EP1867003A1

EP1867003A1 - High-frequency coupler or power splitter, especially a narrow-band 3db coupler or power splitter

Info

Publication number: EP1867003A1
Application number: EP06707501A
Authority: EP
Inventors: Franz Rottmoser; Joachim Herold
Original assignee: Kathrein Werke KG
Current assignee: Kathrein SE
Priority date: 2005-04-07
Filing date: 2006-03-09
Publication date: 2007-12-19
Anticipated expiration: 2026-03-09
Also published as: ATE409360T1; EP1867003B9; US20090051462A1; CN101213705A; DE102005016054A1; DE502006001639D1; CN101213705B; WO2006105847A1; EP1867003B1

Abstract

An improved HF coupler or HF power splitter comprises four connection lines arranged on the same side of the substrate. Two coupling zones are formed on the substrate on two opposite sides; the second coupling zone is connected to the associated connection lines arranged on the side of the substrate opposing the coupling zone, by means of two via holes in an electroplated manner. The capacitors provided at the beginning and at each end of each coupling zone are respectively embodied as interdigital capacitors; and the capacitors are respectively coupled to earth.

Description

High-frequency coupler or power divider, in particular narrow-band and / or 3dB coupler or power divider

The invention relates to a high-frequency coupler or power divider, in particular narrow-band high-frequency coupler or power divider according to the preamble of claim 1.

In high-frequency systems, it is often necessary to split a signal, for example with a power P, into two signals with a power of P / 2 each. Ring couplers are often used for this purpose. Such ring couplers are known, for example, from Zinke Brunswig "Hochfrequenztechnik", Springer-Verlag, 6th edition, 2000, namely from page 192.

These ring couplers are often implemented in microstrip technology.

In addition, however, high-frequency couplers are also known in which the degree of coupling is generally set via front-end or longitudinally coupled lines. For higher coupling levels, as necessary for a power divider, these distances are often very low or even too low to be economically manufactured.

Thus, for example, EP 1 291 959 A1 has disclosed a directional coupler which is constructed, for example, in suspended substrate technology. In other words, a coupling path in stripline technology is provided on a substrate on one side, which are connected to two also in stripline technology formed first and second terminals on the substrate in combination. On the opposite side then a second coupling path is arranged, which lead to a third and fourth output or connection. In plan view, the two coupling paths are arranged at least partially overlapping.

According to the abovementioned prior publication EP 1 291 959 A1, capacitors may also be connected in each case at the two opposite ends of the two coupling paths, the second connection point of which is in each case grounded.

From the same prior publication but other embodiments can be seen, in which the coupler is constructed in Koplanartechnik. In this case, the two coupling lines are each arranged with their two connection points on a common side of the substrate, wherein the coupling paths extend parallel to each other in the smallest possible distance.

Finally, however, is also for example from EP 1 014 472 Bl became a directional coupler known, which in turn is also constructed in suspended-substrate technology. This prior art directional coupler is a broadband directional coupler with at least two coupled coupling sections of different coupling attenuation, in which the coupling sections with loose coupling consist of strip conductors coupled at the end side and the coupling sections with fixed coupling consist of strip conductors coupled on the broad side.

In order to realize the corresponding coupling path with a fixed coupling, in this embodiment through-contacts are provided in the substrate. However, all leads are arranged on one side of the substrate.

With regard to the couplers known from the prior art, it can thus be stated that they are often designed in microstrip technology. Due to the high attenuation of the microstrip line and its sensitivity to fluctuations in the dielectric constants, the disadvantages of these couplers are the large space requirement and the relatively large electrical losses and the high costs for high-quality printed circuit board material.

The disadvantages of the directional coupler in suspended substrate technique are on the one hand high demands on the positioning of the substrate between the two ground surfaces (problems exist here with the correct positioning in the horizontal but also with regard to the exact consideration of the distances between the lid and bottom). These requirements for correct or optimal positioning cause high costs for the mechanical processing. tion and assembly. On the other hand, when designing a coupler, this already determines the case geometry. This is often disadvantageous in terms of reusability or achievement of sufficient flexibility with regard to the realization and implementation of a selected concept for a coupler and for use in other applications.

In addition, it is difficult from an electrical point of view in this technique to compensate for the different phase velocities of the DC and push-pull wave.

The main disadvantages of the directional coupler in coplanar technology are ultimately in the required minimum distances between the longitudinally coupled interconnects and the extent also limited coupling factor. Furthermore, the coupling factor is highly tolerance-dependent (etching tolerances and variations in the dielectric constants of the substrate material exert an adverse influence). Furthermore, a coplanar coupler is not optimal in terms of electrical losses.

As explained above, it is a disadvantage of all three types of couplers that, in particular when used for a modern telecommunications system, they do not have the requisite required properties of a high-frequency coupler, such as e.g. have sufficiently suitable coupling factor, directivity or symmetry or are not feasible or only with considerable development effort.

From the generic GB 2 218 853 A a high-frequency coupler or power divider is known to be known. take on a substrate on one side comprises two trained coupling lines. Both coupling lines are provided at the beginning and at the end with connecting conductors, which lead to staggered terminals. Zwi see the two coupling links capacitors are also provided for coupling both coupling paths and formed.

From EP 1 014 472 Bl a directional coupler is also known to be known. In contrast to the generic state of the art, this directional coupler is formed on a substrate in such a way that the one coupling path is formed on one side of the substrate and the second coupling path coupled therewith is formed on the opposite side of the substrate. In this case, a through connection through the substrate is provided in each case on one side of the coupling path in order to produce an electrical-galvanic connection of a connecting line to an opposite coupling surface.

From US 4,376,921 a microwave coupler is also known to be known, which also has four ports and two coupling links, between the two coupling links - which are kept relatively short - from the beginning to the end capacitors are provided for coupling between the coupling links.

A disadvantage of all types of couplers mentioned above is that they do not have the requisite required properties of a high-frequency coupler, for example with a sufficient coupling factor, sufficient directivity or symmetry, especially when used for a modern telecommunications system, or not can only be realized with considerable development effort.

It is therefore an object of the present invention to provide an improved coupler or power divider, in particular to provide a narrow-band, preferably 3dB coupler which is optimized in terms of cost, size, losses and manufacturing tolerances over conventional solutions.

The object is achieved according to the features specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims.

The RF coupler or power divider according to the invention has a number of positive advantages that offset conventional solutions. The high-frequency coupler according to the invention has a narrow-band structure.

The coupling path itself is formed on two opposite sides of a substrate. However, at the two opposite ends of a coupling path or at the two opposite ends of one of the two coupling paths a via is provided, thereby allowing that ultimately all four external leads (even if one is completed) can be arranged on one side of the substrate. This also opens the possibility that on one side on the substrate - if it should be necessary - further electrical components and components can be provided and connected in conventional soldering. In addition, the coupler or power divider according to the invention has capacitors on the respectively opposite end or connection regions to the respective coupling path, as they are basically also known from EP 1 291 959 A1. By contrast, however, no discrete reactances or capacitors are used, but so-called interdigital capacitors. These have not been used in such power dividers or couplers so far, even if they are basically from Rainee Simons: Coplaner Waveguide circuits, components and systems, 1st edition, New York, Chichester, Weinheim et al: John Wiley & Sons, 2001, known are.

By the solution according to the invention, a power divider or coupler is realized with very little space, the electrical parameters are relatively freely adjustable or preselected within wide limits. Above all, it has low electrical losses. In addition, the power divider or coupler according to the invention is also characterized by its high directivity.

The coupler or power divider according to the invention is also comparatively robust with respect to housing tolerances. This is especially evident in the choice of different cover distances. This robustness to housing tolerances also opens the possibility to reuse individual designs in other applications. In addition, the coupler according to the invention is also comparatively robust to etching tolerances as well as to fluctuations in the dielectric constant of the substrate material. Furthermore, basically no further wiring or concentrated components are necessary, although they could basically be used if necessary. After all All supply lines are provided on the same side of Sub ^¬ stratseite, which is to be regarded as advantageous.

Further advantages, features and details of the invention will become apparent hereinafter from the embodiments illustrated with reference to drawings. Show in detail:

1 shows a schematic plan view of a first embodiment of a coupler according to the invention;

FIG. 2 shows a rear view of the coupler according to the invention shown in FIG. 1;

Figure 3: a section along the line III-III in

FIG. 1;

FIG. 4 shows a representation corresponding to FIG. 1 with respect to an embodiment slightly modified with respect to FIG. 1;

FIG. 5 shows a rear view of the exemplary embodiment according to FIG. 4.

FIG. 1 shows the plan view of a first exemplary embodiment of a coupler or power divider 1 according to the invention, which is constructed on a substrate 3 in the form of a printed circuit board.

On the substrate 3, four surface areas 5 are seen on the upper side 3a of the substrate visible in FIG. bar, which are electrically-isolated from each other by recesses 7. This surface area 5 is a ground area 5.

In the recesses 7, a first coupling path 9 is formed in stripline technique, which extends in a first direction or longitudinal direction on the substrate 3.

At the beginning IIa and at the end IIb of this coupling path 9, a first and second connection line 13a and 13b is provided transversely, which lead to connections 15a and 15b on the one substrate edge 3 '.

The non-conductive recessed area 7 is formed in a top view in the embodiment of Figure 1 H-shaped. In the immediate extension of the connecting line 13a and 13b but separated from these, two more connecting lines 17a and 17b can be seen, leading to the opposite substrate edge 3 "and there form connections 19a and 19b.

At the ends of the connection lines 17a, 17b which are opposite to the connections 19a and 19b, these are provided adjacent to the first coupling path 9 with plated-through holes 21, which extend through bores 21 'through the substrate 3.

As can be seen in particular from the bottom view of FIG. 2, a second coupling path 25 is provided on the lower side 3b reproduced there, which runs parallel to the first coupling path 9 and which-in plan view preferably overlaps completely or at least partially. The length and / or width of both coupling links is in the embodiment shown, at least approximately the same.

As can be seen from the underside of the lower side 3b of the substrate 3 according to FIG. 2, at the beginning 27a and at the end 27b of the second coupling path 25 there are correspondingly two line extensions 25 electrically connected to the second coupling path and designed in stripline technology, in the middle of which are the bores 21 'of the via 21. As a result, the second connection lines 17a and 17b are electrically-galvanically connected to the second coupling path 25 via the aforementioned two plated-through holes.

The length of the coupling lines corresponds to approximately λ / 4. The four supply or connecting lines 13a, 13b and 17a, 17b are implemented in coplanar conductor technology and connect the coupler 1 with further in the present embodiment, not shown in detail high-frequency modules.

To improve the electrical properties, a total of twelve capacitors C are also provided in the embodiment shown, which in each case in the input and output area, ie at the beginning IIa and at the end 12b of the first coupling path 9 or at the beginning 11 'a and at the end of the 12th 'b the second coupling path 25 are located. There, therefore, the capacitors C-9a and C-9b are arranged at one end and the corresponding capacitors C-9c and C-9d at the other end of the first coupling path 9. Corresponding capacitors are also provided at the beginning and end of the second coupling path 25, namely the capacitors C-25a and C-25b and at the opposite end of the coupling path 25 the capacitors C-25c and C-25d. These capacitors are not constructed using discrete components but in the form of interdigital capacitors.

From Figures 1 and 2 but is also seen that in the illustrated embodiment preferably also in the central region, that is at half the length of the respective LD ^'pelstrecke 9 and 25, another capacitor pair C is still provided in each case, which in the illustrated training is designated as C-9e and C-9f and C-25e and ^' C-25f.

In the case of capacitors each having a capacitor area or -hälfte conductively connected to the respective coupling zone 9 and 25 are connected and which each co-operating electrically-galvanically isolated capacitor area ^• or - half to the associated ground plane.

For this purpose, the substrate 3 is also provided on the underside according to FIG. 2 with a circumferentially closed ground surface 31, in the middle region of which a nonconductive recess 33 is provided, within which the longitudinal direction the second coupling path 2 is galvanically separated.

The dimensioning of the interdigital capacitors can be carried out in such a way that specific coupling properties are set or preselected. However, the aforementioned ground planes are necessary in order to ensure defined mass ratios on the one hand and to form a ground potential for the interdigital capacitors on the other hand. The actual coupling thus takes place through the lines 9 formed on the two sides of the substrate 3 and 25 (suspended substrate).

As can be seen from the cross-sectional illustration according to FIG. 3, a depression 37 is preferably formed in a housing 29 below the coupling region. The degree of depression and the distance between the substrate and the associated cover 41 can be freely selected within certain limits.

Notwithstanding the embodiment shown, the capacitors provided preferably in the middle in the coupling paths may also be provided, starting from the center, between the capacitors provided at the beginning and at the end of the respective coupling path. If appropriate, additional capacitors may also be provided between the capacitors provided at the beginning and at the end region of the respective coupling path, that is, more than in the exemplary embodiments shown.

Based on the total coupling length from the initial region IIa to 12b or from the initial region 11 'a to the end region 12' b, the input and output capacitors C-9a, C-9b and C-9c, C-9d and on the gegenüberlie - Side tend the capacitors C-25a, C-25b and C-25c, C-25d are also more offset to the middle. The distance from the beginning and end region may be, for example, quite up to 30% of the total length of the coupling path, but preferably less, in particular less than 25%, 20%, 15% or 10% of the total length of the coupling path. It should be noted that the positioning of the capacitors at the beginning and at the end of the coupler have the greatest effect. The embodiment according to FIGS. 4 and 5 largely corresponds to that according to FIGS. 1 to 3.

The only difference is that, for example, in the plan view of the substrate comparable to the embodiment of Figure 1, the lying on one side of the substrate coupling path 9 is not provided with two leading to the same edge boundary 3 'of the substrate connection lines, but the right in Figure 4 Connection lead 15b, which is electrically-galvanically connected to the coupling path 9, leads to the opposite side 3 "of the substrate to the connection 17b formed there the connection 19b located at the top right in FIG. 4 is electrically-galvanically connected to the connection 19a at the bottom left in FIG. 4.

It therefore follows from the exemplary embodiments explained that the ground areas have recesses 7 on both sides of the substrate in the area of the connection lines as well as the coupling sections 9 and 25. The distance between the coupler paths 9 and 25 and the ground planes is preferably 1.5 to 4 times the width of the line. Likewise, the distance of the connection lines to the adjacent ground planes is approximately 1.5 to 4 times the width of these connecting lines.

As also mentioned, the coplanar coupling lines 9- and 25 are suitably arranged to achieve the desired coupling. In plan view of the substrate, that is perpendicular to the substrate plane, should from Therefore, both coupling lines 9, 25 are either one above the other or have a lateral offset, which is preferably smaller than the width of the coupling line. Thus, the coupling lines in plan view are not adjacent to each other, but overlap. Preferably, the lateral offset is greater than half the width of the coupling conductor track 9 or 25, so that cover both lines at preferably the same width to fifty percent. In other words, the coverage should preferably be more than 0%, in particular more than 10%, more than 20%, more than 30% and preferably more than 50%, in particular based on the width of the coupling tracks 9 and 25.

From the described construction of the coupler or power divider, it can be seen that the four connection conductors 13a, 13b and 17a, 17b are formed by coplanar technology. Likewise, it follows from the description of the embodiments of the invention that the two coupling paths 9 and 25 are formed in suspended substrate technology.

Claims

Claims:

1. Coupler or power divider, in particular RF coupler or RF power divider, having the following features: a substrate (3), - on the substrate (3) two first connecting lines (13a, 13b) are provided, which at a beginning (IIa) and lead to an end (IIb) of a first coupling path (9), - there is provided a second coupling path (25) coupled to the first coupling path (9), to the beginning (27a) and the end (27b) of which two further connection lines (27) 17a, 17b) lead, the four connecting lines (13a, 13b, 17a, 17b) lead away from the respective coupling path to mutually offset terminals (15a,

15b; 19a, 19b), the four connecting lines (13a, 13b, 17a, 17b) are arranged on the same side (3a) of the substrate (3), and - in the longitudinal direction of the two coupling lines (9, 25) are capacitors (C ), preferably at the respective starting region (IIa; 27a) or preferably at the respective end region (IIb; 27b) of the two coupling links (9; 25), characterized by the following further features: the two coupling links (9; 25) are on the substrate formed on two opposite sides (3a, 3b), the first coupling path (9) is electrically-galvanically formed with the two associated connection lines (13a, 13b) on the same side as the coupling path (9), - the second coupling path (25) is in its start and end region (27a, 27b ) via each at least one via (21) with the associated connecting lines (17a, 17b) electrically-galvanically connected, which lie on the coupling path (25) opposite side (3a) of the substrate (3) in the longitudinal direction of the two coupling paths ( 9, 25) of offset capacitors (C), preferably at the beginning (IIa / 18a) and at the respective end (IIb, 18b) of the respective coupling path (9,

25) (C-9a, C-9b, C-9c, C-9d, C-25a, C-25b, C-25c, C-25d) are each formed as interdigital capacitors, and the capacitors ( C-9a, C-9b, C-9c, C-9d, C-25a, C-25b, C-25c, C-25d) are each coupled to the ground.

2. coupler or power divider, in particular RF coupler or RF power divider or coupler according to claim 1, characterized in that at least with respect to a coupling path (9, 25) and preferably with respect to both coupling paths (9, 25) between the beginning and end (IIa, IIb, 18a, 18b) at least one each further capacitor (C-9e, C-9f, C-25e, C-25f) is provided.

3. Coupler or power divider according to claim 2 ^" , characterized in that the additionally provided capacitors (C-9e, C-9f, C-25e, C-25f) in the central region of respective coupling path (9, 25) are arranged.

4. coupler or power divider according to one of claims 1 to 3, characterized in that the one coupling path (9) with the associated connecting lines (13a, 13b) are arranged in plan view so that the connecting lines (13a, 13b) based on lead the coupling path (9) to the same substrate edge (3 ') and preferably at least approximately form a U-shaped conduction in plan view.

5. Coupler or power divider according to one of claims 1 to 4, characterized in that the electrically connected to the second coupling path (25) via the feedthrough (21) connecting cable (17a, 17b) is arranged in plan view so that the Lead connecting lines (17a, 17b) relative to the coupling path (25) to the same substrate edge (3 ") and preferably form approximately a U-shaped conduction path in plan view.

6. coupler or power divider according to claim 4 or 5, characterized in that the one coupling path (9) connected to the connecting line (13 a, 13 b) leads to the one substrate edge (3 ¹ ), whereas with the second coupling path (25) electrically Galvanic lead (17a, 17b) leads to the opposite substrate edge (3 ").

7. Coupler or power divider according to one of claims 1 to 3, characterized in that the one coupling path (9) with the associated connection lines (13a, 13b) are arranged in plan view so that the one Closing line (13a) relative to the coupling path (9) at least with a component in a direction away from the coupling path (9) preferably to a substrate edge (3 ') leads, whereas the second connecting line (13b) with oppositely directed component of the coupling path ( 9) leads away, preferably to the opposite substrate edge (3 ").

8. coupler or power divider according to claim 6 or 7, characterized in that the two connected to the coupling path (9) at the beginning (IIa) and at the end (IIb) connecting lines (13a, 13b) with opposite component, preferably in the opposite direction of the Leading coupling path (9) away, so that preferably in plan looks at least approximately a Z-shaped conduction path is formed.

9. coupler or power divider according to one of claims 6 to 8, characterized in that the (c) with the opposite coupling path (25) via the Durchkon- taktierung (21) electrically-electrically connected connecting lines {IIa, 17b) at the beginning (27a) and at the end (27b) of this coupling path (25) with opposite component and preferably in the opposite direction of the coupling path (25) away, so that preferably in plan view, at least approximately a Z-shaped conduction path is formed.

10. Coupler or power divider according to one of claims 1 to 9, characterized in that in the region of the coupling path (9, 25) and / or in the region of the connecting lines (13a, 13b, 17a, 17b) on the top or bottom of the Substrate (3) formed mass surfaces (5, 31) Recesses (7), in which the connecting lines (13a, 13b, 17a, 17b) and the coupling paths (9, 25) are arranged.

11. Coupler or power divider according to claim 10, characterized in that the distance between the coupling paths (9, 25) and / or the connection lines (13a, 13b, 17a, 17b) and the ground surfaces (5, 31) between 1.5 to 4 corresponds to the width of the coupling path (9, 25) or the width of the connection lines (13a, 13b, 17a, 17b).

12. Coupler or power divider according to one of claims 1 to 11, characterized in that overlap the coupling lines (9, 25) in plan view perpendicular to the surface of the substrate (3) and the overlap region based on the width of the two coupling paths (9, 25 ) is at least 10%, preferably more than 40% or in particular more than 70%.

13. Coupler or power divider according to one of claims 1 to 12, characterized in that the four connecting lines (13a, 13b, 17a, 17b) are formed in coplanar technology.

14. Coupler or power divider according to one of claims 1 to 13, characterized in that the two coupling paths (9; 25) are formed in suspended substrate technology.