Phased array antenna device

Abstract

A phased array antenna device comprises antenna elements arranged in a spatial distribution to emit and receive superposing radio frequency signals to and from different directions. Each antenna element is positioned within a corresponding unit cell. The unit cells are arranged in a non-overlapping manner next to each other. A feeding network for transmitting the antenna signals between a common feeding point and the respective antenna element comprises a plurality of antenna element transmission line segments each running into an antenna element and a corresponding plurality of phase shifting devices. The feeding transmission line segments each comprises more than two transition structures distributed along the feeding transmission line segment. Each transition structure provides for a signal coupling between the feeding transmission line segment and the corresponding antenna element transmission line segment, thereby connecting several dedicated antenna element transmission line segments with the same feeding transmission line segment.

Claims

1. A phased array antenna device (2), comprising: a plurality of antenna elements (5) arranged in a spatial distribution that allows the phased array antenna device (2) to emit and receive superposing radio frequency signals to and from different directions, wherein each antenna element (5) is positioned within a corresponding unit cell (1) of the phase array antenna device (2) and wherein the unit cells (1) are arranged in a non-overlapping manner next to each other; a feeding network for transmitting antenna signals between a common feeding point and the respective antenna element (5), wherein the feeding network comprises a plurality of antenna element transmission line segments (4), each running into an antenna element (5); a plurality of phase shifting devices (7), wherein for each antenna element (5) a corresponding phase shifting device (7) is arranged along the respective antenna element signal transmission line (4) that runs into said antenna element (4); and a plurality of feeding transmission line segments (8), wherein each feeding transmission line segment (8) comprises more than two transition structures (6) distributed along the feeding transmission line segment (8), wherein each transition structure (6) provides for a signal coupling between the feeding transmission line segment (8) and the corresponding antenna element transmission line segment (4), thereby connecting several dedicated antenna element transmission line segments (4) with the same feeding transmission line segment (8).

2. The phased array antenna device (2) according to claim 1, wherein each of the feeding transmission line segments (8) runs along or through more than two unit cells (1) and comprises one transition structure (6) for each of the more than two unit cells (1).

3. The phased array antenna device (2) according to claim 1, wherein each of the feeding transmission line segments (8) runs along a straight line.

4. The phased array antenna device (2) according to claim 1, wherein the feeding transmission line segments (8) are implemented as microstrip transmission lines with a microstrip line arranged at a distance to a ground electrode (16).

5. The phased array antenna device (2) according to claim 1, wherein the feeding transmission line segments (8) are implemented as differential pair transmission lines with two similar differential pair electrodes running along the feeding transmission line segment (8).

6. The phased array antenna device (2) according to claim 1, wherein each of the antenna element transmission line segments (4) is implemented as differential pair transmission line with two similar differential pair electrodes (17, 18) running along the antenna element transmission line segment (4), and wherein at least one of the two differential pair electrodes (17, 18) of the antenna element transmission line segment is galvanically isolated from the corresponding feeding transmission line segment (8).

7. The phased array antenna device (1) according to claim 6, wherein the transition structure (6) comprises two line shaped transition electrodes, wherein the transition structure comprises an overlapping section with a part of least one of the two line shaped transition electrodes running parallel but at a distance to the feeding transmission line segment (8) for signal coupling from the feeding transmission line segment (8) into the antenna element transmission line segment (4), wherein each of the two line shaped transition electrodes runs into a corresponding one of the two differential pair electrodes (17, 18) of the antenna element transmission line segment (4).

8. The phased array antenna device (2) according to claim 7, wherein one of the two line shaped transition electrodes is designed as a balun-type line shaped transition electrode that provides for a phase difference of 180° with respect to the other line shaped transition electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 illustrates a schematic top view of a matrix shaped arrangement of unit cells with several columns of unit cells, whereby each antenna element along a column of unit cells is coupled to a feeding transmission line segment which is designed as a microstrip transmission line.

[0023] FIG. 2 illustrates a schematic cross-sectional view through a part of a unit cell as shown in FIG. 1.

[0024] FIG. 3 illustrates a schematic top view of a matrix shaped arrangement of unit cells similar to the arrangement shown in FIG. 1, whereby the feeding transmission line segment as well as antenna element transmission line segments that run towards the respective antenna elements are designed as microstrip transmission lines.

[0025] FIG. 4 illustrates a schematic cross-sectional view through a part of a unit cell as shown in FIG. 3.

[0026] FIG. 5 illustrates a schematic top view of a matrix shaped arrangement of unit cells similar to the arrangements shown in FIGS. 1 and 3, whereby the feeding transmission line segment is designed as a microstrip transmission line and whereby the respective antenna element transmission line segments are designed as differential pair transmission lines.

[0027] FIG. 6 illustrates a schematic cross-sectional view through a part of a unit cell as shown in FIG. 5.

[0028] FIG. 7 illustrates a schematic top view of a transition structure that provides for a signal coupling between a microstrip transmission line and a microstrip transmission line.

[0029] FIG. 8 illustrates a schematic top view of a transition structure that provides for a signal coupling between a microstrip transmission line and a differential pair transmission line.

DETAILED DESCRIPTION

[0030] FIG. 1 illustrates a schematic top view of a matrix shaped arrangement of unit cells 1 within a phased array antenna device 2. The matrix shaped arrangement of unit cells 1 comprises several columns 3 of unit cells 1, whereby adjacent columns 3 of unit cells 1 are positioned with a small offset in the direction of the columns 3. However, such an offset is not mandatory for a matrix shaped arrangement of unit cells 1.

[0031] Each of the non-overlapping unit cells 1 comprises an antenna element transmission line segment 4 that runs towards an antenna element 5. The antenna element 5 that is schematically illustrated in FIG. 1 is designed as a bowtie dipole antenna. The antenna element transmission line segment 4 runs from a transition structure 6 located near a border of the unit cell 1 along several bends towards the antenna element 5 that is located near the center of the unit cell 1. At least a part of the antenna element transmission line segment 4 is used as a phase shifting device 7.

[0032] For each column 3 of the unit cells 1 a feeding transmission line segment 8 runs along the corresponding column 3 and traverses all unit cells 1 within said column 3. Within each unit cell 1 the feeding transmission line segment 8 traverses the corresponding transition structure 6. Within the transition structure 6, a part of a radio frequency signal that is transmitted along the feeding transmission line segment 8 is coupled into the corresponding antenna element transmission line segment 4 and transmitted along this antenna element transmission line segment 4 towards the antenna element 5 of the corresponding unit cell 1. An exemplary design of such a transition structure 6 is illustrated in FIG. 8.

[0033] For each unit cell 1 an individual phase shift of the radio frequency signal that is transmitted along the antenna element transmission line segment 4 is preset by the corresponding phase shifting device 7. The radio frequency signals that are emitted from each of the antenna elements 5 superimpose each other, resulting in a peak intensity of the superimposed radio frequency signal that is emitted from the phased array antenna device 2, whereby the direction of the peak intensity can be preset and modified by individually controlling and presetting the phase shift of each of the radio frequency signals of each antenna element 5, i.e. from each of the unit cells 1. In a similar manner it is possible to intensify the sensitivity for receiving radio frequency signals coming from a specific direction with respect to a plane defined by the matrix shaped arrangement of the unit cells 1 by applying a correct phase shift to each of the incoming radio frequency signals that are received by the antenna elements 5 and transmitted along the antenna element transmission line segments 4 towards the respective transition structures 6 and fed into the common feeding transmission line segment 8. Bias voltage lines that are required for applying and controlling an individual phase shift of each phase shifting device 7 must individually connect each of the phase shifting devices 7 with a bias voltage control unit. Such bias voltage lines are not depicted in the figures, but may run within a strip shaped region parallel to the feeding transmission line segments 8 whereby the strip shaped region is arranged between the respective feeding transmission line segment 8 and the row of antenna element transmission line segments 4 adjacent to this feeding transmission line segment 8 but connected to another feeding transmission line segment 8 at the opposite side of the antenna elements 5.

[0034] Each feeding transmission line segment 8 is connected to a common control unit 9 via a corporate feed network 10. The corporate feed network 10 comprises a cascading arrangement of corporate feed transmission line segments 11, whereby starting from the control unit 9 each corporate feed transmission line segment 11 branches into two successive corporate feed transmission line segments 11 until after a final branch the corresponding successive corporate feed transmission line segments 11 run into the corresponding feeding transmission line segments 8.

[0035] Due to the feeding transmission line segments 8, the number and the total length of the successive corporate feed transmission line segments 11 that are required to transmit the signals between the common control unit 9 and each of the antenna elements 5 is significantly reduced. As each of the corporate feed transmission line segments 11 require some space and a minimum distance to other signal transmitting components like e.g. the antenna element transmission line elements 4 with the phase shifting devices 7, this results in a more compact and space saving design of the matrix shaped arrangement of unit cells 1 and thus of the phased array antenna device 2.

[0036] FIG. 2 illustrates a sectional view of a part of a unit cell 1 shown in FIG. 1. The phased array antenna device 2 comprises a first substrate layer 12 for the feeding transmission line segments 8, and two second substrate layers 13 for the antenna element transmission line segments 4 and the phase shifting devices 7. The two second substrate layers 13 are made of glass, and the first substrate layer 12 can also be made of glass or any other suitable dielectric material. The feeding transmission line segment 8 are designed as microstrip transmission lines with a line shaped microstrip electrode 14 at a first surface 15 of the first substrate layer 12, and with a plane shaped ground electrode 16 at a second surface 15′ opposite to the first surface 15. One of the second substrate layers 13 can be in direct contact with the plane shaped ground electrode 16 or arranged at a distance to the plane shaped ground electrode 16 with an intermitting layer of e.g. air or a solid dielectric material, as exemplarily illustrated in FIG. 2.

[0037] Each transition structure 8 provides for a signal coupling between the feeding transmission line segment 8 and the corresponding antenna element transmission line segment 4 that is designed as a differential pair transmission line with two differential pair electrodes 17, 18 that are arranged in between the two second substrate layers 13 at opposing but facing surfaces 19, 20. The volume between the two second substrate layers 13 is filled with a tunable dielectric material, e.g. a tunable liquid crystal material 21. Applying an electric potential difference between the two differential pair electrodes 17, 18 results in an electric field that affects the tunable dielectric material, which results in a preset phase shift of the radio frequency signal that is transmitted along the antenna element transmission line segment 4 which also acts as the phase shifting device 7. By presetting individual phase shifts for each of the antenna elements 5 of the unit cells 1, the direction of a peak intensity of a resulting superimposed radio frequency signal that is emitted from the matrix shaped arrangement of the antenna elements 5 can be preset and adapted to provide for enhanced signal communication between the phased array antenna device 2 and any other communication device that emits or receives radio frequency signals that are compatible with the superimposed radio frequency signal of the phased array antenna device 2.

[0038] FIGS. 3 and 4 illustrate another embodiment of the phased array antenna element 2. Both, the feeding transmission line segments 8 and the antenna element transmission line segments 4 are designed as microstrip transmission lines. Thus, there are only two second substrate layers 13 required. The plane shaped ground electrode 16 and the line shaped microstrip electrode 14 of the feeding transmission line segment 8 are arranged between the two second substrate layers 13 at opposing but facing surfaces 19, 20. The line shaped microstrip electrode 14 of the feeding transmission line segment 8 and a line shaped microstrip electrode 22 of the antenna element transmission line segments 4 are arranged at the same surface 19, whereby the plate shaped ground electrode 16 is arranged on the other surface 20. The volume between the two second substrate layers 13 is filled with a tunable dielectric material, e.g. a tunable liquid crystal material 21. An exemplary design of the transition structure 6 that couples the radio frequency signal between the feeding transmission line segment 8 and the corresponding antenna element transmission line segment 4 is illustrated in FIG. 7. For each unit cell 1 and the corresponding antenna element 5 that is designed as a patch antenna and that is not shown in FIGS. 3 and 4, the correct phase shift can be preset by applying the corresponding electric potential difference between the line shaped microstrip electrode 22 and the plate shaped ground electrode 16 of the antenna element transmission line 4, as the line shaped microstrip electrode 22 is not galvanically connected to the feeding transmission line segment 8.

[0039] FIGS. 5 and 6 illustrate yet another embodiment of the phased array antenna device 2 with only two second substrate layers 13, whereby the feeding transmission line segment 8 is designed as a microstrip transmission line and whereby the antenna element transmission line segments 5 are designed as differential pair transmission lines.

[0040] FIG. 7 schematically illustrates an exemplary embodiment of a transition structure 6 that can be used to couple a radio frequency signal between two microstrip transmission lines. The line shaped microstrip electrode 14 of the feeding transmission line segment 8 runs along a straight line. An end section 23 of the line shaped microstrip electrode 22 of the antenna element transmission line segment 4 forms a line shaped transition electrode and runs parallel but at a distance to the line shaped microstrip electrode 14 of the feeding transmission line segment 8, whereby the length of the parallel section of the line shaped microstrip electrode 22 is adapted and preset to provide for a strong signal coupling of a radio frequency signal between the line shaped microstrip electrode 14 of the feeding transmission line segment 8 and the line shaped microstrip electrode 22 of the antenna element transmission line segment 4.

[0041] FIG. 8 schematically illustrates another exemplary embodiment of a transition structure 6 that allows for the coupling of a radio frequency signal between a microstrip transmission line and a differential pair transmission line. An end section 24 of the first line shaped differential pair electrode 17 forms a line shaped transition electrode and runs parallel but at a distance and preferably at another substrate to the line shaped microstrip electrode 14 of the feeding transmission line segment 8. For clarification purposes the first line shaped differential pair electrode 17 is illustrated with dashed lines. After the end section 24, the first line shaped differential pair electrode 17 runs along a U-shaped delay course that results in a 180° phase shift with respect to the signal that is coupled into the second line shaped differential pair electrode 18. The U-shaped delay course can also be regarded as being part of the line shaped transition electrode of the transition structure 6. The second line shaped differential pair electrode 18 can be connected or coupled with or without a galvanic connection to the line shaped microstrip electrode 14 of the feeding transmission line segment 8. FIG. 8 illustrates a galvanic connection designed as a branch of the line shaped microstrip electrode 14 of the feeding transmission line segment 8 into a branching line shaped differential pair electrode 18 of the antenna element transmission line segment 4.

[0042] While the present invention has been described with reference to exemplary embodiments, it will be readily apparent to those skilled in the art that the invention is not limited to the disclosed or illustrated embodiments but, on the contrary, is intended to cover numerous other modifications, substitutions, variations and broad equivalent arrangements that are included within the spirit and scope of the following claims.