EP1407508B1 - Directional coupler - Google Patents

Abstract

An improved directional coupler is distinguished by the following features: an attenuation circuit is adjacent and is connected to each of the two coupling line ends on the coupler substrate, or an attenuation circuit is connected to one coupling line end with a terminating resistor ( 49 ) being connected to the other coupling line end on the coupler substrate, electrical level evaluation is provided on the coupler substrate, and an interface device for connection of possibly unshielded cables is provided on the coupler substrate, or possibly unshielded cables are connected to the level evaluation circuit device or are connected downstream from this on the coupler substrate, via which the RF signals which are obtained via the coupling line piece can be passed on in the form of analog signals.

Description

The invention relates to a directional coupler according to the preamble of claim 1, as he is known from DE-A1-199 28 943 is known.

Another directional coupler is for example from DE 23 20 458 C2 became known. It consists of an unbalanced one Stripline and a coaxial line, in which the stripline coupled to the coaxial inner conductor is. The strip conductor is in the coupling zone in an exposed recess of the outer conductor of the coaxial line fitted, the ground conductor of the stripline at the same time the interrupted by the recess Shielding of the coaxial line forms.

In order for such a directional coupler and the inductive Set coupling is, according to the above-mentioned DE-A1-199 28 943 proposed, the base plate as a circular Substrate disc form, in a corresponding cylindrically shaped cutout sits. This is the substrate wafer with the coupling piece angularly rotatable.

By the rotation of the coupling line in the electromagnetic Coaxial cable field is thus the directional coupler calibrated. However, the adjustment is limited only to the coupling damping. Achieving a high leveling sash, which is of great importance in practice, contributes this solution does not matter.

The tapped in the described prior art Direction coupling signal quantities are known to an external Evaluation device supplied, via coaxial cable. Because high-frequency signals are decoupled, must therefore also high quality and costly Coaxial cable and of course equally high quality and costly Coaxial connector can be used. Thereby it should be ensured that also with regard to the characteristic impedance a high quality connection and therefore one good directivity is feasible.

An adjustable directional directional coupler is basically also known from US-A-4,476,447. By twisting, the distance between an arcuate Coupling section and a passage line changed be to get an appropriate setting here and Make adjustment.

The arrangement of the level detector in this prior publication has no influence on the directivity. A wave passing through the coupler according to the pre-publication US-A-4 476 447 advances in the direction in no measurement is to be made at the other gate the coupling line a signal. Occurring reflections would flow through the coupling line and at the detector appear. This falsifies the signal to be measured and the directivity is reduced. This should be done by a provided for this resistor according to this prior publication be avoided.

The object of the present invention is therefore to provide a to provide improved directional coupler, which in total more cost-effective construction the achievement of improved signal values allows.

The object is achieved with the subject matter of claim 1. Advantageous embodiments of the invention are in specified in the dependent claims.

The invention accordingly proposes that on the base plate of the directional coupler then to the two ends the coupling piece per a damping circuit provided is.

Above all, on the directional coupler itself, i. prefers on the base plate, an electronic level evaluation intended. Furthermore, an interface device accommodated, at the however - there the high frequency signal processing takes place on the directional coupler itself - Only an unshielded cable can be connected can. Namely, it is preferred at this interface device a ribbon cable connected, which of course Very high quality coaxial cable connections much cheaper can be provided.

By this construction according to the invention are not only Drastic cost advantages over conventional solutions realized, but it results in much improved Values for the directivity.

The advantages according to the invention are therefore particularly great, there on the base plate of the directional coupler at both Ends ever a damping circuit is provided. This opens up the possibility that at the Auskoppelleitung the signals of both directions continue to be used or can be further processed ("double coupler"). Becomes in contrast, one side of the coupling line with a Shooting resistance completed, so only can a signal path are evaluated. This would mean, that for the forward and the return respectively a separate Coupler would be required. When using one each Directional coupler for each direction (namely one for the Flow and one for the return) would have the directivity be set separately for each branch, giving two separate coupler is necessary (double adjustment effort). This would also be no integration on one common PCB possible and the transmitter would have to be realized on a third circuit board become. This in turn would require that connection between the coupler and the third circuit board using high quality and therefore very expensive Hochfrequenzkoaxialleitungen would be performed. These disadvantages are in the solution according to the invention path.

In a preferred embodiment of the invention for the attenuators a known n-circuit or, for example, a T-circuit using the used corresponding resistors. Especially this one Circuitries can easily on the base plate or the directional coupler are recognized.

In particular, by using a π-attenuator or by using a T-attenuator can be the detection of the return and the flow on one Particularly easy to realize PCB, causing the Evaluation electronics of the printed circuit board with high integration density can be integrated. By exact assembly of the coupling piece, the directional coupler has a high Directivity. Improved when using multilayer material the achievable directivity of the coupler still once. In addition, this also allows integration density increase again.

Above all, it is surprising that by using Attenuators (which reduces the signal level) but ultimately achieve an improved directivity and this especially for broadband applications.

In addition, on the respective arm of the directional coupler also be housed filter blocks.

Furthermore, the accommodation proves to be particularly favorable a level detector on the directional coupler, i. especially on the base plate.

Finally, it is provided in a development of the invention, that in addition to the directional coupler Memory module, preferably a non-volatile EEPROM memory module is located in which the transfer function at least one and preferably both coupling arms stored with electronic evaluation. In order to is now a clear assignment between adjacent RF level value and resulting detector voltage ensured. All component tolerances of directional coupler and Evaluation electronics are on a common module summarized and stored. This will also Replacing individual modules in one device considerably simplified. Because in previously known coupler systems had in contrast to the replacement of individual Components either a complex adjustment on Whole unit or it had to be very high quality, tightly tolerated individual components are used, which are balance-free in mutual interaction.

Figur 1 :

eine schematische perspektivische Darstellung eines Koaxialleiters mit einem Anschlussbereich für den Richtkoppler;

Figur 2 :

eine schematische Vertikalschnittdarstellung durch die Grundplatte des Richtkopplers und des Koaxialleiters;

Figur 3 :

eine schematische Draufsicht auf die Darstellung gemäß Figur 2;

Figur 4 :

eine vergrößerte Detaildarstellung auf den das Koppelstück sowie die elektronischen Baugruppen und Komponenten umfassenden Grundplatte des Richtkopplers einschließlich eines Erweiterungsabschnittes;

Figur 5 :

einen schematischen Schaltplan zur Verdeutlichung der auf der Grundplatte befindlichen Elektronik; und

Figur 6 :

eine zu Figur 5 abgewandelte Schaltungsanordnung für einen nicht zur Erfindung gehörenden einarmigen Richtkoppler, bei welchem der eine Ausgang des Richtkopplers über einen Abschlusswiderstand abgeschlossen und am anderen Ausgang nicht ein Π-förmiges, sondern ein T-förmiges Dämpfungsglied vorgesehen ist.

The invention will be explained in more detail with reference to drawings. In detail:

FIG. 1:

a schematic perspective view of a coaxial conductor with a connection region for the directional coupler;

FIG. 2:

a schematic vertical sectional view through the base plate of the directional coupler and the coaxial conductor;

FIG. 3:

a schematic plan view of the representation of Figure 2;

FIG. 4:

an enlarged detail of the coupling piece and the electronic components and components comprehensive base plate of the directional coupler including an extension section;

FIG. 5:

a schematic diagram illustrating the electronics located on the base plate; and

FIG. 6:

a modified to Figure 5 circuit arrangement for a non-invention belonging to the one-armed directional coupler, wherein the one output of the directional coupler via a terminating resistor and at the other not a Π-shaped, but a T-shaped attenuator is provided.

In Figures 1 et seq. A directional coupler is shown, the one continuous Koaxialleitungsstück 1 with a in Figure 1 shown in perspective view and relatively massive designed outer conductor 3 and with an inner conductor. 5 includes.

The outer conductor 3 has an embodiment shown in the embodiment square or rectangular outer diameter on. Under formation of an inside of the outer conductor. 3 hollow cylindrical spacer space 7 is from the outer conductor 3 electrically isolated in the embodiment shown cylindrical inner conductor 5 is provided extending.

On the outer conductor 3 is - as in particular from Figure 1 can be seen - a support or mounting portion 11th preferably in the form of a depression or cutout intended. In a coupling zone 13 thus formed is a exposed recess 15, i. a window 15 in the Wall of the outer conductor 3 is provided.

In this coupling zone 13 then the coupler 19 with the Kopplersubstrat 19 ', for example, by several laterally to the exposed recess 15 offset screws 16 permanently mounted on the outer conductor 3, wherein at the bottom of the coupler substrate 19 'is a coupling lead 23 is provided. The coupling line has a length of preferably <λ / 4, in particular a length of> λ / 16, especially around λ / 8. These are in the places where the Screw 16 sit in the wall of the outer conductor. 3 appropriate threaded holes incorporated with the corresponding bores 18 in the coupler substrate 19 ' are aligned to screw in the corresponding screws 16.

The coupling line piece 23 may be in a predetermined Alignment on the Kopplersubstrat 19 'be provided in such a way that according to experience favorable values for the coupling damping result.

The coupling lead 23 may for example consist of a Stripline consist. In the same way, but a wire hanger or a wired component (resistor) are used.

The coupler substrate 19 'is in the form of a multilayer film constructed by the shielding a Good shielding and thus a total Störstrahlungsfesten Coupler yields. Through the multilayer layer 19 'is characterized by the exposed recess 15 interrupted shielding of the coaxial line completely closed again.

About vias are on the coupling lead 23 in the relevant electromagnetic field tapped signals passed to the coupler top, where the electronic components are located, the the decoupled RF signals directly into analog low-frequency voltages convert for further processing.

These are immediately adjacent to the coupling line ends 25 suitably dimensioned attenuators or Damping circuits 27 are provided which are double-sided Forced adaptation serve for the coupling line and thus the Determine the directivity of the coupler fundamentally.

In the embodiment shown in FIG 5 is the damping circuit 27 is designed in the form of a π-circuit, in which a first resistor R1 in each case in the signal line 29 and before and behind the resistor R1 a further grounded or counter-potential Resistor R2 and R3 are connected.

As also shown with reference to FIG. 6, instead of Such an N-shaped damping circuit 27 is a T-shaped Damping circuit can be used, in which two resistors R4 and R5 in the signal line 29 in FIG Are connected in series and between these one on earth or a resistor R6 connected to a counter potential is connected is.

But other attenuation circuits are basically feasible (e.g., fixed attenuators).

From the embodiment shown in FIG 5 is apparent that the electronic RF components on the coupling top identical and symmetrical for both coupling arms are selected and arranged. Because possibly disturbing Influences such as mismatches, component tolerances and temperature drifts act equally on both coupling arms, these influences are compensated against each other.

From the top view according to FIG. 5 it can also be seen that the damping circuits 27 in both coupling arms A, B. downstream of a filter 31 and, for example, a Level detector 33 and an EEPROM 37 housed can, wherein preferably in the EEPROM memory module Transfer function of the two coupling arms together with electronic Evaluation are stored.

The whole arrangement can be including one Interface device 35 on the coupling substrate 19 ' accommodate. Should the central portion 19a of the coupling conductor substrate 19 'for the electronic components not be large enough, the coupler substrate 19 'may next to the central portion 19a, immediately above the free recess 15 on the outer conductor 3 of the Koaxialleitungsstückes 1 is still another laterally projecting Extending portion 19b include (Figure 4).

At the mentioned interface device 35 can now for tapping the analog signals a Gegensteck- or Contact device 36 connected with an unshielded cable be an unshielded example Flat cable 41, which accommodated to an externally Microprocessor module 43 leads.

The coupler substrate 19 'is in the illustrated embodiment built as a 4-layer multilayer, creating the combination made of HF directional coupler and electronic evaluation can be realized on a single compact module. There are two inner layers, the lower inner layer serves as reference ground for the coupling lead. The layer structure of the Kopplersubstrates but also different be executed, for example, with different Substrate thickness or number of layers. The printed circuit board substrate can change for every situation and therefore also different Have quality levels and price ranges.

With reference to FIG. 6, it is not part of the invention per se belonging one-armed trained directional coupler (at which one of the coupling arm on the coupling substrate 19 ' terminated by a terminator 49) shown that attenuators 27 also in the form of the mentioned T-circuit instead of an n-circuit formed could be. This T-circuit can also in the for Invention belonging directional coupler according to Figure 5 instead the π circuit shown there be realized.

In addition to the illustrated embodiments will noted that the coupling lead both in length how width can vary and in different ways Relative position, i. in particular twisting to the underneath the inner conductor can be mounted. The coupling cable does not have to be a stripline be executed. It can also be used as a wire hanger or in the form of a wired component (resistor) be realized.

As already indicated, the location and construction of the Kopplersubstrates different from the embodiments shown be pictured. So, for example different substrate thicknesses or a Kopplersubstrat with one of the embodiment shown deviating position and number are used.

Finally, the printed circuit substrate of different Quality levels and price ranges built be.

As particularly with reference to Figures 4 and 5 results, the electrical and electronic components both on the coupler top, i. the top of the Kopplersubstrates 19 'as well as on the bottom to be appropriate. Finally, the described Assemblies also elements for temperature compensation include, for example, a software or allow hardware temperature compensation.

Furthermore, the assembly on the coupler substrate can also in addition to an absolute level information also difference values level and phase between the two coupling arms deliver. These signals can also be used accordingly evaluated and a subordinate via the ribbon cable Microprocessor can be provided.

Finally, the two coupling arms a and b over separated or common electronic paths 29 evaluated become. In the Auswertepfaden can be used to suppress Interference Frequency determining elements such as bandpasses 31 or bandstop be implemented.

Finally, on the assembly also an additional Circuit or a microprocessor may be provided, which the evaluated and derived therefrom the sizes, such. B. Reflection factor, return loss or standing wave ratio (VSWR) generated. at If necessary, the coupler substrate may need to be larger be formed or it has a larger coupling approach 19b on.

Claims (11)

1. Directional coupler having a coupling line piece (23) which is coupled to a coaxial inner conductor (5) of coaxial line pieces (1) and, for this purpose, the coupling line piece (23) is provided on or adjacent to a coupler substrate (19') which is arranged on a resting or mounting section (11) of the outer conductor (3) of the coaxial line piece (1) in the region of a cutout (15) in the outer conductor (3), and the coupling line piece (23) is in this way held in the space between the inner conductor (5) and the outer conductor (3), with additional circuit elements of the directional coupler being attached to the coupler substrate (19'), characterized by the following further features:

   an attenuation circuit (27) is adjacent and is connected to each of the two coupling line ends (25) on the coupler substrate (19'),

   electrical level evaluation (33) is provided on the coupler substrate (19') for the attenuated signals, and

   an interface device (35) for connection of cables (41) is provided on the coupler substrate (19'), or an additional circuit or a microprocessor is provided, evaluates the detector voltages obtained and produces variables derived from them.
2. Directional coupler according to Claim 1, characterized in that the attenuation circuit (27) is in the form of a Π circuit (R1, R2, R3).
3. Directional coupler according to Claim 1, characterized in that the attenuation circuit (27) is in the form of a T circuit (R4, R5, R6).
4. Directional coupler according to one of Claims 1 to 3, characterized in that a memory module (37) which is preferably in the form of an EEPROM memory module (37) is also provided on the coupler substrate (19') and is used to store the transfer function of both coupling arms, and of electronic evaluation.
5. Directional coupler according to one of Claims 1 to 4, characterized in that the coupler substrate (19') has a multilayer structure.
6. Directional coupler according to one of Claims 1 to 5, characterized in that the coupler substrate (19') has a section (19a) in the region of the exposed cutout (15) in the outer conductor (3) in the coaxial line piece (1), and in that an additional extension section (19b) is provided at least in a lateral direction from this section (19a), for holding further electrical or electronic components.
7. Directional coupler according to one of Claims 1 to 6, characterized in that the coupling line piece (23) is in the form of a stripline, a wire clip or a wired component.
8. Directional coupler according to one of Claims 1 to 7, characterized in that the electronic components are fitted or provided on the upper face of the coupler substrate (19') and/or on the lower face of the coupler substrate (19').
9. Directional coupler according to one of Claims 1 to 8, characterized in that elements for temperature compensation are furthermore also provided on the coupler substrate (19').
10. Directional coupler according to one of Claims 1 to 9, characterized in that, in addition to assemblies for detecting absolute level information, the directional coupler also has assemblies for detecting difference values between the level and phase between the two coupling arms (A, B).
11. Directional coupler according to one of Claims 1 to 10, characterized in that components which determine a frequency, in particular bandpass filters (31) or bandstop filters, are provided in at least one coupling arm (A, B), preferably in both coupling arms (A, B), in particular for suppressing interference frequencies.

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