Antenna equipment

Abstract

To provide a compact antenna device capable of operating over a wide bandwidth. [Solution] The antenna device comprises a ground conductor, a feed point, a first conductor connected to the feed point and operating in a first frequency band, and a second conductor electrically coupled to the first conductor at a distance and operating in a second frequency band. The second conductor has a grounding portion connected to the ground conductor and a proximity portion closest to the first conductor. The second conductor has a convex portion in the conductor connecting the grounding portion and the proximity portion that protrudes away from the first conductor.

Description

Technical Field

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

Background Art

[0002] In recent years, a communication system that utilizes position information and improves security through ultra-wideband wireless communication, called UWB (Ultra-Wide Band), has attracted attention. The hardware responsible for UWB wireless communication needs to be configured to handle ultra-wideband signals, and the antenna, which is an element of the hardware, also needs to operate in an ultra-wideband manner. Antennas mainly operate by resonance, and since the resonance structure of an antenna mainly depends on the wavelength, the antenna size inevitably becomes large in order to cover a wide frequency band. On the other hand, devices equipped with UWB are being miniaturized to a size that can be carried by users, and the shape of the antenna is required to be small.

[0003] Conventionally, as an ultra-wideband antenna used in UWB, an antenna such as that in Patent Document 1 is known. Patent Document 1 realizes an antenna device for transmitting and receiving radio waves in the gigahertz (GHz) band in a wideband manner using a flat-plate passive element adjacent to two orthogonal sides constituting a planar antenna element when viewed from the upper surface of the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The two radiating elements that make up the antenna shown in Patent Document 1 are each composed of straight lines, and the flat, unpowered element extends only in the direction approaching the flat, powered antenna element. In order to adjust the resonant frequency while having constraints on the area in which the antenna can be placed, it is necessary to extend the open end of the flat, unpowered element, making it difficult to achieve both miniaturization of the antenna device and a wide bandwidth for the antenna device.

[0006] Therefore, the present invention aims to provide a compact antenna device capable of operating over a wide bandwidth. [Means for solving the problem]

[0007] An antenna device in one aspect of the present invention that achieves the above objective is, Ground conductor and, Power supply unit and A first conductor connected to the power supply unit and operating in a first frequency band, A second conductor is electrically coupled to the first conductor at a distance from it and operates in a second frequency band, Equipped with, The second conductor has a grounding portion connected to the ground conductor and a proximity portion that is closest to the first conductor. The second conductor is characterized in that it has a protrusion that extends away from the first conductor in the direction of the conductor connecting the ground portion and the proximity portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an antenna device that is compact and capable of operating over a wide bandwidth. [Brief explanation of the drawing]

[0009] [Figure 1] (A) and (B) are diagrams showing the overall configuration of the antenna according to the first embodiment. [Figure 2] A diagram showing the dimensions of the antenna according to the first embodiment. [Figure 3]A figure showing the results of an electromagnetic field simulation of an antenna according to the first embodiment. [Figure 4] Figures (A) to (D) show modified examples of the antenna according to the first embodiment. [Figure 5] A diagram showing the change in characteristics when the distance between the antennas according to the first embodiment is changed. [Figure 6] (A) and (B) are diagrams showing design examples that achieve miniaturization of the antenna according to the first embodiment. [Figure 7] (A) and (B) are diagrams showing the overall configuration of the antenna according to the second embodiment. [Figure 8] A diagram showing the dimensions of the antenna according to the second embodiment. [Figure 9] (A) and (B) are diagrams showing the overall configuration of the antenna according to the third embodiment. [Figure 10] A diagram showing the dimensions of the antenna according to the third embodiment. [Figure 11] (A) and (B) are diagrams showing the overall configuration of the antenna according to the fourth embodiment. [Figure 12] A diagram showing the dimensions of the antenna according to the fourth embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] <First Embodiment> Figures 1(A) and 1(B) are overall configuration diagrams of the antenna device 1 according to this embodiment. Figure 1(B) shows a cross-sectional view of the antenna device 1 in the YZ plane passing through the dashed line A-A' in Figure 1(A).

[0012] The antenna device 1 includes a first radiating element 101, a second radiating element 102, a ground 103, a dielectric 104, and a feeding section 105. In the present embodiment, it is assumed that the first radiating element 101 and the second radiating element 102 are arranged on the dielectric 104, and the ground 103 is arranged on the same plane.

[0013] One end of the first radiating element 101 is connected to the feeding section 105, and the other end has a conductor (first conductor) that extends in a direction away from the ground 103 (the +Y-axis direction in the figure) and then becomes an open end. Here, the feeding section 105 can obtain the reference potential of the exciting signal from the ground 103. The open end of the first radiating element 101 is close to the second radiating element 102. The first radiating element 101 will be described as being disc-shaped in the example shown in Fig. 1(A), but it may be polygonal. Also, although the first radiating element 101 is illustrated as a monopole antenna, it only needs to be operable at a predetermined frequency (first frequency) by being fed by the feeding section 105, and a patch antenna or a slot antenna may be applied.

[0014] Note that the feeding section 105 may be directly fed from, for example, a 50Ω signal line (not shown) wired to the ground 103, or may be fed from outside the antenna device 1 via, for example, a 50Ω coaxial line (not shown) whose outer conductor is grounded to the ground 103. The feeding section 105 may receive a transmission signal input by a wireless communication circuit (not shown), or may receive a signal arriving from the outside by the wireless communication circuit.

[0015] The second radiating element 102 is a powerless element having a conductor connecting a ground portion that is connected to the ground 103 and a proximity portion that approaches the first radiating element 101. In the example in Figure 1, it is shown as having a linear conductor of equal width that extends away from the ground 103 (in the +Y axis direction in the figure) and then bends and extends further in the direction approaching the first radiating element 101 (in the -X axis direction in the figure), but it may also be a tapered conductor. The extended portion does not come into contact with the first radiating element 101, but electromagnetically couples with the first radiating element 101 by moving away from the first radiating element in the Y axis direction and approaching it. It also has a convex portion 203 that protrudes in other directions (in the +X axis direction and the +Y axis direction) in a way that widens the line width from the bent portion.

[0016] The protrusion 203 is an extension portion positioned so that its open end extends in the +XY axis direction, that is, away from the first radiating element 101. This makes it possible to lengthen the electrical length of the peripheral portion (peripheral portion 212 in Figure 2) of the second radiating element 102 that is opposite to the peripheral portion (peripheral portion 211 in Figure 2) that faces the first radiating element 101. In other words, the protrusion 203 forms a part of the longer peripheral portion of the peripheral portion connecting the ground portion 201 and the proximity portion 202. This makes it possible to broaden the operating frequency while suppressing the increase in the mounting area of ​​the second radiating element 102.

[0017] The second radiating element 102 has an element shape that allows the resonant element length to be adjusted by a protrusion while ensuring electrical coupling with the first radiating element 101 in the Y-axis direction. In this embodiment, the distance L between the first radiating element 101 and the second radiating element 102 facing it is shorter than the line width W at the point where the second radiating element 102 is grounded to the ground 103.

[0018] Here, the power supply unit 105 excites only the first radiating element 101, and the first radiating element 101 excites the second radiating element 102 by coupling on the open end side (in the +Y axis direction in the figure). The first radiating element 101 and the second radiating element 102 each exhibit physical resonance due to their structure. Therefore, the first radiating element 101, which has a shorter element length, resonates in a higher frequency band (first frequency band), while the second radiating element 102, which has a relatively longer element length than the first radiating element 101, resonates in a lower frequency band (second frequency band) than the first radiating element 101.

[0019] For the antenna device 1 to exhibit ultra-broadband resonance, the resonant frequency bands of the first radiating element 101 and the second radiating element 102 must be combined so that they are continuous. Therefore, in this embodiment, the shape of the first radiating element 101 and the shape of the region and protrusions of the second radiating element 102, including the adjacent portion 202, that faces the first radiating element 101 can be at least design parameters.

[0020] Although the antenna device 1 shown in Figure 1 is shown as being composed of a dielectric 104 and a conductor, additional elements may be added to shorten the element length while maintaining ultra-broadband resonance. For example, an inductor (not shown) may be inserted into the second radiating element 102. Also, a matching element (not shown), such as an inductor or capacitor, may be inserted between the feed point 105 and the first radiating element 101 to match the characteristic impedance with that of the feed point 105.

[0021] Figure 2 shows the dimensions of the first radiating element 101, the second radiating element 102, and the ground 103 that constitute the antenna device 1 in this embodiment.

[0022] The first radiating element 101 is a disc-shaped element with a diameter of 3.5 mm. The second radiating element 102 includes a ground portion 201 connected to the ground 103, a proximity portion 202 connected to the first radiating element 101 at a distance, and a protrusion 203 positioned on a conductor connecting the ground portion 201 and the proximity portion 202. The ground portion 201 and the proximity portion 202 are connected by a linear conductor having width, and the protrusion 203 is positioned between the ground portion 201 and the proximity portion 202 in an electrical path.

[0023] The grounding portion 201 is a linear conductor having a width that connects to the ground 103. Although the grounding portion 201 is shown as having a uniform width, it may have a tapered shape as will be described later in the second embodiment. The proximity portion 202 includes the point of the second radiating element 102 that is closest to the first radiating element 101.

[0024] For example, if the first radiating element 101 has a disc shape and an arc-shaped outer edge (first outer edge), the second radiating element 102 has an arc-shaped outer edge (second outer edge) that is concentric with the first radiating element 101, as shown in Figure 2. The proximity portion 202 is located on the arc-shaped outer edge. In one example, the arc-shaped outer edge of the second radiating element 102 is positioned close to the point furthest from the point where the power supply portion 105 connects to the first radiating element 101. In one example, the length of the second outer edge is greater than the line width of the ground portion 201.

[0025] Furthermore, as will be described later in the modified examples, if the first radiating element 101 has a triangular, rectangular, or other polygonal shape, the proximity portion 202 of the second radiating element 102 is positioned so as to face the side opposite to the point to which the power supply unit 105 is connected.

[0026] In this embodiment, the protrusion 203 has a square shape. In this embodiment, the ground portion 201 and the adjacent portion 202 are connected by a linear conductor having a bent portion, and the protrusion 203 is positioned on the bent portion. However, the ground portion 201 and the adjacent portion 202 may be connected by an arc-shaped conductor, in which case the protrusion 203 does not need to be positioned on the bent portion. Also, although the protrusion 203 is shown extending in both the X and Y directions in the example in Figure 2, it may extend in only one of the X or Y directions. Furthermore, the protrusion 203 may be a planar conductor having a circular, triangular, rectangular, or other polygonal shape, and its shape is not limited to a square.

[0027] In this embodiment, the dielectric 104 constituting the 30mm x 44mm substrate outline is FR4 (Flame Retardant Type 4) epoxy with a thickness of 1mm in the Z-axis direction. Furthermore, the ground 103, the first radiating element 101, and the second radiating element 102 provided on the surface of the substrate in the +Z-axis direction are copper thin films with a thickness of 35um in the Z-axis direction.

[0028] The length a of the second radiating element 102 extending from the ground 103 in the +Y axis direction is 8 mm, and the side length b of the square forming the convex portion in the +X axis direction and the +Y axis direction is 4 mm. The length c of the second radiating element 102 extending from the convex portion in the -X axis direction is 8.5 mm, and the line width d of the ground portion 201 connected to the ground 103 is 1.5 mm. The minimum separation distance e between the first radiating element 101 and the second radiating element 102 is 0.5 mm.

[0029] The ground 103 has a sufficiently large electrical length at the frequency of the signal excited by the power supply unit 105, and as an example, it is provided with a conductor of 30 mm square.

[0030] Figure 3 shows the results of an electromagnetic field simulation of the antenna device 1 shown in Figure 2. In Figure 3, the vertical axis represents the reflection characteristic S11 [dB], and the horizontal axis represents the frequency [GHz].

[0031] In the electromagnetic field simulation shown in Figure 3, the reflection coefficient (S11) is -6dB or less in the 3.1GHz-10.6GHz frequency band, which is the ultra-wideband (UWB) frequency band allocated by the FCC (Federal Communications Commission). Therefore, the antenna device resonates in the 3.1GHz-10.6GHz frequency band and can be used as an antenna device compliant with the IEEE 802.15.4z standard.

[0032] (modified version) Figure 4 shows examples 1 to 4 of possible shape changes for the first radiating element 101 and the second radiating element 102 in this embodiment.

[0033] The first radiating element 101 has a wide shape in the X-axis direction toward the open end from the power supply section 105, which makes it possible to broaden the high-frequency resonance of the resonance obtained by the first radiating element 101. For this reason, the first radiating element 101 may have a polygonal shape such as a triangle (modification example 1 shown in Figure 4(A)) or a tiered shape (modification example 2 shown in Figure 4(B)), and the effect of broadening the high-frequency resonance is expected to be the same as in the case of a disc shape. In such a case, as shown at 401 in Figure 4(A), a part of the side of the second radiating element 102 (the second side) is positioned to face the side of the first conductor (the first side) that faces the point where it connects to the power supply section 105, and the second side acts as the proximity part. In one example, the length of the second side is greater than the line width of the ground part of the second radiating element 102.

[0034] Furthermore, the second radiating element 102, by having a protrusion 203, is responsible for broadening the bandwidth of the low-frequency resonant frequencies among the resonances obtained by the antenna device 1. For this reason, the second radiating element 102 has a shape in which at least the open end of the protrusion 203 extends in the +X axis and +Y axis directions, such as a triangle (modification example 3 shown in Figure 4(C)) or a circle (modification example 4 shown in Figure 4(D)), and is expected to have the effect of broadening the low-frequency resonance, similar to a square shape.

[0035] Furthermore, the separation distance e between the first radiating element 101 and the second radiating element 102 should be smaller than the line width d of the connection with the ground 103. If the separation distance e is too large, the strength of the coupling between the first radiating element 101 and the second radiating element 102 will decrease, and the second radiating element 102 will cease to function as a parasitic element of the first radiating element 101. In other words, it will not be possible to connect the high-frequency resonance and the low-frequency resonance on the frequency axis through electrical coupling.

[0036] Figure 5 shows the results of electromagnetic field simulation analysis of the radiation characteristics of antenna device 1 when the distance e is varied. The length a of the conductor extending in the +Y axis direction from ground 103 is 8 mm, the side length b of the square constituting the convex part is 4 mm, the distance c extending in the -X axis direction from the convex part is 8.5 mm, and the line width d of the ground part 201 is 1.5 mm.

[0037] As shown in Figure 5, when the separation distance e is increased by 0.5 mm increments, it was shown that when it exceeds the line width b of 1.5 mm, the frequency bandwidth in which S11 is -6 dB or less due to the first radiating element 101 and the second radiating element 102 narrows in the UWB frequency band.

[0038] From the above, it can be seen that the first radiating element 101, which is the feeding element of the antenna device 1, and the second radiating element 102, which is the unfed element, each have parameters that broaden the resonance bandwidth, and furthermore, when combined, they have parameters that make the resonance frequency continuous. In addition, since the shape of the second radiating element 102, including the protrusion 203, and the shape of the first radiating element 101 can be flexibly changed, it can be seen that this is an antenna device with a high degree of design freedom.

[0039] Note that the combination of shapes of the power supply element and the powerless element shown in Figures 2 and 4 is not limited. For example, the disc-shaped first radiating element 101 may be combined with the second radiating element 102 shown in Figures 4(A) and 4(B).

[0040] Figure 6 shows an example of an antenna design that is miniaturized while maintaining ultra-wideband resonance compared to the antenna shape in Figure 1. In the example in Figure 6, the second radiating element 102 has a shape that includes a circular arc concentric with the disk of the first radiating element 101. In other words, the second conductor connecting the ground portion and the coupling portion of the second radiating element 102 has a circular arc shape, and the convex portion has a linear conductor with width. Furthermore, by orienting the open end of the convex portion in the +X axis direction, the electrical length of the peripheral portion of the second radiating element 102 opposite to the peripheral portion facing the first radiating element 101 can be increased. In one example, the line width of the linear conductor of the convex portion is greater than the line width of the ground portion. Moreover, by positioning the outer edge of the circular arc shape including the proximity portion 202 of the second radiating element 102 equidistant from a part of the outer edge of the circular arc shape constituting the circular first radiating element 101, the coupling strength between the proximity portion 202 and the first radiating element 101 can be increased. This makes it possible to design a compact antenna that fits within an antenna area of ​​13.5mm x 9.5mm while satisfying the UWB frequency band. Since devices incorporating UWB are expected to be miniaturized for portability, reducing the mounting area of ​​the antenna device can be an advantageous design point for implementation.

[0041] As described above, the antenna device according to this embodiment comprises a first radiating element connected to a power supply section and a second radiating element connected to ground and electromagnetically coupled to the first radiating element at a distance from it. Furthermore, a protrusion is provided on the conductor connecting the adjacent portion of the second radiating element, which is closest to the first radiating element, and the grounded portion, which is connected to ground, so as to protrude away from the first radiating element. This makes it possible to miniaturize the antenna device while broadening the operating frequency of the antenna device by broadening the resonant frequency of the second radiating element.

[0042] <Second Embodiment> Figures 7(A) and 7(B) are overall configuration diagrams of the antenna device 2, which includes a second radiating element arranged in multiple layers of a substrate. Figure 7(A) shows a top view of the antenna device 2 in the XY plane, and Figure 7(B) shows a cross-sectional view of the antenna device 2 along the dashed line A-A' in Figure 7(A). Note that the same reference numerals are used for structures and dimensions similar to those in the first and second embodiments, and their explanations are omitted.

[0043] The antenna device 2 comprises a second radiating element 102 including a conductor 701 in the first layer, a conductor 702 in the second layer, and vias 703, the first radiating element 101, a ground 103, a dielectric 104, and a feeding section 105, and resonates in the range of 3.1 GHz to 10.6 GHz.

[0044] The first radiating element 101 and the conductor 701 are arranged in a first layer corresponding to the surface of the substrate made of dielectric 104, and a ground 103 is further arranged on the same plane. The conductor 702 is arranged in a second layer parallel to the first layer of dielectric 104. In one example, the first layer is the surface of the substrate, and the second layer is the back surface of the substrate.

[0045] The first radiating element 101 has one end connected to the power supply unit 105, and the other end is a power supply element that extends away from the ground 103 (in the +Y axis direction in the figure) and then becomes an open end. Here, the power supply unit 105 can obtain the reference potential of the excitation signal from the ground 103. The open end of the first radiating element 101 is also close to the conductor 701 of the second radiating element 102. The first radiating element 101 has a disc shape, for example, as shown in Figure 7(A).

[0046] The conductor 701 of the second radiating element 102 has one end grounded to the ground 103, and the other end extends away from the ground 103 (in the -X axis direction and the +Y axis direction in the figure). At the end of the extension, it is separated from and close to the first radiating element 101 in the X axis direction and the Y axis direction. The second radiating element 102 also has a conductor 702 (corresponding to the conductor of the protruding part) that extends in another direction (in the +X axis direction) from the open end of the conductor 701 via a via 703 that penetrates the dielectric 104 in the Z axis direction.

[0047] That is, the conductor 701 has an element shape that ensures electrical coupling with the first radiating element 101 in the X-axis and Y-axis directions, while the resonant element length is variable by the conductor 702. Here, the distance between the radiating element 101 and the conductor 701 facing it is shorter than the line width of the point where the conductor 701 is grounded to the ground 103. Note that the via 703 may be an interlayer via, in which case the conductor 702 may be provided in the intermediate layer of the substrate.

[0048] Similar to the first embodiment, the power supply unit 105 excites only the first radiating element 101, and the first radiating element 101 excites the conductor 701 by coupling on the open end side (in the +Y axis direction in the figure). The first radiating element 101 and the second radiating element 102, which consists of the conductor 701, via 703, and conductor 702, each exhibit physical resonance due to their structure. Therefore, the first radiating element 101, which has a shorter element length, resonates at a higher frequency, while the second radiating element 102, which has a relatively longer element length than the first radiating element 101, resonates at a lower frequency than the first radiating element 101.

[0049] For the antenna device 2 to exhibit ultra-broadband resonance, the resonant frequency bands of the first radiating element 101 and the second radiating element 102 must be combined so that they are continuous. For this reason, the shape of the first radiating element 101 and the shapes of the conductors 701 and 702 of the second radiating element 102 that face the first radiating element 101 can be at least design parameters of the antenna device 2.

[0050] Figure 8 shows the dimensions of the first radiating element 101, conductor 701, via 703, conductor 702, and ground 103 that constitute the antenna device 2 according to this embodiment.

[0051] The dielectric 104, which constitutes the 30mm x 44mm outer dimensions of the substrate, is FR4-epoxy with a thickness of 1mm in the Z-axis direction. The ground 103, the first radiating element 101, and the conductor 701, provided on the surface of the substrate in the +Z-axis direction, are thin copper films with a thickness of 35um in the Z-axis direction. The conductor 702, provided on the back surface of the substrate in the -Z-axis direction, is also a thin copper film with a thickness of 35um in the Z-axis direction. The first radiating element 101 has a disc-shaped conductor with a diameter of 3.5mm.

[0052] The conductor 701 of the second radiating element 102 extends from the ground 103 in the -X axis direction and the +Y axis direction, and is a linear element with a distance b on the arc opposite the first radiating element 101 being approximately 5.2 mm, and a line width a connecting to the ground 103 being 1.5 mm.

[0053] The conductor 702 of the second radiating element 102 extends from the via 703 in the +X direction at a distance c of 9 mm, and the via 703 has a cylindrical shape with a diameter of 0.8 mm and a height of 1 mm. Here, the distance between the conductor 701 of the first radiating element 101 and the conductor 701 of the second radiating element 102 is 0.5 mm.

[0054] The ground 103 shall have a sufficiently large electrical length at the frequency of the signal that excites the power supply unit 105, for example, 30 mm square.

[0055] By connecting conductors 701 and 702 with via 703, the electrical length of the second radiating element 102 can be further increased by the length of the via, allowing for a wider bandwidth of the low-frequency resonant frequency band while maintaining the antenna size when viewed from the substrate thickness direction (Z-axis direction). In other words, the antenna can be miniaturized while maintaining the resonant frequency obtained by the antenna device 2.

[0056] Furthermore, when mounting the antenna to the device, the antenna characteristics may fluctuate if metal parts (not shown), resin housings (not shown), or the human body (not shown) are in close proximity to the first radiating element 101. However, by placing only the conductor 702 on the back surface of the substrate via the via 703, the conductor 702 can be kept away from metal parts, resin, and the human body mounted on the surface of the substrate in the Z-axis direction. Therefore, if the SAR (Specific Absorption Rate) characteristics or antenna characteristics of the antenna device 2 are affected by the coupling between the conductor 702 and the aforementioned metal parts, resin, or human body which are different from those of the antenna device 2, an improvement in characteristics can be expected.

[0057] <Third Embodiment> Figures 9(A) and 9(B) show the overall configuration of the antenna device 3, in which the second radiating element is placed on the back surface of the substrate. Note that the same reference numerals are used for structures and dimensions similar to those in the first and second embodiments, and their explanations are omitted.

[0058] Figure 9(B) is a cross-sectional view of antenna device 3 in the YZ plane along the dashed line A-A' in Figure 9(A).

[0059] The antenna device 3 comprises a first radiating element 101, a second radiating element 102, a ground 103, a dielectric 104, and a feed point 105, and resonates between 3.1 GHz and 10.6 GHz.

[0060] The first radiating element 101 is placed in the first layer, which corresponds to the surface of the substrate made of dielectric 104, and a ground 103 is placed on the same plane. The second radiating element 102 is placed in the second layer, which corresponds to the back surface of the substrate made of dielectric 104, and a ground 103 (401 removed from Figure 9(B)) is placed on the same plane. That is, the ground 103 is located on both the front and back surfaces of the substrate and is maintained at the same potential by ground vias (not shown), etc. The first radiating element 101 has one end connected to the power supply unit 105, and the other end is a power supply element that extends away from the ground 103 (in the +Y axis direction in the figure) and then becomes an open end. Here, the power supply unit 105 can obtain the reference potential of the excitation signal from the ground 103. The open end of the first radiating element 101 is also close to the second radiating element 102. The first radiating element 101 has a disc shape, for example, as shown in Figure 9(A).

[0061] The second radiating element 102 has a ground portion at one end connected to the ground 103, and the other end extends away from the ground 103 (in the -X axis direction and +Y axis direction in the figure). At the extended end, it is coupled to the first radiating element 101, spaced apart in the X axis direction and Y axis direction. It also has a convex portion (corresponding to a conductor of the convex portion) that extends in another direction (+X axis direction) by folding back from the open end adjacent to the first radiating element 101. Here, when viewed from the substrate thickness direction (Z axis direction), the first radiating element 101 and the second radiating element 102 do not overlap.

[0062] Figure 10 shows the various dimensions of the antenna device shown in Figure 9.

[0063] The dielectric material forming the 30mm x 44mm substrate outline is FR4-epoxy with a thickness of 1mm in the Z-axis direction. The ground 103 and the first radiating element 101, located on the surface of the substrate in the +Z-axis direction, are thin copper films with a thickness of 35um in the Z-axis direction. The second radiating element 102, located on the back surface of the substrate in the -Z-axis direction, is also a thin copper film with a thickness of 35um in the Z-axis direction.

[0064] The first radiating element 101 has a disc-shaped conductor with a diameter of 3.5 mm. The second radiating element 102 extends from the ground 103 in the -X axis direction and the +Y axis direction, and is a linear element with a distance b of approximately 5.2 mm to the arc opposite the first radiating element 101 and a line width a of 1.5 mm connecting to the ground 103. The distance c of the second radiating element 102 extending in the +X axis direction is 9 mm.

[0065] Here, the distance between the first radiating element 101 and the second radiating element 102 is 0.5 mm when viewed from the substrate thickness direction (Z-axis direction) and 1 mm in the substrate thickness direction (Z-axis direction). The ground 103 has a sufficiently large electrical length at the frequency of the signal excited by the power supply unit 105, and is 30 mm square as an example.

[0066] Thus, the antenna device according to this embodiment includes a first radiating element which is a feeding element arranged in the first layer, a second radiating element which is a non-passing conductor arranged in the second layer, and ground conductors arranged in the first and second layers. Furthermore, the second radiating element is provided with a convex portion that extends away from the first radiating element. This makes it possible to broaden the bandwidth of the second radiating element.

[0067] <Fourth Embodiment> Figures 11(A) and 11(B) show an antenna device 4 in which the second radiating element is placed on the back surface of the substrate. Figure 11(B) is a cross-sectional view of the antenna device 4 in the YZ plane along the dashed line A-A' in Figure 11(A).

[0068] The antenna device 4 comprises a first radiating element 101, a second radiating element 102, a ground 103, a dielectric 104, and a feeding unit 105, and resonates between 3.1 GHz and 10.6 GHz. The first radiating element 101 is placed in a first layer corresponding to the surface of the substrate made of dielectric 104, and the ground 103 (401 removed from Figure 11(B)) is placed on the same plane. The second radiating element 102 is placed in a second layer corresponding to the back surface of the substrate made of dielectric 104, and the ground 103 is placed on the same plane. That is, the ground 103 is placed on the front and back surfaces of the substrate, connected by ground vias (not shown), etc., and maintained at the same potential.

[0069] The first radiating element 101 has one end connected to the power supply unit 105, and the other end is a power supply element that extends away from the ground 103 (in the +Y axis direction in the figure) and then becomes an open end. Here, the power supply unit 105 can obtain the reference potential of the excitation signal from the ground 103. The open end of the first radiating element 101 is also close to the second radiating element 102. The first radiating element 101 has a disc shape, for example, as shown in Figure 9(A).

[0070] The second radiating element 102 has one end grounded to the ground 103, and the other end extends away from the ground 103 (in the -X axis direction and the +Y axis direction in the figure). At the end of the extension, it is spaced apart from and close to the first radiating element 101 in the X axis direction and the Y axis direction. The second radiating element 102 also has a convex portion (corresponding to the conductor of the convex portion) that extends away from the first radiating element 101 (in the +X axis direction) by folding back from the open end that is close to the first radiating element 101. Here, when viewed from the substrate thickness direction (Z axis direction), parts of the first radiating element 101 and the second radiating element 102 overlap in region 1101. In other words, in the antenna device 4 according to this embodiment, the distance between the first radiating element 101 and the second radiating element 102 is equal to the thickness of the substrate, and the close portion is located in region 1101.

[0071] Figure 12 shows the various dimensions in Figure 11. The dielectric material constituting the 30mm x 44mm substrate outline is FR4-epoxy with a thickness of 1mm in the Z-axis direction, and the ground 103 and the first radiating element 101 provided on the surface of the substrate in the +Z-axis direction are copper thin films with a thickness of 35um in the Z-axis direction. The second radiating element 102 provided on the back surface of the substrate in the -Z-axis direction is also a copper thin film with a thickness of 35um in the Z-axis direction.

[0072] The first radiating element 101 is a disc-shaped conductor with a diameter of 3.5 mm. The second radiating element 102 extends from the ground 103 in the -X axis direction and the +Y axis direction. The open end facing the first radiating element 101 is a linear element with a distance b in the Y axis direction of approximately 4 mm and a line width a connecting to the ground 103 of 1.5 mm. The second radiating element 102 extends a distance c in the +X axis direction of 9 mm. Here, the distance between the first radiating element 101 and the second radiating element 102 is 1 mm in the substrate thickness direction (Z axis direction).

[0073] The ground 103 has a sufficiently large electrical length at the frequency of the signal excited by the feed point 105, for example, 30 mm square. By arranging the first radiating element 101, which is the feed element, and the second radiating element 102, which is the unfed element, on separate layers of the substrate, the degree of design freedom is increased. Furthermore, by arranging the first radiating element 101 and the second radiating element 102 so that their surfaces face each other across the substrate, the electrical coupling can be strengthened. As a result, when viewed from the substrate thickness direction (Z-axis direction), the bandwidth of the low-frequency resonant frequency can be widened while maintaining the antenna size. In other words, the antenna can be miniaturized while maintaining the obtained resonant frequency.

[0074] <Other Embodiments> The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0075] (Summary of the embodiments) This embodiment includes the following communication device.

[0076] (Item 1) An antenna device, Ground conductor and, Power supply unit and A first conductor connected to the power supply unit and operating in a first frequency band, A second conductor is electrically coupled to the first conductor at a distance from it and operates in a second frequency band, Equipped with, The second conductor has a grounding portion connected to the ground conductor and a proximity portion that is closest to the first conductor. The antenna device is characterized in that the second conductor has a protrusion that extends away from the first conductor in the direction of the conductor connecting the ground portion and the proximity portion.

[0077] (Item 2) The second conductor has a linear conductor that is of equal width or tapered at the grounding portion. The antenna device according to item 1, characterized in that the minimum distance between the first conductor and the proximity portion is smaller than the line width of the second conductor at the grounding portion.

[0078] (Item 3) The antenna device according to item 1 or 2, characterized in that the first frequency band has a higher frequency than the second frequency band.

[0079] (Item 4) The second conductor connects the ground portion and the open end and comprises a linear conductor having a width. A first peripheral portion that is close to the first conductor and connects the ground portion and the adjacent portion, It connects the grounding portion and the proximity portion, and has a second peripheral portion that is longer than the first peripheral portion, The antenna device according to any one of items 1 to 3, characterized in that the convex portion forms the second peripheral portion.

[0080] (Item 5) The antenna device according to item 4, characterized in that the linear conductor of the second conductor has a bent portion, and the convex portion is arranged in the bent portion.

[0081] (Item 6) The first conductor has a polygonal conductor, The second conductor has a second side that faces at least a portion of the first side of the first conductor that faces the point to which the power supply unit is connected, The antenna device according to any one of items 1 to 5, characterized in that the adjacent portion of the second conductor is included in the second side.

[0082] (Item 7) The antenna device according to item 6, characterized in that the length of the second side is greater than the line width of the grounding portion.

[0083] (Item 8) The first conductor has a first outer edge that is arc-shaped, The second conductor has a second outer edge that is concentric with the first outer edge and has an arc shape. The antenna device according to any one of items 1 to 5, characterized in that the adjacent portion of the second conductor is included in the second outer edge.

[0084] (Item 9) The antenna device according to item 8, characterized in that the first outer edge includes the point of the first conductor furthest from the point to which the power supply is connected.

[0085] (Item 10) The antenna device according to item 8 or 9, characterized in that the length of the second outer edge is greater than the line width of the grounding portion.

[0086] (Item 11) The substrate further comprises a first surface and a second surface parallel to the first surface, The first conductor and the ground conductor are arranged on the first surface. The antenna device according to any one of items 1 to 10, characterized in that the convex portion is arranged on the second surface.

[0087] (Item 12) The substrate further comprises a first surface and a second surface parallel to the first surface, The proximity portion is arranged on the second surface, The antenna device according to any one of items 1 to 4, characterized in that, when viewed in the thickness direction of the substrate, the adjacent portion and at least a part of the first conductor overlap.

[0088] (Item 13) The antenna device according to any one of items 1 to 12, characterized in that the protrusion includes a circular, rectangular, or triangular planar conductor that partially overlaps with a linear or tapered conductor connecting the ground portion and the open end of the second conductor.

[0089] (Item 14) The antenna device according to any one of items 1 to 13, characterized in that the protrusion includes a rectangular planar conductor, and the width of the protrusion is greater than the width of the grounding portion.

[0090] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0091] 101: First radiating element, 102: Second radiating element, 103: Ground, 104: Dielectric, 105: Feed point, 201: Grounding point, 202: Proximity point, 203: Protrusion, 601: Antenna region

Claims

1. An antenna device, Ground conductor and, Power supply unit and A first conductor connected to the power supply unit and operating in a first frequency band, A second conductor is electrically coupled to the first conductor at a distance from it and operates in a second frequency band, Equipped with, The second conductor has a grounding portion connected to the ground conductor and a proximity portion that is closest to the first conductor. The antenna device is characterized in that the second conductor has a protrusion that extends away from the first conductor in the direction of the conductor connecting the ground portion and the proximity portion.

2. The second conductor has a linear conductor that is of equal width or tapered at the grounding portion. The antenna device according to claim 1, characterized in that the minimum distance between the first conductor and the proximity portion is smaller than the line width of the second conductor at the grounding portion.

3. The antenna device according to claim 1, characterized in that the first frequency band has a higher frequency than the second frequency band.

4. The second conductor connects the ground portion and the open end and comprises a linear conductor having a width. A first peripheral portion that is close to the first conductor and connects the ground portion and the adjacent portion, It connects the grounding portion and the proximity portion, and has a second peripheral portion that is longer than the first peripheral portion, The antenna device according to claim 1, characterized in that the convex portion forms the second peripheral portion.

5. The antenna device according to claim 4, characterized in that the linear conductor of the second conductor has a bent portion, and the convex portion is arranged in the bent portion.

6. The first conductor has a polygonal conductor, The second conductor has a second side that faces at least a portion of the first side of the first conductor that faces the point to which the power supply unit is connected, The antenna device according to claim 1, characterized in that the adjacent portion of the second conductor is included in the second side.

7. The antenna device according to claim 6, characterized in that the length of the second side is greater than the line width of the grounding portion.

8. The first conductor has a first outer edge that is arc-shaped, The second conductor has a second outer edge that is concentric with the first outer edge and has an arc shape. The antenna device according to claim 1, characterized in that the adjacent portion of the second conductor is included in the second outer edge.

9. The antenna device according to claim 8, characterized in that the first outer edge includes the point of the first conductor furthest from the point to which the power supply is connected.

10. The antenna device according to claim 8, characterized in that the length of the second outer edge is greater than the line width of the grounding portion.

11. The substrate further comprises a first surface and a second surface parallel to the first surface, The first conductor and the ground conductor are arranged on the first surface. The antenna device according to any one of claims 1 to 10, characterized in that the convex portion is arranged on the second surface.

12. The substrate further comprises a first surface and a second surface parallel to the first surface, The proximity portion is arranged on the second surface, The antenna device according to any one of claims 1 to 4, characterized in that the adjacent portion and at least a part of the first conductor overlap when viewed in the thickness direction of the substrate.

13. The antenna device according to claim 1, characterized in that the protrusion includes a circular, rectangular, or triangular planar conductor that partially overlaps with a linear or tapered conductor connecting the ground portion and the open end of the second conductor.

14. The antenna device according to claim 1, characterized in that the protrusion includes a rectangular planar conductor, and the width of the protrusion is greater than the width of the grounding portion.

Images