Array antenna

Abstract

The present invention provides an array antenna capable of increasing the beam deflection angle in a direction perpendicular to the direction in which multiple sub-arrays are arranged along a straight line. [Solution] Multiple subarrays are arranged on a substrate. Each of the multiple subarrays includes two radiating elements, which are arranged two-dimensionally in a first direction and a second direction that are parallel to and mutually orthogonal to the in-plane direction of the substrate, and are arranged along a straight line with respect to the first direction to form multiple subarray rows. Each of the multiple subarrays includes a radiating element that includes a conductor pattern including a pair of first edges parallel to a third direction that is inclined with respect to the first and second directions, and a pair of second edges that are orthogonal to the third direction. The spacing in the second direction of the straight line parallel to the first direction that connects the geometric centers of the multiple subarrays included in each of the multiple subarray rows is narrower than the dimension in the second direction of each of the multiple subarrays.

Description

Technical Field

[0005] , ,

[0001] The present invention relates to an array antenna.

Background Art

[0002] Patent Document 1 discloses an array antenna capable of performing beam steering in both the azimuth direction and the elevation direction and suppressing an increase in the number of phase shift control targets. This conventional array antenna is composed of one sub-array formed by four radiating elements arranged in two rows and two columns, and a plurality of sub-arrays are two-dimensionally arranged in the first direction and the second direction perpendicular to each other.

[0003] The plurality of sub-arrays are arranged along a straight line in the first direction. In the second direction, one of the two adjacent sub-arrays in the second direction is arranged shifted in the first direction with respect to the other. Therefore, the array pitch of the sub-arrays in the first direction as a whole becomes small. As a result, the deflection angle of the beam in the first direction becomes large.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional array antenna, the deflection angle of the beam becomes large in the first direction in which a plurality of sub-arrays are arranged along a straight line, but the deflection angle of the beam does not become large in the second direction orthogonal thereto. An object of the present invention is to provide an array antenna capable of increasing the deflection angle of the beam in a direction orthogonal to the direction in which a plurality of sub-arrays are arranged along a straight line.

Means for Solving the Problems

[0006] According to one aspect of the present invention, circuit board and Each of the subarrays includes two radiating elements and is arranged two-dimensionally in a first and second direction that is parallel to and mutually orthogonal to the in-plane direction of the substrate, and is arranged along a straight line in the first direction to form a plurality of subarray rows. Equipped with, Each of the plurality of subarrays includes a radiating element that comprises a conductor pattern including a pair of first edges parallel to a third direction inclined with respect to the first and second directions, and a pair of second edges perpendicular to the third direction. An array antenna is provided in which the spacing in the second direction of the straight lines parallel to the first direction that connect the geometric centers of the plurality of subarrays included in each of the plurality of subarray rows is narrower than the dimension in the second direction of each of the plurality of subarrays. [Effects of the Invention]

[0007] The second-direction beam deflection angle can be increased by making the second-direction beam deflection angle narrower than the second-direction spacing of the straight lines parallel to the first direction that connect the geometric centers of the multiple subarrays contained in each of the multiple subarray rows. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1A is a plan view of one sub-array 10 constituting the array antenna according to the first embodiment, and Figure 1B is a plan view of the array antenna according to the first embodiment. [Figure 2] Figure 2 is a block diagram of an antenna module equipped with an array antenna according to the first embodiment. [Figure 3] Figure 3 is a cross-sectional view of a portion of the antenna module shown in Figure 2. [Figure 4] Figures 4A and 4B are plan views of one subarray 10 of an array antenna according to a modification of the first embodiment. [Figure 5]Figure 5A is a plan view of one sub-array 10 of the array antenna according to the second embodiment, and Figure 5B is a plan view of the array antenna according to the second embodiment. [Figure 6] Figure 6A is a plan view of one sub-array 10 of the array antenna according to the third embodiment, and Figure 6B is a plan view of the array antenna according to the third embodiment. [Figure 7] Figure 7 is a plan view of the array antenna according to the fourth embodiment. [Modes for carrying out the invention]

[0009] [First Embodiment] The array antenna according to the first embodiment will be described with reference to the drawings from Figure 1A to Figure 3.

[0010] Figure 1A is a plan view of one subarray 10 constituting an array antenna according to the first embodiment. The subarray 10 includes two radiating elements 11. As will be explained later with reference to Figure 1B, multiple subarrays 10 are arranged two-dimensionally in a mutually orthogonal first direction (hereinafter referred to as the x-direction) and a second direction (hereinafter referred to as the y-direction). The two radiating elements 11 are arranged side by side in the y-direction. That is, the line connecting the geometric centers of the two radiating elements 11 is parallel to the y-direction.

[0011] The radiating element 11 is composed of a conductive pattern including a pair of first edges 11A parallel to a third direction (hereinafter referred to as the u-direction) that is inclined with respect to the x-direction and y-direction, and a pair of second edges 11B parallel to a direction perpendicular to the u-direction (hereinafter referred to as the v-direction). In the first embodiment, the u-direction is inclined at 45° with respect to the x-direction. The shape of the radiating element 11 in plan view is a square or a rectangle. The shape of the radiating element 11 may be a rounded square, a rounded rectangle, a square or rectangle with triangular cut-off vertices, etc.

[0012] Each radiating element 11 is provided with a first feed point 12A and a second feed point 12B. For example, the first feed point 12A is positioned slightly inward from the midpoint of one of the first edges 11A, and the second feed point 12B is positioned slightly inward from the midpoint of one of the second edges 11B. The radio waves radiated when power is supplied to the first feed point 12A and the radio waves radiated when power is supplied to the second feed point 12B are mutually orthogonal linearly polarized waves. When one radiating element 11 is translated in the y direction, it overlaps with the other radiating element 11, and the first feed point 12A and second feed point 12B of one radiating element 11 also overlap with the first feed point 12A and second feed point 12B of the other radiating element 11, respectively.

[0013] Figure 1B is a plan view of an array antenna according to the first embodiment. Multiple sub-arrays 10 are arranged two-dimensionally in the x and y directions parallel to the in-plane direction of the multilayer substrate 50. In the x direction, multiple sub-arrays 10 are arranged along a straight line to form multiple sub-array rows 20. In Figure 1B, two radiating elements 11 constituting one sub-array 10 are hatched with the same density.

[0014] Let Px be the x-axis pitch of the multiple subarrays 10 that make up each of the multiple subarray rows 20. Focusing on two subarray rows 20 that are adjacent in the y-axis direction, the multiple subarrays 10 in one subarray row 20 are shifted in the x-axis direction by half the array pitch Px compared to the multiple subarrays 10 in the other subarray row 20.

[0015] Let Lx be defined as a straight line parallel to the x-direction that connects the geometric centers of the multiple sub-arrays 10 contained in each of the multiple sub-array rows 20. The y-direction spacing Wy of line Lx is narrower than the y-direction dimension Sy of each of the multiple sub-arrays 10. Here, the y-direction dimension Sy of the sub-array 10 is defined as the distance in the y-direction from one end to the other of the region in which the two radiating elements 11 are arranged.

[0016] That is, a part of one sub-array 10 and a part of the sub-array 10 adjacent to it in the y direction are arranged in a common range with respect to the y direction. In other words, two adjacent sub-arrays 10 in the y direction have an overlap with respect to the y direction. Such an arrangement becomes possible because the first edge 11A (u direction) of the radiation element 11 is inclined with respect to the x direction and two adjacent sub-arrays 10 in the y direction are shifted in the x direction.

[0017] FIG. 2 is a block diagram of an antenna module equipped with an array antenna according to the first embodiment. This antenna module includes a first mixer 51A, a second mixer 51B, a first branch transmission line 52A, a second branch transmission line 52B, a plurality of high-frequency circuits 60, and a plurality of sub-arrays 10.

[0018] The first mixer 51A up-converts a baseband signal or an intermediate frequency signal and inputs it to the first branch transmission line 52A. The first branch transmission line 52A equally distributes the high-frequency signal input from the first mixer 51A to the plurality of high-frequency circuits 60. The second mixer 51B up-converts a baseband signal or an intermediate frequency signal and inputs it to the second branch transmission line 52B. The second branch transmission line 52B equally distributes the high-frequency signal input from the second mixer 51B to the plurality of high-frequency circuits 60.

[0019] Each of the high-frequency circuits 60 includes a plurality of antenna terminals, and the first power supply points 12A and the second power supply points 12B of the plurality of radiation elements 11 are connected to the plurality of antenna terminals via power supply lines 57. The first power supply points 12A of the two radiation elements 11 of one sub-array 10 are connected to the same antenna terminal, and the second power supply points 12B of the two radiation elements 11 of one sub-array 10 are connected to another same antenna terminal. That is, a high-frequency signal branched from one power supply line 57 is input to the first power supply points 12A of the two radiation elements 11 in the sub-array 10, and a high-frequency signal branched from another power supply line 57 is input to the second power supply points 12B. Each of the high-frequency circuits 60 amplifies the input high-frequency signal, performs phase adjustment, and outputs it from the plurality of antenna terminals.

[0020] The high-frequency signal output from the antenna terminal of the first branch transmission line 52A is input to the first feed point 12A of the multiple radiating elements 11, and the high-frequency signal output from the antenna terminal of the second branch transmission line 52B is input to the second feed point 12B of the multiple radiating elements 11.

[0021] The high-frequency circuit 60 synthesizes the high-frequency signals received by the radiating elements 11 of the multiple subarrays 10 and inputs them to the first branch transmission line 52A and the second branch transmission line 52B. The first branch transmission line 52A synthesizes the high-frequency signals input from the multiple high-frequency circuits 60 and inputs them to the first mixer 51A. The second branch transmission line 52B synthesizes the high-frequency signals input from the multiple high-frequency circuits 60 and inputs them to the second mixer 51B. The first mixer 51A and the second mixer 51B each have the function of down-converting the high-frequency signals input from the first branch transmission line 52A and the second branch transmission line 52B to baseband signals or intermediate frequency signals, respectively.

[0022] The high-frequency circuit 60 has the function of operating the multiple subarrays 10 as a phased array antenna by adjusting the phase of the high-frequency signals supplied to the multiple subarrays 10. A high-frequency circuit 60 having this function is sometimes called a beamforming IC (BFIC).

[0023] Figure 3 is a cross-sectional view of a portion of the antenna module shown in Figure 2. The first mixer 51A and multiple high-frequency circuits 60 are mounted on one side of the multilayer substrate 50. Multiple radiating elements 11 are formed on the other side of the multilayer substrate 50. Each of the multiple radiating elements 11, together with, for example, a ground conductor plate provided on the multilayer substrate 50, constitutes a patch antenna.

[0024] The first mixer 51A is connected to a plurality of high-frequency circuits 60 via a first branch transmission line 52A consisting of strip lines or microstrip lines arranged within the multilayer substrate 50. Each of the plurality of high-frequency circuits 60 is connected to a radiating element 11 via a power supply line 57 provided on the multilayer substrate 50.

[0025] Next, we will describe the excellent effects of the first embodiment. In the first embodiment, the effective array pitch of the multiple subarrays 10 in the x-direction is half the array pitch Px of the multiple subarrays 10 in one subarray row 20, so the swing angle of the beam in the x-direction can be increased. Furthermore, the effective array pitch of the multiple subarrays 10 in the y-direction is the spacing Wy of the straight line Lx (Figure 1B), which is smaller than the y-direction dimension Sy of the subarrays 10, so the swing angle of the beam in the y-direction can be increased compared to a configuration in which the spacing Wy is wider than the dimension Sy.

[0026] Furthermore, because the overall y-direction dimension of the array antenna is reduced, it is possible to shorten the length of the feed line. This reduces transmission loss.

[0027] Furthermore, in the first embodiment, in each subarray 10, two radiating elements 11 are arranged in the y-direction, and in the x-direction, the dimensions of the subarray 10 are equal to the dimensions of one radiating element 11. Therefore, compared to a configuration in which, for example, four radiating elements 11 are arranged in 2 rows and 2 columns in each subarray 10, the array pitch in the x-direction of the subarray 10 can be made smaller. As a result, the swing angle of the beam in the x-direction can be made larger.

[0028] Furthermore, in the first embodiment, the first edge 11A and the second edge 11B of the radiating element 11 are inclined at 45° with respect to the x and y directions, so that the edges of multiple radiating elements 11 aligned in a straight line in the x direction are not positioned parallel to each other. In addition, the edges of two radiating elements 11 within the subarray 10 are also not positioned parallel to each other. As a result, the isolation between the radiating elements 11 can be improved.

[0029] Next, an array antenna according to a modification of the first embodiment will be described with reference to Figures 4A and 4B. Figures 4A and 4B are plan views of one sub-array 10 of the array antenna according to a modification of the first embodiment. In the first embodiment, when one radiating element 11 in the sub-array 10 (Figure 1A) is translated in the y direction and superimposed on the other radiating element 11, the first feed point 12A and the second feed point 12B of the one radiating element 11 also overlap with the first feed point 12A and the second feed point 12B of the other radiating element 11, respectively.

[0030] In contrast, in the modified example shown in Figure 4A, when one radiating element 11 is translated in the y-direction and superimposed on the other radiating element 11, the first feed point 12A of one radiating element 11 coincides with the first feed point 12A of the other radiating element 11, but the second feed point 12B does not coincide. In this case, a 180° phase difference should be applied to the high-frequency signals supplied to the second feed points 12B of the two radiating elements 11.

[0031] In the modified example shown in Figure 4B, when one radiating element 11 is translated in the y-direction and superimposed on the other radiating element 11, neither the first feed point 12A nor the second feed point 12B of one radiating element 11 overlaps with the first feed point 12A and the second feed point 12B of the other radiating element 11. In this case, a 180° phase difference should be applied to the high-frequency signals supplied to the first feed point 12A of the two radiating elements 11, and a 180° phase difference should also be applied to the high-frequency signals supplied to the second feed point 12B.

[0032] As shown in the modified examples in Figures 4A and 4B, when one of the two radiating elements 11 in the subarray 10 is translated and superimposed on the other, the feed points do not necessarily have to overlap. In such cases, the phase of the high-frequency signal supplied to the feed points can be adjusted.

[0033] [Second Example] Next, the array antenna according to the second embodiment will be described with reference to Figures 5A and 5B. The configuration common to the array antenna of the first embodiment and its modified form, as described with reference to Figures 1A to 4B, will be omitted from this description.

[0034] Figure 5A is a plan view of one sub-array 10 of the array antenna according to the second embodiment, and Figure 5B is a plan view of the array antenna according to the second embodiment. Note that the multilayer substrate 50 (Figure 1B) is omitted in Figure 5B. In the second embodiment as well, multiple sub-arrays 10 are arranged two-dimensionally in the x and y directions, and are arranged along a straight line Lx in the x direction. In Figure 5B as in Figure 1B, two radiating elements 11 constituting one sub-array 10 are hatched with the same density.

[0035] As shown in Figure 5A, in the first embodiment (Figure 1A), the u and v directions along which the first edge 11A and second edge 11B of the radiating element 11 are aligned are inclined at 45° with respect to the x and y directions. In contrast, in the second embodiment, the r-angle of the u and v directions along which the first edge 11A and second edge 11B of the radiating element 11 are aligned, with respect to the x and y directions, is not 45°. The positional relationship between the two radiating elements 11 is the same as in the first embodiment, and when one radiating element 11 is translated in the y direction, it overlaps with the other radiating element 11.

[0036] As shown in Figure 5B, in the second embodiment, as in the first embodiment, if we focus on two adjacent sub-array rows 20 in the y-direction, the sub-arrays 10 included in one sub-array row 20 are shifted in the x-direction by half the array pitch Px relative to the sub-arrays 10 included in the other sub-array row 20. Furthermore, as in the first embodiment, the y-direction spacing Wy of the line Lx parallel to the x-direction that connects the geometric centers of the sub-arrays 10 included in each of the sub-array rows 20 is narrower than the y-direction dimension Sy of each of the sub-arrays 10.

[0037] Next, we will describe the excellent effects of the second embodiment. In the second embodiment, as in the first embodiment, the beam swing angle can be increased in both the x and y directions, and the isolation between the radiating elements 11 can be improved.

[0038] As in the second embodiment, the inclination angles in the u and v directions relative to the x and y directions are not limited to 45°. Note that as the inclination angle approaches 0°, it becomes difficult to make the spacing Wy narrower than the dimension Sy. The inclination angles in the u and v directions relative to the x and y directions must be such that the spacing Wy can be made narrower than the dimension Sy. As an example, it is preferable to set the inclination angle within the range of 45° ± 15°.

[0039] [Third Embodiment] Next, an array antenna according to the third embodiment will be described with reference to Figures 6A and 6B. The configuration common to the array antenna of the first embodiment and its modified form, as described with reference to Figures 1A to 4B, will be omitted from this description.

[0040] Figure 6A is a plan view of one sub-array 10 of the array antenna according to the third embodiment, and Figure 6B is a plan view of the array antenna according to the third embodiment. In the third embodiment as well, multiple sub-arrays 10 are arranged two-dimensionally in the x and y directions, and are arranged along a straight line Lx in the x direction. In Figure 6B as in Figure 1B, two radiating elements 11 constituting one sub-array 10 are hatched with the same density.

[0041] In the first embodiment (Figure 1A), two radiating elements 11 within a single subarray 10 are arranged side-by-side in the y-direction. However, in the third embodiment, the radiating elements 11 contained in each of the multiple subarrays 10 are arranged offset in a direction that is inclined with respect to both the x-direction and the y-direction. For example, as shown in Figure 6A, the u-direction and v-direction are inclined at 45° with respect to the x-direction and the y-direction, and the two radiating elements 11 are arranged side-by-side in the v-direction. Furthermore, the two radiating elements 11 contained in each of the multiple subarrays 10 are arranged so that they overlap with respect to both the x-direction and the y-direction.

[0042] Furthermore, in the first embodiment (Figure 1B), one of two adjacent sub-array rows 20 in the y-direction is shifted in the x-direction by half the array pitch Px relative to the other. In contrast, in the third embodiment, if we focus on two adjacent sub-array rows 20 in the y-direction, translating one sub-array row 20 in the y-direction causes it to overlap with the other sub-array row 20. In other words, the multiple sub-arrays 10 are arranged along a straight line with respect to the y-direction as well.

[0043] In the third embodiment, as in the first embodiment, the y-direction spacing Wy of the line Lx parallel to the x-direction that connects the geometric centers of the multiple subarrays 10 contained in each of the multiple subarray rows 20 is narrower than the y-direction dimension Sy of each of the multiple subarrays 10. Furthermore, in the third embodiment, the spacing Wx of the line Ly parallel to the y-direction that connects the geometric centers of the multiple subarrays 10 aligned in the y-direction is narrower than the x-direction dimension Sx of each of the multiple subarrays 10.

[0044] Next, we will describe the excellent effects of the third embodiment. In the third embodiment, as in the first embodiment, the y-direction spacing Wy of the line Lx parallel to the x-direction that connects the geometric centers of the multiple subarrays 10 contained in each of the multiple subarray rows 20 is narrower than the y-direction dimension Sy of each of the multiple subarrays 10. Therefore, the swing angle of the beam in the y-direction can be increased.

[0045] Furthermore, in the third embodiment, within a single sub-array row 20, portions of two adjacent sub-arrays 10 in the x-direction are arranged in a common range with respect to the x-direction. That is, the two sub-arrays 10 overlap with respect to the x-direction. Therefore, the beam deflection angle in the x-direction can be increased compared to a configuration in which the two sub-arrays 10 are arranged without overlap.

[0046] [Fourth embodiment] Next, the array antenna according to the fourth embodiment will be described with reference to Figure 7. The configuration common to the array antenna of the first embodiment and its modified form, as described with reference to Figures 1A to 4B, will be omitted from this description.

[0047] Figure 7 is a plan view of the array antenna according to the fourth embodiment. In the first embodiment (Figure 1B), if we focus on two adjacent sub-array rows 20 in the y direction, the sub-arrays 10 included in one sub-array row 20 are shifted in the x direction by half the array pitch Px relative to the sub-arrays 10 included in the other sub-array row 20. In contrast, in the fourth embodiment, if we focus on two adjacent sub-array rows 20 in the y direction, the sub-arrays 10 included in one sub-array row 20 are shifted in the x direction by one-third the array pitch Px relative to the sub-arrays 10 included in the other sub-array row 20.

[0048] More specifically, the sub-array 10 in sub-array row 20 on the negative side of the y-axis is shifted by Px / 3 to the positive side of the x-axis. As a result, the entire array antenna has multiple sub-arrays 10 arranged in the x-direction with an array pitch of Px / 3. In the y-direction, as in the first embodiment, two sub-arrays 10 are arranged to overlap.

[0049] Next, we will describe the excellent effects of the fourth embodiment. In the fourth embodiment, as in the first embodiment, the beam deflection angle can be increased in the y-direction. Furthermore, the beam deflection angle can be increased even further in the x-direction. As in the fourth embodiment, the amount of displacement in the x-direction of two adjacent sub-array rows 20 in the y-direction may be Px / 3, or more generally, Px / n (where n is an integer of 2 or more). It is preferable that the overall configuration consists of multiple sub-arrays 10 arranged at equal pitches in the x-direction.

[0050] The embodiments described above are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects and benefits from similar configurations in multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the embodiments described above. For example, it will be obvious to those skilled in the art that various modifications, improvements, and combinations are possible. [Explanation of symbols]

[0051] 10 sub-arrays 11 Radiation element 11A First Edge 11B 2nd Edge 12A First power supply point 12B Second power supply point 20 Sub-alley rows 50 circuit boards 51A No. 1 Mixer 51B No. 2 Mixer 52A First Branch Transmission Line 52B Second Branch Transmission Line 57 Power line 60 High-Frequency Circuits

Claims

1. circuit board and Each of the subarrays includes two radiating elements and is arranged two-dimensionally in a first and second direction that is parallel to and mutually orthogonal to the in-plane direction of the substrate, and is arranged along a straight line in the first direction to form a plurality of subarray rows. Equipped with, Each of the plurality of subarrays includes a radiating element that comprises a conductor pattern including a pair of first edges parallel to a third direction inclined with respect to the first and second directions, and a pair of second edges perpendicular to the third direction. An array antenna in which the spacing in the second direction of the straight lines parallel to the first direction that connect the geometric centers of the plurality of subarrays included in each of the plurality of subarray rows is narrower than the dimension in the second direction of each of the plurality of subarrays.

2. The array antenna according to claim 1, wherein the radiating elements included in each of the plurality of subarrays are arranged in the second direction.

3. Focusing on two adjacent subarray rows in the second direction among the plurality of subarray rows, the array antenna according to claim 2 is arranged such that the plurality of subarrays included in one subarray row are offset in the first direction relative to the plurality of subarrays included in the other subarray row.

4. The array antenna according to claim 2 or 3, wherein the third direction is inclined at 45° with respect to the first direction.

5. The radiating elements included in each of the plurality of subarrays are arranged to be offset in a direction that is inclined with respect to either the first direction or the second direction, and are arranged so that the radiating elements overlap with respect to either the first direction or the second direction. The array antenna according to claim 1, wherein the plurality of sub-arrays are arranged in a straight line with respect to the second direction.

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