Array antenna and wireless communication module

Abstract

This array antenna comprises a dielectric substrate, a plurality of antenna elements positioned on the dielectric substrate, and a peripheral conductor positioned on the dielectric substrate. Each of the plurality of antenna elements includes a first radiation plate to which power is supplied, a second radiation plate positioned on the radiation side of the first radiation plate, and a ground conductor positioned on the non-radiation side of the first radiation plate. The peripheral conductor is positioned in at least a partial section of a circulation region that collectively surrounds a plurality of the second radiation plates included in the plurality of antenna elements in planar perspective.

Description

Array Antenna and Wireless Communication Module

[0001] The present disclosure relates to an array antenna and a wireless communication module.

[0002] WO 2019 / 054094 describes an array antenna having a plurality of antenna elements.

[0003] The array antenna according to the present disclosure includes: a dielectric substrate; a plurality of antenna elements located on the dielectric substrate; and a peripheral conductor located on the dielectric substrate. Each of the plurality of antenna elements includes a first radiation plate to be fed, a second radiation plate located on the radiation side of the first radiation plate, and a ground conductor located on the anti-radiation side of the first radiation plate. The peripheral conductor is located at least in part in a circumferential region that collectively surrounds the plurality of second radiation plates included in each of the plurality of antenna elements in a plan view.

[0004] The wireless communication module according to the present disclosure includes the above-described array antenna and a signal processing circuit electrically connected to the array antenna.

[0005] According to the present disclosure, an array antenna and a wireless communication module with improved characteristics can be provided.

[0006] This is a perspective view showing an array antenna according to Embodiment 1 of the present disclosure. This is a cross-sectional view taken along the line B-B in Figure 1A. This is a characteristic diagram showing the radiation pattern of the array antenna of Embodiment 1. This is a diagram showing the structure of a conventional array antenna. This is a diagram showing the radiation pattern of a conventional array antenna. This is a diagram showing the structure of an array antenna of Comparative Example 1. This is a diagram showing the radiation pattern of an array antenna of Comparative Example 1. This is a diagram showing the structure of an array antenna of Comparative Example 2. This is a diagram showing the radiation pattern of an array antenna of Comparative Example 2. This is a diagram showing the structure of an array antenna of Embodiment 2. This is a diagram showing the radiation pattern of an array antenna of Embodiment 2. This is a diagram showing the structure of an array antenna of Embodiment 3. This is a diagram showing the radiation pattern of an array antenna of Embodiment 3. This is a diagram showing the structure of an array antenna of Embodiment 4. This is a diagram showing the radiation pattern of an array antenna of Embodiment 4. This is a diagram showing the structure of an array antenna of Embodiment 5. This is a diagram showing the radiation pattern of an array antenna of Embodiment 5. This is a diagram showing the structure of an array antenna of Embodiment 6. This is a diagram showing the radiation pattern of an array antenna of Embodiment 6. This is a diagram showing the structure of an array antenna of Embodiment 7. This is a diagram showing the radiation pattern of an array antenna of Embodiment 7. This is a diagram showing the structure of an array antenna of Embodiment 8. This is a diagram showing the radiation pattern of an array antenna of Embodiment 8. This is a diagram showing the structure of an array antenna of Embodiment 9. This figure shows the radiation pattern of the array antenna of Embodiment 9. This figure shows the structure of the array antenna of Embodiment 10. This figure shows the radiation pattern of the array antenna of Embodiment 10. This figure shows the structure of the array antenna of Embodiment 11. This figure shows the radiation pattern of the array antenna of Embodiment 11. This figure shows the structure of the array antenna of Embodiment 12. This figure shows the radiation pattern of the array antenna of Embodiment 12. This is a graph showing the relationship between the distance from the peripheral conductor to the first and second radiating plates and the gain in the zenith direction. This figure shows the structure of the array antenna of Embodiment 13. This figure shows the radiation pattern of the array antenna of Embodiment 13. This figure shows the structure of the array antenna of Embodiment 14. This figure shows the radiation pattern of the array antenna of Embodiment 14. This is a graph showing the relationship between the height of the peripheral conductor and the gain in the zenith direction.This figure shows the structure of the antenna in Comparative Example 3. This graph shows the relationship between the height of the peripheral conductor 4 and the gain in the zenith direction in Comparative Example 3. This figure shows the structure of the array antenna in Embodiment 15. This figure shows the radiation pattern of the array antenna in Embodiment 15. This is a perspective view showing the array antenna in Embodiment 16. This is a perspective view showing the array antenna in Embodiment 17. This is a cross-sectional view showing a wireless communication module of an embodiment of the present disclosure.

[0007] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings.Hereinafter, the Z direction from the ground conductor 34 toward the first radiating plate 31 will be considered upward, and the X-Y direction along the upper surface 21 of the dielectric substrate 2 will be considered horizontal.Hereinafter, "plane view" means viewing from a direction perpendicular to the upper surface 21 of the dielectric substrate 2.Also, "effective wavelength" means the wavelength of the signal at the center frequency of the frequency band of the array antenna 1 within the dielectric substrate 2.The effective wavelength will be represented as "λ".This embodiment will be described with a transmission signal frequency band of 57 GHz to 71 GHz and a center frequency of 64 GHz, but this disclosure is not limited to this frequency band.Also, "resonance direction Y" means the direction of propagation of the electric field wave generated on the surface of the first radiating plate 31 when a wireless signal is transmitted in one antenna element 3.The resonance direction Y corresponds to the direction along the line segment connecting the center of the first radiating plate 31 and the feed point to which the feed conductor 33 is connected. Furthermore, the direction perpendicular to the resonance direction Y in the horizontal direction is denoted as the "non-resonant direction X". "Plate-shaped" means a shape that extends along a plane and has thickness. Plate-shaped can also be described as film-shaped. In the drawings, to reduce the complexity of the lines, the dielectric substrate 2 is depicted as transparent in the perspective view, but the actual dielectric substrate 2 may be opaque. Also, the cross-sectional view is drawn with the size and aspect ratio of each part distorted.

[0008] (Embodiment 1) Figure 1A is a perspective view showing an array antenna 1 according to Embodiment 1 of the present disclosure. Figure 1B is a cross-sectional view taken along the line B-B in Figure 1A. Figure 2 is a diagram showing the radiation pattern of the array antenna 1 of Embodiment 1. Figures 3A and 3B are diagrams showing the structure and radiation pattern of a conventional array antenna 81.

[0009] The array antenna 1 of Embodiment 1 comprises a dielectric substrate 2 and a plurality of antenna elements 3 located on the dielectric substrate 2. Each antenna element 3 has a first radiating plate 31 to which power is supplied, a second radiating plate 32 located on the radiating side of the first radiating plate 31 (i.e., opposite the ground conductor 34, specifically above), and a ground conductor 34 located on the anti-radiating side of the first radiating plate 31 (i.e., opposite the second radiating plate 32, specifically below). Each antenna element 3 may also be called a stacked patch antenna. The first radiating plate 31 and the second radiating plate 32 may be conductors. The first radiating plate 31 and the second radiating plate 32 may be plate-shaped extending horizontally. The first radiating plate 31 may have a rectangular planar shape, and two intersecting sides may be of approximately equal length. The second radiating plate 32 may have a rectangular planar shape, and two intersecting sides may be of approximately equal length. Approximately equal length means that the length of one side is within ±10% of the length of the other side. The length of one of the two sides may be {(1 / 2) × λ} ± 10%. The second radiating plate 32 is located on the upper surface 21 of the dielectric substrate 2 and may be exposed to the outside. The first radiating plate 31 may be called the first radiating conductor or the first radiating patch. The second radiating plate 32 may be called the second radiating conductor or the second radiating patch. By having the first radiating plate 31 and the second radiating plate 32, the transmission frequency can be broadened.

[0010] The grounding conductor 34 may have a common configuration for multiple antenna elements 3. That is, the grounding conductor 34 included in each of the multiple antenna elements 3 may be a continuous, integrated grounding conductor 34. The grounding conductor 34 is a continuous plate-shaped conductor that extends in the planar direction and may be called a solid grounding conductor. "Solid" means extending widely. The grounding conductor 34 may be positioned so as to overlap the entire area where the multiple second radiating plates 32 and the peripheral conductors 4 described below are located in a planar perspective view. However, the grounding conductor 34 may have multiple through-holes 34a through which transmission signals pass to each of the multiple antenna elements 3. Note that the grounding conductor 34 is not limited to the integrated configuration described above, and may be divided into multiple parts corresponding to each of the multiple antenna elements 3.

[0011] Each antenna element 3 may have a feeding conductor 33 that supplies power to the first radiating plate 31. The feeding conductor 33 may be a conductor that connects the first radiating plate 31 to a wiring conductor located below the ground conductor 34 via a through hole 34a. Note that the supply of power to the first radiating plate 31 is not limited to being performed via the feeding conductor 33 connected to the first radiating plate 31; for example, a configuration in which power is supplied non-contact by coupling via a dielectric (i.e., coupling via a predetermined impedance) may be adopted.

[0012] Multiple antenna elements 3 may have a common resonance direction Y and be arranged in multiple rows and multiple columns. Multiple antenna elements 3 may also be arranged in a matrix where each row and each column is orthogonal. Hereinafter, the group of multiple first radiating plates 31 and multiple second radiating plates 32 included in each of the multiple antenna elements 3 will be referred to as "radiating plate group g30".

[0013] The array antenna 1 of Embodiment 1 may further include a peripheral conductor 4 located on the dielectric substrate 2. The peripheral conductor 4 may be located in a circumferential region 5 that surrounds a plurality of antenna elements 3 in a planar perspective view. In Embodiment 1, the peripheral conductor 4 is located throughout the entire circumferential region 5. The peripheral conductor 4 may be electrically floating. The peripheral conductor 4 may be in the shape of a plate extending horizontally.

[0014] The peripheral conductor 4 may be located higher than the ground conductor 34 and at a height less than or equal to the height of the second radiating plate 32. Specifically, in Embodiment 1, the peripheral conductor 4 is located at the same height as the first radiating plate 31.

[0015] <Radiation Pattern> As a wireless transmission technology using an array antenna 1, there is beamforming technology that controls the radiation direction of a wireless signal by shifting the phase of the signal transmitted to multiple antenna elements 3 among the multiple antenna elements 3. In beamforming technology, the radiation direction of a wireless signal can be well controlled if the array antenna 1 has the following radiation pattern. That is, when a signal of the same phase is transmitted to each of the multiple antenna elements 3 of the array antenna 1, the radiation pattern is such that the direction of the wireless signal is pointed towards the zenith Z (i.e., vertically upward) with high directivity. Furthermore, the array antenna 1 can improve energy efficiency by having high gain. Combining these, it can be concluded that for an array antenna 1 applied to beamforming technology, a radiation pattern with high gain in the zenith Z direction and high directivity towards the zenith Z direction is desirable. All radiation patterns shown below represent the characteristics when a signal of the same phase is transmitted to each of the multiple antenna elements 3.

[0016] Figures 2 and 3B show the radiation pattern of the array antenna 1 of Embodiment 1 and the radiation pattern of a conventional array antenna 81. In the characteristic diagram of the radiation pattern, the solid line represents the gain of radiation in the Y-Z direction, and the dashed line represents the gain of radiation in the X-Z direction. The Y-Z direction of the solid line is along the Y-Z plane which includes the resonant direction Y, and the X-Z direction of the dashed line is along the X-Z plane which includes the non-resonant direction X. The above-mentioned Y-Z plane and X-Z plane are planes that pass through the center of the radiating plate group g30. In the characteristic diagram, "0 [deg]" corresponds to the zenith direction Z. The same applies to the characteristic diagrams of the following radiation patterns.

[0017] The conventional array antenna 81 in Figure 3A has the same structure as the array antenna 1 of Embodiment 1, except that it does not have a peripheral conductor 4. Comparing Figure 2 and Figure 3B, it can be seen that the array antenna 1 of Embodiment 1 has a gain of 3 dB or more in the zenith direction Z, and a significant improvement in directivity in the radiation direction including the resonance direction Y.

[0018] The improvement in the above characteristics is due to the following mechanism. In a conventional array antenna 81 (see Figure 3A), the area of ​​the dielectric substrate 82 in the planar direction may include a blank area 86 around the multiple antenna elements 83 where no antenna elements 83 are located. For example, if the size of the dielectric substrate 82 is matched to the size of the signal processing circuit (specifically, an integrated circuit) for the purpose of mounting a signal processing circuit (specifically, an integrated circuit) below the array antenna 81, a blank area 86 may be necessary. Furthermore, in a configuration with a blank area 86, it becomes necessary to position a ground conductor 84 below the blank area 86 to prevent unintended signal leakage from the signal processing circuit to the multiple antenna elements 83. In this configuration, when the multiple antenna elements 83 are driven, an electric field propagates along the ground conductor 84 to the blank area 86 of the dielectric substrate 82. This generates radiation from the blank area 86 to the outside of the substrate, and this radiation reduces the directivity of the wireless signal and the gain in the zenith direction Z.

[0019] On the other hand, according to the array antenna 1 of Embodiment 1, as described above, it has a large grounding conductor 34 that extends beyond the arrangement area of ​​the multiple first radiating plates 31 and the multiple second radiating plates 32 in a planar view. However, even though the grounding conductor 34 extends, the presence of the peripheral conductor 4 reduces the radiation of the electric field propagated horizontally from the periphery of the radiating plate group g30 to the outside from the upper surface 21 of the dielectric substrate 2. Therefore, a high gain in the zenith direction Z and high directivity are achieved.

[0020] <Conductor arrangement around the antenna element> Figures 4A and 4B show the structure and radiation pattern of the array antenna 81A of Comparative Example 1. Figures 5A and 5B show the structure and radiation pattern of the array antenna 81B of Comparative Example 2.

[0021] The array antenna 1 of Embodiment 1 may have a configuration that, in planar perspective, does not have a grid-shaped conductor 94 (see Figure 4A) that separates adjacent antenna elements 3 in the vertical, horizontal, and diagonal directions, nor a frame-shaped conductor 95 (see Figure 5A) that separates the periphery of individual antenna elements 3. In other words, the array antenna 1 of Embodiment 1 may have a configuration that, in planar perspective, does not have conductors in the area inside the circumferential region 5 and that does not overlap with the first radiating plate 31 and the second radiating plate 32. More specifically, the array antenna 1 of Embodiment 1 may have a configuration that, in planar perspective, has conductors (specifically peripheral conductors 4) only in the circumferential region 5, excluding the second radiating plate 32, the first radiating plate 31, and the conductor connected to the first radiating plate 31. However, "in planar perspective" in this paragraph means the case where only the height above the grounding conductor 34 and up to the second radiating plate 32 is viewed, and conductors located below the grounding conductor 34 are not relevant.

[0022] As shown in Figures 4B and 5B, the array antenna 81A having a grid-shaped conductor 94 and the array antenna 81B having a frame-shaped conductor 95 do not provide a significant improvement over conventional designs in terms of gain in the zenith direction Z and directivity in the zenith direction Z. In Comparative Examples 1 and 2, the conductors 94 and 95 are located at the same height as the powered radiating plate (i.e., the radiating plate corresponding to the first radiating plate 31 in this embodiment).

[0023] The grid-like conductor 94 and frame-like conductor 95 described above enhance the isolation characteristics of individual antenna elements 3. However, the array antenna 1 of this embodiment does not have such a configuration to enhance isolation characteristics. Therefore, in the array antenna 1 of this embodiment, the electric field waves from the multiple antenna elements 3 mutually influence each other within the dielectric substrate 2. These electric field waves are then combined and radiated as radio waves. On the other hand, the presence of the peripheral conductor 4 reduces the radiation of electric field waves that tend to spread around the radiating plate group g30 to the outside as radio waves. In other words, the characteristics of the array antenna 1 of Embodiment 1 (see Figure 2) are significantly better than those of the comparative example (see Figures 4B and 5B) which has grid-like conductors 94 and frame-like conductors 95 separating individual antenna elements 3. The improved characteristics are due to the elimination of conductors separating individual antenna elements 3 and the presence of the peripheral conductor 4. Therefore, the array antenna 1 of this embodiment enables the radiation of radio waves with high directivity and high gain, allowing for the effective application of beamforming technology.

[0024] <Regarding the horizontal position of the peripheral conductor 4> Next, embodiments 2 to 12 in which the horizontal position of the peripheral conductor 4 is different will be described. Figures 6A to 16A show the array antennas 1A to 1K of embodiments 2 to 12 according to this disclosure, respectively. Figures 6B to 16B show the radiation patterns of embodiments 2 to 12, respectively. The radiation patterns in Figures 6B to 16B were obtained from simulations performed in a configuration in which the peripheral conductor 4 is located at the same height as the first radiating plate 31.

[0025] As shown in the array antenna 1A of Figure 6A, the peripheral conductor 4 may be located in at least the region 51 adjacent to the first gap 61 within the circumferential region 5. The first gap 61 refers to the gap (i.e., space) between the second radiator 32A and the second radiator 32B, when two second radiators 32 adjacent in the non-resonant direction X among the multiple second radiators 32 on the outermost periphery of the radiator group g30 are referred to as the first pair of second radiators 32A and the second pair of second radiators 32B. In the case of the multiple antenna elements 3 of Embodiment 2, since the configuration is 2 rows and 2 columns, all second radiators 32 correspond to the outermost second radiators 32. However, when there are 3 rows and 3 columns or more, the outermost second radiators 32 and the second radiators 32 located inward are included.

[0026] Furthermore, the peripheral conductors 4 may be positioned on one side and the other side of the resonance direction Y relative to the radiating plate group g30. The peripheral conductors 4 may be positioned symmetrically with respect to the resonance direction Y, or they may be positioned asymmetrically on one side and the other side, for example, with slightly different distances to the radiating plate group g30. Symmetrical with respect to the resonance direction Y means that they are mirror-image symmetric with respect to a plane that passes through the center of the radiating plate group g30 and is perpendicular to the resonance direction Y.

[0027] As shown in the array antenna 1B of Figure 7A, the peripheral conductor 4 may be located at at least one corner 54 of the circumferential region 5. The circumferential region 5 is the region along the outer edge g30a of the radiating plate group g30 in a planar perspective view, and has corners 54 similar to the outer edge g30a. The outer edge g30a corresponds to the shortest circumferential circuit surrounding the radiating plate group g30 in a planar perspective view.

[0028] Furthermore, the peripheral conductors 4 are located at each of the four corners 54 of the circumferential region 5, and may be located on one side and the other side in the resonance direction Y relative to the radiating plate group g30. The multiple peripheral conductors 4 may be located symmetrically or asymmetrically in the resonance direction Y. The peripheral conductors 4 located at the four corners 54 may be located symmetrically or asymmetrically in the non-resonant direction X. Symmetrical with respect to the non-resonant direction X means that they are mirror-symmetric with respect to a plane that passes through the center of the radiating plate group g30 and is perpendicular to the non-resonant direction X.

[0029] As shown in the array antenna 1C of Figure 8A, the peripheral conductor 4 may be located in at least the region 52 adjacent to the second gap 62 within the circumferential region 5. The second gap 62 refers to the gap (i.e., space) between the second radiator 32C and the second radiator 32D when two second radiators 32 adjacent in the resonance direction Y among the multiple second radiators 32 on the outermost periphery of the radiator group g30 are referred to as the third set of second radiators 32C and the fourth set of second radiators 32D. In Embodiment 4, since the multiple antenna elements 3 have a 2x2 configuration, all second radiators 32 correspond to the outermost second radiators 32. However, when there are 3x3 or more rows, the outermost second radiators 32 and the second radiators 32 located inward are included.

[0030] Furthermore, the peripheral conductors 4 may be positioned on one side and the other side of the non-resonant direction X relative to the radiating plate group g30. The peripheral conductors 4 may be positioned symmetrically or asymmetrically in the non-resonant direction X.

[0031] As shown in the array antenna 1D of Figure 9A, the peripheral conductor 4 may be located at least in the four corners 54 of the circumferential region 5 and in all (two in this embodiment) regions 51 adjacent to all first gaps 61. Furthermore, the peripheral conductor 4 may be located symmetrically or asymmetrically with respect to the resonance direction Y.

[0032] As shown in the array antenna 1E of Figure 10A, the peripheral conductor 4 may be located over the entire length of one side 55 of the circumferential region 5 in at least one direction in the resonant direction Y. One side 55 refers to the region from one corner 54 (see Figure 7A) to another adjacent corner 54 in the non-resonant direction X. Furthermore, the peripheral conductor 4 may be located similarly to the radiating plate group g30 on both sides in the resonant direction Y. The peripheral conductor 4 may be located symmetrically or asymmetrically in the resonant direction Y.

[0033] As shown in the array antenna 1F of Figure 11A, the peripheral conductor 4 may be located in a region 51a adjacent to the first gap 61, where the length L51a is smaller than the length L61 of the first gap 61. In other words, the non-resonant length L51a of the peripheral conductor 4 located in the region 51a adjacent to the first gap 61 may be smaller than the length L61 of the first gap 61. Furthermore, the peripheral conductor 4 may be located on both sides of the resonance direction Y relative to the radiating plate group g30. The peripheral conductor 4 may be located symmetrically or asymmetrically in the resonance direction Y.

[0034] As shown in the array antennas 1G and 1H in Figures 12A and 13A, the peripheral conductor 4 may be located in only one of the two regions 51 adjacent to the first gap 61.

[0035] As shown in the array antennas 1I and 1J of Figures 14A and 15A, the peripheral conductors 4 may be located at two corners 54, one on one side and the other on the other side of the four corners 54 in the resonance direction Y.

[0036] As shown in the array antenna 1K of Figure 16A, the peripheral conductor 4 may be located at one of the four corners 54.

[0037] As the peripheral conductors 4 are positioned as described above, the directivity and gain in the zenith direction Z of the array antennas 1A to 1J are improved compared to when they are not positioned, as shown in Figures 6B to 16B. In particular, the positioning of the peripheral conductors 4 in the regions 51 and 51a adjacent to the first gap 61 significantly improves the directivity and gain in the zenith direction Z, as shown in Figures 6B, 9B to 13B. Furthermore, the positioning of the peripheral conductors 4 at the corners 54 significantly improves the directivity and gain in the zenith direction Z, as shown in Figures 7B, 9B, 10B, 14B to 16B. Moreover, by positioning the peripheral conductors 4 on one side of the resonance direction Y relative to the radiating plate group g30, the inclusion of radiation to one side in the horizontal direction in the radiation pattern can be reduced, as shown in Figures 6B, 7B, 9B to 11B.

[0038] <Regarding the width and distance of the peripheral conductors> Figures 1A and 1B show the width w of the peripheral conductor 4 and the distances D1 and D0 between the peripheral conductor 4 and the first radiating plate 31 and the second radiating plate 32 in the resonance direction Y. The width w means the length along the plane direction perpendicular to the circumferential direction in the circumferential region 5. Distance D1 means the shortest distance between the outer edge g30a of the radiating plate group g30 in a planar perspective and the inner edge of the peripheral conductor 4 extending in the non-resonant direction X. Distance D0 means the shortest distance between the center line in the width direction of the peripheral conductor 4 (i.e., the center line extending in the non-resonant direction X) and the outer edge g30a of the radiating plate group g30 in a planar perspective. As mentioned above, the outer edge g30a means the shortest circumferential line surrounding the radiating plate group g30 in a planar perspective.

[0039] The width w of the peripheral conductor 4 may be N × λ (where N is an integer) ± 10%. As shown in the characteristics table 1 below, by adopting the above width w, the gain of the array antenna 1 in the zenith direction Z can be further improved. Characteristics table 1 shows the results of simulations performed on the array antenna 1 of Embodiment 1 for multiple dimensions in which the width w of the peripheral conductor 4 and the distance D1 are different. Characteristics table 1 shows that the gain in the zenith direction Z is maximized at a width w of N × λ or in its vicinity.

[0040]

[0041] Figure 17 is a graph showing the relationship between distance D0 and gain in the zenith direction Z. This graph shows the results of simulations performed on the array antenna 1 of Embodiment 1 with multiple dimensions in which the width of the peripheral conductor 4 and the distance D0 are different.

[0042] The distance D0 of the surrounding conductor 4 may be λ ± 10%. As shown in the graph in Figure 17, by adopting the above distance D0, the gain of the array antenna 1 in the zenith direction Z can be further improved. From this graph, it can be seen that in all cases where the width w is changed to (1 / 4) × λ, (2 / 4) × λ, and (3 / 4) × λ, the gain in the zenith direction Z is maximized in the vicinity where the distance D0 is 1 × λ. In the graph in Figure 17, the distance D0 of 1 × λ is shown as a thick dashed line.

[0043] Incidentally, the definitions of the distances D0 and D1 can be generalized and applied as follows for a configuration in which the peripheral conductor 4 is located in a part of the circumferential region 5, such as in FIG. 6A or FIG. 7A. That is, the distance D0 corresponds to the shortest distance in the non-resonant direction X between the center P0 (see FIG. 1B) in the width direction of the peripheral conductor 4 and the second radiation plate 32 when the remaining peripheral conductors 4 and the plurality of second radiation plates 32 are viewed through in the non-resonant direction X, excluding the peripheral conductors located in the region extending along the resonant direction Y in the circumferential region 5. The distance D1 corresponds to the shortest distance in the non-resonant direction X between the peripheral conductor 4 and the second radiation plate 32 when the remaining peripheral conductors 4 and the plurality of second radiation plates 32 are viewed through in the non-resonant direction X, excluding the peripheral conductors located in the region extending along the resonant direction Y in the circumferential region 5.

[0044] <Regarding the height of the peripheral conductor>Next, embodiments 13 and 14 in which the position of the peripheral conductor 4 in the height direction is different will be described. FIGS. 18A and 19A show the array antennas 1L and 1M of embodiments 13 and 14 according to the present disclosure. FIGS. 18B and 19B show the radiation patterns of embodiments 13 and 14, respectively. FIG. 20 is a graph showing the relationship between the height of the peripheral conductor 4 and the gain in the zenith direction Z. The graph of FIG. 20 shows the results of simulations for a plurality of configurations with different heights of the peripheral conductor 4.

[0045] As shown in the array antennas 1L and 1M of FIGS. 18A and 19A, the peripheral conductor 4 may be located above the ground conductor 34 and at a height not exceeding the height of the second radiation plate 32.

[0046] Furthermore, the peripheral conductor 4 may be located at the same height as the first radiation plate 31. By adopting this height, the gain in the zenith direction Z of the array antenna 1 can be further improved. The graph of FIG. 20 shows that the gain in the zenith direction Z is maximized in the vicinity where the height of the peripheral conductor 4 is the same as the height h1 of the first radiation plate 31. Also, the graph shows that even when the height of the peripheral conductor 4 is increased to the height h2 of the upper surface 21 of the dielectric substrate 2, the gain in the zenith direction Z exceeds that of the array antenna 81 without the peripheral conductor 4.

[0047] <Differences in operation from the configuration of adding a peripheral conductor around one antenna element>FIG. 21A is a diagram showing the structure of the antenna 81C of Comparative Example 3. FIG. 21B is a graph showing the relationship between the height of the peripheral conductor 4 and the gain in the zenith direction Z in Comparative Example 3. Comparative Example 3 in FIG. 21A is a configuration in which a peripheral conductor 4 is added to a single antenna element 3, and is the same as the configuration of Embodiment 1 in FIGS. 1A and 1B except that the antenna element 3 is alone. Specifically speaking, the width w and the distance D1 of the peripheral conductor 4 are the same in Embodiment 1 and Comparative Example

[0048] The graph in FIG. 21B shows the characteristics of the antenna 81C having a single antenna element 3. As shown in the graph, the height of the peripheral conductor 4 is changed from the height at which it contacts the ground conductor 34 (that is, slightly above the height h0 of the ground conductor 34) through the height h1 of the first radiation plate 31 to the height h2 of the second radiation plate 32. Then, at the height h2, the gain of the radio signal in the zenith direction Z becomes lower than that of the configuration without the peripheral conductor 4. On the other hand, as shown in the graph of FIG. 20, in the configuration where the peripheral conductor 4 is added around the entire plurality of antenna elements 3, even when the peripheral conductor 4 is positioned at the same height as the height h2 of the second radiation plate 32, the gain of the radio signal in the zenith direction Z is improved compared to the configuration without the peripheral conductor 4 This indicates that different actions are exerted by the peripheral conductor 4 when the peripheral conductor 4 is added around a single antenna element

[0049] <Regarding other arrangements of the peripheral conductor>FIG. 22A shows the array antenna 1N of Embodiment 15 according to the present disclosure. FIG. 22B shows the radiation pattern of Embodiment 15. Like the array antenna 1N, the plurality of peripheral conductors 4 may include a peripheral conductor 4A having a first height and a peripheral conductor 4B having a second height different from the first height. In a plan view, the peripheral conductor

[0050] <Array Antennas with Many Antenna Elements> Figures 23 and 24 show array antennas 1O and 1P of embodiments 16 and 17, respectively, which include more antenna elements 3. Array antennas 1O and 1P have 8 rows and 8 columns of antenna elements 3. Even with many antenna elements 3, the peripheral conductors 4 are preferably located in at least a part of the circumferential region 5 that collectively surrounds the multiple second radiating plates 32 included in each of the multiple antenna elements 3. Furthermore, the peripheral conductors 4 may be located in multiple regions 51 adjacent to all first gaps 61, as in the array antenna 1O of Figure 23. In addition, the peripheral conductors 4 may be located in the four corners 54. Also, the peripheral conductors 4 may be located throughout the entire circumferential region 5, as in the array antenna 1P of Figure 24. Increasing the area in which the peripheral conductors 4 are located enhances the effect of the peripheral conductors 4.

[0051] <Wireless Communication Module> Figure 25 shows a wireless communication module 100 according to an embodiment of the present disclosure. The wireless communication module 100 of this embodiment comprises an array antenna 1 and a signal processing circuit 110 electrically connected to the array antenna 1. The array antenna 1 may be replaced with array antennas 1A to 1P of other embodiments. The signal processing circuit 110 is connected to each of the plurality of antenna elements 3 so as to be able to output a transmission signal to each feed conductor 33, or so as to be able to input a transmission signal from each feed conductor 33. The array antenna 1 has a second layer 22 of the dielectric substrate 2 located on the opposite side of the first radiating plate 31 with a ground conductor 34 in between, and wiring conductors 71 connecting the plurality of feed conductors 33 and the terminals 111 of the signal processing circuit 110 may be located on the second layer 22. The transmission path that transmits signals by the wiring conductors 71 may have a stripline structure in which a ground conductor 72 is located at least in one of the vertical directions. The signal processing circuit 110 is an integrated circuit and may be bonded to the dielectric substrate 2 via a conductive bonding material 73 such as solder.

[0052] According to the wireless communication module 100 of this embodiment, wireless transmission with better characteristics becomes possible. Furthermore, by applying beamforming technology to signal processing, the controllability of the radiation direction of the wireless signal can be further improved.

[0053] Embodiments of the present disclosure have been described above. However, the array antenna and wireless communication module of the present disclosure are not limited to the embodiments described above, and the details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention.

[0054] An embodiment of the present disclosure is described below. In one embodiment, (1) an array antenna comprises a dielectric substrate, a plurality of antenna elements located on the dielectric substrate, and a peripheral conductor located on the dielectric substrate, wherein each of the plurality of antenna elements includes a first radiating plate that is fed, a second radiating plate located on the radiating side of the first radiating plate, and a ground conductor located on the anti-radiating side of the first radiating plate, wherein the peripheral conductor is located in at least a part of a circumferential region that collectively surrounds a plurality of second radiating plates included in each of the plurality of antenna elements in a planar perspective view.

[0055] (2) In the array antenna described in (1) above, the grounding conductors included in each of the plurality of antenna elements are a continuous, integrated grounding conductor, and in planar perspective, the integrated grounding conductor overlaps the plurality of second radiating plates and the peripheral conductor.

[0056] (3) In the array antenna described in (1) or (2) above, when the second radiating plate is considered to be above the ground conductor included in one of the antenna elements, the peripheral conductor is located above the ground conductor and at a height below the second radiating plate.

[0057] (4) The array antenna described in (3) above has a peripheral conductor that is plate-shaped and extends in the same direction as the first radiating plate, and the peripheral conductor is located at the same height as the first radiating plate.

[0058] (5) Any one of the array antennas described in (1) to (4) above, wherein the circumferential region is a region along the shortest outer circumference that collectively surrounds the plurality of second radiating plates and has a plurality of corners, and the peripheral conductor is located at at least one corner of the circumferential region.

[0059] (6) Any one of the array antennas described in (1) to (5) above, wherein the plurality of second radiating plates include two second radiating plates located on the outermost periphery of the plurality of second radiating plates and adjacent to each other in the non-resonant direction with a first gap in between, and the peripheral conductor is located in at least an intermediate region of the circumferential region adjacent to the first gap in the resonant direction.

[0060] (7) In any one of the array antennas described in (1) to (6) above, when the plurality of first radiating plates and the plurality of second radiating plates included in each of the plurality of antenna elements are referred to as a group of radiating plates, the peripheral conductor is located on one side and the other side in the resonance direction relative to the group of radiating plates.

[0061] (8) In any one of the array antennas described in (1) to (7) above, the peripheral conductor is located throughout the entire circumference region.

[0062] (9) Any one of the array antennas described in (1) to (8) above has a planar width of the peripheral conductor that is an integer multiple of ±10% of the effective wavelength of the transmitted or received signal.

[0063] (10) Any one of the array antennas described in (1) to (9) above, when viewing the remaining peripheral conductor and the plurality of second radiating plates in the non-resonant direction, excluding the peripheral conductor located in the region of the circumferential region that extends in the resonant direction, the shortest distance in the non-resonant direction between the center of the peripheral conductor in the width direction and the plurality of second radiating plates is ±10% of the effective wavelength of the transmitted signal or received signal.

[0064] In one embodiment, (11) the wireless communication module comprises one of the array antennas described in (1) to (10) above, and a signal processing circuit electrically connected to the array antenna.

[0065] This disclosure can be used in array antennas and wireless communication modules.

[0066] 1, 1A-1P Array antenna 2 Dielectric substrate 21 Top surface 3 Antenna element 31 First radiating plate 32 Second radiating plate 33 Feed conductor 34 Ground conductor 34a Through hole g30 Radiating plate group g30a Outer edge 4, 4A, 4B Peripheral conductors 5 Circular region 51, 51a, 52 Region 54 Corner 55 Side 61 First gap 62 Second gap 100 Wireless communication module 110 Signal processing circuit w Width D0, D1 Distance

Claims

1. An array antenna comprising: a dielectric substrate; a plurality of antenna elements located on the dielectric substrate; and a peripheral conductor located on the dielectric substrate, wherein each of the plurality of antenna elements includes: a first radiating plate that is fed with power; a second radiating plate located on the radiating side of the first radiating plate; and a ground conductor located on the anti-radiating side of the first radiating plate, wherein the peripheral conductor is located in at least a part of a circumferential region that collectively surrounds the plurality of second radiating plates included in each of the plurality of antenna elements in a planar perspective view.

2. The array antenna according to claim 1, wherein the grounding conductors included in each of the plurality of antenna elements are a continuous, integrated grounding conductor, and in a planar perspective view, the integrated grounding conductor overlaps the plurality of second radiating plates and the peripheral conductor.

3. When the second radiating plate is considered to be above the ground conductor included in one of the antenna elements, the peripheral conductor is located above the ground conductor and at a height below the second radiating plate, the array antenna according to claim 1 or 2.

4. The array antenna according to claim 3, wherein the peripheral conductor is plate-shaped and extends in the same direction as the first radiating plate, and the peripheral conductor is located at the same height as the first radiating plate.

5. The array antenna according to any one of claims 1 to 4, wherein the circumferential region is a region along the shortest outer circumference that collectively surrounds the plurality of second radiating plates and has a plurality of corners, and the peripheral conductor is located at at least one corner of the circumferential region.

6. The array antenna according to any one of claims 1 to 5, wherein the plurality of second radiating plates include two second radiating plates located on the outermost periphery of the plurality of second radiating plates and adjacent to each other in the non-resonant direction with a first gap in between, and the peripheral conductor is located in at least an intermediate region of the circumferential region adjacent to the first gap in the resonant direction.

7. When the plurality of first radiating plates and the plurality of second radiating plates included in each of the plurality of antenna elements are referred to as a group of radiating plates, the peripheral conductor is located on one side and the other side in the resonant direction relative to the group of radiating plates, as described in any one of claims 1 to 6.

8. The array antenna according to any one of claims 1 to 7, wherein the peripheral conductor is located throughout the entire circumference region.

9. The array antenna according to any one of claims 1 to 8, wherein the width of the peripheral conductor in the planar direction is an integer multiple of ±10% of the effective wavelength of the transmitted signal or the received signal.

10. An array antenna according to any one of claims 1 to 9, wherein, excluding the peripheral conductor located in the region of the circumferential region that extends in the resonant direction, when the remaining peripheral conductor and the plurality of second radiating plates are viewed through in the non-resonant direction, the shortest distance in the non-resonant direction between the center of the peripheral conductor in the width direction and the plurality of second radiating plates is ±10% of the effective wavelength of the transmitted signal or received signal.

11. A wireless communication module comprising an array antenna according to any one of claims 1 to 10, and a signal processing circuit electrically connected to the array antenna.

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