Phased array antenna device

Abstract

A phased array antenna device comprises antenna elements positioned within a corresponding unit cell. The unit cells are arranged non-overlappingly next to each other. A feeding network transmits antenna signals between a common control unit and the respective antenna element. The feeding network comprises a plurality of antenna element transmission line segments, each running into an antenna element, and a plurality of phase shifting devices. Several feeding transmission line segments, each comprising more than two transition structures are provided. Each transition structure couples a signal into a corresponding antenna element transmission line segment. The transition structure for an antenna element transmission line segment that runs into a unit cell is positioned in the direction of the feeding transmission line segment passing by or traversing this unit cell at a phase shifting distance that is larger than an extension of the unit cell measured in this direction.

Claims

1. A phased array antenna device (1), comprising: a plurality of antenna elements arranged (2) in a spatial distribution that allows for the phased array antenna device (1) to emit and receive superposing radio frequency signals to and from different directions, wherein each antenna element (2) is positioned within a corresponding unit cell (3) of the phase array antenna device (1) and wherein the unit cells (3) are arranged in a non-overlapping manner next to each other; a feeding network (5) for transmitting antenna signals between a common control unit (4) and the respective antenna element (2), wherein the feeding network (5) comprises a plurality of antenna element transmission line segments (10), each running into an antenna element (2); a plurality of phase shifting devices (11), wherein for each antenna element (2) a corresponding phase shifting device (11) is arranged along the respective antenna element signal transmission line (10) that runs into said antenna element (2); and a plurality of feeding transmission line segments (7), wherein each feeding transmission line segment (7) comprises more than two transition structures (9) distributed along the feeding transmission line segment (7), wherein each transition structure (9) provides for a signal coupling into a corresponding antenna element transmission line segment (10), thereby connecting several dedicated antenna element transmission line segments (10) with the same feeding transmission line segment (7), and wherein the transition structure (9) for an antenna element transmission line segment (10) that runs into a unit cell (3) is positioned in the direction of the feeding transmission line segment (7) passing by or traversing this unit cell (3) at a phase shifting distance that is larger than an extension of the unit cell (3) measured in this direction.

2. The phased array antenna device (1) according to claim 1, wherein the phase shifting distance is between one and two extensions of the unit cell (3).

3. The phased array antenna device (1) according to claim 1, wherein subsequent transition structures (9) are designed in such a way that the antenna element transmission line segments (10) of consecutive transition structures (9) along a feeding transmission line segment (7) are arranged at opposite sides of the feeding transmission line segment (7).

4. The phased array antenna device (1) according to claim 3, wherein all antenna element transmission line segments (10) that originate on a first side of the feeding transmission line segment (7) run in a first direction parallel to the direction of the feeding transmission line segment (7), whereas all antenna element transmission line segments (10) that originate on a second side of the feeding transmission line segment (7) opposite to the first side run in a second direction that is opposite to the first direction.

5. The phased array antenna device (1) according to claim 1, wherein all antenna element transmission line segments have the same length.

6. The phased array antenna device (1) according to claim 1, wherein all sections of the antenna element transmission line segments (10) run parallel to the feeding transmission line segment (7) or at an angle less than 50° with respect to the feeding transmission line segment (7) to which the respective antenna element transmission line segment (10) is coupled via the transition structure (9).

7. The phased array antenna device (1) according to claim 1, wherein the unit cells (3) are arranged in a matrix shaped arrangement, and wherein each of the feeding transmission line segments (7) runs along a straight line that traverses or passes by a plurality of unit cells (3) that are arranged along a straight line.

8. The phased array antenna device (1) according to claim 1, wherein the feeding transmission line segments (7) are implemented as microstrip transmission lines with a line shaped microstrip electrode (12) arranged at a distance to a plane shaped ground electrode.

9. The phased array antenna device (1) according to claim 1, wherein the feeding transmission line segments (7) are implemented as differential pair transmission lines with two similar line shaped differential pair electrodes running along the feeding transmission line segment (7).

10. The phased array antenna device (1) according to claim 1, wherein each of the antenna element transmission line segments (10) is implemented as differential pair transmission line with two similar differential pair electrodes (16, 18) running along the antenna element transmission line segment (10), and wherein at least one of the two differential pair electrodes (16) of the antenna element transmission line segment (10) is electrically isolated from the corresponding feeding transmission line segment (7).

11. The phased array antenna device (1) according to claim 10, wherein the transition structure (9) comprises two line shaped transition electrodes (12, 15), wherein the transition structure (9) also comprises an overlapping section with a part of least one of the two line shaped transition electrodes (15) running parallel but at a distance to the feeding transmission line segment (7) for signal coupling from the feeding transmission line segment (7) into the antenna element transmission line segment (10), and wherein each of the two line shaped transition electrodes (12, 15) runs into a corresponding one of the two differential pair electrodes (18, 16) of the antenna element transmission line segment (10).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 illustrates a schematic representation of a phased array antenna device with a plurality of unit cells arranged within a matrix shaped pattern and each comprising an antenna element, whereby each antenna element is connected to a control unit via a feeding network for transmitting radio frequency signals between the control unit and the antenna elements.

[0032] FIG. 2 illustrates a schematic top view of a row of unit cells, whereby a feeding transmission line segment that runs along this row of unit cells comprises a transition structure for each unit cell and with an antenna element transmission line segment for signal transmission between a transition structure and a corresponding antenna element.

[0033] FIG. 3 illustrates a schematic top view of two rows of unit cells, whereby a feeding transmission line segment that runs along these rows of unit cells comprises transition structures with antenna element transmission line segments that are arranged on opposite sides of the feeding transmission line segment.

[0034] FIG. 4 illustrates a schematic top view of a matrix shaped arrangement of unit cells with several feeding transmission line segments each running along one row of unit cells.

[0035] FIG. 5 illustrates a schematic top view of two rows of unit cells similar to FIG. 3, but with a different arrangement and design of the antenna element transmission line segments.

[0036] FIG. 6 illustrates a schematic top view of a matrix shaped arrangement of unit cells.

[0037] FIG. 7 illustrates a schematic top view of another embodiment of a matrix shaped arrangement of unit cells.

[0038] FIG. 8 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.

[0039] FIG. 9 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

[0040] FIG. 1 shows a schematic illustration of a phased array antenna device 1 comprising a plurality of antenna elements 2, whereby the antenna elements 2 are arranged on a plane in a matrix shaped topology. All antenna elements 2 are schematically illustrated as squares. The antenna elements 2 can be of any design or type of radiation element that emits or receives radio frequency signals of electromagnetic radiation. The plane can be divided into a corresponding plurality of unit cells 3 each comprising one antenna element 2 and a region around this antenna element 2. Adjacent unit cells 3 do not overlap, but are immediately adjacent to each other and form a matrix shaped arrangement that is adapted to the position of the antenna elements 2. The extension of a unit cell 3 in a given direction equals the distance between adjacent antenna elements 2 in this direction. The shape of a unit cell 3 can be rectangular as shown in FIG. 1. A unit cell 3 may also be of any other shape, e.g. honeycombed or circular. A unit cell 3 usually has no structural limitation.

[0041] The phased array antenna device 1 also comprises a control unit 4 for controlling radio frequency signals that are received or emitted by the antenna elements 2. Signal transmission between the control unit 4 and each of the antenna elements 2 is provided by a feeding network 5. The feeding network 5 comprises a corporate feed network. Corporate feed transmission line segments 6 of the corporate feed network originate from the control unit 4 and, after several branchings, run into feeding transmission line segments 7. Each of the feeding transmission line segments 7 runs along a straight line along a row 8 of unit cells 3 within the matrix shaped arrangement of unit cells 3. Each feeding transmission line segment 7 traverses through several unit cells 3 and comprises a corresponding number of transition structures 9. Each antenna element 2 is connected to a corresponding transition structure 9 via an antenna element transmission line segment 10 that are not shown in FIG. 1, but in FIGS. 2 to 4. Thus, a radio frequency signal that originates from the control unit 4 is transmitted along corporate feed transmission line segments 6 and along a feeding transmission line segment 7 and via a transition structure 9 along a successive antenna element transmission line segment 10 to the corresponding antenna element 2. In case of a reception of a radio frequency signal with an antenna element 2, the radio frequency signal travels along the antenna element transmission line segment 10 and through the transition structure 9 into the corresponding feeding transmission line segment 7 and via the corporate feed transmission line segments 6 towards the control unit 4.

[0042] The antenna element transmission line segments 10 is also designed for affecting the phase of the radio frequency signal and therefore used as a phase shifting device 11. However, the minimum length of the antenna element transmission line segment 10 that is required for performing a phase shift that is sufficient for a useful superimposition of the radio frequency signals of all antenna elements 2 exceeds the extension of a unit cell 3. Conventional phased array antenna devices 1 comprise antenna element transmission line segments 10 with a spiral or meandering course that is arranged within the corresponding unit cell 3. However, each curve or corner along the course of the antenna element transmission line segment 10 causes unwanted electromagnetic radiation emission that affects the signal quality and that interferes with signal transmission along other antenna element transmission line segments or feeding transmission line segments 7.

[0043] In order to avoid curves and corners along the course of the antenna element transmission line segment 10, the antenna element transmission line segment 10 connects the antenna element 2 of a given unit cell 3 with a transition structure 9 that is located in another unit cell 3 at a phase shifting distance d that exceeds the extension of the unit cells 3 in any direction. Preferably, the phase shifting distance d is large enough to allow for an essentially straight-line course of the antenna element transmission line segment 10 as schematically illustrated in FIGS. 2 to 4. The course of the antenna element transmission line segment 10 is significantly different from a spiral or meandering course and mainly a straight-line course with only a small lateral offset that is necessary to bridge the lateral distance of the antenna element 2 from the transition structure 9 at the feeding transmission line segment 7. The design and course of the antenna element transmission line segments 10 can be adapted to cause the least possible electromagnetic radiation emission during signal transmission of a radio frequency signal along the antenna element transmission line segments 10.

[0044] Furthermore, due to the straight-line course of the feeding transmission line segments 7 the space requirements for transmission lines that connect each antenna element 2 with the control unit 4 are significantly smaller than the space requirements for a conventional corporate feed network. In addition, the straight-line course of the feeding transmission line segments 7 also reduces unwanted emission of electromagnetic radiation during signal transmission along the feeding transmission line segments 7.

[0045] The design that is schematically illustrated in FIG. 2 comprises a feeding transmission line segment 7 that runs along one row 8 of unit cells 3. The feeding transmission line segment 7 comprises transition structures 9 and antenna element transmission line segments 10 that each originate at the same side of the feeding transmission line segment 7 and that each run to an antenna element 2 within the next but one unit cell 3 within the same row 8 of unit cells 3.

[0046] The design that is schematically illustrated in FIG. 3 comprises a feeding transmission line segment 7 with is connected to antenna elements 2 on opposite sides of the feeding transmission line segment 7. For each consecutive transition structure 9 arranged along the course of the feeding transmission line segment 7 the corresponding antenna element transmission line segment 10 originates at an opposite side of the feeding transmission line segment 7 and runs essentially parallel to the feeding transmission line segment 7 until the next but one unit cell 3 and the antenna element 2 that is located within this unit cell 3. Due to the alternating position and course of the antenna element transmission line segments 10, the course of the respective antenna element transmission line segments 10 can be even less curved than the corresponding course of the antenna element transmission line segments 10 shown in FIG. 2.

[0047] FIG. 4 schematically illustrates an exemplary design of a matrix shaped arrangement of unit cells 3 with several rows 8, whereby adjacent rows 8 have an offset in the direction of the respective rows 8 with respect to each other. Each feeding transmission line segment 7 is connected to several antenna element transmission line segments 10 that are arranged alternately at opposite sides of the feeding transmission line segment 7.

[0048] Preferably, the antenna element transmission line segments 10 are designed and manufactured as differential pair transmission lines with two differential pair electrodes that run essentially parallel and with a distance towards each other. The feeding transmission line segments 7 can be designed and manufactured as microstrip transmission lines with a line shaped microstrip electrode that runs at a distance to a plane-shaped ground electrode. However, it is also possible to have feeding transmission line segments 7 designed and manufactured as differential pair transmission lines or to have antenna element transmission line segments 10 designed and manufactured as microstrip transmission lines.

[0049] FIG. 5 schematically illustrates an exemplary design of a feeding transmission line segment 7 that is connected to antenna elements 2 on opposite sides of the feeding transmission line segment 7. This aspect of the topology is similar to the embodiment shown in FIG. 3. However, the direction of the antenna element transmission line segments 10 that originate at a first side of the feeding transmission line segment 7 differs from the direction of the antenna element transmission line segments 10 that originate at a second side of the feeding transmission line segment 7 that is opposite to the first side. Thus, e.g. the direction of the antenna element transmission line segments 10 that originate on the left side of the feeding transmission line segment 7 as shown in FIG. 5 is upwards, whereas the direction of the antenna element transmission line segments 10 that originate on the right side of the feeding transmission line segment 7 as shown in FIG. 5 is downwards.

[0050] FIG. 6 schematically illustrates another exemplary embodiment of a matrix shaped arrangement and connection of antenna elements 2 in corresponding unit cells 3. Adjacent rows of the matrix shaped arrangement of antenna elements 2 have no offset with respect to each other. Thus, the antenna elements 2 are located along straight lines in rows 8 and columns.

[0051] Similar to the embodiment that is illustrated in FIG. 5, the direction of the antenna element transmission line segments 10 that originate at a first side of the feeding transmission line segment 7 is opposite to the direction of the antenna element transmission line segments 10 that originate at a second side of the feeding transmission line segment 7 that is opposite to the first side. Different to the embodiment of FIG. 5, all antenna element transmission line segments 10 have equal length. Such a topology is considered very advantageous, as this topology allows for operating the antenna elements 2 with sequential rotation, i.e. with opposite polarization of radiation of adjacent antenna elements 2. Furthermore, due to the identical length of the antenna element transmission line segments 10 the design and control of the phase shifting devices 11 along the antenna element transmission line segments 10 can be identical as well.

[0052] In FIG. 7 another embodiment with a matrix shaped arrangement of antenna elements 2 is shown. Adjacent rows for antenna elements 2 and corresponding unit cells 3 have an offset with respect to each other. The arrangement of antenna element transmission line segments 10 on opposite sides of the feeding transmission line segments 7 and the opposite directions of consecutive antenna element transmission line segments 10 are similar to the embodiment shown in FIG. 6. In addition, FIG. 7 shows bias voltage lines 19 that run towards each of the antenna element transmission line segments 10. Each bias voltage line 19 allows for the application of an individual bias voltage to an electrode of the corresponding antenna element transmission line segment 10, thereby controlling the phase shift that is applied by the corresponding phase shifting device 11 to a radio frequency signal that is transmitted along the antenna element transmission line segment 10.

[0053] FIG. 8 schematically illustrates an exemplary embodiment of a transition structure 9 that can be used to couple a radio frequency signal between two microstrip transmission lines. A line shaped microstrip electrode 12 of the feeding transmission line segment 7 runs along a straight line. An end section 13 of a line shaped microstrip electrode 14 of the antenna element transmission line segment 10 forms a line shaped transition electrode and runs parallel but at a distance to a line shaped microstrip electrode 14 of the feeding transmission line segment 7, whereby the length of the parallel end section 13 of the line shaped microstrip electrode 14 is adapted and preset to provide for a strong signal coupling of a radio frequency signal between the line shaped microstrip electrode 12 of the feeding transmission line segment 7 and the line shaped microstrip electrode 14 of the antenna element transmission line segment 10.

[0054] FIG. 9 schematically illustrates another exemplary embodiment of a transition structure 9 that allows for the coupling of a radio frequency signal between a microstrip transmission line and a differential pair transmission line. An end section 15 of the first line shaped differential pair electrode 16 forms a line shaped transition electrode and runs parallel but at a distance and preferably at another substrate to the line shaped microstrip electrode 12 of the feeding transmission line segment 7. For clarification purposes the first line shaped differential pair electrode 16 is illustrated with dashed lines. After the end section 15, the first line shaped differential pair electrode 16 runs along a U-shaped delay course 17 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 17 can also be regarded as being part of the line shaped transition electrode of the transition structure 9. 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 12 of the feeding transmission line segment 7. FIG. 8 illustrates a galvanic connection designed as a branch of the line shaped microstrip electrode 12 of the feeding transmission line segment 7 into a branching line shaped differential pair electrode 18 of the antenna element transmission line segment 10.

[0055] 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.