EP0351514B1 - Waveguide twist - Google Patents

Abstract

A waveguide twist for rotating the polarisation plane consists of rectangular hollow conductors wound constantly about its axis, but which require a not inconsiderable constructional length. In a conventional polarisation filter, although it is possible for the propagation direction to be positioned mutually parallel using an elbow, the polarisation planes are however rotated by 90 DEG in the two waveguide branches. In order to provide a waveguide twist, especially for use in a polarisation filter having a small space requirement, with simple means, it is provided that two parallel adjacent waveguides are connected to one another via a common coupling window which is arranged centrally in the one waveguide in the longitudinal direction and off-centre in the other waveguide. When two rectangular waveguides are employed, the coupling window is arranged on the one hand centrally on the narrow side and off-centre on the wide side on the other waveguide. The waveguide twist is also especially suitable for polarisation filters. <IMAGE>

Description

The invention looks from a waveguide twist, as is known from DE-PS 976 910 or DE-OS 27 48 956.

The straight waveguide is the basic element in waveguide technology. For example, pipe elbows and pipe angles are used to change the direction of hollow pipes. In the case of contra-angles, the corner is bevelled to reduce the adjustment error. Mostly, manifolds with a continuous curvature and a constant cross-section are used. The curvature, usually 90 °, can be carried out in the direction of the electrical field lines (E-bend), i.e. in the case of the rectangular hollow line over the broad side, or in the direction of the magnetic field lines (H-bend), i.e. in the case of rectangular hollow line in the direction of the narrow side.

For example, if the plane of polarization is to be rotated by a small angle in the direction of propagation, B. described in DE 27 48 956 A1, two rectangular hollow pipes to be connected are rotated against each other by this small angle with minor adaptation errors, of course no opening is allowed. With a larger twist angle required to rotate the direction of polarization, usually 90 °, reckeck hollow lines twisted around their axis, so-called waveguide twists, are used. However, this also shows that such waveguide twists naturally require a not insignificant axial length.

Of course, the waveguide provided with a rectangular cross section can also be twisted helically as a whole about its longitudinal axis in order to change the polarization plane by 90 °, as is described, for example, in DE-PS 976 910.

The changes in direction of waveguides mentioned at the outset have meaning, for. B. in the implementation of a polarizing switch. Such polarization switches are known for example from DE 33 45 689 A1, DE 30 10 360 C2 and GB-PS 1 591 719. These broadband polarization switches are used to separate orthogonally linearly polarized electromagnetic waves. For example, an input-side waveguide section has a rectangular or square cross-section with two coupling windows that lie opposite one another laterally, from which rectangular waveguide arms branch off and open into a common broadband branch with the inclusion of elbows.

If it is a matter of polarization switches that are completely implemented in waveguide technology, they are essentially based on the same principle. They consist of a round or square waveguide to which two or more waveguides are connected. Two main wave types with mutually perpendicular polarization planes can be propagated in the square or round waveguide, which are coupled separately from one another in one or more rectangular waveguides assigned only to one polarization.

This functional principle can be implemented in a simple embodiment with a polarization switch in such a way that a waveguide with a square cross section is provided for the transmission of two waves with polarization planes oriented perpendicular to one another. To decouple one polarization plane, a transverse short circuit is arranged in it and on the opposite side of the waveguide section which is square to the cross section, a rectangular coupling window running in the longitudinal direction, that is to say in the direction of propagation, is arranged in which the electromagnetic wave is coupled out with the polarization plane lying in the plane of the coupling window. By means of a bend or an angle applied here, this electromagnetic wave can only be deflected by 90 ° in such a way that the direction of propagation of the two waves, which are now each separated on a waveguide branch, takes place parallel to one another. A corresponding waveguide polarization switch therefore comprises, on one connection side, the two polarization gates one above the other for the two waveguide branches, in which the two separate electromagnetic waves are transmitted. Even if, by arranging an H-bend after the coupling window, the direction of propagation of the two coupled waves can be brought into line and the connections of the two switch outputs can lie in one plane, it remains to be determined that the orientation of the two connecting waveguides is perpendicular to each other. The two polarizations separate from one another in different waveguides in the same direction due to the way in which they are coupled, but their orientation in space is still perpendicular to one another. If, for example, microwave converters are to be connected downstream, as is required in satellite technology, then these must also be aligned with the polarization lying perpendicular to one another, which is not always desirable from a structural point of view is when the microwave converters are rectangular in cross-section and thus take up more space. In principle, however, it would also be conceivable for a so-called "twist", that is to say a so-called "waveguide twist", to be arranged at least in one of the two waveguide branches. However, this would lead to an axial extension of the required installation space, since then, for example, a microwave converter could only be installed offset by the installation length of the so-called "twist".

The object of the present invention is therefore to create a waveguide twist, in particular for a waveguide polarization switch, in order to create the possibility of a polarization plane rotation of 90 ° with the smallest space requirement.

The object is achieved with the subject matter of claim 1. Advantageous configurations and uses of this object are specified in the subclaims.

The present invention indeed enables the possibility of a rotation of the polarization plane by, for example, 90 ° in an astonishing manner with the smallest installation space. This is made possible by the way in which one waveguide branch is coupled to the other, so that the electromagnetic waves in one polarization plane are coupled into the other waveguide branch by rotating their polarization plane by 90 °.

When using the claimed object in a waveguide polarization switch, this leads to the fact that, for example, a waveguide section for transmitting two main wave types H₁₀ and H₀₁ with two mutually perpendicular polarization planes is provided with a rectangular coupling window, so that after coupling one polarization plane into a subsequent waveguide branch, the coupled polarization plane is rotated by 90 ° in such a way that the polarization plane is parallel to one another in the waveguide branch downstream of the coupling window and downstream of the short circuit.

The principle according to the invention can be used not only with the shaft types H₁₀ and H₀₁, that is to say with square or rectangular waveguides in cross section, but also with waveguides with round wave cross section with the shaft types H₁₁ and H₁₁.

Finally, for the purpose of adaptation, the waveguides can also be provided with discontinuities.

In contrast to the waveguide twist described above, which represents a waveguide arrangement for rotating the direction of polarization of electromagnetic vibrations, a device for partially coupling electromagnetic waves has become known from GB-A 795 862. In particular, FIG. 4 shows an arrangement on which two waveguides with a rectangular cross section sit one on top of the other. One of the waveguides sits with its narrow long side on the second waveguide on its wide long side, in a symmetrical central longitudinal direction. Two coupling windows are provided between the two waveguides, each deviating at an angle from the longitudinal extent and thus resulting in a coupling window covering that - based on the entire length of both coupling windows - then also extends over the entire width of the narrow longitudinal side of the one waveguide.

This is a partial coupling in the manner of a 4-pole circuit, with only a fraction of a shaft being decoupled from the one waveguide and partially rotated. In particular, the graphical representation according to FIG. 8 also shows that the coupling factor can be comparatively low in accordance with the desired partial decoupling.

In contrast, the present invention relates to a waveguide twist in which a practically completely loss-free 100% rotation of the shafts is carried out.

Fig. 1 :

ein erstes Ausführungsbeispiel eines Hohlleiter-Polarisationsdrehers in schematischer perspektivischer Darstellung; und

Fig. 2 :

ein weiteres Ausführungsbeispiel in perspektivischer Darstellung im Falle einer Hohlleiter-Polarisationsweiche .

Fig. 3 :

eine rückwärtige Ansicht der Darstellung gem. Fig. 2.

Fig. 4 und 5 :

eine Querschnittsdarstellung und eine rückwärtige Ansicht einer abgewandelten Polarisationsweiche.

Exemplary embodiments of the invention are illustrated below with the aid of the drawing. Show in detail

Fig. 1:

a first embodiment of a waveguide polarization rotator in a schematic perspective view; and

Fig. 2:

a further embodiment in perspective in the case of a waveguide polarization switch.

Fig. 3:

a rear view of the representation acc. Fig. 2.

4 and 5:

a cross-sectional view and a rear view of a modified polarization switch.

In Fig. 1 is a rectangular first waveguide 1 for example for transmitting a linearly polarized electromagnetic Shaft type H₁₀ shown. At the end of the waveguide 1 running centrally in the longitudinal direction on the narrow side 3, a coupling window 5 is provided, the height of which generally corresponds to the broad side of the waveguide 1. In practice, however, the height of the coupling window 5 will generally be up to approximately 10% less than the broad side of the waveguide 1. The narrow side of the coupling window 5 is only half as long as its length. In principle, an example of the magnetic field line 7 is shown in front of the waveguide 1 in FIG. 1.

Via a waveguide angle 9 arranged at the end of the waveguide 1, the direction of propagation is changed by 90 ° to the vertical without changing the polarization plane.

A second waveguide 13 is arranged above the first waveguide 1. The second waveguide 13 is parallel to the waveguide 1, in such a way that the two coupling windows 5 lie one on top of the other. However, the coupling window 5 in the second waveguide 13 is also arranged in its longitudinal direction, but off-center to the longitudinal axis. In addition, the longitudinal or broad sides of the waveguide 13 to the first waveguide 1 are interchanged by 90 °, so that in the waveguide 13, for example, an electromagnetic wave of the type H 1 can be excited.

With this arrangement, the electromagnetic field lines 7 shown in FIG. 1 are coupled onto the second waveguide 13 via the coupling window 5 in such a way that magnetic field lines 15 are excited there. This is only achieved by the eccentric arrangement of the coupling window 5 with respect to the second waveguide 13. Because in the coupling window 5, the magnetic field lines are rectified, so that an electromagnetic wave is excited in the second waveguide 13 due to the specific geometry, the polarization plane of which is 90 ° to the incoming electromagnetic wave Wave in the first waveguide 1 is twisted. This basic principle can also be implemented in the case of a waveguide polarization oak as illustrated schematically in FIG. 2.

Fig. 2 differs from Fig. 1 in that instead of the first waveguide 1, a waveguide with a square cross-section for transmitting two main electromagnetic waves with mutually perpendicular polarization planes, i.e. for example, transmission of an H₁₀ and H₀₁ wave is used. Below the also in this embodiment running in the longitudinal direction centrally arranged coupling window 5, a short circuit 9 'is arranged instead of an H-angle or H-bend. The function of this short circuit 9 'is the same, however, because the electromagnetic wave with the polarization plane extending in the vertical longitudinal direction to the level of the coupling window 5, in the exemplary embodiment shown thus the H₀₁ wave via the coupling window 5 in the upper waveguide section 13 while rotating the Polarization plane can be coupled through 90 ° as explained in FIG. 1.

Behind the short circuit 9 ', which is arranged approximately centrally but opposite the coupling window in the first waveguide 1, only the electromagnetic wave with parallel alignment to the short circuit, that is to say in the exemplary embodiment shown, the H₁₀ wave is transmitted into the subsequent waveguide branch 17.

Because of this arrangement, the linearly polarized, mutually perpendicular electromagnetic waves transmitted in the first waveguide 1 have now been split onto the two waveguide branches 13 and 17 in such a way that the two polarization planes are parallel to one another. The coupling window is on the same upper side of the waveguide branch 17 usually an upper short-circuit bridge 9˝ to achieve better decoupling.

In practice, this has the result that on the output side of the waveguide polarization switch, two polarization gates 19 and 21 lying one above the other are formed lying in a common plane 23, to which, for example, a microwave converter with the same overall length and the same parallel alignment to one another can now be attached. Both polarization gates are only slightly laterally offset.

The invention has been explained, inter alia, for a waveguide polarization switch using a square waveguide with two rectangular waveguide connections. The principle of operation also applies in general to a round waveguide to which two or more rectangular waveguides are connected. In a square or round waveguide, two main wave types with mutually perpendicular polarization planes can be propagated, which can be coupled separately from one another into one or more rectangular waveguides assigned only one polarization.

By replacing a square waveguide with a round waveguide, the shaft types H₁₁ and H₁₁ can be transmitted.

Finally, it is noted that the waveguides can be provided with discontinuities for the purpose of adaptation, which can also be formed in the side walls transverse to the coupling window.

In the following, reference is made to a modified exemplary embodiment of a polarization switch according to FIGS. 4 and 5.

With this polarization switch, the first waveguide 1 is also square. However, in contrast to the exemplary embodiment according to FIGS. 2 and 3, the one linearly polarized waveguide wave type does not propagate in an extended axial direction to the waveguide 1, but is coupled out via a separate coupling-out window 5 ', which runs centrally in the longitudinal direction on the one in FIG. 4 shown left side wall of the waveguide 1 is introduced. This is followed by an angle 27 for reversing the direction.

The coupling-out of the second linearly polarized wave type, which is perpendicular to the first wave type, takes place via the coupling window 5, which is introduced in FIG. 4 on the opposite right side of the waveguide 1 and is attached there eccentrically in the waveguide 1, as can be seen in particular from FIG. 5 is. There, the second type of waveguide wave is decoupled while rotating the plane of polarization and also reversed in the direction by a subsequent angle 25. Opposite the decoupling window 5 'or the coupling window 5, a short circuit 9' is attached. At the end of the direction of propagation to the waveguide 1, a waveguide termination 31 is provided.

In contrast to the exemplary embodiment according to FIGS. 2 and 3, the rectangular waveguide emanating from the waveguide 1 to the coupling or decoupling window 5 or 5 'are aligned with one another with their narrow sides, whereas in the exemplary embodiment according to FIGS. 2 and 3 those after the coupling window 5 continuous waveguide branches 13 and 17 are aligned with each other with their broad side. But also in the embodiment according to FIGS. 4 and 5, the two polarization gates 19 and 21 belonging to the two waveguide branches 13 and 17 can lie in a common plane.

Claims (14)

1. A hollow waveguide-twist, consisting of a first and a second hollow waveguide (1, 13), which overlap in a coupling region, where they comprise a common coupling window (5), which lies in a plane parallel with the E field lines of the H₁₀ wave of the first hollow waveguide (1) and is off-centre in the surface parallel with the H plane of the second hollow waveguide for the purpose of producing a coupling of the waves which are rotated in their orientation by 90°.
2. A hollow waveguide-twist according to claim 1, characterised in that the first and the second hollow waveguide (1, 13) are two rectangular hollow waveguides and that the coupling window (5) is disposed at the first rectangular hollow waveguide in the centre of the narrow side thereof and at the second hollow waveguide (13) off-centre of the broad side thereof.
3. A hollow waveguide-twist according to claim 1 or 2, characterised in that the coupling window (5) sits in the second hollow waveguide (13) directly at the edge of the broad side of the hollow waveguide (13).
4. A hollow waveguide-twist according to any one of claims 1 to 3, characterised in that an H-bend, an H-angle piece or a short circuit is disposed at the end of the first hollow waveguide (1) after the coupling window (5).
5. Application of a hollow waveguide-twist according to any one of claims 1 to 4 for a polarization separating filter, characterised in that the first hollow waveguide (1) is designed for the purpose of transmitting two linear polarised main wave types having polarisation planes aligned perpendicular with respect to each other, that in this hollow waveguide (1) opposite to the coupling window (5) installed at the centre and parallel with the direction of travel of the waves a short circuit (9′) is disposed for the purpose of further transmitting only the main wave type with a polarisation plane parallel with the plane of the coupling window (5) and for over-coupling the other main wave type with the polarisation plane standing perpendicular to the first and to the plane of the coupling window in the second hollow waveguide (13) in such a manner that the polarisation planes are in each case parallel with each other, as are the directions of travel of the two linear polarised waves in the two hollow waveguide branches (13, 17).
6. Application according to claim 5, characterised in that at the first hollow waveguide the coupling window (5) for the purpose of uncoupling one linear polarised main wave type in the direction of travel lies off-centre and at the opposite side to the first hollow waveguide (1) but displaced in the direction of travel and a second uncoupling window (5′) is attached at the centre for the purpose of further transmitting only the other main wave type, which likewise extends in the longitudinal direction of the first hollow waveguide (1) in such a manner, that the polarisation planes of the two linear polarised waves lie in each case parallel with each other in the two hollow waveguide branches (13, 17) coupled in each case at the centre at the coupling window or uncoupling window (5, 5′).
7. Application according to claim 6, characterised in that in each case a bend or angle (25 27) which reverses the direction of travel of the waves is connected to the coupling and uncoupling window (5, 5′).
8. Application according to claim 6 or 7, characterised in that the coupling window (5) is disposed downstream of the opposite lying uncoupling window (5′) in the direction of travel of the first hollow waveguide (1) for the purpose of coupling the waves which are rotated in their orientation by 90°.
9. Application according to any one of claims 6 to 8, characterised in that in each case opposite the coupling and uncoupling window (5, 5′) and in advance of a hollow waveguide closure (31) which closes the first hollow waveguide (1) is disposed a short circuit (9′) which reduces the width of the wider cross-section extending transverse thereto by virtue of the first hollow waveguide (1).
10. Application according to any one of claims 5 to 9, characterised in that the first hollow waveguide (1) comprises a rectangular cross-section for the purpose of transmitting a H₁₀- and H₀₁ wave.
11. Application according to claim 10, characterised in that the two hollow waveguide branches (13, 17) which are disposed downstream of the coupling window (5) and the short circuit (9′) consist in each case of a rectangular hollow waveguide, the elongated or rather broad sides of which are aligned equally.
12. Application according to any one of claims 5 to 11, characterised in that the two hollow waveguide branches (13, 17) are each connected to a polarisation gate (19, 21) which lie in a common connecting plane (23) at the polarisation separating filter.
13. Application according to any one of claims 5 to 12, characterised in that the first hollow waveguide (1) comprises a round cross-section for the purpose of transmitting the wave types H₁₁ and H_11.
14. Application according to any one of claims 5 to 13, characterised in that the hollow waveguide (1, 13, 17) are provided for the purpose of matching the discontinuities.

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