WO2025195591A1

WO2025195591A1 - Stripline system

Info

Publication number: WO2025195591A1
Application number: PCT/EP2024/057422
Authority: WO
Inventors: Martin Haun; Ramzi GMIHA; Anian KAFFL; Korbinian OBERMAIER; Jan GRÄVENDIECK
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2024-03-20
Filing date: 2024-03-20
Publication date: 2025-09-25
Anticipated expiration: 2026-09-20

Abstract

A stripline system (1) according to the invention comprises a transmission line module (10) and a conductive chamber (20), wherein the transmission line module (10) is aligned inside the chamber (20) The transmission line module (10) comprises a component carrier (11), at least two substrates (12a, 12b), the at least two substrates (12a, 12b) comprising a first substrate (12a) and a second substrate (12b), and at least one connecting conductor (14a, 14b), the at least one connecting conductor (14a, 14b) comprising a first connecting conductor (14a). The at least two substrates (12a, 12b) are mounted to the component carrier (11). A first conductive component (15a) is aligned on the first substrate (12a) and a second conductive component (15b) is aligned on the second substrate (12b). The first conductive component (15a) is electri- cally connected to the second conductive component (15b) by the first connecting conductor (14a).

Description

Stripline system

Technical field

The invention refers to a stripline system.

It is industry goal to reduce losses in the base station antenna signal distribution and phase shifter network. Traditional signal distribution is realized by lossy RF-cables which are combined with a centralized phase shifter.

In the last years the industry is introducing a new approach where the signal distribution and phase shifting function is highly integrated into a metal cavity housing. Low loss strip-lines for signal distribution are combined with a distributed dielectric linear phase shifter. The metal cavity housing is forming a chamber and is mostly realized by an extruded aluminium profile. An inner strip-line conductor is aligned inside the chamber and is either a single printed circuit board (PCB) or a single sheet metal structure.

The cavity inner structure must be realized over full vertical system length, which is typically around 1 to 2.6 meter. PCBs larger than 1 meter get very expensive. Large metal structures come with high tooling cost because of the large tool, have limitations in the possible structures and are not intrinsically stable like PCBs which means that supporting elements must be used to maintain the conductor shape.

State of the art in realizing the cavity housing is to use an extruded aluminium profile. Material thickness is around 1 .5 to 2 mm due to process reasons. That means that a lot of raw aluminium must be used which drives cost.

Multiple cavity systems must be combined to realize a multiport antenna. Also, integrating the cavity systems mechanically and electrically with an antenna reflector is difficult, as coupling single extruded housings to the reflector involves complicated joining techniques to guarantee electrical performance.

WO2022141023A1 discloses a phase shifter, wherein a first substrate and a second substrate are connected via a connecting piece. The IEEE article titled “Characteristics and Some Applications of Stripline Components”, published in IRE Transactions on Microwave Theory and Techniques ( Volume: 3, Issue: 2, March 1955) discloses a stripline system with dielectric sheets.

Summary

A stripline system according to the invention comprises a transmission line module and a conductive chamber. The transmission line module is aligned inside of the chamber. The transmission line module comprises a component carrier, at least two substrates, the at least two substrates comprising a first substrate and a second substrate, and at least one connecting conductor, the at least one connecting conductor comprising a first connecting conductor. The at least two substrates are mounted to the component carrier. A first conductive component is aligned on the first substrate and a second conductive component is aligned on the second substrate. The first conductive component is electrically connected to the second conductive component by the first connecting conductor.

A stripline system is a system in which a central conductor is sandwiched between two conductive planes. The conductive planes are typically ground planes or are electrically connected to have the same electric potential. The stripline system is preferably a suspended stripline system. The chamber is formed by the conductive planes and the transmission line module comprises the central conductor. The stripline system is a so-called chamber system or cavity system.

The transmission line module is aligned inside of the chamber. The transmission line module comprises some or all of the conductive lines or circuits that are enclosed by the chamber. The transmission line module comprises the component carrier, the at least two substrates and the at least one connecting conductor. The connecting conductor is preferably a sheet metal part or comprises multiple sheet metal parts. The at least two substrates and the at least one connecting conductor are sandwiched in between two walls of the chamber and are preferably separated from the walls of the chamber by an airgap and/or a dielectric material.

The at least two substrates are mounted to the component carrier. The first conductive component is aligned on the first substrate and the second conductive component is aligned on the second substrate. In particular, the first substrate is a printed circuit board (PCB) and the second substrate is a printed circuit board. The first conductive component is preferably a stripline conductor on the first substrate. The second conductive component is preferably a stripline conductor on the second substrate. The first conductive component is electrically connected to the second conductive component by the first connecting conductor. Thus, a circuit that is inside the chamber can be designed to extend over multiple substrates and parts of the circuit can be formed by the first connecting conductor.

In particular for larger stripline systems, for example for stripline systems with a length of over one meter, it is no longer necessary to align all required circuits on a single substrate. At the same time, the mounting of the at least two substrates to the component carrier allows to provide stability to the transmission line module. Therefore, a handling of the transmission line module during manufacturing, for example when inserting the transmission line module into the chamber, is much easier. Also, as the relative position of the at least two substrates is fixed due to the component carrier, there is limited mechanical stress that is applied to the connection points at which the first conductive component is coupled with the first connecting conductor.

The proposed stripline system allows to overcome the problems and limitations of the existing technology by using a hybrid approach. Hybrid means a mix of smaller PCB's and sheet metal parts. A method how to join the single parts as well as method on how to feed in the hybrid structure into the chamber housing is presented.

The invention allows to lower costs, as large PCBs or expensive tools for big sheet metal structures can be avoided. This is especially valid for lower quantities. Faster and cheaper prototyping is possible, as smaller parts are used which are fast and cheap to prototype. Also, the substrates allow to realize fine and complex structures, while the connecting conductor, for example a sheet metal part, can bridge long distances.

In particular, the stripline system according to the invention is configured to provide a base station antenna signal distribution and in particular a phase shifting technology, which is based on dielectric linear phase shifter technology. A low loss cavity I chamber system signal distribution is provided.

The dependent claims define advantageous embodiments of the invention.

In particular, the first substrate is extending in a first substrate plane and comprises a recess, wherein a first portion of a first end of the first connecting conductor is aligned in the first substrate plane and is aligned inside the recess of the first substrate. Accordingly, parts of the first connecting conductor are aligned in the same plane with the first substrate. This allows a connection between the first connecting conductor and the first conductive component can be designed to have a low overall height and a defined distance between the walls of the chamber and the first connecting conductor is provided. Also, the alignment of the first connecting conductor inside the recess can avoid undesired movement of the first connecting conductor. Optionally, the second substrate is extending in a second substrate plane and comprises a recess, wherein a first portion of a second end of the first connecting conductor is aligned in the second substrate plane and is aligned inside the recess of the second substrate. The first substrate plane is optionally equal to the second substrate plane.

In particular, a second portion of the first end of the first connecting conductor is aligned in a surface plane that is parallel to the first substrate plane and is extending over the surface of the first substrate on which the first connecting conductor is aligned, and the second portion of the first end of the first connecting conductor is aligned to be in contact with the first conductive component. Thus, an electrical connection between the first conductive component and the first connecting conductor is aligned above a surface of the first substrate. Consequently, it is not necessary to align the first conductive component in a way that it extends from the top surface of the first substrate to a side surface of the first substrate. Optionally, a second portion of the second end of the first connecting conductor is aligned in a surface plane that is parallel to the second substrate plane and is extending over the surface of the second substrate on which the second connecting conductor is aligned, and the second portion of the second end of the first connecting conductor is aligned to be in contact with the second conductive component.

In particular, the second portion of the first end of the first connecting conductor comprises a through hole and the second portion of the first end of the first connecting conductor is soldered to the first conductive component such that a solder is applied within the through hole. With this, the first end of the first connecting conductor is soldered to the first conductive component. The through hole allows that the solder is applied from one side while the first connecting conductor is already aligned in a final position over the first substrate. This leads to a simplified production process. Optionally, the second portion of the second end of the first connecting conductor comprises a through hole and the second portion of the second end of the first connecting conductor is soldered to the second conductive component such that a solder is applied within the through hole of the second end of the first connecting conductor.

In particular, the first portion of the first end of the first connecting conductor comprises an indentation that engages with a bulge of the first substrate; and/or the first portion of a first end of the first connecting conductor comprises a bulge that engages with an indentation of the first substrate. Therefore, a mechanical locking meachnism is provided that avoids that the first connecting conductor can be pulled out of the recess of the first substrate while being in the first substrate plane. Mechanical stress to the solder that is applied in the through hole is reduced. Optionally, the first portion of the second end of the first connecting conductor comprises an indentation that engages with a bulge of the second substrate; and/or the first portion of the second end of the first connecting conductor comprises a bulge that engages with an indentation of the second substrate.

In particular, the chamber comprises first guiding means that are configured to interact with the component carrier and/or with at least one of the at least two substrates such that the transmission line module is guided along a linear direction inside the chamber, in particular during mounting. This allows a mounting of the transmission line module by sliding it into the chamber.

In particular, the component carrier comprises stripline holding means that are configured to support one of the at least one connecting conductor, in particular the first connecting conductor. This allows to reduce any mechanical stress that is applied to the connection in between the first connecting conductor and the first conductive component.

In particular, the chamber comprises a first wall and a second wall, wherein the transmission line module is aligned in between the first wall and the second wall. The first wall and the second wall can be grounded to provide a shielding for the inside of the chamber.

In particular, the first wall is a first panel sheet element and the second wall is a second panel sheet element. This allows to reduce production costs for the chamber. A panel sheet element is an element that is formed from a sheet-metal. In particular, this leads to lower material cost when compared to using extruded parts. Also, lower tool cost, faster prototyping, larger electrical flexibility and a simplified reflector integration can be achieved.

In particular, the first wall is connected to the second wall by multiple metal spacers. The metal spacers are for example hulls or pins.

In particular, multiple metal spacers are forming a sidewall of the chamber. In particular, a distance between the spacers is selected such that a shielding effect for specific frequencies is achieved. For example, the metal spacers are set in a distance to shield the inside of the chamber from frequencies that are emitted by radiating elements of an antenna that are supplied via the stripline system.

In particular, at least one of the multiple metal spacers is connected to the first wall and/or the second wall by a welding connection. Thus, a stable chamber can be created by the combination of the multiple metal spacers, the first wall and the second wall. In particular, at least one of the multiple metal spacers comprises a notch and is extending through a through hole in at least one of the first wall, the second wall and the component carrier, wherein the at least one of the first wall, the second wall and the component carrier is aligned inside the notch for mounting the at least one of the first wall, the second wall and the component carrier to the at least one of the multiple metal spacers. This allows an easy and cost effective mounting of the stripline system in an industrial manufacturing process. In particular, the notches are formed by a clinching process. Even though it is advantageous to connect the metal spacers to the first wall, the second wall and/or the component carrier by a clinching process, it is noted that alternative techniques techniques like laser welding or screwing can be used to connect the metal spacers to the first wall, the second wall and/or the component carrier.

In particular, a sidewall is connecting the first wall and the second wall to form the chamber, wherein at least a portion of the sidewall is formed by a conductive tape. The conductive tape allows to close open sections of the chamber to improve the shielding.

In particular, the first wall is a reflector of an antenna system. This allows that the first wall has a double functionality. Consequently, the number of parts and material that is required for the antenna can be reduced.

In particular, the stripline system is a phase shifter. In particular, the stripline system is a phase shifter for a macro cell of a mobile communications network. Such antennas often require phase shifters with a length of over 1m. Therefore, the stable construction of the stripline system is advantageous.

Brief description of the drawings

Fig. 1 shows an antenna system with a phase shifter, fig. 2 shows an antenna system with four antenna arrays, wherein each antenna array is connected to a stripline system that is acting as a phase shifter, fig. 3 shows a transmission line module of an exemplary stripline system according to the invention, fig. 4 shows an exemplary stripline system according to the invention, wherein the transmission line module of figure 3 is aligned in a chamber, fig. 5 shows a cross section through an exemplary stripline system according to the invention, fig. 6 shows a cross section through an exemplary stripline system according to the invention, fig. 7 shows a further example of a transmission line module of a stripline system according to the invention, fig. 8a shows a first view of a connection between a first connecting conductor and a first conductive component in a non-connected state, fig. 8b shows a second view of the connection between the first connecting conductor and the first conductive component in the non-connected state, fig. 9a shows a first view of the connection between a first connecting conductor and the first conductive component in a connected state, fig. 9b shows a second view of the connection between the first connecting conductor and the first conductive component in the connected state, fig. 10 shows a cross sectional view of an exemplary stripline system, wherein the chamber comprises walls formed by sheet metal plates, fig. 11 shows a cross sectional view of a stripline system, wherein the stripline system comprises multiple layers, figs. 12a and 12b show methods for manufacturing a stripline system, fig. 13 shows an advantageous mounting of spacers in a stripline system, and fig. 14 shows an advantageous mounting of spacers in a stripline system using mounting tools.

Detailed description

Aspects of the presented invention relate to base station antennas. Base station antennas are typically mounted on a mast and consist of independent antenna systems which are typically arranged in parallel antenna array columns. The antenna systems are connected via a feeder cable to radios which are typically mounted in the direct vicinity of the antenna.

In closer consideration, aspects of the invention relate to the question on how the signal coming from and to the radio is distributed to the single elements of an antenna array of the antenna. Besides signal distribution, also a phase shifting function is required to allow the array to steer the beam of the antenna array. Typically, a centralized phase shifter and coaxial cables are used to realize this function. In the last years a new and alternative building practice to realize this function emerged. This building practice is often called “chamber system” or “cavity system”. A cavity or chamber system realizes the phase shifting and signal distribution by applying a low- loss strip-line technique where the strip-line inner conductor is either formed by a PCB or sheet metal structure and the outer-conductor is formed out of an extruded aluminum chamber. The phase shifting function is realized by moving small dielectric elements over the line structure. The dielectric loaded line parts change their electrical length and thus the phase of the signal.

Figure 1 shows an antenna system 100. In particular, the antenna system 100 is a base station antenna. The antenna system 100 comprises a stripline system 1 according to the invention, wherein the stripline system 1 is configured to be a phase shifter.

The antenna system 100 comprises multiple radiating elements 101 - 105, the multiple radiating elements 101 - 105 comprising a first radiating element 101 , a second radiating element 102, a third radiating element 103, a fourth radiating element 104 and a fifth radiating element 105.

The first radiating element 101 , the second radiating element 102, the third radiating element 103, the fourth radiating element 104 and the fifth radiating element 105 are forming an antenna array. A direction of a main coil of the antenna array can be changed by the stripline system 1 by shifting the phases of the signals that are provided to the radiating elements 101 - 105 of the antenna array.

The radiating elements 101 - 105 are connected to the stripline system 1 via radiating element connections 18a - 18e. In particular, the first radiating element 101 is connected to the stripline system 1 by a first radiating element connections 18a. The second radiating element 102 is connected to the stripline system 1 by a second radiating element connections 18b. The third radiating element 103 is connected to the stripline system 1 by a third radiating element connections 18c. The fourth radiating element 104 is connected to the stripline system 1 by a fourth radiating element connections 18d. The fifth radiating element 105 is connected to the stripline system 1 by a fifth radiating element connections 18e.

An input signal is provided to the stripline system 1 via an input port 30. The phase of the input signal is shifted for the individual radiating elements 101 - 105 and is provided to the radiating elements 101 - 105 via the radiating element connections 18a - 18e.

Fig. 2 shows the antenna system 100 with four antenna arrays, wherein each antenna array is connected to a stripline system 1 that is acting as a phase shifter. The antenna system 100 comprises the stripline system 1 and three further stripline systems 2, 3, 4, which are connected to corresponding radiating elements 106, 107, 108. Due to the viewing direction, only the first radiating element 101 of the first antenna array is visible if Fig. 2. The three further stripline systems 2, 3, 4 are of the same construction type as the stripline system 1 and are arranged parallel to each other. The stripline systems 1 , 2, 3, 4 are aligned below a reflector plate 5 of the antenna system 100. Optionally, the reflector plate 5 is forming a sidewall for each one of the stripline systems 1 , 2, 3, 4.

Figs. 3 and 4 are showing an exemplary stripline system 1 according to the invention, which can be used as the stripline system 1 of the antenna system 100. The stripline system 1 comprises a transmission line module 10 and a conductive chamber 20, wherein the transmission line module 10 is aligned inside of the chamber 20.

Fig. 3 shows the transmission line module 10 of the stripline system 1. The transmission line module 10 comprises a component carrier 11 and at least two substrates 12a, 12b. In this example, the transmission line module 10 comprises seven substrates 12a to 12g. Each one of the substrates 12a to 12g is a printed circuit board (PCB). The substrates 12a to 12g comprise a first substrate 12a, a second substrate 12b, a third substrate 12c, a fourth substrate 12d, a fifth substrate 12e, a sixth substrate 12f and a seventh substrate 12g. All of the substrates 12a - 12g are mounted to the component carrier 11. The component carrier is preferably a dielectric plate, for example a plastic plate. The substrates 12a to 12g are mounted to the component carrier 11 , which means that the substrates 12a to 12g are mechanically connected to the component carrier 11 such that a relative position between the substrates 12a to 12g and the component carrier 11 is fixed. For example, the substrates 12a to 12g are screwed, clamped or glued to the component carrier 11 . For example, the component carrier 11 comprises a groove and one or more of the substrates 12a to 12g are extending into the groove to be held in position in respect to the component carrier 11.

Conductive components 15a -15g, for example conductor lines, are aligned on each one of the substrates 12a to 12g. The conductive components 15a -15g comprise first conductive components 15a that are aligned on the first substrate 12a, second conductive components 15b that are aligned on the second substrate 12b, third conductive components 15c that are aligned on the third substrate 12c, fourth conductive components 15d that are aligned on the fourth substrate 12d, fifth conductive components 15e that are aligned on the fifth substrate 12e, sixth conductive components 15f that are aligned on the sixth substrate 12f and seventh conductive components 15g that are aligned on the seventh substrate 12g. The conductive components 15a -15g and connecting conductors 14a - 14f are together forming a conductor network that is connecting the input port 30 with radiating element connections 18a - 18h. In the example of Fig. 3, the transmission line module 10 comprises eight radiating element connections 18a - 18h. It is noted that this number of eight radiating element connections 18a - 18h is chosen by example. The transmission line module 10 can comprise more or less of the radiating element connections 18a - 18h, for example the transmission line module 10 can comprise the six radiating element connections 18a - 18f of the antenna array 100 of fig. 1. Additional substrates can be added to increase the number of radiating element connections 18a - 18e or further circuits might be added as conductive components on the at least two substrates 12a, 12b to increase the number of radiating element connections 18a - 18e. Also, one or more of the substrates 12a to 12g can be omitted if less radiating element connections 18a - 18f are required.

To form the conductor network that is connecting the input port 30 with the radiating element connections 18a - 18e, it is necessary that the conductive components 15a -15g that are aligned on different substrates 12a to 12g are interconnected. For this, the transmission line module 10 comprises the connecting conductors 14a - 14f. The connecting conductors 14a - 14f comprise a first connecting conductor 14a, a second connecting conductor 14b, a third connecting conductor 14c, a fourth connecting conductor 14d, a fifth connecting conductor 14e and a sixth connecting conductor 14f. The first connecting conductor 14a is electrically connecting the first conductive component 15a of the first substrate 12a with the second conductive component 15b of the second substrate 12b. The first connecting conductor 14a is formed by a sheet-metal. The first connecting conductor 14a is connected to the first conductive component 15a via a first connection 16a on a first side of the first connecting conductor 14a and is connected to the second conductive component 15b via a second connection 16b on a second side of the first connecting conductor 14a.

The second connecting conductor 14b is connecting the second conductive component 15b of the second substrate 12b with the third conductive component 15c of the third substrate 12c. The third connecting conductor 14c is connecting the second conductive component 15b of the second substrate 12b with the fourth conductive component 15d of the fourth substrate 12d. The fourth connecting conductor 14d is connecting the fourth conductive component 15d of the fourth substrate 12d with the sixth conductive component 15f of the sixth substrate 12f. The fifth connecting conductor 14e is connecting the sixth conductive component 15f of the sixth substrate 12f with the fifth conductive component 15e of the fifth substrate 12e. The sixth connecting conductor 14f is connecting the sixth conductive component 15f of the sixth substrate 12f with the seventh conductive component 15g of the seventh substrate 12g. With this structure, an electrical path from the input port 30, which is connected to the fourth conductive component 15d of the fourth substrate 12d, to each one of the radiating element connections 18a - 18e is provided. Each one of the connecting conductors 14a - 14f is connected to one of the substrates 12a - 12g on a first side and is connected to a different one of the substrates 12a to 12g on a second side. The connections between any side of the connecting conductors 14a - 14f and any one of the conductive components 15a-15g, which includes the first connection 16a and the second connection 16b, have the same structure, wherein an exemplary advantageous structure will be described in the following by referring to figs. 8a to 9b.

The transmission line module 10 is a self-supporting structure, wherein the component carrier 11 is providing structural stability to the structure. This decreases the forces that are acting on the connections 16a, 16b and allows easier handing of the transmission line module 10 in a mounting process in which the transmission line module 10 is inserted into the chamber 20.

Fig. 3 shows that the substrates12a - 12g, in particular PCBs, and sheet metal parts are mounted to the component carrier 11. Internal interfaces, for example the connections 16a, 16b, exist to connect sheet metal parts and PCBs. External interfaces, for example the input port 30 and the radiating element connections 18a - 18h, exist and allow to establish a connection to radio and radiating elements 101 - 105. Fig. 4 shows an alignment of the transmission line module 10 of the stripline system 1 in the chamber 20 of the stripline system 1. The chamber 20 comprises a first wall 40 and a second wall 41 , wherein the first wall 40 is parallel to the second wall 41. The first wall 40 and the second wall 41 are parallel to a plane in which the first substrate 2a is extending and in which the first conductive component 15a is aligned. The first wall 40 and the second wall 41 are parallel to a plane in which the component carrier 11 is extending. The chamber has a first sidewall 42 and a second sidewall 43, wherein the first sidewall 42 is parallel to the second sidewall 43 and each one of the first sidewall 42 and the second sidewall 43 is connecting the first wall 40 to the second wall 41. The chamber has a third sidewall 43 and a fourth sidewall 44, wherein the third sidewall 43 is parallel to the fourth sidewall 44 and each one of the third sidewall 43 and the fourth sidewall 44 is connecting the first wall 40 to the second wall 41. The transmission line module 10 is aligned in between the first sidewall 42 and the second sidewall 43. For this, the transmission line module 10 has a dimension that allows a positioning of the transmission line module 10 inside the chamber, wherein the component carrier 11 is optionally in contact with the first wall 40 and the second wall 41 such that the substrates 12a to 12g are held in between the first wall 40 and the second wall 41. Optionally, the component carrier 11 is in contact with the first sidewall 42 and/or the second sidewall 43 for positioning the substrates 12a to 12g in the chamber. In addition or in the alternative, one or more of the substrates 12a - 12g is in contact with at least one of the sidewalls 42, 43, 44, 45 to hold the transmission line module 10 in a fixed position inside the chamber 20.

The chamber 20 is a conductive chamber. For example, the first wall 40, the second wall 41, the first sidewall 42 and the second sidewall 43 are metallic walls. It is noted that the second sidewall 43 preferably comprises an opening that is providing access to the input port 30. The first sidewall 42 preferably comprises one or more openings that are providing access to the radiating element connections 18a - 18h. For example, a contact to the radiating elements 18a - 18e is guided through the openings that are providing access to the radiating element connections 18a - 18h.

The transmission line module 10 is aligned in between the first wall 40 and the second wall 41. In an example, the transmission line module 10 is slided into the chamber 20 from a front end of the chamber 20. In another example, the first wall 40, the second wall 41 of the chamber 20 are formed of sheet metal panels, wherein the transmission line module 10 is positioned in between the sheet metal panels in a stacking process.

Dielectric components 17a - 17g are aligned in between the conductive components 15a - 15g and the first wall 40 and/or the second wall 41 of the chamber 20. In this example, a first dielectric component 17a is aligned over the first substrate 12a. The first dielectric component 17a is mounted movably between the first substrate 12a and the first wall 40. Depending on the position of the first dielectric component 17a over the first conductive component 15a of the first substrate 12a, a wave resistance of the first conductive component 15a or portions of the first conductive component 15a is reduced or increased, which allows to shift the phase of a signal that is transmitted towards the radiating element connections 18a, 18b of the first substrate 12a. One of the conductive components 15a - 15g is aligned over each one of the substrates 12a - 12g. That is, a second dielectric component 17b is aligned in between the second conductive component 15b of the second substrate 12b and the first wall 40, a third dielectric component 17c is aligned in between the third conductive component 15c of the third substrate 12c and the first wall 40, a fourth dielectric component 17d is aligned in between the fourth conductive component 15d of the fourth substrate 12d and the first wall 40, a fifth dielectric component 17e is aligned in between the fifth conductive component 15e of the fifth substrate 12e and the first wall 40, a sixth dielectric component 17f is aligned in between the sixth conductive component 15f of the sixth substrate 12f and the first wall 40, and a seventh dielectric component 17g is aligned in between the seventh conductive component 15g of the seventh substrate 12g and the first wall 40. The dielectric components 17a-17gcan be coupled, such that the conductive components 15a - 15g are moving together in the chamber 20, for example in the up-down direction of Fig. 4.

Fig. 5 shows a cross sectional view of an exemplary stripline system 1 according to the invention, for example the stripline system 1 of Fig. 4, wherein the chamber 20 comprises guiding means 51, 52, 53, 54 that are configured to interact with the component carrier 11 and/or with at least one of the at least two substrates 12a - 12g such that the transmission line module 10 is guided along a linear direction inside the chamber 20.

The guiding means 51, 52, 53, 54 comprise first guiding means 51 , 52, wherein the first guiding means 51 , 52 are configured to interact with the component carrier 11. The first guiding means 51, 52 are formed by a first rail 51 that is extruding from the first wall 40 and by a second rail 52 that is extruding from the second wall 41. The component carrier 11 comprises a first groove on a surface that is aligned towards the first wall 40. The component carrier 11 comprises a second groove on a surface that is aligned towards the second wall 41. The first groove engages with the first rail 51 and the second groove engages with the second rail 52 and the component carrier 11 can be slided into the chamber 20 along the first rail 51 and the second rail 52. It is noted that the rails and grooves are interchangeable. For example, in alternative embodiments, the first wall 40 and the second wall 41 comprise a first groove and a second groove, while the component carrier 11 comprises the first rail and the second rail. Even if the component carrier 11 is mounted differently and is not slided into the chamber 20, such a combination of the first rail 51 and the second rail 52 with the first groove and the second groove will ensure a stable mounting of the component carrier 11 in the chamber 20.

The guiding means 51 , 52, 53, 54 comprise second guiding means 53, 54, wherein the second guiding means 53, 54 are configured to interact with the with at least one of the at least two substrates 12a - 12g. In this example, the second guiding means 53, 54 comprise a first groove 53, which is extending along the first sidewall 42. The first groove 53 has a width that allows the substrates, in this example the first substate 12a to extend into the first groove 53. The second guiding means 53, 54 comprise a second groove 54, which is extending along the second sidewall 43. The second groove 54 has a width that allows the substrates, in this example the second substate 12b to extend into the second groove 54. The component carrier 11 can be slided into the chamber 20 along the first groove 53 and the second groove 54, wherein the substrates 12a - 12g are guided by the grooves. Even if the component carrier 11 is mounted differently and is not slided into the chamber 20, such a combination of the first groove 53 and the second groove 54 and the substrates will ensure a stable mounting of the component carrier 11 in the chamber 20. It is noted that the cross sectional view of Fig. 5 is only showing the first substrate 12a and the second substrate 12b. However, it is advantageous that also the third substrate 12c, the fifth substrate 12e and the seventh substrate 12g engage with the first groove 53. Also, it is advantageous that the fourth substrate 12d and the sixth substrate 12f engage with the second groove 54.

Fig. 6 shows a cross sectional view of an exemplary stripline system 1 according to the invention, for example the stripline system 1 of Fig. 4, wherein the component carrier 11 comprises stripline holding means 55 that are configured to support one of the at least one connecting conductors 14a -14f. The stripline holding means 55 are either a part of the component carrier 11 or attached to the component carrier 11. Optionally, the stripline holding means 55 are aligned to engage with the first groove 53 or the second groove 54.

Also, a preferable technique is shown to arrange the substrates 12a -12g on the component carrier 11 , which can be slided into the chamber 20. The component carrier 11 itself is guided and the substrates 12a - 12g are attached to the component carrier 11. For example, a PIN is pressed into the chamber 20 by a groove I feather feature. It is not important if the groove is located on the walls 40, 41 or the component carrier 11. The component carrier 11 itself has a groove where the edge of a substrate is inserted. A feature to connect component carrier 11 and the substrates 12a-12g mechanically is a hole drilled into the substrates 12a-12g and the component carrier 11 or a hot melting of the component carrier 11 itself to secure the substrates 12a - 12g position. The profile shape of the component carrier 11 makes it suitable for an extrusion process which makes the part very cost effective. Fig. 7 shows an exemplary transmission line module 10, wherein the transmission line module 10 essentially corresponds to the transmission line module 10 as described with Fig. 3, wherein some of the substrates 12a-12g are omitted. In particular, the second substrate 12b, the third substrate 12c, the fourth substrate 12d and the fifth substrate 12e are omitted. It can be seen that a connecting conductor is not necessarily limited to form a linear connection element between two of the substrates 12a, 12b. Rather than that, the first connective conductor 14a’ can be configured to connect multiple substrates and/or can be configured to form parts of the circuits that are inside the chamber 20 and that are aligned such that the dielectric components 17a - 17g are aligned in between these parts of the connection element and the first wall 40 and/or the second wall 41 of the chamber 20 for providing the phase shift functionality. In other words, functionalities that are provided by the conductive components 15a of the transmission line module 10 of Figure 3 can be implemented by the connecting elements by shaping the connecting elements accordingly.

In the example of Figure 7, the sixth substrate 12f can be understood to be a second substrate 12a’, as it is connected to the first substrate 12a via the first connecting conductor 14a’. The first connecting conductor 14a’ is further forming the circuits that are implemented by the omitted second substrate 12b, third substrate 12c and fourth substrate 12d. The first connecting conductor 14a’ can be formed of multiple components, in particular by multiple sheet metal parts. That is, sheet metal parts are optionally connected to each other at a connection point 31 to form complex structures, which allows to use a reduced amount of sheet metal for the complex structure. The component carrier 11 is preferably supporting the structure that is formed by any one of the connecting conductors.

Consequently, it can be seen that certain structures or functions are not realized on a substrate but on bigger sheet-metal parts which then are interfaced to chamber external interfaces and/or substrates inside the chamber 20 and I or other smaller sheet metal structures. The size of this bigger sheet-metal structures is significantly smaller than the width of the chamber 20.

Accordingly, it is an option to also attach parts of the metal strip line to the component carrier 11 . A metal strip line holder part can be attached to the component carrier parts by applying the same joining option as used for the substrates 12a - 12g. The metal strip line holder can either extend to a groove in the chamber housing end as shown on the left side in figure 6 or end at the strip line itself but then must be sustained by supports to secure the distance to the chamber housing as shown on the right side in figure 6 . Optionally, the metal strip line holder can be a plastic part. Figures 8a, 8b, 9a and 9b are showing an exemplary connection between the first conductive component 15a of the first substrate 12a and the first connecting conductor 14a. That is, an exemplary first connection 16a is shown. The same type of connection is used for all connections between any one of the conductive components 15a-15g of the substrates 12a - 12g and any one of the connecting conductors 14a - 14f. Figures 8a and 8b show the exemplary connection in a not connected state. Figures 9a and 9b show the exemplary connection in a connected state. Figure 8b shows a cross sectional view of the connection of Fig. 8a. Figure 9b shows a cross sectional view of the connection of Fig. 9a. Figures 8a and 9a show a top-down view onto the plane in which the first substrate 2a is extending, wherein this plane is also referred to as first substrate plane.

Referring to Figs. 8a and 8b, a first end of the first connecting conductor 14a is shown, wherein the first end is the end of the first connecting conductor 14a that is connected to the first conductive component 15a via the first connection 16a on the first side of the first connecting conductor 14a. It is noted that a second end of the first connecting conductor 14a that is connected to the second conductive component 15b of the second substrate 12b via the second connection 16b on the second side of the first connecting conductor 14a is optionally formed in a corresponding manner.

The first substrate 12a is extending in the first substrate plane and comprises a recess 60. The first conductive component 15a is guided on the first substrate 12a such than an end section of the first conductive component 15a is adjacent to the recess 60.

The first end of the first connecting conductor 14a comprises a first portion 61, a transition portion 62 and second portion 63. The transition portion 62 is in between the first portion 61 and the second portion 63 and is connecting the first portion 61 to the second portion 63.

The first portion 61 of the first end of the first connecting conductor 14a is aligned in a first plane and the second portion 63 of the first end of the first connecting conductor 14a is aligned in a second plane that is parallel to the first plane. Once the first connecting conductor 14a is connected to the first conductive component 15a of the first substrate 12a, the first plane is the first substrate plane and the second plane is the first surface plane, wherein the first surface plane is defined by the surface of the first substrate 12a on which the first conductive component 15a is extending. Thus, if in a connected state, the second portion 63 of the first end of the first connecting conductor 14a is aligned in the first surface plane that is parallel to the first substrate plane and is extending over the surface of the first substrate 12a to be in contact with the first conductive component 15a. The transition portion 62 is configured to overcome the height difference between the first surface plane and the first substrate plane. The first portion 61 of the first end of the first connecting conductor 14a is aligned in the first substrate plane and therefore in the same plane as the first substrate 12a.

Optionally, the second portion 63 of the first end of the first connecting conductor 14a comprises a through hole 64. This through hole 64 allows the application of a solder to connect the second portion 63 of the first connecting conductor 14a to the first conductive component 15a. The solder in the through hole 64 is then connecting the second portion 63 of the first connecting conductor 14a to the first conductive component 15a. The through hole 64 is acting as a solder trap which serves as reservoir for an extensive amount of solder and creates an additional solder fillet. This improves mechanical and electrical stability. The electrical stability is increased as no solder balls can form which then would capacitively load the interface by reducing the clearance to the chamber housing. The mechanical stability is increased by creating a longer solder fillet by the hole.

Optionally, the first portion 61 of the first end of the first connecting conductor 14a comprises an indentation 65 that engages with a bulge 66 of the first substrate 12a. The indentation 65 and the bulge 66 are in combination forming a mechanical locking structure. In addition or in the alternative, the first portion 61 of the first end of the first connecting conductor 14a comprises a bulge that engages with an indentation of the first substrate 12a. In both cases, a mechanical form-fit locking feature is realized which eases pre-assembly by holding the metal part in place before soldering without the need for additional fixtures.

Figures 9a and 9b show the exemplary connection in a connected state. The first portion 61 of the first end of the first connecting conductor 14a is aligned inside the recess 60 of the first substrate 12a. The second portion 63 of the first end of the first connecting conductor 14a is aligned to be in contact with the first conductive component 15a. The second portion 63 of the first end of the first connecting conductor 14a is soldered to the first conductive component 15a such that a solder is applied within the through hole 64. The indentation 65 of the first portion 61 of the first connecting conductor 14a is engaged with the bulge 66 of the first substrate 12a.

Figs. 8a to 9b show an interface design to connect PCBs and sheet metal strip-line parts. There are two independent features: First is a mechanical form-fit locking feature realized with two noses in PCB and sheet-metal which eases pre-assembly by holding the metal part in place before soldering without the need for additional fixtures. Second is a solder trap which serves as reservoir for an extensive amount of solder and creates an additional solder fillet.

Fig. 10 shows an exemplary design of the chamber 20, wherein the chamber 20 is depicted in a cross-sectional view. The transmission line module 10 is aligned inside of the chamber, wherein details of the transmission line module 10 are omitted in Fig. 10. The first wall 40 of the chamber 20 is formed by a first panel sheet element and the second wall 41 of the chamber 20 is formed by a second panel sheet element. The first panel sheet element and the second panel sheet element are both made of a sheet metal.

One of the advantages of such a design is that the sheet metal parts are cheaper than an extruded profile. It is another advantage of the sheet metal housing that it is possible to freely position the GND distance bolts. Extruded housing in contrast only provides the GND short cut on the chamber sides which results in higher mode coupling at a frequency defined by chamber width. This means that there is no limit for chamber width which allows for implementation of more complex functions like filters, diplexers/duplexer.

The first wall 41 , that is the first panel sheet element, is connected to the second wall 41 , that is the second panel sheet element, by multiple metal spacers 70, 71. For example, the metal spacers comprise a metal shell or metal pin.

The metal spacers (bolts I PIN) control the distance between two sheet-metal parts and must be galvanically joined to the sheet-metals. The spacers are preferably placed where high ground currents are present.

Optionally, the multiple metal spacers 70, 71 are forming a sidewall of the chamber 20. In this case, the transmission line module 10 or at least the conductor network that is connecting the input port or ports 30 with radiating element connections 18a - 18h is aligned in between metal spacers that are forming opposing sidewalls of the chamber 20.

Optionally, at least a portion of the sidewall that is connecting the first wall 40 and the second wall 41 to form the chamber 20 is formed by a conductive tape 72, for example adhesive aluminium tape. The conductive tape 72 is preferably an adhesive tape that is connected to the first wall 40 and to the second wall 41 to connect the first wall 40 and the second wall 41 . A ground connection by the conductive tape 72 (capacitive short cut) is also possible where low ground currents are present. This helps to reduce the number of spacers and therefore reduces cost.

Forming the walls 40, 41 of the chamber 20 by panel sheet elements also allows to construct more complex shapes and designs for the stripline system 1 , which can be seen by example in fig. 11. For example, one or both of the first wall 40 and the second wall 41 can be split into different portions, each portion being connected to the other wall by the metal spacers 70, 71. In particular, the first wall 40 and/or the second wall 41 can serve a further purpose. For example, the first wall 40 is the reflector 5 of the antenna system 100. It is noted that it is advantageous that the first wall 40 is the reflector 5 of an antenna system 100 for all embodiments of the invention. Chambers out of extruded profiles have the drawback that they must somehow be joined to the reflector 5 as the system out of several chambers can’t be extruded in one part or it would be very expensive to do so. The sheet-metal chamber can use the reflector 5 as part of the chamber which further saves cost and can also improve signal and reflector GND management.

The metal spacers 70, 71 are configured to control the distance between two sheet-metal parts that are forming the first wall 40 and the second wall 41 and are galvanically joined to the sheetmetals. The spacers are placed where high ground currents are present.

Using the concept of stacking panel sheet elements and the transmission line module 10, it is possible to extend the stripline system 1 to comprise two or more chambers 20, wherein each chamber comprises a transmission line module 10, wherein parallel stripline systems, for example parallel phase shifters for different polarisations, are created. In this case, the first wall of one stripline system is forming the second wall of the adjacent stripline system. Further referring to fig. 11 , it can also be understood that chambers of parallel stripline systems can be created.

A method for manufacturing the stripline system 1 is illustrated in Figs. 12a and 12b, wherein Fig. 12a shows a method in which the transmission line module 10 is slided into the chamber. That is, the transmission line module 10 is moved over its entire own length into the chamber 20 until it reaches its final mounting position in the chamber 20. Fig. 12b discloses a method that is applicable in case the chamber 20 is formed by using panel sheet elements that are connected by the spacers 70, 71. In the method that is shown in Fig. 12b, the transmission line module 10 is stacked onto the second panel sheet element that is forming the second wall 41 in a first step S1. After that, the first panel sheet element that is forming the first wall 40 is stacked onto the transmission line module 10 in a second step S2. A further element that comprises the dielectric components 17a - 17g is stacked to be in between the first wall 40 and the transmission line module 10 or in between the second wall 41 and the transmission line module 10. Therefore, the chamber 20 is closed by mounting the first wall 40 after the transmission line module 10 is already aligned, which avoids that the transmission line module 10 has to be slided into the chamber 20 over its full length.

The construction of the chamber 20 using panel sheet element is advantageous, as it allows a stacking of the different layers of the stripline system 1 during manufacturing. The inner struc- tures can be mounted before the chamber 20 is closed. Complicated feed-in procedure like necessary for a closed chamber 20 can be avoided. In addition, the metal spacers 70, 71 are optionally engaging with through holes in the substrates or the component carrier 11 , which allows to keep the transmission line module 10 in its final mounting position. A module that comprises the dielectric components 17a - 17g optionally comprises longholes that are engaging with the metal spacers 70, 71 such that the module is mounted movably inside the chamber 20.

Figs. 13 and 14 show exemplary techniques for stacking the sheet panel elements and the transmission line module 10 using the metal poles 70, 71.

In the example of Fig. 13, each one of the multiple metal spacers 70, 71 comprises a notch and is extending through a through hole in the component carrier 11. It is noted that the metal spacers 70, 71 are not necessarily formed by a single metal part. For example, two metal parts can be connected to form each metal spacer, wherein the notch is formed in between the metal parts, which allows a mounting of the component carrier 11. In the example of Fig. 12 the metal spacers 70, 71 are soldered, screwed, clinched or welded to the first wall 40 and the second wall 40.

In particular, clinching is a PIM stable solution as is realizes a very good galvanic contact between bolt and sheet metal part. Another advantage is that it does not need any additive material to realize the connection and therefore can be very cheap. One option would be only to clinch the spacers to the middle sheet metal parts and to join the other sheet metal parts by for example screwing, spot or laser welding. A threat must be implemented in the bolts in the screwing case. This is further illustrated by Fig. 13.

It is an option to also clinch the top and bottom sheet metal, that is the first wall 40 and the second wall 41. First, the spacers are clinched in the middle layer, for example the transmission line module 10 or another sheet metal for forming multiple layers of a chamber 20, then the first wall 40 and/or the second wall 41 is clinched with the help of a big tool in a suitable press. This is further illustrated by Fig. 14.

In the example that is shown in Fig.14, at least one of the multiple metal spacers 70, 71 comprises a notch and is extending through a through hole in the first wall 40, the second wall 41 and the component carrier 11 , wherein the at least one of the first wall 40, the second wall 41 and the component carrier 11 is aligned inside the notch for mounting the first wall 40, the second wall 41 and the component carrier 11 to the at least one of the multiple metal spacers 70, 71. More specifically, the multiple metal spacers 70, 71 comprise multiple notches and are extending through a through hole in the first wall 40, the second wall 41 and the component carrier 11 , wherein each one of the first wall 40, the second wall 41 and the component carrier 11 is aligned inside a corresponding notch for mounting the first wall 40, the second wall 41 and the component carrier 11to the multiple metal spacers 70, 71 . The notches can be the result of a clinching process. That is, the notches are preferably formed by a compression of the metal spacers 70, 71. For example, the multiple metal spacers 70, 71 are compressed between a first tool 80 and a second tool 81 such that at least the ends of the metal spacers 70, 71 are extending to a diameter that does no longer allow the ends of the metal spacers 70, 71 to move through the through holes in the first wall 41 and the second wall 42.

The chamber 20 according to any one of the described examples is typically located close to the radiating elements 101 - 105 and is typically directly interfaced with the multiple radiating elements 101 - 105 to avoid additional losses.

According to the art, the inner line structure of the chamber is typically realized by either a single PCB or a single sheet metal part which is feed into the closed chamber profile including the dielectric elements. Both technologies have advantages and disadvantages and have in common that large structures come with high cost.

PCBs have the advantage that they can provide a very flexible and small-scale structurability of the line features. They also bring their own mechanical stability with their stiff substrate. An additional advantage is the possibility to mount components, like for example a resistor for a Wilkinson combiner, with industry standard processes. One disadvantage is that they bring in some losses into the strip-line as the substrate comes with dielectric losses. PCBs are economically available to a length of approximately 48“, which is around 1200 mm. This is much too short for typical base station antenna arrays. A signal distribution length up to 2600 mm is required.

Sheet metal structures have the advantage that they don’t introduce additional dielectric losses into the system as they do not need and carrier substrate. But the missing carrier is also a disadvantage when it comes to larger structures. They get quite limp which causes handling and logistics effort and therefore additional cost. Big sheet metal structures are typically punched and therefore require a large tool which is very expensive. Thera are other disadvantages which come with the manufacturing process: Small-scale features are not easy to realize and tolerances are no easy to keep over large structures.

According to aspects of the invention, a mix of PCB and a sheet metal structure is provided, which allows to combine the advantages of PCBs and sheet metal structures and allows to minimize the drawbacks coming with large structures.

Claims

1. A stripline system (1), comprising a transmission line module (10) and a conductive chamber (20), wherein the transmission line module (10) is aligned inside of the chamber (20); wherein the transmission line module (10) comprises a component carrier (11), at least two substrates (12a, 12b), the at least two substrates (12a, 12b) comprising a first substrate (12a) and a second substrate (12b), and at least one connecting conductor (14a, 14b), the at least one connecting conductor (14a, 14b) comprising a first connecting conductor (14a); wherein the at least two substrates (12a, 12b) are mounted to the component carrier (11); wherein a first conductive component (15a) is aligned on the first substrate (12a) and a second conductive component (15b) is aligned on the second substrate (12b); and wherein the first conductive component (15a) is electrically connected to the second conductive component (15b) by the first connecting conductor (14a).

2. The stripline system (1) according to claim 1 , wherein the first substrate (12a) is extending in a first substrate plane and comprises a recess, wherein a first portion (61) of a first end of the first connecting conductor (14a) is aligned in the first substrate plane and is aligned inside the recess (60) of the first substrate (12a).

3. The stripline system (1) according to claim 2, wherein a second portion (63) of the first end of the first connecting conductor (14a) is aligned in a surface plane that is parallel to the first substrate plane and is extending over the surface of the first substrate (12a) on which the first connecting conductor (14a) is aligned, and wherein the second portion (63) of the first end of the first connecting conductor (14a) is aligned to be in contact with the first conductive component (15a).

4. The stripline system (1) according to claim 3, wherein the second portion (63) of the first end of the first connecting conductor (14a) comprises a through hole (64), and wherein the second portion (63) of the first end of the first connecting conductor (14a) is soldered to the first conductive component (15a) such that a solder is applied within the through hole.

5. The stripline system (1) according to any one of claim 2 to 4, wherein the first portion (61) of the first end of the first connecting conductor (14a) comprises an indentation (65) that engages with a bulge (66) of the first substrate (12a); and/or wherein the first portion (61) of the first end of the first connecting conductor (14a) comprises a bulge that engages with an indentation of the first substrate (12a).

6. The stripline system (1) according to any one of the previous claims, wherein the chamber (20) comprises guiding means (51 , 52, 53, 54) that are configured to interact with the component carrier (11) and/or with at least one of the at least two substrates (12a, 12b) such that the transmission line module (10) is guided along a linear direction inside the chamber (20).

7. The stripline system (1) according to any one of the previous claims, wherein the component carrier (11) comprises stripline holding means (55) that are configured to support one of the at least one connecting conductor (14a, 14b).

8. The stripline system (1) according to any one of the previous claims, wherein the chamber (20) comprises a first wall (40) and a second wall (41), wherein the transmission line module (10) is aligned in between the first wall (40) and the second wall (41).

9. The stripline system (1) according to claim 8, wherein the first wall (40) is a first panel sheet element and the second wall (41) is a second panel sheet element.

10. The stripline system (1) according to any one of claims 8 or 9, wherein the first wall (40) is connected to the second wall (41) multiple metal spacers (70, 71).

11. The stripline system (1) according to claim 10, wherein multiple metal spacers (70, 71) are forming a sidewall of the chamber (20).

12. The stripline system (1) according to any one of claims 10 or 11 , wherein at least one of the multiple metal spacers (70, 71) is connected to the first wall (40) and/or the second wall (41) by a welding connection, or wherein at least one of the multiple metal spacers (70, 71) comprises a notch and is extending through a through hole in at least one of the first wall (40), the second wall (41) and the component carrier (11), wherein the at least one of the first wall (40), the second wall (41) and the component carrier (11) is aligned inside the notch for mounting the first wall (40), the second wall (41) and the component carrier (11) to the at least one of the multiple metal spacers (70, 71).

13. The stripline system (1) according to any one of claims 8 to 12, wherein a sidewall is connecting the first wall (40) and the second wall (31) to form the chamber (20), wherein at least a portion of the sidewall is formed by a conductive tape (72).

14. The stripline system (1) according to any one of claims 8 to 13, wherein the first wall (40) is a reflector (5) of an antenna system (100).

15. The stripline system (1) according to any one of the previous claims, wherein the stripline system (1) is a phase shifter.