EP2897213B1 - Broadband signal splitting with sum signal absorption - Google Patents

Description

The invention relates to a (BSmS) for transmitting signals over a predetermined bandwidth, which corresponds to the maximum bandwidth of a conventional T-branch.

Such a (BSmS) comprises a common waveguide having a first predetermined cross section and four Seitenarmhohlleiter with a predetermined second cross section. Two first, opposite side arm waveguides extend along a first axis. Two second, opposite side arm waveguides extend along a second axis, the first and second axes being orthogonal to each other. The common plane is orthogonal to a major axis of the common waveguide.

An orthomode transducer (OMT) is a passive component of microwave technology. It is used for the separation or combination of orthogonally polarized electromagnetic waves. Current communication systems consist of a satellite receiver and transmitter with antennas for satellite communication. There, the Orthomodenkoppler takes over the task of a diplexer or circulator when receive and transmit signals are polarized orthogonally, and passes both signals together via an antenna.

Due to manufacturing inaccuracies, minimal unbalanced discontinuities may occur. This results in phase differences of the various electromagnetic waves and ultimately in the merging of the individual waves to unwanted interference signals. When the signals are combined, the relative phase shift in the individual propagation paths of the electromagnetic waves deviates slightly from a desired value of 180 °. If one subtracts two signals from each other, a certain amount of sums remains, the amplitude of which depends on the deviation of the phase from the nominal value.

By using a conventional T-junction (a so-called tee junction) as signal branching, as in Fig. 4 is shown, caused by the manufacturing tolerance such sum signals. The sum signals resonate due to the high quality of the Orthomodenkopplers inside an antenna feed network and can not be absorbed due to a missing sum signal waveguide (ports). This creates unwanted resonance peaks in the scattering parameters.

An advantage of conventional T-junction, as in Fig. 4 is shown to cover the maximum waveguide bandwidth of transmissible frequencies. If a signal is fed to the so-called delta port of the symmetrical T-branch, denoted by 1, it is divided into the two collinear side arms 2, 3 for each -3 dB of the power with a phase offset of ideally 180 °, the phase offset as above described, may deviate unfavorably from 180 °, depending on the manufacturing tolerance.

To dampen the resonance peaks, a so-called magic T-branch is used instead of the conventional T-branching as signal branching for coupling a signal. The sum signals, which result from a relative phase shift, are absorbed in this material in the Orthormenkoppler material of the waveguide absorber.

As a magic T-branching, Hybrid Tee is called in hybrid technology a hybrid or 3dB coupler. In practice, this component finds application in microwave components. It is a more power-stable alternative to a rat-race coupler used in microstrip line technology. Magic tea (so-called magic tea) is a combination of an E-plane and an H-plane T-branch. In order to be able to guarantee correct functioning, a so-called matching structure (matching structure) is provided inside the magic T-branch. The magic T-junction only works in one certain frequency range and the transmission behavior varies very much with the geometry of the matching structure.

The name magic T-branch is derived from the electrical power flow inside the junction. An exemplary magic T-branch is in Fig. 5 shown. A signal which is fed to the Summentor 8, divided to the same amplitude and phase position on the collinear side arms 6, 7.

In contrast, a signal which is fed to the difference gate 5 of the magic T-branch is split to the same amplitude but with a phase shift of 180 ° to the side arms 6, 7. The electric field of the dominant field wave type in each gate is perpendicular to the broad side of the waveguide. Thus, the signals 5S, 8S in the E-plane gate (difference gate 5) and in the H-plane gate (Summentor 8) are polarized orthogonal to each other. As described, this variant is disadvantageously limited in bandwidth to about 40% over the bandwidth of the conventional T-branch.

US 2005/0200430 A1 discloses a waveguide orthomodic coupler for use in VHF, UHF, microwave band, and micrometer waveband. A coupler is also off MA Meyer, et al, Applications of the Turnstile Junction, IRE Transactions on Microwave Theoy and Techniques, IEEE, 1955 known.

It is therefore an object of the present invention to provide a waveguide signal branching, which suppresses unwanted resonance peaks in the scattering parameters at high bandwidth, in particular a bandwidth corresponding to the bandwidth of a conventional T-branch.

This object is achieved by a waveguide signal branch according to the features of claim 1. Advantageous embodiments emerge from the dependent claims.

A waveguide signal branch for transmitting signals is proposed which comprises a common waveguide with a first predetermined cross section and four side arm waveguides with a predetermined cross section. The cross sections of the Seitenarmhohleiter may also be different. Two first, opposite side arm waveguides of the four side arm waveguides extend along a first axis. Two second, opposite side arm waveguides extend along a second axis. The first and second axes are orthogonal to each other. The (BSmS) is characterized in that the two first side arm waveguides are terminated with a waveguide absorber.

With the (BSmS) Orthomodenkoppler can be designed, which allow an increase in bandwidth and a strong damping of manufacturing tolerances resulting resonance peaks in the scattering parameters. In particular, the invention (BSmS) is able to operate with a bandwidth that corresponds to the bandwidth of a conventional T-branch, as exemplified in US Pat Fig. 4 is shown. The energy of the sum signals is decoupled into the side arm waveguides terminated with the waveguide absorber and absorbed in the waveguide absorbers.

The first predetermined cross section of the common waveguide may be rectangular. The first predetermined cross section of the common waveguide may be square. The first predetermined cross section of the common waveguide may be elliptical. The first predetermined cross section of the common waveguide may be round. The first predetermined cross section of the common waveguide may in principle have any cross section.

The second predetermined cross section of the four side arm waveguides may be rectangular. The second predetermined cross section of the four side arm waveguides may be square. The second predetermined cross section of the four side arm waveguides may be elliptical. The second predetermined cross section of the four side arm waveguides may be round. The second predetermined cross section of the four side arm waveguides may in principle have any desired cross section.

According to a further embodiment, the two second side arm waveguides can be arranged collinearly and / or formed.

In a further embodiment it can be provided that the four side arm waveguides are arranged offset and / or formed out of the common plane, so that e.g. each two of the Seitenarmhohlleiter are arranged in a respective common plane, wherein the two planes are different. These two levels may or may not be parallel to one another.

It may further be provided that in the interior of the (BSmS), in particular in the interior of the common waveguide, a matching structure is provided, whose geometry is adapted to a desired transmission behavior. For example, the matching structure is analogous to a magic T-branch.

The inventive (BSmS) is characterized in a further embodiment in that signals over a total bandwidth with a phase offset of 180 ° can be split or coupled.

Fig. 1

eine bekannte Signalkette mit für einen Telekommunikationssatelliten typischen Komponenten;

Fig. 2

eine schematische Darstellung der Nutzung von benachbarten Frequenzbändern für die Übertragung von Sende- und Empfangssignalen:

Fig. 3

eine schematische Darstellung eines typischen Orthomodenkopplers;

Fig. 4

eine bekannte konventionelle T-Verzweigung;

Fig. 5

eine bekannte magische T-Verzweigung;

Fig. 6

eine perspektivische Darstellung der erfindungsgemäßen Breitband Signalverzweigung mit Summensignalabsorption;

Fig. 7

eine Seitenansicht der erfindungsgemäßen Breitband Signalverzweigung mit Summensignalabsorption aus Fig. 6;

Fig. 8

eine Aufsicht der erfindungsgemäßen Breitband Signalverzweigung mit Summensignalabsorption aus Fig. 6; und

Fig. 9

einen Vergleich von Rückflussdämpfungsparametern (Return-Loss-Parameter) der erfindungsgemäßen Breitband Signalverzweigung mit Summensignalabsorption und einer magischen T-Verzweigung.

The invention will be described in more detail below with reference to embodiments in the drawing. Show it:

Fig. 1

a known signal chain with components typical for a telecommunications satellite;

Fig. 2

a schematic representation of the use of adjacent frequency bands for the transmission of transmit and receive signals:

Fig. 3

a schematic representation of a typical Orthomodenkopplers;

Fig. 4

a known conventional T-junction;

Fig. 5

a known magic T branch;

Fig. 6

a perspective view of the broadband signal branching according to the invention with sum signal absorption;

Fig. 7

a side view of the broadband signal branching according to the invention with sum signal absorption Fig. 6 ;

Fig. 8

a plan view of the broadband signal branching according to the invention with sum signal absorption Fig. 6 ; and

Fig. 9

a comparison of return loss parameters (return loss parameter) of the broadband signal branching invention with sum signal absorption and a magic T-branch.

The antenna design of today's standard telecommunications payload of a satellite is being developed as a function of electromagnetic, thermomechanical, technological and design constraints. The main objective in designing the antennas of a telecommunications payload is to maximize the amplification of electromagnetic waves over a complex shaped geographic area. Furthermore, a high usable bandwidth is desired. For this purpose, a multiple utilization of frequency and polarization known to those skilled in the art is used. Another requirement is high performance.

To drive horn antennas available today (so-called Feed Horn) with Doppelpolarisationsausnutzung an antenna feed network (so-called. Feedchain) is used, which allows the merging or separating of two linearly or circularly polarized orthogonal signals that the satellite receives and transmits.

Fig. 1 shows a block diagram of a typical signal chain of a telecommunications satellite. The system can process signals with orthogonal polarization both in the transmit (Tx) and in the receive band (Rx). A vertically polarized transmission signal is designated VTx and shown by a vertical arrow with a solid line. A horizontally polarized transmission signal is designated HTx and represented by a horizontal arrow with a broken line. A vertically polarized received signal is denoted by VRx and shown by a vertical arrow with a solid line. A horizontally polarized receive signal is shown with HRx and a horizontal arrow with a broken line. The transmission signals VTx, HTx are also provided with hatching.

The interface between an antenna ANT and the payload, ie the antenna feed network, is formed by an orthomode transducer (OMT). The Orthomodenkoppler OMT separates in the case of reception, the antenna signals VRx, HRx broadband according to their polarization (vertical (V) or horizontal (H)) in the orthogonal components, before these in an associated transmit / receive diplexer DV, DH in terms of frequency in the transmit (Tx) and receive (Rx) bands are separated. Conversely, in the transmission case, the orthomode coupler OMT merges the vertically and horizontally polarized signals VTx, HTx supplied to it by the diplexers DV, DH and supplies them to the antenna ANT for transmission. In this way, the satellite is able to process four independent signals. The known division of a frequency range f into a frequency band for transmission signals (Tx band) and reception signals (Rx band) is schematically shown in FIG Fig. 2 shown.

The core of the antenna feed network is thus the orthomode coupler OMT, which divides the antenna signals according to their polarization into the orthogonal components. In order to further maximize the transmission capacity, one uses broadband adapted structures, with which a larger or largest possible frequency range use can be realized.

As in Fig. 3 schematically, a conventional orthomode coupler OMT comprises a waveguide 1 with a circular or square cross-section, which is connected to the antenna ANT (cf. Fig. 1 ) connected is. In each case a rectangular waveguide 2, 3 is connected to the diplexer DV for vertically polarized signals and the diplexer DH for horizontally polarized signals. As in the introduction with the 4 and 5 described, such a Orthomodenkoppler can be formed by a conventional or a magic T-branch, the conventional T-branch due to unavoidable manufacturing tolerances undesirable resonance peaks in the scattering parameters and the magic T-branch has the disadvantage of a smaller compared bandwidth ,

The proposed (BSmS) included in the Fig. 6 to 8 is shown, avoids these disadvantages and at the same time allows an increase in bandwidth and a strong damping of the manufacturing tolerances resulting resonance peaks in the scattering parameters.

The BSMS fitted over the entire rectangular waveguide bandwidth comprises four side arm waveguides (side gates) 21, 22, 23, 24 of rectangular, elliptic or any other arbitrary cross section, the side arm waveguides 21, 22, 23, 24 being symmetrically arranged in a plane , In this case, the opposite Seitenarmhohlleiter 21, 23 along a first axis 27 and the opposite Seitenarmhohlleiter 22, 24 extend along a second axis 28. The first and the second axis 27, 28 are arranged orthogonal to each other and lie in a common plane. The common plane is orthogonal to a major axis (longitudinal axis) 30 of a common waveguide 11. The common waveguide 11 may be a square, elliptical, circular waveguide or waveguide of any other shape. In the present description, it is designed as a circular waveguide.

The opposite side arm waveguides 21, 23 are symmetrically terminated with a waveguide absorber 25, 26. The waveguide absorbers 25, 26 are slid over the sidearm waveguides 21, 23 in the manner of a cap, or are located inside the sidearm waveguides. The waveguide absorbers 25, 26 consist of an electrically and or magnetically lossy material (for example ECCOSORB).

In the interior of the waveguide arrangement, a matching structure, not shown in greater detail, whose geometry is adapted to a desired transmission behavior.

The (BSmS) comprises four symmetrically arranged rectangular waveguides 21, 22, 23, 24 (or waveguide of any other shape) with a common waveguide 11 together. This mechanical 5-port combines the function of a conventional T-branch with the function of a magic T-branch in an antenna feed network. Transmit and receive signals can thus be divided or coupled over the entire waveguide bandwidth with a phase shift of 180 ° as in a conventional T-branch.

The resulting due to the manufacturing inaccuracy sum signals which resonate inside the Orthomodenkopplers be absorbed in the two waveguide absorbers 25, 26 of the Orthomodenkopplers.

A comparison of the return-loss parameter between a magic T-branch and a broadband branch is shown Fig. 9 , This shows the frequency range normalized. Typical values for the required return loss parameters are usually about -30 dB (curve K1). The curve K2 shows the course of the return-loss parameters for the magic T-branch. The curve of the return loss parameter for the inventive (BSmS) is marked with K3. In Fig. 9 It is easy to see that with the symmetric (BSmS) the so-called return loss parameters over a relative frequency range 60% better than -30dB. In contrast, the magical T-branching only reaches about 40%.

LIST OF REFERENCE NUMBERS

1

common waveguide, circular or square

2

Side arm waveguide, rectangular

3

Side arm waveguide, rectangular

5

Summentor of a magic T-junction

6

Side arm of a magic T-branch

7

Side arm of a magic T-branch

8th

Difference gate of a magic T-branch

10

Waveguide Orthomodenkoppler

11

common waveguide

21

Seitenarmhohlleiter

22

Seitenarmhohlleiter

23

Seitenarmhohlleiter

24

Seitenarmhohlleiter

25

Waveguide absorber

26

Waveguide absorber

27

first axis

28

second axis

30

Main axis (longitudinal axis)

OMT

Orthomodenkoppler

ANT

antenna

DH

diplexer

DV

diplexer

VRx

vertically polarized received signal

HRx

horizontally polarized received signal

VTx

vertically polarized transmission signal

HTx

horizontally polarized transmission signal

Claims (7)

1. A broadband signal junction with sum signal absorption (10) for transmitting signals, comprising:

   - a common hollow conductor (11) with a first predefined cross-section; and

   - four side arm hollow conductors (21, 22, 23, 24) disposed in a common plane, the four side arm hollow conductors having a predefined cross-section, wherein two first opposing side arm hollow conductors (21, 23) extend along a first axis and two second opposing side arm hollow conductors (22,24) extend along a second axis, wherein the first and the second axis are disposed orthogonal to one another lying in the common plane, and wherein the common plane runs orthogonally to a main axis of the common hollow conductor,

   characterized in that
   the two first side arm hollow conductors (21, 23) end with a respective hollow conductor absorber (25, 26).
2. The broadband signal junction with sum signal absorption of claim 1, wherein the first predefined cross-section of the common hollow conductor is rectangular, square, elliptical, or round.
3. The broadband signal junction with sum signal absorption of claim 1 or 2, wherein the predefined cross-section of the four side arm hollow conductors (21, 22, 23, 24) is rectangular, square, elliptical, or round.
4. The broadband signal junction with sum signal absorption according to any one of the foregoing claims, wherein the two second side arm hollow conductors (22, 24) are disposed and/or designed collinear.
5. The broadband signal junction with sum signal absorption according to any one of the foregoing claims, wherein the four side arm hollow conductors (21, 22, 23, 24) are disposed and/or designed offset from the common plane.
6. The broadband signal junction with sum signal absorption according to any one of the foregoing claims, including a matching structure disposed inside of the junction, wherein the matching structure has a geometry matched to a desired transmission behavior and can have any arbitrary shape.
7. The broadband signal junction with sum signal absorption according to any one of the foregoing claims, wherein the signals are split or coupled over an entire bandwidth with a phase shift of 180°.

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