Antenna device

Abstract

An antenna device is provided. A first edge of a ground layer extends in a first direction. A radiating element is disposed apart from the ground layer in a thickness direction of the ground layer. A feed line supplies a high-frequency signal to the radiating element. A pair of stubs is disposed at a position sandwiching the radiating element in the first direction. The stubs are connected to the ground layer. A distance from the radiating element to the first edge in a second direction orthogonal to the first direction is 1 / 4 or less of a wavelength corresponding to a resonant frequency of the radiating element when viewed from above. Even if the structure is such that the radiating element is close to the edge of the ground layer, the disorder of the beam pattern can be suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to an antenna device. BACKGROUND

[0002] A patch antenna (in this specification, referred to as a half patch antenna) in which a single side (rear edge) of a radiating element is short-circuited, and the area of the radiating element is miniaturized to about 1 / 2 is disclosed in Patent Literature 1. In the half patch antenna disclosed in Patent Literature 1, by shortening the lateral distance of the front edge of the radiating element, which is on the opposite side to the rear edge, from the corresponding edge of the ground layer, a desired radiation characteristic is obtained.

[0003] Patent Literature 1: U.S. Patent No. 9865926 SUMMARY

[0004] According to the research of the present inventor, it was found that in the case where the radiating element is brought close to the edge of the ground layer, there is a case where the beam pattern is disturbed. An object of the present application is to provide an antenna device which can suppress the disturbance of the beam pattern even for a structure in which the radiating element is brought close to the edge of the ground layer.

[0005] According to one aspect of the present application, there is provided an antenna device including:

[0006] a ground layer having a first edge extending in a first direction;

[0007] a radiating element disposed apart from the ground layer in the thickness direction of the ground layer;

[0008] a supply line supplying a high-frequency signal to the radiating element; and

[0009] a pair of stubs disposed at a position sandwiching the radiating element in the first direction, connected to the ground layer,

[0010] a distance from the radiating element to the first edge in a second direction orthogonal to the first direction is 1 / 4 or less of a wavelength corresponding to the resonant frequency of the radiating element in plan view.

[0011] It was found that if the distance from the radiating element to the first edge is close, a high-frequency current propagating along the first edge is generated in the ground layer, and the beam pattern is disturbed by the high-frequency current. The pair of stubs suppresses the propagation of the high-frequency current. Thus, the disturbance of the beam pattern is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a perspective view of a conductor portion of the antenna device of the first embodiment.

[0013] Figure 2is a plan view of the conductor portion of the antenna device of the first embodiment.

[0014] Figure 3A and Figure 3B are respectively Figure 2 are sectional views on the dotted line 3A-3A and the dotted line 3B-3B of

[0015] Figure 4 is a sectional view on the dotted line 4-4 of Figure 2

[0016] Figure 5A and Figure 5B are respectively a diagram showing the current distribution at a certain time of the high-frequency current flowing in the ground layer of the antenna device of the first embodiment and the comparative example.

[0017] Figure 6A and Figure 6B are respectively a chart showing the angle dependence of the directivity gain of the antenna device of the first embodiment Figure 5A ) and the comparative example Figure 5B ).

[0018] Figure 7 is a chart showing the relationship between the distance Dz and the directivity gain of the antenna device in the direction of θ = 90°, .

[0019] Figure 8 is a chart showing the relationship between the length of the stub and the directivity gain of the antenna device in the direction of θ = 90°, .

[0020] Figure 9 is a perspective view of the conductor portion of the antenna device of the first embodiment.

[0021] Figure 10 is a perspective view of the conductor portion of the antenna device of the first embodiment.

[0022] Figure 11 is a perspective view of the metal portion of the antenna device of the second embodiment.

[0023] Figure 12 is a chart showing the angle dependence of the directivity gain of the antenna device of the second embodiment.

[0024] Figure 13 is a perspective view of the metal portion of the antenna device of the third embodiment.

[0025] Figure 14 is a chart showing the angle dependence of the directivity gain of the antenna device of the third embodiment.

[0026] ​Figure 15 is a plan view of the antenna device of the fourth embodiment.

[0027] Figure 16 is a perspective view of a metal portion of the antenna device of the fifth embodiment.

[0028] Figure 17 is a plan view of a conductor portion of the antenna device of the sixth embodiment.

[0029] Figure 18 is a plan view of the antenna device of the seventh embodiment.

[0030] Figure 19 is a plan view of the antenna device of the modification of the seventh embodiment. DETAILED DESCRIPTION

[0031] [First Embodiment]

[0032] Referring to the drawings, the antenna device of the first embodiment will be described. Figures 1-8

[0033] Figure 1 and Figure 2 are a perspective view and a plan view of a conductor portion of the antenna device of the first embodiment, respectively. The antenna device of the first embodiment includes a first layer ground layer 41, a second layer ground layer 42, a third layer ground layer 43, and a radiating element 20 provided to a dielectric substrate. A direction from the third layer ground layer 43 to the first layer ground layer 41 is defined as upward.

[0034] The radiating element 20 is disposed upward at a distance from the first layer ground layer 41. The radiating element 20 is composed of a metal plate disposed in parallel to the ground layer 41, and has a rectangular shape in plan view. An edge of the radiating element 20 corresponding to one long side of the rectangle is referred to as a front edge 20F. An edge on the opposite side of the front edge 20F is referred to as a rear edge 20R.

[0035] The ground layer 41 has a first edge 41A in a straight line and a second edge 41B on the opposite side of the first edge 41A. Figure 2 The second layer ground layer 42 and the third layer ground layer 43 also have first edges 42A, 43A, respectively, which coincide with the first edge 41A in plan view. In plan view, the radiating element 20 is disposed between the first edge 41A and the second edge 41B of the ground layer 41. In plan view, the front edge 20F of the radiating element 20 overlaps a part of the first edge 41A of the ground layer 41.

[0036] ​An orthogonal coordinate system is defined in which a direction parallel to the first edge 41A is the z direction, a direction orthogonal to the first edge 41A and parallel to the ground layer 41 is the y direction, and a normal direction of the ground layer 41 is the x direction. The direction from the first edge 41A toward the second edge 41B is defined as the positive direction of the y axis. The direction from the ground layer 41 toward the radiating element 20 is defined as the positive direction of the x axis. The polar angle Θ with the positive direction of the z axis as the reference and the azimuth angle Φ with the positive direction of the x axis in the xy plane as the reference represents the direction from the radiating element 20.

[0037] The feeding line 30 is connected to the feeding point 21 of the radiating element 20. The feeding point 21 is disposed between the midpoint of the front edge 20F and the geometric center of the radiating element 20. The high-frequency signal is supplied to the radiating element 20 through the feeding line 30. Details will be described later Figure 3A The structure of the feeding line 30 is described in detail.

[0038] A plurality of short-circuit vias 24 are disposed along the back edge 20R of the radiating element 20. The plurality of short-circuit vias 24 short-circuit the back edge 20R of the radiating element 20 and the ground layer 41. The half-patch antenna is constituted by the radiating element 20 and the ground layer 41.

[0039] Short stubs 50 connected to the ground layer 41 are disposed at positions sandwiching the radiating element 20 in the z direction. The short stub 50 includes a first portion 50A extending upward (in the positive direction of the x axis) from the ground layer 41 and a second portion 50B extending from the front end of the first portion 50A in the positive direction of the y axis. The distance in the z direction from the center of the connection site of the short stub 50 and the ground layer 41 to the radiating element 20 is denoted by Dz. The distance Dz from one short stub 50 to the radiating element 20 is equal to the distance Dz from the other short stub 50 to the radiating element 20.

[0040] The distance from the center of the connection site of the short stub 50 and the ground layer 41 to the first edge 41A of the ground layer 41 is denoted by Dy. The second portion 50B of the short stub 50 includes a circular pad region corresponding to the alignment accuracy in the manufacturing process at the connection site of the first portion 50A and the second portion 50B. The pad region is larger than the first portion 50A in plan view and includes the first portion 50A. The pad region included in the second portion 50B is disposed so as to be in contact with the first edge 41A in plan view. In this case, the sum of the interval between the outer periphery of the pad region of the second portion 50B and the outer periphery of the first portion 50A and the radius of the first portion 50A is equal to the distance Dy.

[0041] Figure 3A and Figure 3B are Figure 2cross-sectional view on the dotted line 3A-3A and the dotted line 3B-3B. The radiating element 20 and the second portion 50B of the stub 50 are arranged on the upper surface of the dielectric substrate 60, and the third layer ground layer 43 is arranged on the lower surface. The first layer ground layer 41 is arranged in the inner layer of the dielectric substrate 60. The second layer ground layer 42 and the power supply line 30 are arranged between the first layer ground layer 41 and the third layer ground layer 43. The power supply line 30 is arranged in the same layer as the second layer ground layer 42. The strip line of the three-plate structure is formed by the power supply line 30 and the ground layers 41, 43 above and below the power supply line 30.

[0042] The power supply line 30 is connected to the power supply point 21 of the radiating element 20 via a conductor member 31 extending in the thickness direction of the dielectric substrate 60. The conductor member 31 is arranged, for example, in the same layer as the ground layer 41, includes an inner layer pad 31B separate from the ground layer 41, a via hole 31A connecting the inner layer pad 31B and the power supply line 30, and a via hole 31C connecting the inner layer pad 31B and the radiating element 20. The inner layer pad 31B is slightly larger than the via holes 31A, 31C when viewed from above. The difference in size is set according to the alignment accuracy in the manufacturing process.

[0043] The back edge 20R of the radiating element 20 is short-circuited to the first layer ground layer 41 by the short-circuit via hole 24. In addition, a margin depending on the alignment accuracy in the manufacturing process is ensured between the connection portion of the short-circuit via hole 24 and the radiating element 20 and the back edge 20R. The front edge 20F of the radiating element 20 and the first edge 41A of the ground layer 41 are arranged at the same position in the y direction. In addition, the first edges 42A, 43A of the second layer ground layer 42 and the third layer ground layer 43 are also arranged at the same position as the front edge 20F in the y direction.

[0044] The second portion 50B of the stub 50 and the ground layer 41 are connected by the first portion 50A. The first portion 50A is arranged slightly inward of the first edge 41A of the ground layer 41.

[0045] Figure 4 is Figure 2 cross-sectional view on the dotted line 4-4. The radiating element 20 is arranged on the upper surface of the dielectric substrate 60, and the ground layer 43 is arranged on the lower surface. The radiating element 20 is short-circuited to the inner layer ground layer 41 by a plurality of short-circuit via holes 24. The ground layer 42 and the power supply line 30 are arranged between the ground layer 41 and the ground layer 43.

[0046] Next, the excellent effects of the first embodiment are described with reference to the drawings. Figures 5A-6B

[0047] ​The distribution of the high-frequency current flowing in the ground layer 41 was simulated when the radiating element 20 was excited at a frequency corresponding to the resonant frequency of the radiating element 20. The resonant frequency of the radiating element 20 was 60 GHz. At this time, the effective wavelength (hereinafter, referred to as the effective wavelength) taking into account the wavelength shortening effect due to the dielectric constant of the dielectric substrate 60 was about 3.40 mm. In addition, unless otherwise specified, the "wavelength corresponding to the resonant frequency" means the "effective wavelength corresponding to the resonant frequency". Furthermore, the resonant frequency of the radiating element 20 was determined by the size of the radiating element 20 in the y direction, the positional relationship of the radiating element 20 to the first edge 41A of the ground layer 41, the positional relationship of the radiating element 20 to the stub 50, and the like.

[0048] Figure 5A and Figure 5B are diagrams of the current distribution of a certain instant of the high-frequency current flowing in the ground layer 41 of the antenna device of the first embodiment and the comparative example, respectively. The antenna device of the comparative example is the same as the structure obtained by removing the stub 50 from the antenna device of the first embodiment. In Figure 5A and Figure 5B , the region where the surface current density is relatively large is indicated by a relatively light color.

[0049] In the antenna device of the comparative example ( Figure 5B ), in the position of the first edge 41A, a region where the surface current density is relatively large periodically appears in the z direction. If time elapses from the time indicated by Figure 5B , the region where the surface current density is relatively large moves in a direction away from the radiating element 20. That is, it is found that the high-frequency current propagating along the first edge 41A is generated.

[0050] On the other hand, in the antenna device of the first embodiment ( Figure 5A ), it is found that the current is concentrated around the mounting position of the stub 50. Since the high-frequency current generated in the ground layer 41 directly below the radiating element 20 and propagating along the first edge 41A is reflected by the stub 50, the propagation of the high-frequency current along the first edge 41A is suppressed.

[0051] Next, the beam patterns of the antenna devices of the first embodiment ( Figure 6A ) and the comparative example ( Figure 6B ) are described with reference to Figure 5A and Figure 5B .

[0052] Figure 6A and Figure 6B are graphs showing the angle dependence of the directivity gain of the antenna devices of the first embodiment ( Figure 5A ) and the comparative example ( Figure 5B ), respectively. The horizontal axis indicates the azimuth angle in units of "°" The vertical axis represents the polar angle θ in degrees. Relatively lighter colors represent areas with relatively higher directivity gain.

[0053] In the antenna device of the first embodiment, as Figure 6A As shown, the directivity gain in azimuth The range of the azimuth angle is about 45°±10° and the polar angle θ is about 90°±10°. The main beam is formed in a direction of approximately 45° and a polar angle θ of approximately 90°.

[0054] In contrast, in the comparative example, Figure 6B As shown in FIG, the range of relatively high directivity gain appears in many scattered places. That is, the beam pattern is disordered. In addition, when the polar angle θ is fixed at 90° (i.e., in the xy plane), the azimuth angle When the φ changes, no obvious beam pattern appears. The disturbance of the beam pattern is caused by the high-frequency current propagating along the first edge 41A of the ground layer 41 becoming a new wave source.

[0055] In the first embodiment, it is possible to suppress secondary radiation originating from the high-frequency current propagating along the first edge 41A of the ground layer 41. As a result, an excellent effect of suppressing disturbance of the beam pattern is achieved.

[0056] Next, refer to Figure 7 , the distance Dz from the stub 50 to the radiation element 20 in the z direction ( Figure 2 ). If the location of stub 50 attached to ground layer 41 is too far from radiating element 20, the distance that high-frequency current can propagate from radiating element 20 to stub 50 increases, thereby reducing the effect of installing stub 50. Furthermore, if stub 50 is too close to radiating element 20, ground layer 41 in an area farther from stub 50 than stub 50, as viewed from radiating element 20, couples with radiating element 20, generating high-frequency current. Since stub 50 is not positioned along the path where this high-frequency current propagates away from radiating element 20, the high-frequency current propagates along first edge 41A. Therefore, it is believed that there is a preferred range for distance Dz.

[0057] Figure 7 Is the distance Dz and θ=90°, The graph shows the relationship between the directivity gain of the antenna device in the direction of the y-axis (i.e., the positive direction of the y-axis). The horizontal axis represents the distance Dz in units of "μm", and the vertical axis represents the directivity gain in units of "dBi". The effective wavelength corresponding to the resonant frequency of the radiating element 20 is approximately 3.40 mm. Figure 7As shown in the graph, by making the distance Dz 1 / 15 or more and 1 / 4 or less of the effective wavelength, a higher directivity gain can be obtained.

[0058] Next, with reference to Figure 8 , a preferred range of the length of the stub 50 will be described. Here, the length of the stub 50 corresponds to the total length of the x-direction dimension of the first portion 50A and the y-direction dimension of the second portion 50B.

[0059] Figure 8 is a graph showing the relationship between the length of the stub 50 and the directivity gain of the antenna device in the direction of θ = 90°, , that is, the positive direction of the y-axis. The horizontal axis shows the length of the stub 50 in units of "μm", and the vertical axis shows the directivity gain in units of "dBi". As shown in the graph, by setting the length of the stub 50 in a range of 21% or more and 25% or less of the effective wavelength, a higher directivity gain can be obtained.

[0060] Next, a preferred range of the distance Dy Figure 2 from the connection site of the stub 50 to the first edge 41A will be described. In order to stop the propagation of the high-frequency current along the first edge 41A, it is preferable to place the connection site of the stub 50 close to the first edge 41A. With reference to Figure 5B , it is known that in the region along the first edge 41A away from the radiating element 20, even if the position from the first edge 41A to the inside of the ground layer 41 is entered to a position corresponding to 1 / 4 of the effective wavelength of the resonant frequency of the radiating element 20, a sufficiently large surface current flows. Therefore, as long as the distance Dy from the connection site of the stub 50 to the first edge 41A is 1 / 4 or less of the effective wavelength corresponding to the resonant frequency of the radiating element 20, it is considered that a sufficient effect of stopping the propagation of the high-frequency current along the first edge 41A can be obtained.

[0061] Next, with reference to Figure 9 , a modification of the first embodiment will be described.

[0062] Figure 9 is a perspective view of the conductor portion of the antenna device of the modification of the first embodiment. In the first embodiment Figure 1 , a plurality of short-circuit vias 24 are arranged along the back edge 20R of the radiating element 20. In contrast, in the present modification, a short-circuit via 24 is arranged at each of both ends of the back edge 20R of the radiating element 20. The short-circuit via 24 is not arranged at a site other than the both ends of the back edge 20R. In the present modification, the radiating element 20 and the ground layer 41 also function as a half-patch antenna. As such, under the condition that the radiating element 20 and the ground layer 41 function as a half-patch antenna, the number and arrangement of the short-circuit vias 24 are determined.

[0063] Next, referring to Figure 10 A further modification of the first embodiment will be described.

[0064] Figure 10 is a perspective view of a conductor portion of an antenna device of a further modification of the first embodiment. In the first embodiment Figure 1 ), the radiating element 20 is included in the first layer ground layer 41 when viewed from above. In contrast, the first layer ground layer 41 of the antenna device of the present modification has a shape in which the portion overlapping the radiating element 20 in the first layer ground layer 41 of the antenna device of the first embodiment Figure 1 ) is removed.

[0065] Therefore, the first edge 41A of the ground layer 41 does not overlap the front edge 20F of the radiating element 20 when viewed from above. However, the extension line of the first edge 41A overlaps the front edge 20F when viewed from above.

[0066] Further, in the first embodiment Figure 4 ), the power supply line 30 is disposed in the same layer as the second layer ground layer 42. In contrast, in the present modification, the power supply line 30 is disposed in the same layer as the first layer ground layer 41, and a gap portion in which the metal film is removed is ensured between the power supply line 30 and the ground layer 41.

[0067] The second layer ground layer 42 includes the radiating element 20 when viewed from above. A portion of the first edge 42A of the ground layer 42 coincides with the front edge 20F of the radiating element 20 when viewed from above. The radiating element 20 is short-circuited to the second layer ground layer 42 through the short-circuit via hole 24 provided at both ends of the rear edge 20R.

[0068] In the present modification, the second layer ground layer 42 is provided on the lower surface of the dielectric substrate, and the third layer ground layer is not provided.

[0069] In the present modification, the vicinity of the end portion of the first edge 41A of the first layer ground layer 41 close to the radiating element 20 is coupled to the radiating element 20, and a high-frequency current propagating along the first edge 41A is generated. The stub 50 suppresses the propagation of the high-frequency current along the first edge 41A. Further, a high-frequency current propagating along the first edge 42A of the second layer ground layer 42 is also generated. The stub 50 is also connected to the second layer ground layer 42 at the same position as the connection position to the first layer ground layer 41. Therefore, the stub 50 also suppresses the propagation of the high-frequency current along the first edge 42A of the second layer ground layer 42. Thus, it is possible to suppress the disorder of the beam pattern.

[0070] As shown in the modification Figure 10 , the first layer ground layer 41 can also have a structure that does not overlap the radiating element 25 when viewed from above.

[0071] Next, another modified example of the first embodiment will be described.

[0072] In the first embodiment, the radiating element 20 and the ground layer 41 form a half-patch antenna, but a conventional patch antenna can also be formed. By removing the short-circuit via 24 from the antenna device of the first embodiment and increasing the y-direction dimension of the radiating element 20 to twice the dimension of the radiating element 20 of the half-patch antenna, a conventional patch antenna can be formed.

[0073] In the first embodiment, the radiating element 20 is rectangular in plan view, but may be in another shape that can function as a patch antenna or a half-patch antenna. For example, it may be a shape obtained by cutting the four corners of a rectangle into squares or a rectangle.

[0074] [Second embodiment]

[0075] Next, refer to Figure 11 and Figure 12 The antenna device of the second embodiment will be described. Figures 1-4 The common structures of the drawings are omitted.

[0076] Figure 11 This is a perspective view of the metal portion of the antenna device according to the second embodiment. In the first embodiment, second portion 50B of stub 50 extends from the front end of first portion 50A in the positive direction of the y-axis. In contrast, in the second embodiment, second portion 50B of stub 50 extends from the front end of first portion 50A, parallel to first edge 41A, and away from radiating element 20.

[0077] Figure 12 This is a graph showing the angular dependence of the directivity gain of the antenna device of the second embodiment using shades of light. The horizontal axis shows the azimuth angle in units of "°". The vertical axis represents the polar angle θ in units of "°". A relatively light color represents an area with relatively high directivity gain. In the second embodiment, the antenna device ( Figure 6A ) Similarly, at the polar angle θ = 90°, that is, in the xy plane, at the azimuth angle The directivity gain increases within the range of about 45°±10°. Figure 6B Compared with the beam pattern of the antenna device of the comparative example shown, it can be seen that the disturbance of the beam pattern is reduced.

[0078] [Third embodiment]

[0079] Next, refer to Figure 13 and Figure 14 The antenna device of the third embodiment will be described.Figures 1-4 The common structures of the drawings are omitted.

[0080] Figure 13 This is a perspective view of the metal portion of the antenna device according to the third embodiment. In the first embodiment, the second portion 50B of the stub 50 extends from the front end of the first portion 50A in the positive direction of the y-axis. In contrast, in the second embodiment, the second portion 50B of the stub 50 extends from the front end of the first portion 50A in the negative direction of the y-axis.

[0081] Figure 14 This is a graph showing the angular dependence of the directivity gain of the antenna apparatus of the third embodiment using shades of light. The horizontal axis shows the azimuth angle in units of "°". The vertical axis represents the polar angle θ in units of "°". A relatively light color represents an area with relatively high directivity gain. In the second embodiment, the antenna device ( Figure 6A ) Similarly, at the polar angle θ = 90°, that is, in the xy plane, at the azimuth angle The directivity gain increases within the range of about 45°±10°. Figure 6B Compared with the beam pattern of the antenna device of the comparative example shown, it can be seen that the disturbance of the beam pattern is reduced.

[0082] As described in the first to third embodiments, the second portion 50B ( Figure 1 、 Figure 11 、 Figure 13 ) is not particularly limited. In addition, in the second embodiment, as Figure 12 As shown, at polar angles θ of about 10° and about 170°, the azimuth angle In the range of -70° to 30°, a region with the same degree of directivity gain as the main beam is generated. Figure 14 As shown, four areas with the same directivity gain as the main beam are generated. To improve directivity, it is preferable to extend the second portion 50B of the stub 50 from the front end of the first portion 50A in the positive direction of the y-axis as in the first embodiment.

[0083] Furthermore, if the direction in which the second portion 50B of the stub 50 extends is changed, the input impedance of the antenna device changes. By appropriately designing the direction in which the second portion 50B extends, impedance matching of the antenna device can be achieved.

[0084] [Fourth embodiment]

[0085] Next, refer to Figure 15 The antenna device of the fourth embodiment will be described. Figures 1-4 The common structures of the drawings are omitted.

[0086] Figure 15 is a plan view of the antenna device of the fourth embodiment. In the first embodiment ( Figure 2 ), the front edge 20F of the radiating element 20 coincides with a part of the first edge 41A of the ground layer 41 when viewed from above. In contrast, in the fourth embodiment, the front edge 20F of the radiating element 20 is disposed at a position receding from the first edge 41A toward the second edge 41B when viewed from above. The distance in the y direction between the first edge 41A and the front edge 20F is denoted by Gy. The distance Gy can also be defined as the distance in the y direction from the first edge 41A to the radiating element 20. The distance in the y direction from the back edge 20R of the radiating element 20 to the second edge 41B of the ground layer 41 is longer than the distance Gy. That is, the radiating element 20 is disposed at a position deviated toward the first edge 41A side with respect to the ground layer 41 when viewed from above.

[0087] Even if the front edge 20F of the radiating element 20 is disposed at a position receding from the first edge 41A of the ground layer 41 when viewed from above, the ground layer 41 is coupled with the radiating element 20, generating a high-frequency current propagating along the first edge 41A.

[0088] If the distance Gy becomes longer, the high-frequency current propagating along the first edge 41A becomes smaller, and the disturbance of the beam pattern of the antenna device hardly occurs. In this case, there is no need to provide the stub 50. In the case where the distance Gy is 1 / 4 or less of the effective wavelength corresponding to the resonant frequency of the radiating element 20, the disturbance of the beam pattern caused by the high-frequency current propagating along the first edge 41A cannot be ignored. Therefore, in the case where the distance Gy is 1 / 4 or less of the effective wavelength corresponding to the resonant frequency of the radiating element 20, the remarkable effect of providing the stub 50 can be obtained.

[0089] [Fifth Embodiment]

[0090] Next, the antenna device of the fifth embodiment will be described with reference to Figure 16 The antenna device of the fifth embodiment will be described. Hereinafter, the description of the structures common to the antenna device of the first embodiment ( Figures 1-4 ) will be omitted.

[0091] Figure 16 is a perspective view of the metal portions of the antenna device of the fifth embodiment. In the first embodiment, the radiating element 20 and the ground layer 41 ( Figure 1 ) constitute a half-patch antenna. In contrast, in the fifth embodiment, the radiating element 20 includes two straight conductors 20A, 20B disposed in parallel with the first edge 41A, and operates as a dipole antenna.

[0092] One straight conductor 20A is connected with the power supply line 30 via a via hole 25A. The other straight conductor 20B is connected with the ground layer 41 via a via hole 25B, and also connected with the second layer ground layer 42 via a via hole 25C disposed directly below the via hole 25B. The via holes 25A, 25B are composed of a plurality of inner layer pads and a plurality of via holes connecting the upper and lower inner layer pads with each other, for example.

[0093] Positions sandwiching the radiating element 20 in the z direction are respectively provided with stubs 50. The structure of the stubs 50 is the same as that of the stubs 50 of the antenna device of the first embodiment ( Figure 1 、 Figure 3B ). When viewed from above, the distance in the y direction from each of the two straight conductors 20A, 20B to the first edge 41A of the ground layer 41 is 1 / 4 or less of the effective wavelength corresponding to the resonant frequency of the radiating element 20 acting as a dipole antenna.

[0094] Next, the excellent effects of the fifth embodiment are described.

[0095] In the fifth embodiment, the ground layer 41 is coupled with the radiating element 20 acting as a dipole antenna, and generates a high-frequency current propagating along the first edge 41A. The propagation of the high-frequency current along the first edge 41A is suppressed by the stubs 50, and the disorder of the beam pattern can be suppressed.

[0096] [Sixth Embodiment]

[0097] Next, the antenna device of the sixth embodiment is described with reference to Figure 17 The following description of the structure common to the antenna device of the first embodiment described with reference to Figures 1-8 is omitted.

[0098] Figure 17 is a plan view of the conductor portion of the antenna device of the sixth embodiment. The antenna device of the first embodiment has one radiating element 20. In contrast, in the antenna device of the sixth embodiment, a plurality of radiating elements 20 of the same structure as the radiating element 20 of the first embodiment are arranged in the z direction. The power supply line 30 is connected to each of the plurality of radiating elements 20. The ground layer 41 common to the plurality of radiating elements 20 is provided. An array antenna is composed of the plurality of radiating elements 20 and the ground layer 41. The positional relationship of each of the plurality of radiating elements 20 to the first edge 41A of the ground layer 41 is the same as that of the radiating element 20 of the first embodiment to the first edge 41A of the ground layer 41.

[0099] The stub 50 is arranged on both sides of each of the plurality of radiating elements 20 in the z direction. Further, one stub 50 is arranged between two radiating elements 20 adjacent in the z direction, and one stub 50 is shared by the two radiating elements 20 on both sides. The positional relationship of each of the plurality of radiating elements 20 and the stub 50 on both sides is the same as that of the radiating elements 20 and the stub 50 on both sides of the antenna device of the first embodiment. In addition, the positional relationship of each stub 50 and the first edge 41A of the ground layer 41 is the same as that of the stub 50 and the first edge 41A of the ground layer 41 of the antenna device of the first embodiment.

[0100] Next, the excellent effects of the sixth embodiment will be described.

[0101] In the sixth embodiment, the disorder of the respective beam patterns of the radiating elements 20 can also be suppressed as in the first embodiment. Therefore, in the array antenna including the plurality of radiating elements 20, the disorder of the beam patterns can also be suppressed.

[0102] In addition, by arranging one stub 50 between two radiating elements 20 adjacent in the z direction and sharing one stub 50 by the two radiating elements 20, the radiating elements 20 can be arranged close to each other compared to the structure in which the stub 50 is arranged independently for each of the radiating elements 20. Therefore, the degree of freedom in setting the interval of the radiating elements 20 is increased.

[0103] [Seventh Embodiment]

[0104] Next, the seventh embodiment will be described with reference to Figure 18 The antenna device of the seventh embodiment will be described. Hereinafter, the description of the structure common to the antenna device of the fourth embodiment ( Figure 15 ) will be omitted.

[0105] Figure 18 is a plan view of the antenna device of the seventh embodiment. In the fourth embodiment ( Figure 15 ), the radiating element 20 is rectangular when viewed from above. In contrast, in the seventh embodiment, the radiating element 20 is triangular, for example, isosceles triangular. The base of the isosceles triangle is parallel to the first edge 41A of the ground layer 41 when viewed from above, and corresponds to the rear edge 20R of the radiating element 20.

[0106] The feed point 21 is arranged on a perpendicular line descending from the vertex 20C toward the rear edge 20R. The vertex 20C of the three vertices of the radiating element 20, which is shared by two equal sides, is closest to the feed point 21. When viewed from above, the vertex 20C of the isosceles triangle, which is shared by two equal sides, faces the first edge 41A. The distance Gy in the y direction from the radiating element 20 to the first edge 41A is equal to the distance in the y direction from the first edge 41A to the vertex 20C.

[0107] The distance Dz in the z direction from the center of the connection portion of the stub 50 and the ground layer 41 to the radiation element 20 is defined by the z direction interval between the apex 20D of the two ends of the base of the isosceles triangle and the center of the connection portion of the stub 50 and the ground layer 41.

[0108] As in the seventh embodiment, even if the planar shape of the radiation element 20 is made an isosceles triangle, the radiation element 20 operates as a half-patch antenna. At this time, the resonant frequency of the radiation element 20 is determined by the size in the y direction of the radiation element 20, the positional relationship of the radiation element 20 and the first edge 41A of the ground layer 41, the positional relationship of the radiation element 20 and the stub 50, and the like.

[0109] Next, the excellent effects of the seventh embodiment are described.

[0110] In the seventh embodiment, as in the fourth embodiment, in the case where the distance Gy is 1 / 4 or less of the effective wavelength corresponding to the resonant frequency of the radiation element 20, the remarkable effect of providing the stub 50 can be obtained.

[0111] Next, the seventh embodiment is described with reference to Figure 19 to the antenna device of the seventh embodiment.

[0112] Figure 19 is a plan view of the antenna device of the seventh embodiment. In the seventh embodiment, the shape of the radiation element 20 in plan view is an isosceles triangle, but in this modification, the shape of the radiation element 20 in plan view is a semicircle. The edge corresponding to the diameter of the semicircle is equivalent to the rear edge 20R.

[0113] The distance Gy in the y direction from the radiation element 20 to the first edge 41A is equal to the distance in the y direction from the intersection 20E of the perpendicular bisector of the rear edge 20R and the circumference to the first edge 41A. The feed point 21 is located on the radius passing through the intersection 20E.

[0114] As in this modification, the shape of the radiation element 20 in plan view can also be made a semicircle. In addition, the shape of the radiation element 20 in plan view can also be made a shape in which an ellipse is divided into two by the major axis or the minor axis.

[0115] The above-described embodiments are examples, and of course partial substitution or combination of the structures shown in different embodiments can be made. The same effects of the same structures of the plurality of embodiments are not mentioned in each embodiment in turn. Furthermore, the present application is not limited to the above-described embodiments. For example, various changes, improvements, combinations, and the like that are obvious to those skilled in the art can be made.

[0116] Reference Signs

[0117] 20 …radiating element; 20A, 20B …straight conductor; 20C … vertex shared by two equal sides of an isosceles triangle of a radiating element; 20D … vertex of both ends of a base of an isosceles triangle of a radiating element; 20E … intersection of a perpendicular bisector of a back edge of a semicircular radiating element and a circumference; 20F … front edge; 20R … back edge; 21 … power feeding point; 24 … short-circuit via; 25A, 25B, 25C … via; 30 … power feeding line; 31 … conductor member; 31A … via; 31B … inner layer pad; 31C … via; 41 … ground layer; 41A … first edge; 41B … second edge; 42 … ground layer; 42A … first edge; 43 … ground layer; 43A … first edge; 50 … stub; 50A … first portion of stub; 50B … second portion of stub; 60 … dielectric substrate.

Claims

1. An antenna device comprising: a ground layer having a first edge extending in a first direction; at least one radiating element disposed apart from the ground layer in a thickness direction of the ground layer; a feeding line supplying a high-frequency signal to the radiating element; at least two stubs disposed at positions sandwiching the radiating element in the first direction and connected to the ground layer, wherein a distance from the radiating element to the first edge in a second direction orthogonal to the first direction is 1 / 4 or less of a wavelength corresponding to a resonant frequency of the radiating element when viewed in plan.

2. The antenna device according to claim 1, wherein a distance from a position at which the stubs are connected to the ground layer to the first edge in the second direction is 1 / 4 or less of the wavelength corresponding to the resonant frequency of the radiating element.

3. The antenna device according to claim 1 or 2, wherein the radiating element includes a metal plate, the metal plate and the ground layer together constituting a patch antenna, the metal plate has a front edge and a back edge, the front edge is located on the first edge side and the back edge is located on the opposite side of the front edge when viewed in plan, and a distance from the back edge to a second edge of the ground layer on the opposite side of the first edge in the second direction is longer than a distance from the front edge to the first edge of the ground layer in the second direction.

4. The antenna device according to claim 3, wherein a distance from the position at which the stubs are connected to the ground layer to the first edge of the radiating element in the first direction is 1 / 15 or more and 1 / 4 or less of the wavelength corresponding to the resonant frequency of the radiating element.

5. The antenna device according to claim 3 or 4, wherein the stubs each include a first portion extending from the ground layer in the thickness direction of the ground layer and a second portion extending from a front end of the first portion in a direction parallel to the ground layer.

6. The antenna device according to any one of claims 3 to 5, wherein a length of each of the stubs is 21% or more and 25% or less of the wavelength corresponding to the resonant frequency of the radiating element.

7. The antenna device according to any one of claims 1 to 5, wherein the radiating element is disposed in plurality along the first direction, the stubs are disposed at positions sandwiching each of the radiating elements in the first direction, one of the stubs is disposed between two of the radiating elements adjacent in the first direction, and the stub is shared by the two radiating elements.

8. The antenna device according to claim 1 or 2, wherein the radiating element includes two straight conductors constituting a dipole antenna, one of the two straight conductors is connected to the feeding line, and the other of the two straight conductors is connected to the ground layer. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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