WO1993007653A1

WO1993007653A1 - Waveguide coupling arrangement

Info

Publication number: WO1993007653A1
Application number: PCT/EP1992/002170
Authority: WO
Inventors: Masahiro Fujimoto; Chaoying Guo; Gérard Haquet; Jean-Paul Grimm
Original assignee: Thomson Consumer Electronics S.A.
Priority date: 1991-10-03
Filing date: 1992-09-19
Publication date: 1993-04-15

Abstract

The present invention presents a device for coupling energy of waves with more than one polarization direction with the aid of probes, which run to given directions. This can be achieved by providing means for rotating polarization directions of the waves by a given rotation angle and/or by providing transition means between a circular and a rectangular waveguide. It is preferred to use the inventive device as part of a Direct Broadcasting Satellite (DBS) converter for receiving appropriate signals.

Description

Wavegui_pde_CouEiing_Ar£angernent

The nvention relates to a device for coupling energy from waves with several polarization di rect ons to lines of a circuit, and in particular from high-frequency electromagnet ical waves, which are led inside a waveguide. Such a device can also be termed as waveguide coupling ar¬ rangement .

It is generally known, that h gh-frequency waves can be led inside a waveguide and that in dependence on its geometry the wave may have several polar zation di rections.

From the European Patent Application EP 0 350 324 A2 it is known, that two separate probes arranged mutually orthogonal¬ ly are used to effect independent polar zed couplings to produce independent linear orthogonal signals or independent left- and right-handed circularly polarized signals.

Due to the orthognal arrangement of the two probes it is difficult to connect the probes to means for a further treat¬ ment of the received signals, e.g. to a common circuit, which can be realized on one single ci rcuit board.

It is also generally known, that inside a circular waveguide waves with several polarizations, e.g. ci rcularly or linearly polarized, may be guided. Inside a rectangular waveguide with a given height and a given width, which is normally larger than said height, normally only waves with a polarization plane parallel to the height can be led as a dominant mode.

From EP 0 073 511 A2 a satellite broadcasting receiver is known in which two kinds of differently polarized waves can be received ithout reducing the effective area of a parabol- ic antenna by serially arranging two frequency down converter circuits in the direction of an axis of a waveguide provided at the focus of a parabolic antenna.

The receiver of the EP 0 073 511 A2 may comprise two units. Each of which contains a circular waveguide, a strip-Line- shaped probe projected into said circular waveguide, a re¬ flecting element provided backward from said probe in said circular waveguide and microwave circuit having a strip line provided around said circular wave guide and connected with said probe, and a parabolic antenna. Thereby said two units are connected with each other such that said circular waveguide or strip—line-shaped probes have 90 degrees-sh fted relative positions of said probes with respect to an axis of said circular waveguide and said circular waveguides receiv¬ ing two kinds of microwaves polarized perpendicular to each other caught by said parabolic antenna.

By the known construction the separation obtained is not sufficient for some appl cations.

It is an object of this invention to simplify a device for coupling energy from waves with several polarization direc¬ tions and/or to improve separation of signals according to said polarisat ons.

This can be realized by a first version of this invention according to claim 1 and by a second version of this inven¬ tion according to the first independend subclaim.

According to the first version of the invention, means which rotate polarization directions of an electromagnet c wave are provided between probes, which receive signals according to the energy of said polarization directions.

Thereby a first probe is arranged parallel to a first polarization direction and may receive the according signals. The means rotate the polarization directions of the wave by a given angle. Thereby signals of a second polarization di rec¬ tion may be received by a second probe, which is arranged parallel to the second polarization di rection after rotation. By this the direction in which the second probe is arranged can be chosen.

Preferably this direction is the same as the one of the fi rst probe, whereby means for a further treatment of the signals can be arranged more easi ly.

The second version of the present invention includes a first waveguide with a fi rst shape, preferably ci rcular, and a second waveguide with a second shape, preferably rectangular. First ends of said waveguides are connected with each other through a transition element (adapter), which realizes a transition from the fi rst shape to the second shape. The second end of the f rst waveguide s connected with receiving means, e.g. a feeder horn, and the second end of said second waveguide contains a reflecting element.

According to this version of the invention, the transition element reflects a first polarized signal Cor wave) and only another one, orthogonal to the first one, is able to traverse.

Energy of the first polarized signal Cor wave) is coupled by a first probe, which is arranged inside the first waveguide, and energy of the second polarization plane is coupled by a second probe, which is arranged inside the second waveguide.

It is an advantage of the present invention, that its perfor¬ mance is very easy to realize. Thereby a simple and cheap production process, like d e-casting, becomes possible for mass production.

If the fi rst and the second probe are provided in a distance of a quarter wavelength from the respective reflecting ele- ments, the received energy of the polarized signals Cor waves) to be coupled is maximized.

If means, which convert a circularly polarized wave into an linearly polarized wave (depo larizor) , are provided upstream of the first probe, the inventive coupling arrangement can also be used for receiving circularly polarized waves.

The present invention will be better understood with the aid of the following description and accompanying drawings, where¬ in

Fig. 1 shows a state of the art coupling arrangement concerning the first version of the invention,

Fig. 2 to show embodiments of the first version of the Fig. 4 invention;

Fig. 5, 6 show different views of the second version of the inventive coupling arrangement.

Fig. 1 a) shows in principle a state of the art coupling arrangement.

In a circular waveguide 10 a first probe 11 and a second probe 12, which is arranged orthogonally to the first probe 11, are provided. The second probe 12 has a distance from the closed end of the waveguide 10 of a quarter of the wave¬ length, or an odd multiple of this quarter wavelength, of a wave to be received and the distance between the two probes is a half, or an integer multiple of the half, of the said wavelength. Fig 1 b) shows the same arrangement but turned about 90 de¬ grees as can be seen from the coordinate systems showed ahead.

A wave, which travels in z-di rection, with a vertical polarization direction in x-direction and a horizontal polarization direction in y-direction can be detected by the arrangement according to fig. 1.

W th the first probe 11 it s possible to receive signals according to the vertical polarization direction and with the second probe 12 signals according to the horizontal direction can be received.

Fig. 2 to 4 show preferred embodiments of the first version of the invention. Means with the same function as those in the coupling arrangement of fig 1 have the same reference numbers and they wi ll be explained only as far as it is neces¬ sary for the understanding of the invention.

In fig. 2 a) and b) a polarization rotator 13, for example a Faraday rotator, is provided between the first probe 11 and the second probe 12. The probes 11, 12 run in the same di rec¬ tion and by this it is possibl'e to connect them very easi ly to a common circuit board 14.

The vertical polarization can be received by the first probe 11. The polarization rotator 13, which is arranged downstream of the first probe 11, rotates the polarization directions of the wave by 90 degrees. Thereby the polarization direction, which is horizontal before the polarization rotator 13, is vertical behind it. That means, that the probe 12 for receiv¬ ing this polarization can be arranged vertically.

In this embodiment the ci rcuit board 14 is arranged horizon¬ tally. The probes 11, 12 may be led through holes in the board 14 to lines 15 which they are connected to, e.g by soIdering.

Fig 3 a) and b) show another embodiment. The difference to the embodiment of fig 2 is, that here the circuit board 14 is arranged vertically on the waveguide 10. Depending on the shape of the probes 11, 12 an appropriate contact between them and Lines 15 of the circuit board could be chosen.

Fig 4 shows still another embodiment of the first version of the invention. The first probe 11 is arranged in a first part 10a of the waveguide 10 and the second probe is arranged in a second part 10b of the waveguide 10. Preferably the first part 10a is a circular waveguide and the second part 10b is a rectangular waveguide.

A version of the embodiment according to fig 4 may have the variation, that the circuit board 14 is arranged horizontally.

Other versions of the preferred embodiments of the first version of the invention may contain at least one of the following variations: the contact between the probes 11, 12 and lines 15 of the circuit board may be direct or via elastic means, which are in direct contact with the lines 1^; - instead of one common circuit board, more than one may be provided, e. g. in different but given directions. The value of rotation and the arrangement of the probes 11, 12 must be given appropriately; at least one of the probes 11, 12 may be not connected to the circuit board 14, but to other means, e.g. a feeder Line, for a further treatment of the signals; instead of the polarization rotator 13 any other rotat¬ ing means that rotate the polarization directions of the wave may be taken; rotating means ma also be provided upstream of the first probe 11 to adjust the polarization direction to be received by the first probe 11.

Fig. 5 shows a preferred embodiment of the second version of the i nvent ion.

An incoming orthogonally polarized wave 110 is received by a feed horn 111. This feed horn 111 is connected with a ci rcu¬ lar waveguide 112, which is connected with a transition ele¬ ment 113, that realizes a transition from the circular waveguide 112 to a rectangular waveguide 114. At the end of the rectangular waveguide 114 a short plate 114a is provided.

In the circular waveguide a first probe 115 is provided for receiving a horizontally polarized signal of the wave 110 and in the rectangular waveguide 114 a second probe 116 is provid¬ ed for receiving a verti cally polarized signal of the wave 110. The probes 115, 116 are connected with a first receiver 117, and a second receiver 118 respectively. The receivers 117, 118 include well known converting and receiving means.

Fig. 6 shows another view of the second version of the inven¬ tion just including means, which are useful for the under¬ standing of the invention and which are marked with the same reference numbers as in fig. 5. The points of sight of fig 5 and fig. 6 are indicated by the coordinate systems belonging.

The function of this embodiment wi ll now be explained with the aid of the figures 5 and 6.

Inside the circular waveguide 112 all polarized signals of the received wave 110 are able to propagate. One of these planes is the horizontally polarized one, the energy of which can be coupled by the first probe 115 and the appropriate signals are led to the first receiver 117. The transition element 113, which realizes a transition from the circular waveguide 112 to the rectangular waveguide 114, whereby the rectangular waveguide 114 is arranged in such a way, that its width w is larger than its height h, reflects the horizontally polarized signal of the wave 110. That means, as the wave 110 is orthogonally polarized, that only its vertically polarized plane is able to traverse the transi¬ tion element 113.

One can suppose, that said reflection is done at a reflecting plane r. In the preferred embodiment of the inventive cou¬ pling arrangement the difference between the reflecting plane r and the first probe 115 is a quarter wavelength L1 , whereby L1 is the equivallent quater wavelength inside the circular waveguide 112 and transition 113. Thereby a constructive interference of the incoming wave and the reflected wave is realized at the location of the first probe 115.

As the width w of the rectangular waveguide 11^ is larger than its height h, only the vertically polarized plane of. the wave 10 is able to propagate in it. The energy of this plane is coupLed by the second probe 16 and Led to the second re¬ ceiver 118.

In the preferred embodiment the difference between the short plate 114a, which represents a reflecting element, and the second probe 116 is a quarter wavelength L2, whereby L2 is the effective quater wavelength inside the rectangular waveguide 113. Thereby a constructive interference of the incoming wave and the refelected wave is realized at the Locat.ion of the second probe 116.

It should be mentioned, that the values of the distances between the probes 115, 116 and the reflecting plane r or the reflecting element 114a respectively for a constructive intei— ference may also be determined by multiplications by odd numbers of a quarter wavelength, that means by C 2n - 1 ) * L 1 ,

C2n - 1) * L2 respecti ely,

where n is an integer.

Due to the fact, that only the vertically polarized signal is on the one hand able to traverse the transition element 113 and on the other hand able to propagate inside the rectangu¬ lar waveguide, a very good separation between the horizontal¬ ly and the vertically polarized plane waves can be ach eved.

Versions of this embodiment may contain at least one of the following variations: the whole arrangement may be turned, whereby the first probe 115 receives the vertically polarized signal of the wave 110 and the second probe 116 receives its hori¬ zontally polarized signal; the probes 115, 116 may be arranged as part of strip lines of ci rcuit boards, which contain at least parts of the receivers 117, 118; upstream, that means in fig. 5 left, of the first probe 115 means may be provided, which convert a circularly polarized wave into the linearly polarized wave 110; instead of the circular waveguide 112 any other waveguide, which is usable for different kinds of polarizations, may be taken; instead of the rectangular waveguide 113 any other waveguide, which is usable for that kind of polarization, which can traverse the transition element 113, may be taken; instead of the short plate 114a any other reflecting element may be taken; the version 1 and the version 2 of the invention can be combi ned.

Claims

C L A I M S

Waveguide coupling arrangement coupling energy of waves with more than one polarization direction out of a waveguide C10) to means for a further treatment of sig¬ nals according to the energy of the respective polarization directions, whereby probes (11, 12) are provided for every polarization direction to receive the appropriate energy, characterised in that between the probes (11, 12) means (13) are provided, which rotate the polarization directions by a given rotation angle.

Arrangement according to claim 1, characterised in that the means (13) rotate the polarization directions by 90 degrees.

Arrangement according to one of the claims 1 or 2, chai— acterised in that a circuit board (14) is provided, which is in contact with the probes (11, 12).

Arrangement according to one of the claims 1 to 3, char¬ acterised in that said means (13) are a Faraday-type rotator.

Arrangement according to one of the claims 1 to 4, chai— acterised by

- a first probe (115) for receiving energy of a first polarization signal (horizontal) of the wave, said first probe (115) is provided inside a first waveguide (112) upstream of a fi st reflecting element (113) for the first polarization signal, where said first waveguide (112) is usable for different kinds of polarizations,

- a second probe (116) for receiving energy of a sec¬ ond polarization signal (vertical) of the wave, said second probe (116) is provided upstream of a second reflecting element (114a) for the second polarization signal, wherein

- the first reflecting element is shaped as a transi¬ tion element (113) that realizes a transition from the first waveguide (112) to a second waveguide (114), where said second waveguide (114) is usable for one kind of polarization and

- the second probe (116) is provided inside the sec¬ ond waveguide (114).

6. Waveguide coupling arrangement for a polarized wave with

- a first probe (115) for receiving energy of a first polarization signal (horizontal) of the wave, said first probe (115) is provided inside a first waveguide (112) upstream of a first reflecting element (113) for the fi rst polarization signal, where said first waveguide (112) is usable for different kinds of polarizat ons,

- a second probe (116) for receiving energy of a sec¬ ond polarization signal (vertical) of the wave, said second probe (116) is provided upstream of a second reflecting element (114a) for the second polarization signal, characterised in that

- the second probe (116) is provided inside the sec¬ ond waveguide (114).

7. Arrangement according to claim 6, characterised in that the first waveguide (112) is essentially shaped circular and/or the second waveguide (114) is essentially shaped rectangu lar. - 1 ? -

8. Arrangement according to claim 6 or 7, characterised in that the first probe (115) is provided in a distance of essentially a quarter waveLength (L1⁾ or its odd-number mutiplication from the first reflecting element ⁽113⁾ and/or the second probe (116) is provided in a distance of essentially a quarter wavelength (L2) or its odd number multiplication from the second reflecting element.

Arrangement according to one of the claims 6 to 8, chai— acterised in that means are provided upstream of the first probe (115), which convert circularly polarized waves into Linearly polarized waves.