and are aligned opposite one another in pairs, forming a double capacitance, and a second group of four cylinders (8', 9', 10', 11') mutually offset by a predetermined interval in the direction of the waveguide axis, where each cylinder consists of low-loss dielectric material.

Description

Die Erfindung bezieht sich auf einen breitbandigen Mikrowellenstrahler für zwei Polarisationen zur Ausleuchtung eines rotationssymmetrischen Parabolreflektors mit einem Hohlleiter quadratischen oder runden Querschnitts, dessen eine, vom Parabolreflektor abgewendete Bodenfläche mit einer Metallplatte abgeschlossen ist und an den, in Richtung der Hohlleiterachse gegeneinander versetzt und in Umfangsrichtung unter einem Winkel von 90° zueinander angeordnet, zwei vorzugsweise als Koaxialleitungen ausgebildete Zuleitungen angeschlossen sind. Eine solche Anordnung ist aus der CH-A 350 335 bekannt.The invention relates to a broadband microwave radiator for two polarizations for illuminating a rotationally symmetrical parabolic reflector with a waveguide of square or round cross section, the one bottom surface facing away from the parabolic reflector is closed with a metal plate and offset against one another in the direction of the waveguide axis and in the circumferential direction below arranged at an angle of 90 ° to one another, two feed lines, preferably in the form of coaxial lines, are connected. Such an arrangement is known from CH-A 350 335.

Aus der US-A 3 089102 ist ein dual polarisierter Hornstrahler mit einer V-förmigen Verzweigung bekannt, bei dem in den einzelnen Hohlleiterabschnitten an der Hohlleiterinnenwand einander gegenüberliegend kapazitive, zylinderförmige Anpassungselemente angeordnet sind.From US-A 3 089102 a dual polarized horn with a V-shaped branch is known, in which capacitive, cylindrical matching elements are arranged in the individual waveguide sections on the inner waveguide wall.

Durch das «Taschenbuch der Hochfrequenztechnik» von Meinke, H.; Gundlach, F.W., 2. Auflage, 1962, Seite 599 ist es beispielsweise bekannt, das offene Ende eines Hohlleiters direkt oder trichterförmig erweitert zur Abstrahlung leitungsgebundener Mikrowellen in den freien Raum zu benützen. Ein offenes Hohlleiterende hat jedoch eine hohe Reflexion mit starkem Frequenzgang insbesondere bei Annäherung an die Hohlleiterfrequenz der abzustrahlenden Welle. Daher wird beim bekannten Hornstrahler der Hohlleiterquerschnitt stetig erweitert und dadurch die Reflexion reduziert. Dies hat jedoch auch zur Folge, dass die Hauptkeule der Strahlung wesentlich schmäler wird und sich ausserdem eine stärkere Abschattung durch die erweiterte Hornapertur ergibt.Through the "Taschenbuch der Hochfrequenztechnik" by Meinke, H .; Gundlach, F.W., 2nd edition, 1962, page 599, it is known, for example, to use the open end of a waveguide, expanded directly or in a funnel shape, to radiate line-bound microwaves into free space. However, an open waveguide end has a high reflection with a strong frequency response, especially when approaching the waveguide frequency of the wave to be emitted. Therefore, the waveguide cross section of the known horn radiator is continuously expanded, thereby reducing the reflection. However, this also means that the main lobe of the radiation becomes significantly narrower and that there is also greater shadowing due to the enlarged horn aperture.

Bei einem offenen, abrupten Hohlleiterende liegt das Hauptproblem darin, an der Übergangsstelle vom offenen Hohlleiterende in den freien Raum den hier bestehenden, stark frequenzabhängigen Wellenwiderstandssprung breitbandig anzupassen. Während nämlich der Wellenwiderstand des freien Raumes

Figure imgb0001
frequenzunabhängig ist, hat der Quadrathohlleiter den für die Anpassung massgebenden Leitungswellenwiderstand
Figure imgb0002
 In the case of an open, abrupt waveguide end, the main problem lies in adapting the existing, strongly frequency-dependent jump in wave resistance to broadband at the transition point from the open waveguide end to the free space. During the wave resistance of free space
Figure imgb0001
 frequency-independent, the square waveguide has the characteristic line impedance for the adaptation
Figure imgb0002

Der Wellenwiderstandssprung ist

Figure imgb0003
The wave resistance jump is
Figure imgb0003

Der beschränkte Eindeutigkeitsbereich des Quadrathohlleiters zwingt dabei oft zu Betriebsfrequenzen knapp über der H1O-Grenzfrequenz, wobei obiger Wellenwiderstandssprung stark ansteigt.The limited uniqueness range of the square waveguide often forces operating frequencies just above the H 1O cutoff frequency, with the above wave resistance jump increasing sharply.

Der Erfindung liegt die Aufgabe zugrunde, einen einfach aufgebauten, sehr breitbandigen Mikrowellenstrahler zu schaffen, der zwei aufeinander senkrechte Linearpolarisationen von je einem separaten Antennenausgang mit hoher gegenseitiger Entkopplung und kleiner Reflexion abstrahlt und dessen offenes, abruptes Hohlleiterende breitbandig möglichst gut angepasst ist.The invention has for its object to provide a simply constructed, very broadband microwave radiator, which radiates two perpendicular linear polarizations each from a separate antenna output with high mutual decoupling and small reflection and the open, abrupt waveguide end is broadband adapted as well as possible.

Diese Aufgabe wird gemäss der Erfindung in der Weise gelöst, dass an der Innenwand des Hohlleiters nach der die Apertur bildenden Öffnung eine erste Gruppe von vier in Umfangsrichtung jeweils um 90° gegeneinander versetzten und paarweise einander fluchtend gegenüberliegenden, eine Doppelkapazität bildenden Zylindern und eine zweite Gruppe von vier in Richtung der Hohlleiterachse um einen vorgegebenen Abstand jeweils versetzten Zylindern angeordnet sind, wobei jeder Zylinder aus dielektrischem Material mit kleinen Verlusten besteht.This object is achieved according to the invention in such a way that on the inner wall of the waveguide, after the opening forming the aperture, a first group of four cylinders which are offset by 90 ° in the circumferential direction and are opposite one another in pairs and form a double capacity, and a second group of four cylinders, each offset in the direction of the waveguide axis by a predetermined distance, each cylinder being made of dielectric material with small losses.

Vorteilhafte Ausgestaltungen und Weiterbildungen des Anmeldungsgegenstandes sind in den Unteransprüchen angegeben.Advantageous refinements and developments of the subject of the application are specified in the subclaims.

Nachstehend wird die Erfindung anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert. Es zeigen:

  • Fig. 1 eine Antennenanordnung mit einem Mikrowellenstrahler und einem rotationssymmetrischen Parabolreflektor und
  • Fig. 2 einen Mikrowellenstrahler in Einzeldarstellung.
The invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawing. Show it:
  • Fig. 1 shows an antenna arrangement with a microwave radiator and a rotationally symmetrical parabolic reflector and
  • Fig. 2 shows a microwave radiator in an individual representation.

In Fig. 1 ist eine Antennenanordnung mit einem Mikrowellenstrahler 1 (Primärstrahler) und einem von diesem ausgeleuchteten rotationssymmetrischen Parabolreflektor mit einer ebenen Scheitelplatte 15 in der Mitte dargestellt. Der Primärstrahler wird von einer Stütze 13 gehalten, die durch eine Öffnung 14 des Parabolreflektors 12 hindurchgreift. Der Mikrowellenstrahler 1 ist im Ausführungsbeispiel als Hohlleiter quadratischen Querschnitts ausgebildet, der in Fig. 2 in Einzeldarstellung gezeigt ist.1 shows an antenna arrangement with a microwave radiator 1 (primary radiator) and a rotationally symmetrical parabolic reflector illuminated by the latter with a flat crown plate 15 in the middle. The primary radiator is held by a support 13 which extends through an opening 14 in the parabolic reflector 12. In the exemplary embodiment, the microwave radiator 1 is designed as a waveguide with a square cross section, which is shown in detail in FIG. 2.

Der Hohlleiter beim Mikrowellenstrahler ist an der dem Parabolreflektor abgewendeten Bodenfläche mit einer Metallplatte abgeschlossen. Die Ein- und Auskopplung der beiden aufeinander senkrechten H1O-Polarisationen erfolgt mit je einer Koaxialleitung 3, 5, die, in Richtung der Hohlleiterachse gegeneinander versetzt, zwei benachbarte Seitenwände jeweils in der Mitte der Hohlleiterseite durchdringen und deren verlängerter Innenleiter 4, 6 als Koaxialsonde etwa 0,3 a tief in den Hohlleiter hineinragt. a ist dabei die Innenseitenlänge der quadratischen Grundfläche des Hohlleiters. Die öffnungsnahe Koaxialsonde 4 regt mit ihrem senkrechten E-Feld die vertikal polarisierte H1O-Welle an. Ausserdem erzeugt diese Sonde ein elektrisches Längsfeld, das im Quadrathohlleiter ein E11-Störfeld zur Folge hat. Die Länge LE" des Quadrathohlleiterabschnittes von der Einmündung der öffnungsnahen Sonde 3 bis zur Apertur ist dabei so bemessen, dass seine aperiodische E11-Dämpfung gemäss der Anforderung ausreichend gross ist, insbesondere an der kritischen oberen Bandgrenze fOb (λob) der Bedingung genügt:

Figure imgb0004
wobei λKE11 = a √2 ist.The waveguide in the microwave radiator is closed off with a metal plate on the bottom surface facing away from the parabolic reflector. The two mutually perpendicular H 1O polarizations are coupled in and out with a coaxial line 3, 5 which, offset from one another in the direction of the waveguide axis, penetrates two adjacent side walls each in the middle of the waveguide side and their extended inner conductor 4, 6 as a coaxial probe protrudes about 0.3 a deep into the waveguide. a is the inside length of the square base of the waveguide. The coaxial probe 4 near the opening excites the vertically polarized H 10 wave with its vertical E field. In addition, this probe generates a longitudinal electrical field, which results in an E 11 interference field in the square waveguide. The length L E "of the square waveguide section from the confluence of the near-opening probe 3 to the aperture, it is dimensioned such that its aperiodic E 11 attenuation is sufficiently large according to the requirement, in particular at the critical upper band limit f Ob (λ ob ), the condition is sufficient:
Figure imgb0004
 where λKE11 = a √2.

In den Koaxialarmen, deren Länge ca. die Hälfte der Innenseitenlänge a beträgt, sind spezielle Transformatoren mit Induktivitäten L und Kapazitäten C untergebracht, die im Zusammenwirken mit der vorkompensierten Apertur die Breitbandanpassung des Strahlers ermöglichen. Im Abstand von etwa a/2 hinter den beiden Koaxialsonden 4, 6 ist jeweils ein Kurzschluss angeordnet. Dieser wird für die öffnungsnahe Sonde 4 von einem senkrechten Querblech 7 gebildet, das etwa 0,25 a breit ist und das die öffnungsferne Koaxialsonde praktisch nicht stört. Der Kurzschluss für die öffnungsferne Koaxialsonde 6 ist die Metallplatte 2, die den Quadrathohlleiter hinten abschliesst. Der Abstand zwischen dieser Metallplatte 2 und der Hinterkante des Querblechs 7 muss bei der höchsten Betriebsfrequenz fobkleiner als λHob/2 sein. Bei der λ/2 Resonanz dieses beidseitig verschlossenen Raumes tritt nämlich ein starker Einbruch der Entkopplung zwischen beiden Polarisationen auf, und die Reflexion an den Koaxialzugängen steigt resonanzartig an.In the coaxial arms, the length of which is approximately half of the inside length a, special transformers with inductors L and capacitors C are accommodated, which, in cooperation with the precompensated aperture, allow the broadband adaptation of the radiator. A short circuit is arranged at a distance of approximately a / 2 behind the two coaxial probes 4, 6. This is formed for the probe 4 close to the opening by a vertical transverse plate 7 which is approximately 0.25 a wide and which practically does not interfere with the coaxial probe remote from the opening. The short circuit for the coaxial probe 6 remote from the opening is the metal plate 2, which closes the square waveguide at the rear. The distance between this metal plate 2 and the rear edge of the transverse plate 7 must be less than λ Hob / 2 at the highest operating frequency f ob . With the λ / 2 resonance of this space, which is closed on both sides, there is a sharp drop in the decoupling between the two polarizations, and the reflection at the coaxial access increases in a resonance-like manner.

Um die Koaxialzuleitungen gegenüber dem in Fig. 1 skizzierten Verlauf weiter zu verkürzen, ist es zweckmässig, eine der beiden koaxialen Einkopplungen, vorzugsweise die öffnungsferne, unmittelbar vor der Einmündung in den Hohlleiter um 90° abzuwinkeln und gegebenenfalls gleich in die Richtung der schrägen Stütze 13 zu schwen- ken, die den Mikrowellenstrahler in seiner Position hält. Dies ermöglicht die Verwendung gerader, starrer Koaxialzuleitungen mit kleinstmöglicher Dämpfung und Reflexion.In order to further shorten the coaxial feed lines compared to the course sketched in FIG. 1, it is expedient to bend one of the two coaxial couplings, preferably the one remote from the opening, by 90 ° immediately before the junction into the waveguide and, if appropriate, immediately in the direction of the oblique support 13 to schwen- k s, which holds the microwave radiator in position. This enables the use of straight, rigid coaxial cables with the lowest possible attenuation and reflection.

Zur breitbandigen Anpassung des stark frequenzabhängigen Wellenwiderstandssprunges an der Übergangsstelle vom offenen Hohlleiterende in den freien Raum sind im Bereich der Apertur Parallelkapazitäten vorgesehen, vorzugsweise um λH/8 vor der Apertur im Quadrathohlleiter, wobei λH einer mittleren Frequenz des Frequenzbandes zugeordnet ist. Diese Kapazitäten sind jeweils in zwei Teilkapazitäten zerlegt und bestehen aus Zylindern aus dielektrischem Material mit kleinen Verlusten, die an den vier Innenwänden jeweils in der Mitte der Hohlleiterinnenseite einander gegenüberliegen und in Richtung der Hohlleiterachse gegeneinander versetzt angeordnet sind. Beim dargestellten Mikrowellenstrahler nach Fig. 2 sind die Zylinder 8, 8' an der Unterseite, die Zylinder 9, 9' an der Oberseite, die Zylinder 10, 10' an der linken Seite und die Zylinder 11, 11' an der rechten Seite angebracht. Der Abstand zweier Teilkapazitäten bzw. der sie realisierenden Zylinder ist so gewählt, dass er an der oberen Bandgrenze angenähert λHob/4 beträgt. Hier löschen sich also beide Teilkapazitäten gegenseitig fast aus. Dagegen ist bei der wesentlich tieferen Frequenz f" an der unteren Bandgrenze und bei gleichem geometrischem Abstand der Teilkapazitäten wie oben ihr elektrischer Abstand 1 /λHu viel kleiner als bei der höheren Frequenz fob, wobei nicht nur der Frequenzunterschied von fOb nach f" massgebend ist, sondern der demgegenüber wesentlich grössere Wellenlängenunterschied im Hohlleiter. Beide Teilkapazitäten addieren sich daher bei der' unteren Frequenz fu fast, und die resultierende Kapazität wirkt örtlich in der Mitte zwischen den Teilkapazitäten. Der Betrag der resultierenden Kapazität nimmt in gewünschter Weise von der unteren Frequenzgrenze fu nach der oberen Frequenzgrenze fob stark ab. Frequenzgang, Betrag und Ort der resultierenden Kapazität sind über Abstand, Grösse und Lage der Einzelkapazitäten definiert beeinflussbar.Parallel capacitances are provided in the area of the aperture, preferably by λ H / 8 in front of the aperture in the square waveguide, for broadband adaptation of the strongly frequency-dependent wave resistance jump at the transition point from the open waveguide end to free space, where λ H is assigned to an average frequency of the frequency band. These capacitances are each broken down into two partial capacitances and consist of cylinders made of dielectric material with small losses, which are opposite each other on the four inner walls in the middle of the inside of the waveguide and are arranged offset in the direction of the waveguide axis. 2, the cylinders 8, 8 'are attached to the underside, the cylinders 9, 9' to the top, the cylinders 10, 10 'to the left and the cylinders 11, 11' to the right . The distance between two partial capacitances or the cylinders realizing them is selected such that it is approximately λ Hob / 4 at the upper band limit. Here, the two partial capacities almost cancel each other out. In contrast, at the much lower frequency f " at the lower band limit and with the same geometric spacing of the partial capacitances as above, their electrical distance 1 / λ Hu is much smaller than at the higher frequency f ob , whereby not only the frequency difference from f Ob to f " the decisive factor is the significantly larger wavelength difference in the waveguide. Therefore, both capacitances add up at the 'lower frequency f u almost, and the resulting capacitance acts locally in the middle between the partial capacities. The amount of the resulting capacitance decreases in a desired manner from the lower frequency limit f u to the upper frequency limit f ob . Frequency response, amount and location of the resulting capacity can be influenced in a defined manner via the distance, size and location of the individual capacities.

Sehr wichtig ist, dass die Teilkapazitäten nicht als Metallzylinder an der Hohlleiterwand realisiert sind. Solche Zylinder wirken nämlich nur für diejenige Polarisation kapazitiv, deren E-Feld parallel zur Zylinderachse liegt. Dagegen wirken sie für die dazu senkrechte Polarisation induktiv, d.h. die wirksame Hohlleiterbreite für diese Polarisation ist gegenüber der lichten Hohlleiterbreite eingeengt. Somit steigt die zugehörige H10-Grenzfrequenz im Quadrathohlleiter und rückt noch näher an die Banduntergrenze fu, was die Anpassung hier sehr erschwert. Derartige Schwierigkeiten werden vermieden, indem die acht Zylinder hinter der Apertur aus dielektrischem Material mit kleinen Verlusten bestehen. Die dielektrischen Zylinder wirken für beide Polarisationen kapazitiv. Mit einer gezielten Korrektur der öffnungsnahen dielektrischen Zylinder kann ausserdem die dielektrische Störung eines Deckels kompensiert werden, der vorzugsweise zum wetterfesten Verschluss des Strahlers etwa in der Aperturebene angeordnet ist. Die Anregung von Störwellentypen an den dielektrischen Zylindern wird dadurch unterbunden, dass jede Einzelkapazität symmetrisch gestaltet wird, d.h. jeweils aus zwei Hälften an beiden einander gegenüberliegenden Hohlleiterwänden gebildet wird.It is very important that the partial capacities are not realized as metal cylinders on the waveguide wall. Such cylinders act capacitively only for the polarization whose E field is parallel to the cylinder axis. In contrast, they have an inductive effect on the perpendicular polarization, ie the effective waveguide width for this polarization is narrowed compared to the clear waveguide width. The associated H 10 cut-off frequency thus increases in the square waveguide and moves even closer to the lower band limit f u , which makes adaptation very difficult here. Such difficulties are avoided by making the eight cylinders behind the aperture of dielectric material with little loss. The dielectric cylinders act capacitively for both polarizations. With a targeted correction of the dielectric cylinders close to the opening, the dielectric disturbance of a cover can also be compensated, which is preferably arranged approximately in the aperture plane for the weatherproof closure of the radiator. The excitation of interference wave types on the dielectric cylinders is prevented in that each individual capacitance is designed symmetrically, that is to say it is formed in each case from two halves on both mutually opposite waveguide walls.

Die vorstehenden Erläuterungen gelten auch für den Rundhohlleiter, vorzugsweise aber für den Quadrathohlleiter, weil dieser den theoretischen Eindeutigkeitsbereich der relativen Breite √2 aufweist gegenüber nur 1,3 bei Rundhohlleitern.The above explanations also apply to the round waveguide, but preferably to the square waveguide, because this has the theoretical uniqueness range of the relative width √2 compared to only 1.3 for round waveguides.

Die erfindungsgemässen Massnahmen zur Anpassung des Wellenwiderstandssprungs an der Übergangsstelle vom offenen Hohlleiterende in den freien Raum sind selbstverständlich auch anwendbar für Hohlleiter, deren Apertur, abweichend vom exakt abrupten Ende, einen z.B. trichterförmigen Ansatz aufweist.The measures according to the invention for adapting the wave resistance jump at the transition point from the open waveguide end into the free space can of course also be used for waveguides whose aperture, in contrast to the precisely abrupt end, has a e.g. has funnel-shaped approach.

Claims (11)

1. A wide-band microwave radiator for two polarisations, for illuminating a rotation-symmetrical parabolic reflector (12), comprising a waveguide (1) of square or round cross-section whose first base surface faces away from the parabolic reflector (12) and is terminated by a metal plate (2) connected to two supply lines, preferably in the form of coaxial lines (3, 5), mutually offset in the direction of the waveguide axis and together forming an angle of 90° in the peripheral direction, characterised in that the inner wall of the waveguide, following the opening which forms the aperture, has arranged thereon a first group of four cylinders (8, 9, 10, 11) which are mutually offset by 90° in the peripheral direction, and are aligned opposite one another in pairs, forming a double capacitance, and a second group of four cylinders (8', 9', 10', 11') mutually offset by a predetermined interval in the direction of the waveguide axis, where each cylinder consists of low-loss dielectric material.
2. A microwave radiator as claimed in Claim 1, characterised in that the interval between two dielectric cylinders (8-8', 9-9', 10-10', 11-11'), arranged in series in the direction of the waveguide longitudinal axis, is selected such that at the upper band limit it amounts to approximately λHob/4. where λHob is the waveguide wavelength of the highest frequency wave to be transmitted.
3. A microwave radiator as claimed in Claim 1 or 2 comprising a waveguide of square cross-section, characterised in that the supply lines (3, 5) are each connected in the centre of two adjacent side walls, and the dielectric cylinders (8-8', 9-9', 10-10', 11-11') are arranged of opposite inner walls symmetrically to one another in the centre of the four side walls.
4. A microwave radiator as claimed in Claim 3, characterised in that when the supply lines (3, 5) are designed as coaxial lines, their inner conductors (4, 6) extend to form coaxial probes and project into the waveguide (1) by a depth of approximately 0.3 a, where a is the length of the inside of the square base surface of the waveguide.
5. A microwave radiator as claimed in Claim 4, characterised in that the extended inner conductor (4) (coaxial probe) of the coaxial line (3) is arranged close to the opening at a distance LEn from the aperture such that the aperiodic E11-attenuation aapE11 of the En-interference field in this waveguide section at the upper band limit λob fulfills the following equation:
Figure imgb0006
where λKE11 = a √2.
6. A microwave radiator as claimed in Claim 5, characterised in that at an interval corresponding to approximately half the length of the inside (a/2) of the waveguide a short-circuit for the respective polarisation is in each case provided behind the coaxial probes (4, 6).
7. A microwave radiator as claimed in Claim 6, characterised in that the short-circuit for the coaxial probe (4) close to the opening is formed by a vertically arranged transverse sheet-metal plate (7), the breadth of which corresponds to approximately one-quarter of the inside surface of the waveguide.
8. A microwave radiator as claimed in Claim 6, characterised in that the short-circuit for the coaxial probe (6) remote from the opening is formed by the metal plate (2) which terminates the waveguide (1) on one side.
9. A microwave radiator as claimed in one of Claims 7 to 8, characterised in that the distance between the metal plate (2) and the rear edge of the transverse sheet metal plate (7) for the highest operating frequency fOb is smaller than half the waveguide wavelength λHob of the highest frequency wave to be transmitted.
10. A microwave radiator as claimed in one of Claims 4 to 9, characterised in that special transformation elements are arranged in the coaxial line sections (3, 5) with a length of approximately half the inside length (a/2) of the waveguide.
EP84101496A 1983-02-17 1984-02-14 Broadband microwave radiator Expired EP0122391B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84101496T ATE34885T1 (en) 1983-02-17 1984-02-14 WIDE BAND MICROWAVE RADIATOR.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3305494 1983-02-17
DE19833305494 DE3305494A1 (en) 1983-02-17 1983-02-17 BROADBAND MICROWAVE EMITTER

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EP0122391A1 EP0122391A1 (en) 1984-10-24
EP0122391B1 true EP0122391B1 (en) 1988-06-01

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AT (1) ATE34885T1 (en)
DE (2) DE3305494A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1188403B (en) * 1986-03-03 1988-01-14 Gte Telecom Spa DOUBLE POLARIZATION MICROWAVE RECEIVER FOR DIRECT RADIO DIFFUSION RECEIVED FROM SATELLITE
DE3619220A1 (en) * 1986-06-07 1988-02-18 Kolbe & Co Hans CONVERTER SYSTEM
DE4113760C2 (en) * 1991-04-26 1994-09-01 Hirschmann Richard Gmbh Co Arrangement for converting a microwave type

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB801627A (en) * 1955-09-02 1958-09-17 Gen Electric Co Ltd Improvements in or relating to apparatus of the kind including a waveguide
GB835575A (en) * 1955-12-21 1960-05-25 Standard Telephones Cables Ltd An improved multiplexing and filtering device for the u.h.f. band
US3089102A (en) * 1960-04-25 1963-05-07 Electronic Specialty Co Dual polarized horn
FR1527847A (en) * 1967-02-27 1968-06-07 Csf New duplexed excitation of radio antennas
DE1916197A1 (en) * 1969-03-29 1970-10-01 Licentia Gmbh Exciter for the illumination of a parabolic antenna

Also Published As

Publication number Publication date
ATE34885T1 (en) 1988-06-15
DE3471839D1 (en) 1988-07-07
DE3305494A1 (en) 1984-08-23
EP0122391A1 (en) 1984-10-24

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