Antenna device

Abstract

This antenna device comprising: a ground part; and an element at least a part of which is located so as to face the ground part, wherein the element has a plurality of cutout parts on both sides in a first direction and on both sides in a second direction orthogonal to the first direction, and the plurality of cutout parts are twofold symmetric about the geometric center of the element in plan view in which the element is viewed from a direction orthogonal to the ground part.

Description

Antenna device

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

[0002] Patent Document 1 discloses an antenna device including an element made of a metal plate.

[0003] Japanese Patent Application Laid-Open No. 2008-079009

[0004] The antenna device of Patent Document 1 includes a plurality of capacitors, which are lumped constant elements, in order to reduce the size of the antenna device, which increases the number of parts in the antenna device.

[0005] An example of an object of the present invention is to miniaturize an antenna device while suppressing an increase in the number of parts. Other objects of the present invention will become apparent from the description of this specification.

[0006] One aspect of the present invention is an antenna device comprising a ground section and an element positioned so that at least a portion of the element faces the ground section, the element having a plurality of notches on each side in a first direction and on each side in a second direction perpendicular to the first direction, the plurality of notches being two-fold symmetric with respect to the geometric center of the element in a plan view of the element seen from a direction perpendicular to the ground section.

[0007] One aspect of the present invention is an antenna device comprising: a ground section; and an element positioned so that at least a portion of the element faces the ground section, the element having a notch section on each side in a first direction and on each side in a second direction perpendicular to the first direction, the notch section having an open end at an outer edge of the element, and being dyad-symmetric with respect to the geometric center of the element in a planar view of the element seen from a direction perpendicular to the ground section, and the angle formed by the width direction of the open end and the direction in which the notch section extends from the open end is an acute angle.

[0008] One aspect of the present invention is an antenna device comprising: a ground section; and an element positioned so that at least a portion of the element faces the ground section, the element having a notch section and a first opening on each side in a first direction and on each side in a second direction perpendicular to the first direction, the notch section having an open end at an outer edge of the element, the first opening being located between the open end and a geometric center of the element in a planar view when the element is viewed from a direction perpendicular to the ground section, and the notch section and the first opening being two-fold symmetric with respect to the geometric center in the planar view.

[0009] According to the above aspects of the present invention, it is possible to reduce the size of the antenna device while suppressing an increase in the number of parts.

[0010] 1 is a perspective view of an antenna device 10A. FIG. 1 is a plan view of the antenna device 10A. FIG. 2 is a diagram illustrating the VSWR frequency characteristics of an element 31A. FIG. 3 is a diagram for explaining the relationship between the shapes of elements 31A to 31C and VSWR. FIG. 4 is a plan view of an antenna device 10B. FIG. 5 is a diagram illustrating the VSWR frequency characteristics of elements 31A and 31B. FIG. 6 is a plan view of an antenna device 10D. FIG. 7 is a plan view of an antenna device 10E. FIG. 8 is a diagram illustrating the VSWR frequency characteristics of elements 31A, 31B, 31D, and 31E. FIG. 9 is a plan view of an antenna device 10F. FIG. 10 is a diagram illustrating the VSWR frequency characteristics of elements 31A, 31B, and 31F. FIG. 11 is a plan view of an antenna device 10G. FIG. 11 is a diagram illustrating the VSWR frequency characteristics of elements 31A and 31G. FIG. 12 is a plan view of an antenna device 10H. FIG. 13 is a plan view of an antenna device 10I. FIG. 14 is a plan view of an antenna device 10J. FIG. 15 is a plan view of an antenna device 10K. 1 is a diagram showing VSWR frequency characteristics of elements 31A, 31B, and 31H to 31K. FIG. 1 is a plan view of an antenna device 10L. FIG. 1 is a plan view of an antenna device 10M. FIG. 1 is a diagram showing VSWR frequency characteristics of elements 31A, and 31K to 31M. FIG. 1 is a plan view of an antenna device 10N. FIG. 1 is a diagram showing VSWR frequency characteristics of elements 31A, 31J, and 31N. FIG. 1 is a plan view of an antenna device 10P. FIG. 1 is a plan view of an antenna device 10Q. FIG. 1 is a perspective view of an antenna device 100A. FIG. 1 is an exploded perspective view of the antenna device 100A. FIG. 1 is a schematic view of the A-A cross section of the antenna device 100A. FIG. 1 is an exploded perspective view of the antenna device 100B. FIG. 1 is an exploded perspective view of the antenna device 100C. FIG. 1 is a perspective view of an antenna device 200A. FIG. 1 is an exploded perspective view of the antenna device 200A. FIG. 1 is an exploded perspective view of the antenna device 200B. FIG. 1 is an exploded perspective view of the antenna device 200C. FIG. 1 is a perspective view of an antenna device 200D. FIG. 1 is an exploded perspective view of an antenna device 300. 1 is a plan view of a substrate 311. FIG. 2 is a schematic diagram of the BB cross section of the antenna device 200. FIG. 3 is an exploded perspective view of the antenna device 101A. FIG. 4 is an exploded perspective view of the antenna devices 101B and 101C. FIG. 5 is a diagram for explaining the antenna device 201. FIG. 6 is a diagram for explaining the antenna devices 202 to 204.

[0011] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0013] ===Overview of Antenna Device 10A=== Fig. 1 is a perspective view of an air-gap type antenna device 10A. Fig. 2 is a plan view of the antenna device 10A. First, directions and the like in the antenna device 10A will be defined with reference to Figs. 1 and 2.

[0014] 1, the direction from the base plate 30 (described later) toward the element 31A (described later) is defined as the "+Z direction." Therefore, in the following description, the +Z direction may be referred to as the "upper direction," and the -Z direction may be referred to as the "lower direction." Furthermore, the side in the +Z direction may be referred to as the "upper side," and the side in the -Z direction may be referred to as the "lower side."

[0015] The directions parallel to the +Z direction surface of the ground plate 30 (described later) and perpendicular to each other are defined as the "+X direction" and the "+Y direction." In the antenna device 10A, as shown in FIG. 1, the +X direction is also the direction from the geometric center 40A of the element 31A (described later) toward the feed point 41A. Here, the "geometric center" refers to the center of the shape of the outer edge of the element 31A.

[0016] In addition, in FIG. 1, the +Y direction is also the direction from the geometric center 40A of the element 31A toward the inside of the page.

[0017] Each of the +X direction, -X direction, +Y direction, -Y direction, +Z direction, and -Z direction is a direction with a fixed orientation. Rather than being a fixed orientation as described above, both the +X direction and the -X direction may be simply referred to as the "X direction." Similarly, both the +Y direction and the -Y direction may be simply referred to as the "Y direction." Furthermore, both the +Z direction and the -Z direction may be simply referred to as the "Z direction."

[0018] 1 and 2, in order to facilitate understanding of directions and the like in the antenna device 10A, the +X direction, +Y direction, and +Z direction are each represented by a line segment with an arrow. Note that the intersection of these line segments with an arrow does not indicate the coordinate origin. The definitions of the above-mentioned directions and the like are common throughout this specification unless otherwise specified.

[0019] <<Overview of Antenna Device 10A>> The antenna device 10A is, for example, a satellite antenna device that supports circularly polarized radio waves. The antenna device 10A is a planar antenna device that supports radio waves in the L1 band (1559 MHz to 1610 MHz band) of the Global Navigation Satellite System (GNSS).

[0020] However, the antenna device 10A may also be compatible with radio waves in the frequency bands of, for example, the L2 band (1212 MHz to 1254 MHz) or the L5 band (1166 MHz to 1187 MHz).

[0021] Furthermore, the communication standard and frequency band of radio waves supported by the antenna device 10A are not limited to the above-mentioned GNSS, and other communication standards and frequency bands may be used. For example, the antenna device 10A may be compatible with circularly polarized radio waves, such as radio waves in a frequency band for the Satellite Digital Audio Radio Service (SDARS), or linearly polarized radio waves, such as radio waves in a frequency band for Vehicle to Everything (V2X: vehicle-to-vehicle communication, road-to-vehicle communication).

[0022] <<Configuration of Antenna Device 10A>> The antenna device 10A includes a base plate 30 , an element 31A, and a feeder line 32 .

[0023] <Ground plate 30> The ground plate 30 is a member that functions as the ground of the antenna device 10A and corresponds to a “ground portion.” Here, the ground plate 30 is, for example, a square metal plate with a side length of La, but is not limited to this and may be a substantially quadrilateral metal plate.

[0024] The term "approximately quadrilateral" refers to a shape consisting of four sides, including, for example, a square or a rectangle, and may have at least some corners cut out at an angle to the sides. Furthermore, the "approximately quadrilateral" shape may have a notch (recess) or a protrusion (protrusion) on one of the sides.

[0025] The base plate 30 is not limited to a substantially quadrilateral shape, and may be, for example, an arc-shaped member with at least a partial curvature, or a circular or elliptical plate-shaped member. Furthermore, the base plate 30 may have a shape other than a plate-like shape as long as it is a metal member that functions as a ground. In this example, the length La of one side of the base plate 30 is, for example, 150 mm.

[0026] <Element 31A> The element 31A is a conductive member (so-called radiating element) that receives radio waves in a desired frequency band. Here, the element 31A is, for example, a square metal plate with a side length Lb, but is not limited to this and may be a metal plate of other shapes such as a substantially quadrilateral, a circle, an ellipse, etc. The side length Lb of the element 31A is, for example, 90 mm.

[0027] The element 31A is located on the +Z direction side of the ground plane 30 so as to face the ground plane 30. Specifically, the element 31A is supported by a support member (not shown) so that the surface of the element 31A on the -Z direction side and the surface of the ground plane 30 on the +Z direction side are approximately parallel to each other. Note that the support member is omitted here for convenience, but the support member is a member formed of a dielectric material such as resin.

[0028] The element 31A has a feed point 41A located in the +X direction from the geometric center 40A of the element 31A. The feed point 41A is a location to which a feed line 32 (described later) is connected. The feed line 32 is a wiring for transmitting radio waves received by the element 31A to an LNA (Low Noise Amplifier) ​​provided on a circuit board (not shown).

[0029] <<Characteristics of Element 31A>> Figure 3 is a diagram showing the frequency characteristics of the voltage standing wave ratio (VSWR) of the element 31A. In Figure 3, the horizontal axis represents frequency and the vertical axis represents the voltage standing wave ratio. As shown in Figure 3, the voltage standing wave ratio of the element 31A is minimum around 1.5 GHz (specifically, approximately 1487 MHz).

[0030] The frequency at which the voltage standing wave ratio is minimum (i.e., the frequency that the antenna device supports) is determined based on the size of the element 31A, i.e., the length Lb of one side of the element 31A. If the length Lb of one side of the element 31A is shortened, the electrical length of the element 31A also becomes shorter, and the frequency at which the voltage standing wave ratio is minimum increases. For this reason, if the length Lb of one side of the element 31A is shortened in order to reduce the size of the antenna device 10A, the element 31A may not be able to receive radio waves in the desired frequency band (e.g., radio waves in the 1.5 GHz band).

[0031] Therefore, in this embodiment, the element is provided with a "cutout" such as a slit or slot, thereby reducing the size of the element and achieving a miniaturized antenna device, as will be described in detail later. Below, an overview will be given of the characteristics of an element with a slit, and the characteristics of an element when the size of the element with a slit is reduced.

[0032] <<Relationship Between Element Shape and Element Characteristics>> Figure 4 is a diagram illustrating the current distribution flowing on the surfaces of elements 31A to 31C, which have different shapes, and the characteristics of elements 31A to 31C. Elements 31B and 31C are used in antenna devices 10B and 10C, respectively, which are similar to antenna device 10A shown in Figure 1. Here, "current flowing on the surface of the element" refers to current flowing on both the +Z side surface and the -Z side surface of the element, but the figure shows the current flowing on the +Z side surface. Hereinafter, "current flowing on the surface of the element" may be simply referred to as surface current.

[0033] The antenna device 10B includes a ground plane 30, an element 31B, and a feeder line 32, while the antenna device 10C includes a ground plane 30, an element 31C, and a feeder line 32. The configurations of the antenna devices 10B and 10C are the same as those of the antenna device 10A except for the elements 31B and 31C. Therefore, the following description will focus on the elements 31B and 31C.

[0034] The element 31B is a member obtained by providing four slits S1 (described later) in the element 31A, and the element 31C is a member obtained by reducing the size of the element 31B.

[0035] <Element 31A> On the left side of FIG. 4, an image diagram of the current distribution flowing on the surface of the element 31A and a schematic diagram of the frequency characteristics of the voltage standing wave ratio of the element 31A are depicted.

[0036] The magnitude of the current flowing on the surface of element 31A is minimum (here, zero) at each end of element 31A in the +X direction and the -X direction. On the other hand, the magnitude of the surface current is maximum near the center of element 31A in the X direction. In Figure 4, the direction of the surface current in the element is represented by the direction of the arrow, and the magnitude of the surface current is represented by the thickness of the arrow. Also, here, the general path of the current flowing on the surface of element 31A is shown by path P1, indicated by a dotted line.

[0037] 4, for convenience, only the surface current in the −X direction at a certain time is shown, but as time passes, the surface current also flows in the +X direction. In addition, in element 31A, a surface current similar to that in the X direction also flows in the Y direction, but this is not shown here for convenience.

[0038] The diagram at the bottom left of Fig. 4 is a schematic diagram showing the frequency characteristics of the voltage standing wave ratio of the element 31A. Here, the frequency at which the voltage standing wave ratio of the antenna device 10A is minimum is set to frequency F0. Note that frequency F0 is the frequency at which the voltage standing wave ratio in Fig. 3 is minimum.

[0039] <Element 31B> The center of Figure 4 shows an image of the surface current of element 31B and a schematic diagram of the frequency characteristics of the voltage standing wave ratio of element 31B. Four slits S1 are formed in element 31B. Specifically, one slit S1 is formed in the center of each side of element 31B. The length of one side of element 31B is equal to the length Lb of one side of element 31A.

[0040] The surface current of element 31B bypasses slit S1. As a result, a general path P2 (indicated by a dashed line in FIG. 4) of the surface current in the X direction of element 31B is longer than a general path P1 of element 31A. Therefore, the electrical length of element 31B in the X direction is longer than the electrical length of element 31A in the X direction.

[0041] 4 shows the surface current and path P2 in the X direction for element 31B, but the same is true for the Y direction. Therefore, the electrical length of element 31B in the Y direction is also longer than the electrical length of element 31A in the Y direction.

[0042] As a result, as shown in the lower center of Figure 4, the frequency at which the voltage standing wave ratio is minimum in element 31B decreases from frequency F0 to frequency F1. In this way, by using element 31B with slits S1 formed on each side, the frequency that antenna device 10B can accommodate can be lowered. The relationship between the shape of slits S1 and frequency F1 will be described in detail later.

[0043] Element 31C The right side of Fig. 4 shows an image of the current flowing through the surface of element 31C and a schematic diagram of the frequency characteristics of the voltage standing wave ratio of element 31C. Element 31C is, for example, a component obtained by reducing the size of element 31B while maintaining the shape of element 31B. Therefore, the length Lc of one side of element 31B is shorter than the length Lb.

[0044] Here, by adjusting the size of element 31C (i.e., the length Lc of one side of element 31C), the length of a general path P3 (indicated by the two-dot chain line in the figure) of the surface current in the X direction of element 31C can be made substantially equal to the length of path P1. In this case, the electrical length of element 31C in the X direction becomes substantially equal to the electrical length of element 31A in the X direction.

[0045] 4 illustrates the current flowing on the surface in the X direction and the path P3, the same applies to the Y direction. Therefore, the electrical length of element 31C in the Y direction is also approximately equal to the electrical length of element 31A in the Y direction.

[0046] As a result, as shown in the lower left part of Figure 4, with element 31C, the frequency at which the voltage standing wave ratio is minimum can be increased from frequency F1 to frequency F0. In this way, even when element 31C, which is smaller in size than element 31A, is used, characteristics similar to those of element 31A can be obtained. Therefore, by using the smaller-sized element 31C, antenna device 10C can be made smaller than antenna device 10A.

[0047] Here, for example, the element 31B having four slits S1 has been described, but the element that increases the electrical length may have other shapes. Below, the element 31B that can increase the electrical length will be described in detail, and then elements of other shapes will also be described.

[0048] 5 is a plan view of the antenna device 10B. The element 31B has a feed point 41B located in the +X direction from the geometric center 40B of the element 31B. The geometric center 40B and the feed point 41B are similar to the geometric center 40A and the feed point 41A, respectively.

[0049] Element 31B has slits S1 on both sides in the X direction and both sides in the Y direction. Here, "both sides in the X direction of the element" corresponds to the region in the element in the +X direction from the geometric center and the region in the -X direction from the geometric center. Also, "both sides in the Y direction of the element" corresponds to the region in the element in the +Y direction from the geometric center and the region in the -Y direction from the geometric center.

[0050] In element 31B, slot S1 is formed to have two-fold symmetry with respect to geometric center 40B so that the surface current in the X direction and the surface current in the Y direction are balanced. Note that, since the shape of the outer edge of element 31B in Fig. 5 is square, slot S1 consequently has four-fold symmetry with respect to geometric center 40B.

[0051] Note that "n-fold symmetry (n is 2 or 4) with respect to the geometric center" does not necessarily have to be strictly (mathematically) n-fold symmetry, and as long as the desired effect (desired frequency characteristics of voltage standing wave ratio) is obtained, the positions near each side may be shifted from the predetermined positions (positions of strict n-fold symmetry).

[0052] Each of the four slits S1 has an open end E1 at the outer edge of the element 31B and extends from the open end E1 toward the geometric center 40B. The shape of the slit S1 is, for example, a quadrilateral with a width W1 and a length L1 in a plan view (hereinafter simply referred to as a "plan view") of the target element (here, element 31B) viewed from the +Z direction. The slits S1 are formed at the center of each side of the element 31B.

[0053] Fig. 6 shows the relationship between the voltage standing wave ratio of the element 31B and frequency when the length L1 of the slit S1 is changed. For reference, Fig. 6 also shows the frequency characteristics of the voltage standing wave ratio of the element 31A without a slit (solid line in the figure). Here, the width W1 of the slit S1 is set to 1 mm, and the length L1 is changed to 12.75 mm and 20 mm.

[0054] As is clear from Figure 6, when the length L1 of the slit S1 is increased, the current flowing on the surface of the element 31B bypasses the slit S1. As a result, the electrical length of the element 31B is increased, and the minimum value of the voltage standing wave ratio shifts to a lower frequency. Therefore, when element 31C (see Figure 4), which is a reduced version of such element 31B, is used, an antenna device 10C that is smaller than the antenna device 10A can be realized.

[0055] Here, the element 31B having four slits S1 has been described, but the shape of the element that can increase the electrical length (i.e., the element to be reduced) is not limited to this. For example, by forming multiple slits on one side of the element, or by forming a slit and a slot, the electrical length of the element can be effectively increased. The shapes of elements that can be used in this embodiment are described below.

[0056] Regarding the Shape of the Element Antenna Device 10D Fig. 7 is a plan view of the antenna device 10D. The antenna device 10D is configured to include a base plate 30, an element 31D, and a feeder line 32, similar to the antenna device 10A of Fig. 1 .

[0057] The outer edge of element 31D is shaped like a square with sides of length Lb, and element 31D has a feed point 41D located in the +X direction from a geometric center 40D of element 31D. Note that geometric center 40D and feed point 41D are similar to geometric center 40A and feed point 41A, respectively.

[0058] The element 31D has two slits S1 on each side in the X direction and on each side in the Y direction. The two slits S1 extending from each side of the element 31D correspond to "multiple cutout portions."

[0059] The two slots S1 formed in the element 31D are formed so as to have two-fold symmetry with respect to the geometric center 40D. Note that, since the shape of the outer edge of the element 31D in Fig. 7 is square, the two slots S1 are consequently formed so as to have four-fold symmetry with respect to the geometric center 40D.

[0060] <<Antenna Device 10E>> Fig. 8 is a plan view of the antenna device 10E. The antenna device 10E includes a base plate 30, an element 31E, and a feeder line 32, similar to the antenna device 10A of Fig. 1 .

[0061] The outer periphery of element 31E is a square with sides of length Lb, and element 31E has a feed point 41E located in the +X direction from a geometric center 40E of element 31E. Note that geometric center 40E and feed point 41E are similar to geometric center 40A and feed point 41A, respectively.

[0062] The element 31E has three slits S1 on each side in the X direction and on each side in the Y direction. The three slits S1 extending from each side of the element 31E correspond to "multiple cutout portions." The X direction corresponds to the "first direction," and the Y direction corresponds to the "second direction perpendicular to the first direction."

[0063] Furthermore, the three slots S1 extending from each side of the element 31E are formed so as to have two-fold symmetry with respect to the geometric center 40E. Note that, since the outer periphery of the element 31E in Fig. 8 has a square shape, the three slots S1 are consequently four-fold symmetry with respect to the geometric center 40E.

[0064] 9 is a diagram showing the relationship between the voltage standing wave ratio and frequency of the elements 31A, 31B, 31D, and 31E. Here, the width W1 of the slit S1 is 1 mm, and the length L1 is 12.75 mm.

[0065] As the number of slits S1 per side of the element increases, the number of times the current flowing on the surface of the element must bypass the additional slits S1 also increases. As a result, the electrical length of the element becomes longer compared to when there is only one slit S1 per side of the element. As a result, as shown in Figure 9, as the number of slits S1 per side of the element increases, the minimum value of the voltage standing wave ratio shifts to a lower frequency.

[0066] <<Antenna Device 10F>> Fig. 10 is a plan view of the antenna device 10F. The antenna device 10F includes a base plate 30, an element 31F, and a feeder line 32, similar to the antenna device 10A of Fig. 1 .

[0067] The outer edge of element 31F is shaped like a square with sides of length Lb, and element 31F has a feed point 41F located in the +X direction from a geometric center 40F of element 31F. Note that geometric center 40F and feed point 41F are similar to geometric center 40A and feed point 41A, respectively.

[0068] The element 31F has a slit S2 on each of both sides in the X direction and both sides in the Y direction. The slits S2 have open ends E2 at the outer edge of the element 31F. The slits S2 are formed so that the angle formed between the side on which the open ends E2 are located and the direction in which the slits S2 extend is a predetermined angle that is smaller than 90°.

[0069] Specifically, the slit S2 is formed so that the angle θ between the width direction of the open end E2 (the direction of the dashed line in the figure) and the direction in which the slit S2 extends from the open end E2 (the direction of the dashed line in the figure) is an acute angle. The shape of the slit S2 is a substantially quadrilateral with a width W2 and a length L2 in a plan view, and the slit S2 corresponds to a "notch portion."

[0070] The slits S2 extending from each side of the element 31F are formed to have two-fold symmetry with respect to the geometric center 40F. Note that, since the shape of the outer edge of the element 31F in Fig. 10 is square, the slots S2 are consequently four-fold symmetry with respect to the geometric center 40F.

[0071] <<Characteristics of Element 31F>> Figure 11 is a diagram showing the relationship between the voltage standing wave ratio and frequency of elements 31A, 31B, and 31F. For reference, the characteristics of element 31A without a slit and element 31B with slit S1 are also shown. Here, the width W2 of slit S2 is 1 mm, the length L2 is 12.75 mm, and the angle θ is 30°.

[0072] 5, the width direction of the open end E1 of the slit S1 is the X direction, and the slit S1 extends in the Y direction. Therefore, the angle between the width direction of the open end E1 and the extension direction of the slit S1 is 90°.

[0073] 11, the voltage standing wave ratio of element 31F is approximately equal to that of element 31B. Therefore, even if the angle between the width direction of open end E2 and the extension direction of slit S2 is an acute angle (θ = 30°), the path of the surface current that bypasses slit S2 (i.e., the electrical length of the element) can be lengthened, and the same results as those of element 31B can be obtained.

[0074] <<Modified Slits>> Although the shapes of the slits S1 and S2 are described as being linear quadrilaterals, the shape is not limited to this and may be any shape that can increase the electrical length of the element. Specifically, the shapes of the slits S1 and S2 may be, for example, a substantially quadrilateral, a circle, an ellipse, a curved shape (not shown), a meandering shape, a shape that extends along the longitudinal direction and whose width changes along the way, and the like.

[0075] Furthermore, in elements 31D and 31E, the multiple slits extending from one side are all slits S1, but this is not limited to this. For example, instead of forming three identical slits S1 on one side of element 31E, three different slits may be formed: slits S1, S2, and a curved slit (not shown). Furthermore, three slits S1 of different sizes may be formed on one side of element 31E. Even in such a case, the electrical length of element 31E can be increased if multiple slits can be formed to divert the current flowing through the element.

[0076] Here, the shape of the slits and the like have been described, but the "notch" that increases the electrical length of the element is not limited to a slit and may be a slot. Note that a slit is, for example, a "notch that has an open end and a closed end," and a slot is, for example, a "notch that does not have an open end." Below, we will also consider the case where a slot is formed in an element.

[0077] 12 is a plan view of an antenna device 10G including an element having a plurality of slots. The antenna device 10G includes a ground plane 30, an element 31G, and a feeder line 32, similar to the antenna device 10A of FIG.

[0078] The outer edge of element 31G has a square shape with sides of length Lb, and element 31G has a feed point 41G located in the +X direction from a geometric center 40G of element 31G. Note that geometric center 40G and feed point 41G are similar to geometric center 40A and feed point 41A, respectively.

[0079] The element 31G has a slot S10 on each of both sides in the X direction and on each of both sides in the Y direction. The slots S10 are formed to extend along each side of the element 31G. In plan view, the shape of the slot S10 is a quadrilateral with a width W10 and a length L10. Here, the slot corresponds to a "notch" or "opening" that does not have an open end.

[0080] The slots S10 formed along each side of the element 31G are formed so as to have two-fold symmetry with respect to the geometric center 40G. Note that, since the shape of the outer edge of the element 31G in Fig. 12 is square, the slots S10 consequently have four-fold symmetry with respect to the geometric center 40G.

[0081] <<Characteristics of Element 31G>> Figure 13 is a diagram showing the relationship between the voltage standing wave ratio of element 31G and frequency. For reference, the characteristics of element 31A, which does not have a slot, are also shown. The width W10 of slot S10 is set to 1 mm, and the length L10 is changed to 60 mm or 70 mm.

[0082] 13, when the slot S10 is formed, a new resonance due to the slot S10 occurs in a frequency band higher than the desired 1.5 GHz band (in this case, approximately 2 GHz to 2.5 GHz band). The voltage standing wave ratio of the element 31G having the slot S10 with a length L10 of 60 mm is approximately equal to the voltage standing wave ratio of the element 31A. On the other hand, when the length L10 is increased to 70 mm, the frequency at which the voltage standing wave ratio of the element 31G is minimum is approximately 1420 MHz.

[0083] Therefore, in the element 31G, as the length L10 of the slot S10 is increased, the frequency at which the voltage standing wave ratio of the element 31G is minimized shifts to a lower frequency range.

[0084] 6, in the element 31B, the length L1 of the slit S1 is 12.75 mm, and the frequency at which the voltage standing wave ratio of the element 31B is minimum is approximately 1430 MHz. In this way, by forming a relatively short slit in the element (the slit S1 of 12.75 mm, which is shorter than 70 mm), the electrical length of the element can be increased.

[0085] Therefore, in order to increase the electrical length of the element, it is more preferable to form, for example, the above-mentioned slit S1 in the element rather than the slot S10. Next, an element in which a plurality of notches including slits and slots are formed will be described.

[0086] <<Antenna Device 10H>> Fig. 14 is a plan view of the antenna device 10H. The antenna device 10H includes a base plate 30, an element 31H, and a feeder line 32, similar to the antenna device 10A of Fig. 1 .

[0087] The outer edge of element 31H is shaped like a square with sides of length Lb, and element 31H has a feed point 41H located in the +X direction from a geometric center 40H of element 31H. Note that geometric center 40H and feed point 41H are similar to geometric center 40A and feed point 41A, respectively.

[0088] The element 31H has a notch N1 on each of both sides in the X direction and on each of both sides in the Y direction. The notch N1 is a gap formed in the element 31H and includes a slit S20 and a slot S30 continuous with the slit S20.

[0089] The slits S20 are notches extending from each side of the element 31H and have an open end E20 at the outer edge of the element 31H and a closed end E21. The slits S20 extend from the open ends E20 located at the centers of each side of the element 31H toward the geometric center 40H. The shape of the slits S20 is a quadrilateral with a width W20 and a length L20 in a plan view. The slits S20 correspond to the "notch portion."

[0090] The slot S30 is formed so as to be spaced a distance M from each side of the element 31H and extend along each side. The shape of the slot S30 is a rectangle with a width W30 and a length L30 in a plan view. The slot S30 corresponds to a "first opening."

[0091] For example, in the notch N1 formed on the -Y side of the element 31H, the slit S20 extends in the Y direction, and the slot S30 extends in the X direction. In the other three notches N1, the slot S30 is also formed so that the extending direction of the slit S20 intersects with the extending direction of the slot S30.

[0092] In the element 31H, the slot S30 is located between the open end E20 and the closed end E21, so the slit S20 and the slot S30 are continuous.

[0093] The notch N1 formed on each side of the element 31H is formed so as to have two-fold symmetry with respect to the geometric center 40H. Note that, since the outer periphery of the element 31H in Fig. 14 has a square shape, the notch N1 consequently has four-fold symmetry with respect to the geometric center 40H.

[0094] <<Antenna Device 10I>> Fig. 15 is a plan view of the antenna device 101. The antenna device 10I includes a base plate 30, an element 31I, and a feeder line 32, similar to the antenna device 10A of Fig. 1 and the antenna device 10H of Fig. 13 .

[0095] The element 31I has a feed point 41I located in the +X direction from the geometric center 40I of the element 31I, and four notches N2.

[0096] The notch N2 includes a slit S20 and slots S30 and S31. The shape of the slot S31 is a rectangle with a width W31 and a length L31 in a plan view. Here, the length L31 is shorter than the length L30, but, for example, the length L31 and the length L30 may be equal. In other words, the length L30 may be equal to or greater than the length L31. The slot S31 corresponds to "at least one second opening," the length L30 corresponds to the "first length," and the length L31 corresponds to the "second length."

[0097] The slot S31 is located between the slot S30 and the geometric center 40I. As shown in Fig. 15, in the notch N2 formed on the -Y side of the element 31I, the direction in which the slot S31 extends is the X direction. In the other three notches N2, the slot S31 is also formed so that the direction in which the slit S20 extends and the direction in which the slot S31 extends intersect.

[0098] In the element 31I, the slot S31 is located between the open end E20 and the closed end E21, so the slit S20 is continuous with the slots S30 and S31. The notch N2 is formed so as to be two-fold symmetric (and four-fold symmetric) with respect to the geometric center 40I. <<Antenna Device 10J>> Fig. 16 is a plan view of the antenna device 10J. Similar to the antenna device 10A of Fig. 1 and the antenna device 10H of Fig. 13, the antenna device 10J includes a ground plate 30, an element 31J, and a feeder line 32.

[0099] The element 31J has a feed point 41J located in the +X direction from the geometric center 40J of the element 31J, and four notches N3.

[0100] The notch N3 includes the slit S20 and the slots S30 to S32. The shape of the slot S32 is a rectangle with a width W32 and a length L32 in a plan view. Here, the length L32 is shorter than the length L31, but for example, the length L32 and the length L31 may be equal. The slot S32 corresponds to "at least one second opening."

[0101] The slot S32 is located between the slot S30 and the geometric center 40J. Furthermore, as shown in Fig. 16, in the notch N3 formed on the -Y side of the element 31J, the direction in which the slot S32 extends is the X direction. In the other three notches N3, the slot S32 is also formed so that the direction in which the slit S20 extends and the direction in which the slot S32 extends intersect.

[0102] In the element 31J, the slot S32 is located between the open end E20 and the closed end E21, so the slit S20 and the slots S30 to S32 are continuous. The notch N3 is formed so as to be two-fold symmetric (and four-fold symmetric) with respect to the geometric center 40J. <<Antenna Device 10K>> Figure 17 is a plan view of the antenna device 10K. Similar to the antenna device 10A of Figure 1 and the antenna device 10H of Figure 14, the antenna device 10K includes a ground plate 30, an element 31K, and a feeder line 32.

[0103] The element 31K has a feed point 41K located in the +X direction from the geometric center 40K of the element 31K, and four notches N4.

[0104] The notch N4 includes the slit S20 and the slots S30 to S33. The shape of the slot S33 is a rectangle with a width W33 and a length L33 in a plan view. Here, the length L33 is shorter than the length L32, but, for example, the length L33 and the length L32 may be equal. The slot S33 corresponds to "at least one second opening."

[0105] Slot S33 is located between slot S30 and geometric center 40K. As shown in the enlarged view of Figure 17, in notch N4 formed on the -Y side of element 31K, the direction in which slot S33 extends is the X direction. In the other three notches N4, slots S32 are also formed so that the extension direction of slit S20 and the extension direction of slot S33 intersect.

[0106] In the element 31K, the slot S33 is located between the open end E20 and the closed end E21, so the slit S20 and the slots S30 to S33 are continuous. In addition, the notch N4 is formed so as to be two-fold symmetric (and four-fold symmetric) with respect to the geometric center 40K.

[0107] <<Characteristics of Elements 31H to 31K>> Fig. 18 is a diagram showing the relationship between the voltage standing wave ratio and frequency of elements 31A, 31B, and 31H to 31K. For reference, Fig. 18 also shows the characteristics of element 31A without a slot or slit, and element 31B without a slot.

[0108] Here, the width W20 of the slit S20 is 1 mm, and the length L20 is 12.75 mm. Furthermore, the distance M is 1 mm, the widths W30 to W33 of the slots S30 to S33 are each 1 mm, and the distance between each of the slots S30 to S33 in the Y direction is 1 mm. Furthermore, the length L30 is 18.55 mm, the length L31 is 14.55 mm, the length L32 is 10.55 mm, and the length L33 is 6.55 mm.

[0109] 18, a new resonance due to slots S30 to S33 occurs in a frequency band (approximately 2.25 GHz to 2.6 GHz in this case) higher than the desired 1.5 GHz band. Furthermore, as the number of slots in elements 31H to 31K increases, the electrical length of the target element increases, and the frequency at which the voltage standing wave ratio is minimized shifts to a lower frequency.

[0110] In particular, among elements 31H to 31K, the frequency at which the voltage standing wave ratio becomes minimum in element 31K is lower than 1.2 GHz. In this way, by using notch N4, which has a large notch area and a long perimeter among notches N1 to N4, the current flowing through the element can be further diverted, and the electrical length of element 31K can be increased.

[0111] == ...

[0112] The element 31L has a feed point 41L located in the +X direction from the geometric center 40L of the element 31L, and four notches N5.

[0113] The notch N5 includes two slits S20 and slots S30 to S33. The two slits S20 extend from positions symmetrical with respect to the center of each side of the element 31L.

[0114] In the element 31L, the two slits S20 are continuous with the slots S30 to S33. The notch N5 is formed so as to have two-fold symmetry (and four-fold symmetry) with respect to the geometric center 40L.

[0115] <<Antenna device 10M>> Fig. 20 is a plan view of the antenna device 10M. Similar to the antenna device 10K of Fig. 17, the antenna device 10M is configured to include a base plate 30, an element 31M, and a feeder line 32. As will be described in detail later, the element 31M of the antenna device 10M has a notch N6 formed therein, which is a modification of the notch N4 of the antenna device 10K.

[0116] The element 31M has a feed point 41M located in the +X direction from a geometric center 40M of the element 31M, and four notches N6.

[0117] The notch N6 includes three slits S20 and slots S30 to S33. The three slits S20 extend from the center of each side of the element 31M and from positions symmetrical to the center of each side.

[0118] In the element 31M, the three slits S20 are continuous with the slots S30 to S33. The notch N6 is formed so as to have two-fold symmetry (and four-fold symmetry) with respect to the geometric center 40M.

[0119] <<Characteristics of Elements 31L and 31M>> Fig. 21 is a diagram showing the relationship between the voltage standing wave ratio and frequency of the elements 31A, 31K, 31L, and 31M. For reference, Fig. 21 also shows the characteristics of the element 31A and the element 31K that do not have slots or slits.

[0120] 21, a new resonance due to the slots S30 to S33 occurs in a frequency band (here, approximately 2.25 GHz to 2.75 GHz) higher than the desired 1.5 GHz band. In addition, since the number of slits S20 is one, the general current path of element 31K is longer than the general current paths of elements 31L and 31M, and therefore the corresponding frequency of element 31K is the lowest.

[0121] <<Antenna device 10N>> Fig. 22 is a plan view of the antenna device 10N. Similar to the antenna device 10J of Fig. 16, the antenna device 10N is configured to include a base plate 30, an element 31M, and a feeder line 32. As will be described in detail later, the element 31N of the antenna device 10N has a notch N7 formed therein, which is a modification of the notch N3 of the antenna device 10J.

[0122] The element 31N has a feed point 41N located in the +X direction from a geometric center 40N of the element 31N, and four notches N7.

[0123] The notch N7 includes a slit S2 and slots S30 to S32. The slit S2 is the slit formed in the element 31F shown in FIG. 10 as described above. In the element 31N, the slit S2 is continuous with the slots S30 to S32. The notch N7 is formed so as to have two-fold symmetry (and four-fold symmetry) with respect to the geometric center 40N.

[0124] <<Characteristics of Element 31N>> Fig. 23 is a diagram showing the relationship between the voltage standing wave ratio and frequency of the elements 31A, 31J, and 31N. For reference, Fig. 23 also shows the characteristics of the element 31A and the element 31J that do not have slots or slits.

[0125] As shown in Fig. 23, a new resonance occurs due to the slots S30 to S32 in a frequency band higher than the desired 1.5 GHz band (in this case, approximately the 2.25 GHz to 2.75 GHz band). In the element 31J shown in Fig. 16, the width direction of the open end E20 of the slit S20 is the X direction. The slit S20 extends in the Y direction. Therefore, the angle between the width direction of the open end E20 and the extension direction of the slit S20 is 90°.

[0126] 23, the voltage standing wave ratio of the element 31N is approximately equal to that of the element 31J. Therefore, even if the angle between the width direction of the open end E2 and the extension direction of the slit S2 in the element 31N is an acute angle (θ=30°), the same results as those in the element 31J can be obtained.

[0127] <<Antenna device 10P>> Fig. 24 is a plan view of the antenna device 10P. Similar to the antenna device 10K of Fig. 17, the antenna device 10P is configured to include a ground plate 30, an element 31P, and a feeder line 32. As will be described in detail later, the element 31P of the antenna device 10P has a notch N8 including two slots located close to each side of the element 31P.

[0128] The element 31P has a feed point 41P located in the +X direction from the geometric center 40P of the element 31P, and four notches N8.

[0129] The notch N8 includes notches N20 and N21 corresponding to the two slots. The notch N20 includes slots S30 and S31 and a slot S50. The shape of the slot S50 is a rectangle with a length L50 and a width W50. The slot S50 also connects the slots S30 and S31.

[0130] The notch N21 includes slots S32, S33 and a slot S51. The shape of the slot S51 is a rectangle with a length L51 and a width W51. The slot S51 also connects the slots S32 and S33.

[0131] The shape of the notch N8 is similar to the shape of the notch N4 of the element 31K in FIG. 17, so the element 31P having the notch N8 can also lower the corresponding frequency of the element 31P, similar to the element 31K.

[0132] <<Antenna device 10Q>> Fig. 25 is a plan view of antenna device 10Q. Similar to antenna device 10P in Fig. 24, antenna device 10Q is configured to include a ground plate 30, element 31Q, and feeder line 32. As will be described in detail later, element 31PQ of antenna device 10Q has a notch N9 including a slit and a slot that is not continuous with the slit at a position close to each side of element 31Q.

[0133] The element 31Q has a feed point 41Q located in the +X direction from the geometric center 40Q of the element 31Q, and four notches N9.

[0134] The notch N9 includes a slit S60 and a notch N21 corresponding to the slot. The shape of the slit S60 is a rectangle with a length L60 and a width W60. In this example, the slit S60 is formed in the center of each side of the element 31Q, but the length L60 is adjusted so that the slit S60 and the notch N21 are not continuous.

[0135] Even with such a notch N21, the electrical length of the element 31Q can be increased, and the frequency that the element 31Q can accommodate can be lowered. Note that the slit S60 corresponds to the "notch portion," and the notch N21 corresponds to the "first opening."

[0136] Antenna Device of the Present Embodiment The configuration of the antenna device of the present embodiment using the various elements described above will be described below. Note that in the following embodiment, some of the multiple elements described above are used as examples, but the antenna device of the present embodiment may use elements other than the exemplified elements.

[0137] <<Antenna device similar to antenna device 10A>> By reducing the size of the above-mentioned elements 31D to 31F, 31H to 31N, 31P, and 31Q and applying them to an antenna device similar to antenna device 10A of FIG. 1, it is possible to miniaturize the antenna device without increasing the number of parts such as capacitors, which are lumped constant elements.

[0138] <<Antenna Device 100A>> Fig. 26 is a perspective view of the antenna device 100A of this embodiment, and Fig. 27 is an exploded perspective view of the antenna device 100A. Also, Fig. 28 is a schematic cross-sectional view of the antenna device 100A taken along line AA in Fig. 26.

[0139] The antenna device 100A is an air-gap type metal plate antenna, and is configured to include a circuit board 110, an element 111A, and two feeder lines 112. The circuit board 110 is a dielectric plate material, made of, for example, glass epoxy resin, on whose upper surface (surface facing the +Z direction) and lower surface (surface facing the -Z direction) conductive patterns 120 and 121 are formed, respectively.

[0140] The pattern 120 is a component that functions as a ground in the antenna device 100A, and corresponds to a so-called base plate. The shape of the pattern 120 in this embodiment is a substantially square with four notched corners and a slightly rounded shape, but is not limited to this and may be any shape that functions as a ground. Note that an "approximate square" is included in the above-mentioned "approximate quadrilateral," and the pattern 120 corresponds to a "ground portion."

[0141] The pattern 121 is a member that functions as a ground for electronic components (not shown) such as an amplifier that are attached to the circuit board 110 .

[0142] The element 111A is a conductive member (a so-called radiating element) that receives radio waves in a desired frequency band. The element 111A is formed of a metal plate and includes a flat portion 130A and a plurality of legs 131A. Details of the element 111A will be described later.

[0143] The power supply line 112 is a wiring connected to a power supply point 141A (described later) of the planar portion 130A. The power supply line 112 of this embodiment connects the element 111A to an amplifier (not shown) attached to the lower surface of the circuit board 110 via a through hole in the circuit board 110.

[0144] <Details of Element 111A> The planar portion 130A is a portion of the element 111A that is positioned to face the upper surface of the circuit board 110 (i.e., the pattern 120). The shape of the outer edge of the planar portion 130A is a substantially square with four corners cut out in a plan view of the planar portion 130A viewed from the +Z direction. However, the shape of the planar portion 130A in a plan view may be, for example, a substantially quadrilateral such as a rectangle, a circle, or an ellipse.

[0145] Two feed points 141A are provided on the planar portion 130A, located in the −X direction and the −Y direction from a geometric center 140A of the planar portion 130A. A feed line 112 is connected to each of the two feed points 141A. Note that, although a two-feed system using two feed lines 112 is employed in this embodiment, a one-feed system may also be used, for example.

[0146] Furthermore, leg portions 131A extend from each of the four outer edges of the flat portion 130A toward the circuit board 110 in the -Z direction. The element 111A has a notch N4 on each of both sides in the X direction and on each of both sides in the Y direction. Therefore, four notches N4 are formed in the element 111A of this embodiment.

[0147] As described above, "both sides of the element in the X direction" corresponds to the region of the element in the +X direction from the geometric center and the region of the element in the -X direction from the geometric center. Also, "both sides of the element in the Y direction" corresponds to the region of the element in the +Y direction from the geometric center and the region of the element in the -Y direction from the geometric center.

[0148] In element 111A, the "region in the predetermined direction" includes not only flat portion 130A but also leg portion 131A, so notch N4 is formed from the -Z side end of leg portion 131A to flat portion 130A. In this embodiment, slit S20 of notch N4 is formed from the -Z side end of leg portion 131A to flat portion 130A. Note that slots S30 to S33 of notch N4 are formed in flat portion 130A.

[0149] In addition, in the element 111A, the notch N4 is formed to have two-fold symmetry with respect to the geometric center 140A so that the current in the X direction and the current in the Y direction are balanced. Note that, since the shape of the outer edge of the flat portion 130A is approximately square, the notch N4 consequently has four-fold symmetry with respect to the geometric center 140A.

[0150] In this embodiment, all of the slots S30 to S33 of the notch N4 are formed in the flat portion 130A, but this is not limited thereto, and some may be formed in the leg portion 131A. Also, all of the notch N4 may be formed in the leg portion 131A. Even in such a case, the notch N4 has two-fold symmetry and four-fold symmetry with respect to the geometric center 140A.

[0151] In this case, the electrical length from feed point 141 to the outer edge of element 111A (i.e., the end on the -Z side of leg 131A) can be increased, thereby making it possible to reduce the size of element 111A. Therefore, by using such element 111A, it is possible to reduce the size of antenna device 100A without increasing the number of parts such as capacitors, which are lumped constant elements.

[0152] The end on the -Z side of leg 131A corresponds to the "end on the ground side", and notch N4 corresponds to the "notch".

[0153] <Parasitic Capacitor> In this embodiment, in a plan view, the outer edge of the pattern 120 of the circuit board 110 is located inside the outer edge of the planar portion 130A. Therefore, when the element 111A is attached to the circuit board 110, the ends of the four legs 131A are positioned so as to surround the outer edge of the pattern 120. The element 111A is fixed to the circuit board 110 with, for example, an adhesive or double-sided tape.

[0154] In this embodiment, as shown in FIG. 28, the legs 131A extend from each side of the planar portion 130A so that the -Z side ends of the legs 131A are capacitively coupled (i.e., electrically coupled) to the pattern 120.

[0155] Therefore, a parasitic capacitor C with a relatively large capacitance is generated between the -Z side end of the leg 131A and the pattern 120. This allows the antenna device 100A to be further miniaturized. Specifically, in this embodiment, the length of one side of the approximately square planar portion 130A in the antenna device 100A can be set to, for example, 30 mm.

[0156] 28 abuts against the circuit board 110, but is not limited thereto. For example, the leg 131A may penetrate the circuit board 110, with the end of the leg 131A positioned to surround the outer edge of the pattern 121. Alternatively, the leg 131A may have a curved portion such that the end faces the outer edge of the pattern 120 or 121, or may have a curved portion such that the end faces the opposite side from the outer edge of the pattern 120 or 121. Even in this case, a parasitic capacitor C with a relatively large capacitance is generated between the part of the leg 131A closest to the pattern 120 or 121 and the pattern 120 or 121, thereby enabling the antenna device 100A to be further miniaturized.

[0157] <<Antenna device 100B>> Fig. 29 is an exploded perspective view of the antenna device 100B. The antenna device 100B is a metal plate antenna similar to the antenna device 100A, and is configured to include a circuit board 110, an element 111B, and two feeder lines 112. Here, the antenna device 100B and the antenna device 100A have the same configuration except for the element 111B, so only the element 111B will be described.

[0158] Like element 111A, element 111B includes a flat portion 130B and a plurality of leg portions 131B. Two feed points 141B are provided on flat portion 130B, which are located in the −X direction and the −Y direction from a geometric center 140B of flat portion 130B. Note that geometric center 140B and the two feed points 141B are similar to geometric center 140A and the two feed points 141A.

[0159] Element 111B has two slits S1 (i.e., "multiple cutout portions") on each of both sides in the X direction and both sides in the Y direction. Comparing element 111B with element 111A, element 111B is the same except that two slits S1 are provided instead of cutout N4. Slits S1 are formed from the -Z side end of leg portion 131B to flat portion 130B.

[0160] Therefore, by using such an element 111B, it is possible to reduce the size of the antenna device 100B without increasing the number of parts such as capacitors that are lumped constant elements.

[0161] <<Antenna device 100C>> Figure 30 is an exploded perspective view of the antenna device 100C. The antenna device 100C is a metal plate antenna similar to the antenna device 100A, and is configured to include a circuit board 110, an element 111C, and two feeder lines 112. Here, the antenna device 100C and the antenna device 100A have the same configuration except for the element 111C, so only the element 111C will be described.

[0162] Like element 111A, element 111C includes a planar portion 130C and a plurality of leg portions 131C. Two feed points 141C are provided on planar portion 130C, which are located in the −X direction and the −Y direction from a geometric center 140C of planar portion 130C. Note that geometric center 140C and two feed points 141C are similar to geometric center 140A and two feed points 141A, respectively.

[0163] Element 111C has slits S2 (i.e., "cutout portions") on both sides in the X direction and both sides in the Y direction. Element 111C is the same as element 111A except that slits S2 are provided instead of cutouts N4. Slits S2 are formed from the -Z side end of leg portion 131C to flat portion 130C.

[0164] Therefore, by using such an element 111C, it is possible to reduce the size of the antenna device 100C without increasing the number of parts such as capacitors that are lumped constant elements.

[0165] As described above, the antenna devices 100A to 100C have been described as air-gap type metal plate antennas, but the gap between the elements 111A to 111C and the circuit board 110 is not limited to air. For example, instead of air, an insulating member may be placed between the elements 111A to 111C and the circuit board 110. Alternatively, for example, a structure may be used in which a resin holder is placed between the elements 111A to 111C and the circuit board 110, and the resin holder supports the elements 111A to 111C. As another embodiment, a structure in which a resin spacer is placed between the elements 111A to 111C and the circuit board 110 may also be used.

[0166] <<Antenna Device 200A>> FIG. 31 is a perspective view of the antenna device 200A of this embodiment, and FIG. 32 is an exploded perspective view of the antenna device 200A.

[0167] Antenna device 200A is a device including a so-called patch antenna, and is configured to include circuit board 210, dielectric 211, element 212A, ground conductor 213, and feed pin 214. Circuit board 210 is a dielectric plate material on which electronic components (not shown) such as an amplifier are mounted, and is made of, for example, glass epoxy resin.

[0168] The dielectric 211 is a substantially quadrilateral plate-like member made of a dielectric material such as ceramic, etc. However, the shape of the dielectric 211 is not limited to a substantially quadrilateral shape, and may be, for example, a circle or an ellipse.

[0169] An element 212A is formed on the upper surface (surface in the +Z direction) of the dielectric 211, and a ground conductor 213 that functions as the ground of the antenna device 200A is formed on the lower surface. Therefore, the element 212A is positioned to face the ground conductor 213 with the dielectric 211 interposed therebetween. The lower surface of the dielectric 211 is attached to the circuit board 210 by, for example, adhesive, double-sided tape, solder, or the like (not shown). The ground conductor 213 corresponds to the "ground portion."

[0170] The element 212A is a conductive member (a so-called radiating element) that receives radio waves in a desired frequency band. Here, the element 212 is, for example, a square conductive pattern, but is not limited to this and may be a pattern of another shape, such as a substantially quadrilateral, a circle, or an ellipse.

[0171] A hole 222 into which a feed pin 214 (described later) is inserted is formed at the geometric center of the element 212A. The element 212A also has a notch N4 on each of both sides in the X direction and on each of both sides in the Y direction. The notch N4 formed from each side of the element 212A corresponds to a "notch portion, a first opening, and at least one second opening."

[0172] Furthermore, the notch N4 formed on each side of the element 212A is formed so as to have two-fold symmetry with respect to the geometric center of the element 212A (here, the hole 222). Note that, since the shape of the outer edge of the element 212A in Fig. 31 is square, the notch N4 consequently has four-fold symmetry with respect to the geometric center of the element 212A.

[0173] The power supply pin 214 is inserted into the hole 222 of the element 212A, the hole 221 of the dielectric 211, the hole 223 of the ground conductor 213, and the hole 220 of the circuit board 210, and is connected to an electronic component (not shown) such as an amplifier mounted on the lower surface of the circuit board 210.

[0174] In this antenna device 200A, even if the size of the element 212A is reduced, the electrical length of the element 212A can be set to a length corresponding to a desired frequency. Therefore, by using this element 212A, the antenna device 200A can be miniaturized without increasing the number of parts such as capacitors, which are lumped constant elements.

[0175] <<Antenna Device 200B>> Figure 33 is an exploded perspective view of antenna device 200B. Like antenna device 200A, antenna device 200B is a device that includes a patch antenna, and is configured to include a circuit board 210, a dielectric 211, an element 212B, a ground conductor 213, and a feed pin 214. Here, the antenna device 200B and the antenna device 200A have the same configuration except for element 212B, so only element 212B will be described.

[0176] Element 212B is a conductive pattern similar to element 212A. However, element 212B has two slits S1 (i.e., "multiple cutout portions") on each side in the X direction and on each side in the Y direction. Comparing element 212B with element 212A, element 212B is the same except that two slits S1 are provided instead of cutout N4. Therefore, antenna device 200B using such element 212B can also be miniaturized, similar to antenna device 200A.

[0177] <<Antenna Device 200C>> Figure 34 is an exploded perspective view of antenna device 200C. Like antenna device 200A, antenna device 200C is a device that includes a patch antenna, and is configured to include circuit board 210, dielectric 211, element 212C, ground conductor 213, and feed pin 214. Here, since the configuration of antenna device 200C is the same as that of antenna device 200A except for element 212C, only element 212C will be described.

[0178] Element 212C is a conductive pattern similar to element 212A. However, element 212C has slits S2 (i.e., "cutout portions") on both sides in the X direction and both sides in the Y direction. Comparing element 212C with element 212A, element 212C is the same except that slits S2 are provided instead of cutouts N4. Therefore, antenna device 200C using such element 212C can also be miniaturized, similar to antenna device 200A.

[0179] <<Antenna Device 200D>> Figure 35 is a perspective view of antenna device 200D. Like antenna device 200A, antenna device 200D is a device that includes a patch antenna, and is configured to include a circuit board 210, a dielectric 215, an element 212D, a ground conductor (not shown), and a feed pin 214. Here, antenna device 200D and antenna device 200A have the same configuration except for element 212D, dielectric 215, and ground conductor.

[0180] Dielectric 215 is a member made of a dielectric material such as ceramic and having a circular plate shape in a plan view. A circular ground conductor (not shown) is formed on the −Z direction surface of dielectric 215, and element 212D is formed on the +Z direction surface. Note that the circular ground conductor and element 212D are, for example, conductive patterns similar to element 212A.

[0181] Element 212D has a notch N4 on each of both sides in the X direction and on each of both sides in the Y direction. The four notches N4 of element 212D are formed so as to be 2-fold symmetric with respect to the geometric center of element 212A (here, feed pin 214). Note that, because the outer edge of element 212D in FIG. 35 is circular, notches N4 are consequently 4-fold symmetric with respect to the geometric center of element 212D.

[0182] Such element 212D also has a long electrical length, so that antenna device 200D using element 212D can be miniaturized in the same way as antenna device 200A.

[0183] Here, the notches formed on both sides of element 212D in the X direction and both sides of element 212D in the Y direction are not limited to notch N4, and may be any notch that can increase the electrical length of element 212D. Furthermore, the shape of element 212D in a plan view may be elliptical.

[0184] <<Antenna Device 300>> Fig. 36 is an exploded perspective view of the antenna device 300. Fig. 37 is a plan view of the substrate 311, and Fig. 38 is a schematic diagram of the BB cross section of the antenna device 300.

[0185] The antenna device 300 is a planar antenna device that is compatible with radio waves in two frequency bands, for example, the L1 band (1559 MHz to 1610 MHz) and the L5 band (1166 MHz to 1187 MHz) of GNSS. The antenna device 300 includes a base plate 310, substrates 311 and 312, a shield cover 313, a base 314, a seal 315, and a case 316.

[0186] The ground plate 310 is a metal member that functions as the ground of the antenna device 300, and corresponds to a "ground portion." The ground plate 310 has a substantially quadrilateral opening 400 formed therein, into which a feeder line (not shown) from the substrate 311 and the like are inserted.

[0187] The substrate 311 is a dielectric plate material having an approximately square shape with the four corners cut out when viewed from above in the +Z direction. The substrate 311 is made of, for example, glass epoxy resin, and elements 320 and 321a to 321d are formed on the upper surface (surface in the +Z direction) of the substrate 311, as shown in Fig. 37. However, the shape of the substrate 311 in the plan view may be, for example, an approximately quadrilateral such as a rectangle, a circle, or an ellipse.

[0188] The element 320 is a conductive pattern that receives radio waves in the L5 frequency band. The shape of the outer edge of the element 320 is approximately square in a plan view of the element 320 viewed from the +Z direction. However, the shape of the element 320 in a plan view may be, for example, an approximately quadrilateral such as a rectangle, a circle, or an ellipse.

[0189] The element 320 is provided with two feed points 331 located in the −X direction and the −Y direction from a geometric center 330 of the element 320. A feed line (not shown) is connected to each of the two feed points 331. Note that although a two-feed system is employed in this embodiment, a one-feed system or a four-feed system may also be used.

[0190] Three slits S1 are formed on each of the four sides of the outer edge of the element 320. Specifically, the element 320 has three slits S1 on each of both sides in the X direction and on each of both sides in the Y direction. The three slits S1 correspond to a plurality of cutouts.

[0191] In the element 320, the three slits S1 are formed to have two-fold symmetry with respect to the geometric center 330 so that the current in the X direction and the current in the Y direction are balanced. Since the shape of the outer edge of the element 320 is approximately square, the three slits S1 are consequently formed to have four-fold symmetry with respect to the geometric center 330.

[0192] Elements 321a to 321d are four parasitic elements arranged around element 320. Here, elements 321a to 321d are arranged at positions spaced outward from the outer edge of element 320 and capacitively coupled to element 320. Specifically, each of elements 321a to 321d is fed by capacitively coupling with element 320, and functions as an element of the desired frequency. Elements 321a to 321d are arranged at positions spaced apart from both sides of element 320 in the X direction and both sides of element 320 in the Y direction. Elements 321a to 321d are formed to be two-fold symmetric with respect to geometric center 330. Elements 321a to 321d shown in FIGS. 36 and 37 are consequently four-fold symmetric with respect to geometric center 330.

[0193] Element 321a is a parasitic element located on the +X side of element 320, and has a length along the Y direction and a predetermined width. The length of element 321a corresponds to radio waves in the L1 band frequency band. Here, "a length corresponding to radio waves in the L1 band frequency band" refers to, for example, a length on substrate 311 that corresponds to half the wavelength of a typical radio wave in the L1 band frequency band.

[0194] Each of elements 321b to 321d is a parasitic element having the same shape as element 321a. Element 321b is located on the +Y side of element 320. Element 321c is located on the −X side of element 320, and element 321d is located on the −Y side of element 320.

[0195] As described above, each of the elements 321b to 321d is capacitively coupled with the element 320, and therefore the elements 320 and 321b to 321d correspond to radio waves in the L1 and L5 frequency bands.

[0196] In this embodiment, the elements 321a to 321d have the same shape. Therefore, any of the elements 321a to 321d is formed to be dyad-symmetric with respect to the geometric center 330, but this is not limiting. Specifically, the elements 321a to 321d are only required to be arranged at positions where they are capacitively coupled with the element 320 and have a shape that can accommodate radio waves in the L1 band frequency band.

[0197] Furthermore, it is sufficient that the two elements positioned on either side of element 320 have the same length and shape. For example, elements 321a and 321c shown in Figure 37 may be formed to have a first length, and elements 321b and 321d may be formed to have a second length. Furthermore, elements 321a to 321d may be formed to have different shapes and lengths. In this case, elements 321a to 321d can be made to correspond to different frequency bands, and therefore an antenna device including element 320 can be made to correspond to radio waves in multiple frequency bands.

[0198] The element 321a may include two or more element components. In other words, the element 321a may be divided into a plurality of parts. The same applies to the elements 321b to 321d.

[0199] The substrate 312 is a circuit board on which electronic components (not shown), such as amplifiers and capacitors, are attached on the -Z side surface. A power feed line (not shown) is connected to the +Z side surface of the substrate 312. The shield cover 313 is a metal member that protects the amplifiers and other electronic components from noise and the like. In the antenna device 300, the substrate 312 and the shield cover 313 are attached to the -Z side of the base plate 310, as shown in the schematic cross-sectional view of FIG.

[0200] The base 314 is a so-called antenna base of the antenna device 300, and is made of resin. An opening 401 formed in the base 314 is closed with a seal 315. The case 316 covers the base 314 from the +Z side, and houses the base plate 310, the substrates 311 and 312, etc.

[0201] In such antenna device 300, element 320 has three slits S1 on each of both sides in the X direction and both sides in the Y direction. Therefore, the electrical length of element 320 is longer than in a configuration that does not have three slits S1. Therefore, when supporting a desired frequency band, antenna device 300 that uses element 320 can be made more compact than in a configuration that does not have three slits S1.

[0202] Furthermore, element 320 is compatible with radio waves in the L5 frequency band, and elements 321a to 321d are compatible with radio waves in the L1 frequency band, so antenna device 300 can be compatible with radio waves in both the L1 and L5 frequency bands.

[0203] <<Antenna Device 101A>> Figure 39 is an exploded perspective view of the antenna device 101A. The antenna device 101A is an antenna device that supports radio waves in two frequency bands, for example, the L1 and L5 bands in GNSS. The antenna device 101A is an air-gap type metal plate antenna, and is configured to include an element 111A, two feeder lines 112, and a circuit board 150.

[0204] 27, the antenna device 101A has the same configuration as the antenna device 100A shown in Fig. 27 except for the circuit board 150. Therefore, the circuit board 150 will be mainly described here.

[0205] The circuit board 150 is a dielectric substrate having conductive patterns 120, 122a to 122d formed on its upper surface (surface in the +Z direction). The circuit board 150 has a conductive pattern 121 (similar to that shown in FIG. 28) formed on its lower surface (surface in the -Z direction).

[0206] Patterns 122a to 122d are four parasitic elements arranged around pattern 120. Here, each of patterns 122a to 122d is arranged at a position spaced outward from the outer edge of pattern 120 and capacitively coupled to leg 131A of element 111A. Specifically, each of patterns 122a to 122d is fed by capacitively coupling with element 111A and functions as an element of a desired frequency. Each of patterns 122a to 122d is arranged at a position spaced apart from both sides of pattern 120 in the X direction and a position spaced apart from both sides of pattern 120 in the Y direction. Furthermore, patterns 122a to 122d are formed so as to be dyad-symmetric with respect to geometric center 140A of element 111A when viewed from the Z direction.

[0207] Pattern 122a is a quadrilateral parasitic element located on the +X side of pattern 120, and has a length along the Y direction and a predetermined width. The length of pattern 122a corresponds to radio waves in the L1 frequency band.

[0208] Each of patterns 122b to 122d is a parasitic element having the same shape as pattern 122a. Pattern 122b is located on the +Y side of pattern 120. Pattern 122c is located on the −X side of pattern 120, and pattern 122d is located on the −Y side of pattern 120.

[0209] As described above, each of the patterns 122a to 122d is capacitively coupled to the leg 131A of the element 111A, and therefore the antenna device 101A is compatible with radio waves in the L1 and L5 frequency bands.

[0210] The patterns 122a to 122d may be arranged at positions where they are capacitively coupled to the element 320, and may have a shape that is compatible with radio waves in the L1 band frequency band. For example, although the patterns 122a to 122d each have a quadrilateral shape, this is not limiting. Specifically, as shown in pattern 123a, the patterns may have a meandering shape as long as they are compatible with radio waves in the L1 band frequency band.

[0211] Although not shown in Figure 39 for convenience, a pattern similar to pattern 123a may be used instead of the four patterns 122a to 122d. All of patterns 122a to 122d may be meander-shaped, or only some of them may be meander-shaped. By using such meander-shaped patterns, it is possible to further miniaturize the circuit board 150. Furthermore, if the shapes of patterns 122a to 122d are different, they can also be made to correspond to different frequency bands.

[0212] <<Antenna Devices 101B, 101C>> Figure 40 is an exploded perspective view of the antenna devices 101B and 101C. The antenna devices 101B and 101C are antenna devices that are compatible with radio waves in two frequency bands, for example, the L1 and L5 bands in GNSS. The antenna device 101B is configured to include an element 111B, two feed lines 112, and a circuit board 150. The antenna device 101C is configured to include an element 111C, two feed lines 112, and a circuit board 150. These antenna devices 101B and 101C can also achieve the same effects as the antenna device 101A.

[0213] <<Antenna Device 201>> Fig. 41 is a diagram for explaining the antenna device 201. The upper part of Fig. 41 is a plan view of the antenna device 201, and the lower part of Fig. 41 is a perspective view of the antenna device 201.

[0214] Antenna device 201 is a device including a patch antenna, similar to antenna device 200D of Fig. 35, and is configured to include circuit board 210, elements 212D, 230a to 230d, a ground conductor (not shown), feed pin 214, and dielectric 215. Here, antenna device 201 and antenna device 200D have the same configuration except for elements 230a to 230d.

[0215] Elements 230a to 230d are four parasitic elements arranged around element 212D on the +Z-direction surface of dielectric 215. Here, elements 230a to 230d are each arranged at a position spaced outward from the outer edge of element 212D and at a position where they are capacitively coupled to element 212D. Specifically, elements 230a to 230d are each arranged at a position spaced apart from both sides of element 212D in the X direction and a position spaced apart from both sides of element 212D in the Y direction. Furthermore, elements 230a to 230d are formed so as to be dyad-symmetric with respect to the geometric center of element 212D when viewed from the Z direction.

[0216] Element 230a is a parasitic element having an arc shape located on the +X side of element 212D. The length of element 230a corresponds to the radio waves in the L1 band frequency band.

[0217] Elements 230b to 230d are each a parasitic element having the same shape as element 230a. Element 230b is located on the +Y side of element 212D. Element 230c is located on the −X side of element 212D, and element 230d is located on the −Y side of element 212D.

[0218] As described above, each of the elements 230a to 230d is capacitively coupled to the element 212D. Therefore, the antenna device 201D is compatible with radio waves in the L1 and L5 frequency bands. Furthermore, each of the elements 230a to 230d is dyad-symmetric with respect to the geometric center of the element 212D.

[0219] <<Antenna Device 202>> Figure 42(a) is a perspective view for explaining the antenna device 202. The antenna device 202 is a device that includes a patch antenna, similar to the antenna device 201 of Figure 41, and is configured to include a circuit board 210, elements 212D, 231a to 231d, a ground conductor (not shown), a feed pin 214, and a dielectric 215. The antenna device 202 and the antenna device 201 have the same configuration except for the elements 231a to 231d.

[0220] Elements 231a to 231d are four parasitic elements patterned on the side surface of dielectric 215. Here, each of elements 231a to 231d is formed at a position where it is capacitively coupled with element 212D.

[0221] Element 231a is a rectangular parasitic element located on the +X side of the side surface of dielectric 215. The length of element 231a corresponds to the radio waves in the L1 band frequency band.

[0222] Elements 231b to 231d are each a parasitic element having the same shape as element 231a. Element 231b is located on the +Y side of the side of dielectric 215. Element 231c is located on the −X side of the side of dielectric 215, and element 231d is located on the −Y side of the side of dielectric 215.

[0223] As described above, each of the elements 231a to 231d is capacitively coupled to the element 212D. Furthermore, each of the elements 231a to 231d is dyad-symmetric with respect to the geometric center of the element 212D. Therefore, the antenna device 201D is compatible with radio waves in the L1 and L5 frequency bands.

[0224] <<Antenna Device 203>> Figure 42(b) is a perspective view for explaining antenna device 203. Like antenna device 201 in Figure 41, antenna device 203 is a device that includes a patch antenna, and is configured to include circuit board 210, elements 212D, 232a to 232d, a ground conductor (not shown), feed pin 214, and dielectric 215. Here, antenna device 203 and antenna device 201 have the same configuration except for elements 232a to 232d.

[0225] Elements 232a to 232d are four parasitic elements patterned on the +Z side surface of circuit board 210 so as to surround dielectric 215. Here, elements 232a to 232d are each formed at a position where they are capacitively coupled with element 212D. Specifically, elements 232a to 232d are each disposed at a position spaced apart from both sides of element 212D in the X direction and a position spaced apart from both sides of element 212D in the Y direction.

[0226] The element 232a is a parasitic element having an arc shape and located on the +X side of the dielectric 215. The length of the element 232a corresponds to the radio waves in the L1 band frequency band.

[0227] Each of elements 232b to 232d is a parasitic element having the same shape as element 232a. Element 232b is located on the +Y side of dielectric 215. Element 232c is located on the −X side of dielectric 215, and element 232d is located on the −Y side of dielectric 215.

[0228] As described above, each of the elements 232a to 232d is capacitively coupled to the element 212D. Furthermore, each of the elements 232a to 232d is dyad-symmetric with respect to the geometric center of the element 212D. Therefore, the antenna device 202D is compatible with radio waves in the L1 and L5 frequency bands.

[0229] <<Antenna Device 204>> Figure 42(c) is a perspective view for explaining antenna device 204. Like antenna device 201 in Figure 41, antenna device 204 is a device that includes a patch antenna, and is configured to include circuit board 210, elements 212D, 233a to 233d, a ground conductor (not shown), feed pin 214, and dielectric 215. Here, antenna device 204 and antenna device 201 have the same configuration except for elements 233a to 233d.

[0230] Elements 233a to 233d are four parasitic elements formed on the +Z side surface of circuit board 210 so as to surround dielectric 215. Here, each of elements 233a to 233d is disposed at a position where it is capacitively coupled with element 212D. Specifically, each of elements 233a to 233d is disposed at a position spaced apart from both sides of element 212D in the X direction and a position spaced apart from both sides of element 212D in the Y direction.

[0231] The element 233a is a rod-shaped parasitic element located on the +X side of the dielectric 215. The length of the element 233a corresponds to the radio waves in the L1 band frequency band.

[0232] Each of elements 233b to 233d is a parasitic element having the same shape as element 233a. Element 233b is located on the +Y side of dielectric 215. Element 233c is located on the −X side of dielectric 215, and element 233d is located on the −Y side of dielectric 215.

[0233] As described above, each of the elements 233a to 233d is capacitively coupled to the element 212D. Furthermore, each of the elements 233a to 233d is dyad-symmetric with respect to the geometric center of the element 212D. Therefore, the antenna device 203D is compatible with radio waves in the L1 and L5 frequency bands.

[0234] In the antenna devices 201 to 204, the four parasitic elements have the same shape and are formed to be dyad-symmetric with respect to the geometric center of the element 212D, but this is not limitative. Each of the four parasitic elements needs only to be positioned so as to be capacitively coupled with the element 212D and have a shape that can handle radio waves in the L1 band frequency band.

[0235] Although the antenna devices 201 to 204 are configured to use the dielectric 215 and the element 212D that are circular in plan view, this is not limiting. For example, the dielectric 215 and the element 212D may be configured to have a quadrilateral or other shape in plan view.

[0236] Summary According to the present specification, there is provided an antenna device having the following aspects.

[0237] (Aspect 1) Aspect 1 is an antenna device comprising: a ground portion; and an element positioned so that at least a portion faces the ground portion, wherein the element has a plurality of notches on each side in a first direction and on each side in a second direction perpendicular to the first direction, and the plurality of notches are two-fold symmetric with respect to the geometric center of the element in a plan view of the element seen from a direction perpendicular to the ground portion.

[0238] According to the above-described aspect, the element 111B has two slits S1 on both sides in the X direction and on both sides in the Y direction, so that the antenna device 100B can be miniaturized without using, for example, a capacitor, which is a lumped constant element. The two slits S1 correspond to "plurality of cutout portions."

[0239] (Aspect 2) Aspect 2 is an antenna device including a ground portion and an element positioned so that at least a portion of the element faces the ground portion, the element having a notch portion on each side in a first direction and on each side in a second direction perpendicular to the first direction, the notch portions having open ends at outer edges of the element and being dyad-symmetric with respect to the geometric center of the element in a plan view of the element seen from a direction perpendicular to the ground portion, and an acute angle formed between a width direction of the open end and a direction in which the notch portion extends from the open end.

[0240] According to the above-described aspect, the element 111C has the slits S2 on both sides in the X direction and on both sides in the Y direction, so that the antenna device 100C can be miniaturized without using, for example, a capacitor, which is a lumped constant element. Note that the slits S2 correspond to "notches having open ends."

[0241] (Aspect 3) Aspect 3 is an antenna device including a ground portion and an element positioned so that at least a portion thereof faces the ground portion, wherein the element has a notch portion and a first opening on each side in a first direction and on each side in a second direction perpendicular to the first direction, the notch portion has an open end at an outer edge of the element, the first opening is positioned between the open end and a geometric center of the element in a plan view when the element is seen in a direction perpendicular to the ground portion, and the notch portion and the first opening are two-fold symmetric with respect to the geometric center in the plan view.

[0242] According to the above-described aspect, the element 111A has the notch N4 including the slit S20 and the slots S30 to S33 on both sides in the X direction and both sides in the Y direction, so that the antenna device 100A can be miniaturized without using a capacitor, which is a lumped constant element. Note that the slit S20 corresponds to a "notch portion having an open end," and the slot S30 corresponds to a "first opening."

[0243] (Aspect 4) Aspect 4 is the antenna device, wherein the notch and the first opening are continuous with each other.

[0244] According to the above-described aspect, the slits S20 and the slots S30 of the element 111A are continuous with each other, so that the electrical length of the element 111A can be increased.

[0245] (Aspect 5) Aspect 5 is the antenna device, in which the extending direction of the notch portion intersects with the extending direction of the first opening portion.

[0246] According to the above-described aspect, the surface current flowing through the element 111A has a longer path when it detours between the slit S20 and the slot S30, and therefore the electrical length of the element 111A can be increased.

[0247] (Aspect 6) Aspect 6 is an antenna device in which the element has at least one second opening on each of both sides in the first direction and on each of both sides in the second direction, and the at least one second opening is located between the first opening and the geometric center in the planar view and is two-fold symmetric with respect to the geometric center.

[0248] According to the above-described aspect, the surface current flowing through the element 111A must bypass the slot S31, thereby increasing the electrical length of the element 111A. Note that each of the slots S31 to S33 corresponds to "at least one second opening."

[0249] (Aspect 7) Aspect 7 is the antenna device, wherein the notch and the at least one second opening are continuous with each other.

[0250] According to the above-described aspect, the surface current flowing through the element 111A must bypass the slot S31 that is continuous with the slit S20, and therefore the electrical length of the element 111A can be increased.

[0251] (Aspect 8) Aspect 8 is an antenna device in which the direction in which the cutout portion extends intersects with the direction in which the at least one second opening extends, and a first length of the first opening in the direction in which the first opening extends is greater than or equal to a second length of the second opening in the direction in which the at least one second opening extends.

[0252] According to the above-described aspect, the length L30 of the slot S30 on the outer edge side of the element 111A can be made equal to or greater than the length L31 of the slot S31 on the geometric center side, thereby making it possible to increase the electrical length of the element 111A.

[0253] (Aspect 9) Aspect 9 is the antenna device, wherein the element has a planar portion that is quadrilateral in the plan view.

[0254] According to the above-described aspect, the element 111A has the planar portion 130A that is substantially square in plan view, and therefore is easier to process than elements having other shapes (e.g., elliptical shapes).

[0255] (Aspect 10) Aspect 10 is an antenna device in which the element has legs extending from each side of the planar portion toward the ground portion, and the cutout portion is formed from the end of the leg on the ground portion side to the planar portion.

[0256] According to the above-described aspect, the slit S20 is formed from the end of the leg portion 131A on the circuit board 110 side to the flat portion 130A, so that the electrical length of the element 111A can be further increased.

[0257] (Aspect 11) Aspect 11 is an antenna device in which, in the planar view, the outer edge of the ground portion is located inside the outer edge of the planar portion, and the leg portion extends from the side so that the end portion and the ground portion are electrically coupled.

[0258] According to the above-described aspect, the outer edge of the pattern 120 of the circuit board 110 is located inside the outer edge of the flat portion 130A, and the leg portion 131A extends from the side of the flat portion 130A so that the end of the leg portion 131A is capacitively coupled to the pattern 120. As a result, capacitance is generated between the element 111A and the pattern 120, so that the element 111A can be made smaller without using a capacitor as a lumped constant element. Note that the pattern 120 corresponds to a "ground portion."

[0259] (Aspect 12) Aspect 12 is an antenna device including a plurality of parasitic elements, the plurality of parasitic elements being two-fold symmetric with respect to the geometric center.

[0260] According to the above-described aspect, for example, the antenna devices 101A to 101C, 201 to 204, and 300 include an element or pattern that functions as a parasitic element, and therefore, the antenna devices 101A to 101C, 201 to 204, and 300 are compatible with radio waves in two frequency bands, the L1 and L5 bands, of the GNSS.

[0261] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof.

[0262] 10A to 10N, 10P, 10Q, 100A to 100C, 101A to 101C, 200A to 200C, 201 to 204, 300 Antenna device 30 Ground plane 31A to 31N, 31P, 31Q, 111A to 111C, 212A to 212C, 230a to 230d, 231a to 231d, 232a to 232d, 233a to 233d, 320, 321a to 321d Element 40A to 40N, 40P, 40Q, 140A to 140C Geometric center 120, 121, 122a to 122d, 123a Pattern 213 Ground conductor S1, S2, S20, S60 Slit S10, S30 to S33, S50, S51 Slots N1 to N9, N20, N21 Notches L1, L2, L10, L20, L30 to L33, L50, L51, L60, La to Lc Lengths W1, W2, W10, W20, W30 to W33, W50, W51, W60 Width

Claims

1. An antenna device comprising a ground portion and an element positioned such that at least a part thereof faces the ground portion, wherein the element has a plurality of notches on each of both sides in a first direction and on each of both sides in a second direction orthogonal to the first direction, and the plurality of notches are bilaterally symmetric with respect to the geometric center of the element in a plan view of the element as viewed from a direction orthogonal to the ground portion.

2. An antenna device comprising a ground portion and an element positioned such that at least a part thereof faces the ground portion, wherein the element has notches on each of both sides in a first direction and on each of both sides in a second direction orthogonal to the first direction, the notches have open ends at the outer edges of the element, and are bilaterally symmetric with respect to the geometric center of the element in a plan view of the element as viewed from a direction orthogonal to the ground portion, and the angle formed by the width direction of the open ends and the direction in which the notches extend from the open ends is an acute angle.

3. An antenna device comprising a ground portion and an element positioned such that at least a part thereof faces the ground portion, wherein the element has notches and first openings on each of both sides in a first direction and on each of both sides in a second direction orthogonal to the first direction, the notches have open ends at the outer edges of the element, the first openings are positioned between the open ends and the geometric center of the element in a plan view of the element as viewed from a direction orthogonal to the ground portion, and the notches and the first openings are bilaterally symmetric with respect to the geometric center in the plan view.

4. The antenna device according to claim 3, wherein the notch and the first opening are continuous.

5. The antenna device according to claim 4, wherein the direction in which the notch extends and the direction in which the first opening extends intersect.

6. The antenna device according to claim 5, wherein the element has at least one second opening at each of both sides in the first direction and at each of both sides in the second direction, and the at least one second opening is located between the first opening and the geometric center in the plan view and is symmetric about the geometric center twice. Antenna device.

7. The antenna device according to claim 6, wherein the notch and the at least one second opening are continuous. Antenna device.

8. The antenna device according to claim 7, wherein the direction in which the notch extends intersects the direction in which the at least one second opening extends, and a first length of the first opening in the direction in which the first opening extends is not less than a second length of the second opening in the direction in which the at least one second opening extends. Antenna device.

9. The antenna device according to any one of claims 1 to 8, wherein the element has a planar portion having a quadrilateral shape in the plan view. Antenna device.

10. The antenna device according to claim 9, wherein the element has legs extending from respective sides of the planar portion toward the ground portion, and the notch is formed across from an end portion on the ground portion side of the leg to the planar portion. Antenna device.

11. The antenna device according to claim 10, wherein in the plan view, an outer edge of the ground portion is inside an outer edge of the planar portion, and the leg extends from the side such that the end portion and the ground portion are electrically coupled. Antenna device.

12. The antenna device according to any one of claims 1 to 8, comprising a plurality of passive elements, and the plurality of passive elements are symmetric about the geometric center twice. Antenna device.

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