CN111628258A

CN111628258A - Radio frequency device

Info

Publication number: CN111628258A
Application number: CN201910144998.5A
Authority: CN
Inventors: O.H.卡拉贝
Original assignee: Alcon Systems LLC
Current assignee: Alcon Systems LLC
Priority date: 2019-02-27
Filing date: 2019-02-27
Publication date: 2020-09-04

Abstract

The radio frequency device (4) comprises a first substrate layer (2) and a second substrate layer (3) arranged at a distance to each other, wherein the first and second substrate layers (2, 3) comprise electrically conductive transmission line elements (10, 11, 10', 11') on a first surface (6) of the first substrate layer (2) and on a second surface (8) of the second substrate layer (3), which allow transmission of radio frequency signals along a transmission direction. The radio frequency device (4) further comprises more than one conductive intersection (1) between the first surface (6) of the first substrate layer (2) and the second surface (8) of the second substrate layer (3), which provides a conductive connection of the respective conductive transmission line elements (10, 11) on the first and second substrate layers (2, 3). At least one phase shifting region (12) of the radio frequency device (4) comprises a corresponding region of the respective first and second substrate layers (2, 3) for forming at least one radio frequency phase shifting element arranged on the first and second substrate layers (2, 3). All conductive crossings (1) are arranged outside the at least one phase shifting region (12) of the radio frequency device (4), wherein each conductive crossing (1) is electrically connected to a respective phase shifting element.

Description

Radio frequency device

Technical Field

The invention relates to a radio frequency device comprising a first substrate layer and a second substrate layer arranged at a distance from each other, wherein the first and second substrate layers comprise conductive transmission line elements on a first surface of the first substrate layer and on a second surface of the second substrate layer allowing transmission of radio frequency signals along a transmission direction parallel to the first surface of the first substrate layer or parallel to the second surface of the second substrate layer, defined by transmission line elements, and the radio frequency device has a conductive intersection (crossover) between the first surface of the first substrate layer and the second surface of the second substrate layer providing a conductive connection of the conductive transmission line elements on the first surface of the first substrate layer with the conductive transmission line elements on the second surface of the second substrate layer.

Background

In many radio frequency devices, radio frequency signals are transmitted along electrically conductive transmission line elements. Such a transmission line element may be arranged on a surface of the substrate layer. Sometimes, several transmission line elements forming signal paths for radio frequency signals are arranged on two or more surfaces of at least two substrate layers arranged themselves at a distance from each other. Some of the transmission line elements are arranged on opposite surfaces of the two substrate layers. The transmission line elements enable transmission of radio frequency signals along a transmission direction defined by the design, arrangement and orientation of the corresponding transmission line elements at the opposite surfaces, wherein the transmission direction is parallel to at least one of the opposite surfaces of the two substrate layers. If both surfaces of the two substrate layers are arranged parallel to one another, the transport direction is parallel to both opposite surfaces.

For many devices, transmission line elements may be fabricated by well-known methods including deposition methods, lithographic methods, or etching methods, such as, for example, surface micromachining or bulk micromachining. It is also possible to generate transmission line elements by means of a printing method.

Many radio frequency devices require two electrodes forming a transmission line element, like for example a microstrip line, at a distance towards each other. The surfaces of the two substrate layers with the respective transmission line elements have to be arranged at a distance towards each other in order to avoid unwanted electrically conductive connections between the two surfaces and the respective transmission line elements. Typically, a layer of solid dielectric material is arranged between the two substrate layers with the respective transmission line elements, resulting in e.g. a microstrip line arrangement of the respective transmission line elements. However, for some applications the volume between the two substrate layers is at least partially filled with a fluid material (like air or a liquid crystal material), wherein the mechanical properties of such a fluid material do not provide or guarantee the required distance. For such devices, typically one or more spacer elements are arranged between the two substrate layers, which define and provide the distance between the two substrate layers. The volume between the two substrate layers that is not filled by the spacer element can be used for and filled by the fluid material.

For some applications, like for example radio frequency applications based on thin film transistor displays, it is necessary to feed a signal from a transmission line element on the first surface of the first substrate layer to a corresponding transmission line element on the second surface of the second substrate layer at some point. A thin film transistor display having a large number of picture elements, named pixels, comprises a capacitor for each picture element: the voltage applied to the corresponding capacitor can be controlled for that picture element. Typically there is a common ground electrode for all picture elements on the first substrate layer and a dedicated control electrode for each of the picture elements on the second substrate layer. The source voltage driver and most of the control elements are arranged on the same surface of the second substrate layer as the control electrodes. Thus, there is one conductive intersection needed to transfer the common ground electrode signal from the second surface of the second substrate layer to the first surface of the first substrate layer.

If at least one substrate layer easily allows the manufacture of an opening into the substrate layer and the insertion of an electrically conductive connection element (like e.g. a wire or a pin) from the outside through the opening, the electrically conductive connection element can be used to provide an electrically conductive intersection between transmission line elements on both surfaces placed next to or around the opening.

However, for some devices, the two substrate layers are made of a material that does not readily allow openings through the substrate layers, such as, for example, glass. For such substrate layers, the conductive intersection should not require an opening in at least one of the substrate layers. Furthermore, if a fluid dielectric material is used to fill the volume between the two substrate layers, such an opening may contribute to or even cause unwanted leakage of the fluid material through the opening, leading to the need for an additional seal to protect the opening.

In some cases, such a conductive intersection may be achieved by making conductive connections that insert from the side edges of the substrate layers to the transmission line elements on both surfaces, where the respective transmission line elements are contacted from the outside of both substrate layers via the space between the two substrate layers. However, for some applications and devices, such a conductive connection is not possible or is considered disadvantageous.

For some devices, like for example phased array antennas, a large number of antenna elements (e.g. hundreds or thousands of antenna elements) are arranged within a small area. Each antenna element requires at least one phase shifting element and a connection line formed by a transmission line connecting the antenna element with the respective phase shifting element and a feed network. In order to allow a compact phased array antenna device it is considered advantageous to utilize transmission line elements on two substrate layers arranged at a distance towards each other, wherein the transmission line elements for the connecting lines or for the phase shifting elements are arranged at both surfaces of the two substrate layers facing each other. Furthermore, if the conductive cross does not allow an opening in at least one of the two substrate layers, the conductive cross should be formed by means of different pins or wires connecting the two surfaces of the two substrate layers.

Accordingly, there is a need for: a cost-effective and space-saving arrangement and design of the electrically conductive connections allowing to connect transmission line elements arranged on two opposite surfaces of two substrate layers arranged at a distance from each other.

Disclosure of Invention

The invention relates to a radio frequency device as described above, wherein more than one conductive crossover is arranged between the first and second substrate layers. Even though the manufacture of more than one conductive cross-over may require more effort and cost than the manufacture of a single conductive cross-over connected to all transmission line elements requiring such a connection, the use of several conductive cross-overs facilitates the triggering and control of several transmission line elements which are not combined or integrated into a single electrical component of the radio frequency device but are instead associated with, for example, many different phase shifting elements.

According to a preferred embodiment of the invention, the at least one phase shifting region of the radio frequency device comprises a corresponding region of the respective first and second surfaces of the first and second substrate layers with the conductive transmission line elements for forming a number of radio frequency phase shifting elements arranged inside the boundaries of the at least one phase shifting region, wherein all conductive crossings are arranged outside the at least one phase shifting region of the radio frequency device, and wherein each conductive crossing outside the at least one phase shifting region is electrically connected to a respective phase shifting element inside the at least one phase shifting region. By spatially separating the conductive crossings from the surface area required by the phase shifting elements and other components, like for example the radiation emitting element or the coupling element coupling a radio frequency signal to the radiation element outside the substrate layer, a very dense spatial arrangement of phase shifting elements and radiation elements within the phase shifting regions, i.e. inside the boundaries of the phase shifting regions, is possible. For example, when designing a phased array antenna, the shape and distance of the radiating elements and the arrangement of the corresponding phase shifting elements may be designed in order to allow for optimal advantages of the radiation characteristics of the phased array antenna. The area within the phase shift region surrounded and defined by the boundary may be fully used for the phase shift elements and the corresponding radiation elements. Due to the arrangement of the conductive crossings outside the phase shifting regions, the available space for each of the conductive crossings may be maximized without interfering or limiting the phase shifting regions. Thus, a large footprint of each conductive crossover is possible, which facilitates manufacturing of the conductive crossover and improves reliability of the conductive crossover.

The footprint of the conductive intersection may be circular or rectangular. It is also possible to make optimal use of the available space outside the phase shifting regions by designing the conductive crossings with corresponding occupied spaces of different shapes and sizes.

According to an advantageous aspect of the invention, the plurality of conductive crossings are arranged along a line along a boundary of a phase shifting region of the radio frequency device. Arranging the conductive intersections in close proximity to the boundaries of the phase shift regions allows for a short distance between the conductive intersections and the corresponding phase shift elements.

Preferably, the plurality of conductive crossings are arranged along several lines parallel to each other along the boundary of the phase shifting region of the radio frequency device. Furthermore, for many radio frequency devices, it is advantageous to arrange one or more straight lines along two or more straight or curved boundaries of the phase shifting regions. If the radio frequency device comprises two substrate layers having a stack of rectangular shapes, the conductive crossings may be arranged along one, several or all boundaries of the two substrate layers of the stack, creating a large rectangular phase shifting region within an inner region of the two substrate layers. For many applications, like for example phased array antennas, a matrix-like arrangement of a large number of antenna elements with respective phase shifting elements and radiating elements within a phase shifting region of rectangular shape allows a space-saving construction of the phased array antenna and advantageous transmission or reception characteristics of the phased array antenna.

According to an advantageous embodiment of the invention, the respective conductive intersection of a first line is arranged at a distance in the direction of the first line with respect to an adjacent conductive intersection of a second line. The shifted position of the conductive intersection of the second line with respect to the adjacent first line allows for a very compact design of the connection lines connecting the conductive intersection with the dedicated phase shifting element inside the phase shifting region.

Preferably, the conductive intersection comprises a first interdigitated electrode on the first substrate layer, a second interdigitated electrode on the second substrate layer, wherein the first interdigitated electrode on the first substrate layer at least partially overlaps the second interdigitated electrode on the second substrate layer. The first and second crossing electrodes may be fabricated using the same fabrication method and typically in the same fabrication step with the corresponding phase shift elements and connecting lines. For example, the first crossing electrodes (the connection lines and the respective portions of the phase-shifting elements on the first surface of the first substrate layer) may be manufactured by printing or etching or by any other microelectronic manufacturing method.

The first and second interdigitated electrodes define a footprint of the conductive intersection. Typically, the first and second interdigitated electrodes are the same shape and size and are arranged in a stack to completely overlap each other. However, for some devices it may be advantageous to allow for different shapes or sizes or both of the first and second interdigitated electrodes. It is also possible to arrange the first and second interdigitated electrodes on the respective first surface of the first substrate layer and on the second surface of the second substrate layer in such a way that the first and second interdigitated electrodes only partly overlap.

According to an advantageous embodiment of the invention, an electrically conductive material is arranged between at least parts of the overlapping areas of the first and second crossing electrodes, wherein the electrically conductive material electrically connects the first crossing electrodes on the first substrate layer with the second crossing electrodes on the second substrate layer. The conductive material may include, for example, gold plated particles that are conductive and typically dispersed in the binder to form an anisotropic conductive adhesive material, such as an anisotropic conductive film or an anisotropic conductive paste, that may be employed in the connection of the first and second interdigitated electrodes. It is also possible to use known nickel conductive spacers from coatings, adhesives, printing inks, plastics and rubbers to provide the conductive connection between the first and second interdigitated electrodes.

In yet another embodiment of the present invention, the conductive material comprises conductive particles dispersed within a non-conductive matrix material. There are several different conductive particles or conductive coated particles, electro-optic material or anisotropic particles dispersed in a usable polymer matrix suitable for use as a conductive material for electrically connecting the first and second interdigitated electrodes.

It is also possible that the conductive material comprises conductive particles having an average diameter large enough to provide conductive contact with the first interdigitated electrodes and with the second interdigitated electrodes. According to a preferred embodiment of this aspect of the invention, the diameter of the conductive particles is equal to the distance between the first and second interdigitated electrodes. For the manufacture of such conductive intersections, conductive particles may be embedded in a suitable matrix material. The matrix material may be a photoresist. The embedded conductive particles are disposed on the first or second crossover electrodes. Subsequently, the matrix material may be removed, which leaves the conductive particles in between the first and second interdigitated electrodes. The position of the conductive particles relative to the first and second interdigitated electrodes may be secured by pressing the first and second substrate layers towards each other, resulting in a gripping force that prevents the conductive particles from dislodging.

In case the mechanical properties of the selected conductive material provide sufficient mechanical stability, the conductive material between the two crossing electrodes may be designed to also provide a spacer element ensuring the distance between the first and second substrate layers. In this case, it is advantageous to arrange the conductive intersections along all side edges of the two substrate layers, thereby providing mechanical stability of the sandwich of the two substrate layers at a distance from each other with the fluid material layer in between.

According to a further aspect of the invention, the first interdigitated electrodes of the first substrate layer or the second interdigitated electrodes on the second substrate layer, or both, are partially or completely covered by a conductive mechanical protection layer. The electrically conductive mechanical protection layer may be made of, for example, gold or copper, or any suitable electrically conductive material with sufficient mechanical stability or with sufficient thickness or both to provide a mechanical protection layer on top of the first and second interdigitated electrodes. The first and second interdigitated electrodes may then be made of a less mechanically stable material that is also used for the transmission line including the phase-shifting elements, and may provide advantageous characteristics of the transmission line or the fabrication of the transmission line. For example, some or all of the transmission lines and the first and second crossing electrodes may be made of a thin metal, such as, for example, Indium Tin Oxide (ITO).

The conductive intersection may be formed of a conductive material placed between the two conductive mechanical protective layers. In a further embodiment of the invention, the conductive cross is formed from a conductive material of the mechanical protection layer electrically connecting the first crossing electrode on the first substrate layer with the second crossing electrode on the second substrate layer.

According to an aspect of the invention, the encapsulant surrounds some or each of the conductive intersections, or wherein the encapsulant surrounds some or all of the region that includes the conductive intersections, or wherein the encapsulant surrounds some or all of the phase shifting regions. The encapsulant protects the conductive intersections from interfering with materials or external conditions originating from the volume between the two substrate layers, e.g., from interfering with the liquid crystal material used to control and manipulate the phase shift elements within the phase shift regions.

Drawings

The present invention will be more fully understood, and further features will become apparent, when reference is made to the following detailed description and the accompanying drawings. The drawings are merely representative and are not intended to limit the scope of the claims. Indeed, those skilled in the art will appreciate that various modifications and changes may be made to the invention without departing from the inventive concepts thereof upon a reading of the following description and a review of the current drawings. Similar parts depicted in the drawings are referred to by the same reference numerals.

Figure 1 illustrates a cross-sectional view of a conductive intersection between first and second substrate layers,

fig. 2 illustrates a schematic top view of a first substrate layer having a plurality of conductive intersections, each conductive intersection connected to a phase shifting element and then to a radiating element,

figure 3 illustrates a cross-sectional view of the substrate layer shown in figure 2 along the line III-III in figure 2,

figure 4 illustrates a perspective view of a first substrate layer having a plurality of conductive intersections arranged along side edges of the first substrate layer outside of phase-shift regions,

figure 5 illustrates a schematic top view of a first substrate layer having a plurality of conductive intersections arranged along two lines along side edges of the first substrate layer,

fig. 6 illustrates a schematic top view of a first substrate layer having a plurality of conductive intersections arranged along two lines along side edges of the first substrate layer, wherein the positions of the conductive intersections of the first line are shifted with respect to those of the second line,

figure 7 illustrates a cross-sectional view of another embodiment of a conductive intersection between first and second substrate layers,

FIG. 8 illustrates a cross-sectional view of yet another embodiment of a conductive intersection between first and second substrate layers, an

FIG. 9 illustrates a cross-sectional view of yet another embodiment of a conductive intersection between first and second substrate layers.

Detailed Description

Fig. 1 shows a cross-sectional view of a first embodiment of a conductive intersection 1 between a first substrate layer 2 and a second substrate layer 3 of a radio frequency device 4. The conductive intersection 1 between the first and second substrate layers 2, 3 comprises a first interdigitated electrode 5 arranged on a first surface 6 of the first substrate layer 2 and a second interdigitated electrode 7 arranged on a second surface 8 of the second substrate layer 3. The two

substrate layers

2, 3 are arranged parallel and with the first surface 6 of the first substrate layer 2 facing the second surface 8 of the second substrate layer 3. Both

substrate layers

2, 3 are made of glass.

The volume between the first 5 and second 7 interdigitated electrodes is filled with a conductive material 9, the conductive material 9 providing a conductive connection between the first 5 and second 7 interdigitated electrodes. The first interdigitated electrodes 5 are connected to transmission line elements 10 on the first surface 6 of the first substrate layer 2 and the second interdigitated electrodes 7 are connected to transmission line elements 11 on the second surface 8 of the second substrate layer 3. The conductive intersection 1 provides a conductive connection between a transmission line element 10 on the first surface 6 of the first substrate layer 2 and a transmission line element 11 on the second surface 8 of the second substrate layer 3. No openings or bores are required in the first substrate layer 2 or in the second substrate layer 3.

Fig. 2 and 3 illustrate an exemplary embodiment of a radio frequency device 4 having a number of phase shifting elements 20 and a number of coupling structures 21 arranged on a first surface 6 of a first substrate layer 2 and on a second surface 8 of a second substrate layer 3. Each coupling structure 21 couples a radio frequency signal to a corresponding radiating element arranged outside the first and second substrate layers 2, 3. Each phase shifting element 20 is formed by one or more transmission line elements 10 'on the first surface 6 of the first substrate layer 2 and by one or more transmission line elements 11' on the second surface 8 of the second substrate layer 3. Each phase shifting element 20 is on one side conductively connected to a dedicated conductive crossover 1 via a connection line 14, the dedicated conductive crossover 1 providing a bias voltage for operating and controlling the corresponding phase shifting element 20. The phase shifting element 20 is on the other side conductively connected via a connection line 14 to a dedicated coupling structure 21, which dedicated coupling structure 21 couples the radio frequency signal to the corresponding radiating element. Thus, for each signal path of a radio frequency signal transmitted to the coupling structure 21, and thus to the corresponding radiating element, via the phase shifting element 20, the dedicated conductive crossover 1 facilitates triggering and controlling the phase shifting element 20, resulting in individual phase control of the corresponding radiating element, such that a superimposed beam of the phased array antenna may be steered in two dimensions (e.g., in azimuth and elevation). The volume between the first and second substrate layers 2, 3 is filled with a tunable dielectric material, i.e. with a liquid crystal material 19 that can be used to control the respective phase shift created by the corresponding phase shifting device 20.

Fig. 4 shows a perspective view of a first substrate layer 2 having a plurality of conductive crossings 1 arranged outside the phase shifting regions 12. The boundaries 22 of the phase-shifting regions 12 are indicated by dot-dash lines and are located in the inner regions of the respective first and second substrate layers 2, 3. In order to demonstrate the arrangement of the conductive cross 1 on the first substrate layer 2, the second substrate layer 3 mounted on top of the first substrate layer 2 is only indicated by dashed lines. Inside the phase shifting region 12, phase shifting elements 20 and coupling structures 21 of the phased array antenna are positioned. Outside the phase shifting regions 12, a plurality of conductive crossings 1 is arranged along a side edge 13 of the first substrate layer 2. By separating the conductive intersection 1 from the phase shifting region 12 comprising the phase shifting elements 20 and the coupling structure 21, both the phase shifting elements 20 and the coupling structure 21 can be arranged to optimize the transmission and reception characteristics of a phased array antenna without having to take into account the space requirements for the conductive intersection 1. Furthermore, the footprint of the conductive cross 1 may be large enough to provide a reliable conductive connection between the first and second substrate layers 2, 3 without interfering with the design and arrangement of the phase shifting elements and the coupling structure 21 or the radiating elements. The conductive intersections 1 are arranged along a line parallel to the side edges 13. Which are conductively connected to phase shifting elements inside the phase shifting regions 12 via connection lines 14.

Fig. 5 illustrates a schematic top view of a first substrate layer 2 according to another embodiment of the invention, the first substrate layer 2 having a plurality of conductive crossings 1 arranged along two lines along a side edge 13 of the first substrate layer 2. The connecting lines 14 of the first straight conductive intersection 1 adjacent to the phase shifting regions 12 are directed to the phase shifting regions 12. The connection lines 14 of the conductive crossings 1 of the second line further away from the phase shifting regions 12 are gathered at the side opposite to the phase shifting regions 12, and every two connection lines 14 are guided to the phase shifting regions 12 through two lines of the conductive crossings 1.

Fig. 6 illustrates a schematic top view of a first substrate layer 2 according to another embodiment of the invention, the first substrate layer 2 having a plurality of conductive crossings 1 arranged along two lines along a side edge 13 of the first substrate layer 2. The positions of the conductive intersections 1 of the first line are shifted with respect to those of the second line. Thus, for all conductive crossings 1, the connection line 14 may be directed to the phase shifting region 12. The total length of all the connecting lines 14 of this embodiment is smaller than the total length of all the connecting lines 14 of the embodiment shown in fig. 5.

Fig. 7 shows a cross-sectional view of another embodiment of a conductive intersection 1 between a first and a

second substrate layer

2, 3. The first and

second intersecting electrodes

5, 7 and the adjoining connection line 14 are made of indium tin oxide ITO. Both the first and the second

interdigitated electrodes

5, 7 are covered by a conductive

mechanical protection layer

15, 16 made of gold or copper.

Fig. 8 shows a cross-sectional view of a further embodiment of the conductive intersection 1 between the first and second substrate layers 2, 3. Instead of the separate conductive material 9, the volume between the first and second

interdigitated electrodes

5, 7 is filled with the material 17 of the conductive

mechanical protection layer

15, 16, i.e. with gold or copper or any other conductive material suitable for providing mechanical protection. In order to establish a conductive connection. The additional material 17 of the conductive

mechanical protection layer

15, 16 may be added in a single manufacturing step, e.g. by an additive manufacturing method, as indicated on the bottom side of the conductive intersection 1, or the additional material 17 of the conductive

mechanical protection layer

15, 16 may be added in a separate manufacturing step, as indicated on the top side of the conductive intersection 1.

Fig. 9 shows a cross-sectional view of a further embodiment of a conductive intersection 1 between a first and a

second substrate layer

2, 3. The conductive intersection 1 is surrounded by a sealant 18, which sealant 18 prevents any direct contact of the conductive material 9 with any other material (like the liquid crystal material 19) filled between the first and second substrate layers 2, 3.

Claims

1. Radio frequency device (4), the radio frequency device (4) comprising a first substrate layer (2) and a second substrate layer (3) arranged at a distance towards each other, wherein the first and second substrate layers (2, 3) comprise conductive transmission line elements (10, 11, 10', 11') on a first surface (6) of the first substrate layer (2) and on a second surface (8) of the second substrate layer (3) allowing transmission of radio frequency signals along a transmission direction parallel to the first surface (6) of the first substrate layer (2) or parallel to the second surface (8) of the second substrate layer (3), and the radio frequency device (4) has a conductive intersection (1) between the first surface (6) of the first substrate layer (2) and the second surface (8) of the second substrate layer (3) providing a conductive transmission line element (10) on the first surface (6) of the first substrate layer (2) and the second substrate layer (3) -electrically conductive connection of an electrically conductive transmission line element (11) on the second surface (8) of the second substrate layer (3), characterized in that more than one electrically conductive intersection (1) is arranged between said first and second substrate layers (2, 3).

2. The radio frequency device (4) according to claim 1, characterized in that the at least one phase shifting region (12) of the radio frequency device (4) comprises corresponding regions of the respective first and second surfaces (6, 8) of the first and second substrate layers (2, 3) with conductive transmission line elements (10 ', 11') for forming a number of radio frequency phase shifting elements (20) arranged inside the boundaries of the at least one phase shifting region (12), and in that all conductive crossings (1) are arranged outside the at least one phase shifting region (12) of the radio frequency device (4), wherein each conductive crossing (1) outside the at least one phase shifting region (12) is electrically connected to a respective phase shifting element (20) inside the at least one phase shifting region (12).

3. A radio frequency device (4) according to claim 2, characterized in that a plurality of conductive crossings (1) are arranged along a line along the border of a phase shifting region (12) of the radio frequency device (4).

4. A radio frequency device (4) according to claim 2, characterized in that a plurality of conductive crossings (1) are arranged along several lines along the border of a phase shifting region (12) of the radio frequency device (4).

5. A radio frequency device (4) according to claim 4, characterized in that the respective conductive intersection (1) of a first line is arranged at a distance in the direction of the first line with respect to the adjacent conductive intersection (1) of a second line.

6. A radio frequency device (4) according to one of the preceding claims, characterized in that a conductive crossover (1) comprises a first crossover electrode (5) on the first substrate layer (2) and a second crossover electrode (7) on the second substrate layer (3), wherein the first crossover electrode (5) on the first substrate layer (2) at least partly overlaps the second crossover electrode (7) on the second substrate layer (3).

7. A radio frequency device (4) according to claim 6, characterized in that a conductive material (9) is arranged between at least parts of the overlapping areas of the first and second crossing electrodes (5, 7), wherein the conductive material (9) electrically connects the first crossing electrode (5) on the first substrate layer (2) with the second crossing electrode (7) on the second substrate layer (3).

8. The radio frequency device (4) according to claim 7, characterized in that the conductive material (9) comprises conductive particles dispersed in a non-conductive matrix material.

9. The radio frequency device (4) according to claim 7, characterized in that the conductive material (9) comprises conductive particles having an average diameter large enough to provide conductive contact with the first crossing electrode (5) and with the second crossing electrode (7).

10. A radio frequency device (4) according to claims 6 to 9, characterized in that the first crossing electrodes (5) of the first substrate layer (2) and/or the second crossing electrodes (7) on the second substrate layer (3) are covered by a conductive mechanical protection layer (15, 16).

11. A radio frequency device (4) according to claim 10, characterized in that the conductive crossover (1) is formed by a conductive material of a mechanical protection layer (15, 16) electrically connecting a first crossover electrode (5) on the first substrate layer (2) with a second crossover electrode (7) on the second substrate layer (3).

12. The radio frequency device (4) according to one of the preceding claims, characterized in that an encapsulant (18) surrounds some or each of the conductive intersections (1), or in that an encapsulant surrounds some part or all of the area comprising the conductive intersections (1), or in that an encapsulant surrounds some part or all of the phase shifting regions (12).