Antenna device and electronic apparatus

Abstract

Provided are an antenna device and an electronic apparatus with which it is possible to obtain required double resonance characteristics and widen a frequency band. An antenna device (100) according to the present disclosure comprises: a plate-shaped conductor (10) that has an opening (10a); a signal line (20a) that supplies a signal from a power supply circuit (30); a first coil that is electrically connected or indirectly connected to the middle of the signal line (20a); a GND line (20c) that is electrically connected to a conductor on a second side of the opening (10a) which is opposite a first side thereof; an excitation electrode (40) disposed at a position which overlaps the opening (10a) in a plan view of the opening (10a); a second coil having one end thereof electrically connected to the excitation electrode (40) and the other end thereof electrically connected or indirectly connected to the conductor (10) on the second side; and at least one capacitor (60) for capacitively coupling the conductor on the first side and the conductor on the second side. The first coil and the second coil are disposed at magnetically coupled positions.

Description

Antenna device and electronic device

[0001] The present disclosure relates to the technology of antenna devices and electronic devices.

[0002] In recent years, electronic devices that operate in a plurality of frequency bands have been developed. Antenna devices used in such electronic devices are required to widen the usable frequency band, and for example, slot antennas having multiple resonance characteristics have been proposed (Patent Document 1: US Patent Application Publication No. 2023 / 0008815). In this antenna device, a signal line from a feeding circuit is connected to a slot (opening), and the slot is excited by current. Furthermore, in this antenna device, by bypassing the slot with an impedance element having frequency characteristics, the slot size is changed in a pseudo manner to obtain multiple resonance characteristics.

[0003] US Patent Application Publication No. 2023 / 0008815

[0004] However, in the antenna device disclosed in Patent Document 1 (US Patent Application Publication No. 2023 / 0008815), in a frequency band where a large amount of current flows through the impedance element provided to bypass the slot, no excitation occurs in the slot portion on the side where the feeding circuit is not connected to the impedance element. Therefore, there have been cases where the required multiple resonance characteristics cannot be obtained with this antenna device.

[0005] The present disclosure has been made to solve such problems, and an object thereof is to provide an antenna device and an electronic device that can obtain required multiple resonance characteristics and can widen a frequency band.

[0006] An antenna device according to this disclosure comprises a plate-shaped conductor having an opening; a signal line for supplying a signal from a power supply circuit; a first coil electrically connected or indirectly connected to the signal line; a GND line electrically connected to a conductor on the second side of the opening opposite to the first side to which the signal line is electrically connected or indirectly connected; an excitation electrode positioned to overlap the opening when the opening is viewed from above; a second coil having one end electrically connected to the excitation electrode and the other end electrically connected or indirectly connected to a conductor on the second side; and at least one capacitor capacitively coupling the conductor on the first side and the conductor on the second side. The first coil and the second coil are positioned to be magnetically coupled.

[0007] The electronic device according to this disclosure comprises a power supply circuit and the antenna device described above.

[0008] In the antenna device according to this disclosure, by providing a first coil in the middle of the signal line and electrically connecting an excitation electrode to a second coil that is magnetically coupled to the first coil, the required double-resonance characteristics can be obtained and the frequency bandwidth can be broadened.

[0009] This is a schematic diagram of an antenna device in an embodiment. This diagram illustrates the current flow during resonance of an antenna device having a bypass circuit. This diagram shows the frequency characteristics of the reflection coefficient of the antenna device in an embodiment. This diagram shows the frequency characteristics of the radiation efficiency of the antenna device in an embodiment. This is a schematic diagram of an antenna device in modified example 1. This is a schematic diagram of an antenna device in modified example 2. This is a schematic diagram of an antenna device in modified example 3. This is a schematic diagram of an antenna device in modified example 4. This is a schematic diagram of an antenna device in modified example 5. This is a schematic diagram of an antenna device in modified example 6.

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] [Embodiment] Figure 1 is a schematic diagram of the antenna device 100 in an embodiment. The antenna device 100 is a slot antenna, and an opening 10a (slot) is formed in a plate-shaped conductor 10. The antenna device 100 is a current-excited slot antenna in which a signal line from the power supply circuit 30 is electrically connected to the opening 10a, and the opening 10a is excited by the current in the signal line. The antenna device 100 has double resonance characteristics in a band including, for example, the approximately 2.5 GHz band and the approximately 5 GHz to 7 GHz band, and communication in that band is possible. The antenna device 100 is also built into electronic devices such as laptop computers, mobile phones, smartphones, or tablets. The electronic device includes at least the antenna device 100 and the power supply circuit 30.

[0012] The antenna device 100 electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 (first side) of the opening 10a on the left side of Figure 1. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. Here, "electrically connected" means that the conductor 10 and the signal line 20a are physically directly connected and conducting electricity. However, the conductor 10 and the signal line 20a may be connected indirectly. "Indirectly connected" means that the conductor 10 and the signal line 20a are not physically directly connected, but are connected via other circuit elements or by electric field coupling, etc. The same definitions apply to "electrically connected" and "indirectly connected" hereafter.

[0013] The signal line 20a is the internal conductor of the coaxial cable 20 that connects the antenna device 100 and the power supply circuit 30. The coaxial cable 20 has an insulator 20b outside the signal line 20a, and a GND line 20c as an external conductor further outside the insulator 20b. The GND line 20c is electrically connected to the conductor 10 by a fixed part 20d such as soldering. Therefore, the conductor 10 is at GND potential.

[0014] The GND line 20c is electrically connected to the conductor 10 on the lower side 10a2 (second side) of the opening 10a, which is opposite the upper side 10a1. As a result, the signal line 20a is wired to span from the lower side 10a2 to the upper side 10a1 of the opening 10a. Note that the signal line 20a and the GND line 20c are not limited to being provided as a coaxial cable 20, and the signal line 20a and the GND line 20c may be provided as separate wires.

[0015] As shown in Figure 1, the opening 10a in the conductor 10 is rectangular in shape, with the sides in the Y direction being shorter than the sides in the X direction. However, the opening 10a is not limited to a rectangular shape; it may be a polygon or other shape as long as the signal line 20a can cross from one side (second side) to the other side (first side). The conductor 10 is, for example, copper foil formed on a PCB (Printed Circuit Board). Note that the conductor 10 is not limited to copper foil formed on a PCB; it may be a metal plate such as a copper plate or an aluminum plate.

[0016] The antenna device 100 functions as a current-excited slot antenna, which excites the opening 10a (slot) by passing current through the signal line 20a. Furthermore, by providing an electromagnetic field coupling element 50 in the middle of the signal line 20a, the antenna device 100 functions as an antenna device with double resonance characteristics.

[0017] The electromagnetic field coupling element 50 is, for example, a rectangular parallelepiped chip component that contains two coils L1 (first coil) and L2 (second coil), forming a transformer in which coils L1 and L2 are magnetically coupled. Specifically, the electromagnetic field coupling element 50 is made up of a ceramic layer insulator (ceramic element) formed by stacking multiple substrates (ceramic green sheets) on which the coil wiring is formed.

[0018] Coil L1 is provided in the middle of the signal line 20a. Although both ends of coil L1 shown in Figure 1 are electrically connected to the signal line 20a, one end may be indirectly connected via other circuit elements or by electric field coupling, etc. For example, one end of coil L1 may be electrically connected to the conductor 10 via other circuit elements such as a capacitor or inductor.

[0019] One end of coil L2 is electrically connected to the excitation electrode 40, and the other end of coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a. The excitation electrode 40 (also called the excitation conductor, feed line, or simply microstrip line) is positioned so as to overlap with the opening 10a when viewed from above. Furthermore, the excitation electrode 40 is a strip shape that extends along the long side of the opening 10a in the negative X direction (opposite direction of the arrow). Therefore, the excitation electrode 40 acts as a capacitive feeding element with respect to the opening 10a, and the opening 10a with the excitation electrode 40 functions as a passive antenna.

[0020] The antenna device 100 is further provided with a capacitor 60 (bypass circuit) on the right side of Figure 1 to bypass (capacitively couple) the opening 10a. The excitation electrode 40 is located in the portion of the opening 10a on the side of the coil L1 where the capacitor 60 is not provided (the left side of the opening 10a in the figure) when the opening 10a is viewed from above.

[0021] Figure 2 is a diagram illustrating the current flow during resonance in an antenna device with a bypass circuit. Figure 2(a) shows the frequency characteristics of the reflection coefficient of an antenna device with a bypass circuit. In Figure 2(a), the horizontal axis represents frequency and the vertical axis represents the reflection coefficient. In an antenna device with a bypass circuit, as shown in Figure 2(a), fundamental resonance occurs in the band including approximately 2.5 GHz (band I), and harmonic resonance occurs in the band including approximately 5 GHz to approximately 7 GHz (band II).

[0022] Figure 2(b) is a diagram illustrating the current flow in an antenna device during fundamental wave resonance. In Figure 2(b), the direction of the current is indicated by an arrow, and the amount of current is indicated by the thickness of the arrow. That is, a dark arrow indicates a large amount of current, and a light arrow indicates a small amount of current. From Figure 2(b), it can be seen that a large amount of current flows through the bypass circuit in the antenna device during fundamental wave resonance.

[0023] On the other hand, Figure 2(c) is a diagram illustrating the current flow in the antenna device during harmonic resonance. Similarly, in Figure 2(c), the direction of the current is indicated by an arrow, and the amount of current is indicated by the thickness of the arrow. From Figure 2(c), it can be seen that in the antenna device during harmonic resonance, not much current flows through the bypass circuit, and the current flows almost equally between the feed circuit and the bypass circuit.

[0024] An antenna device with a simple power supply circuit and bypass circuit can obtain the frequency characteristics shown in Figure 2(a). However, when considering applying this antenna device to a Wi-Fi® antenna, it does not obtain a double-resonance characteristic that sufficiently covers the bandwidth (band II) including the harmonic resonance of approximately 5 GHz to approximately 7 GHz.

[0025] Therefore, in the antenna device 100 according to this embodiment, as shown in Figure 1, an electromagnetic field coupling element 50 is provided in the middle of the signal line 20a, and the excitation electrode 40 functions as a powerless antenna, thereby obtaining a double resonant characteristic that covers bandwidth II. Here, if a double resonant characteristic that covers bandwidth II is to be obtained, the excitation electrode 40 and the electromagnetic field coupling element 50 may be provided in the capacitor 60 on the bypass circuit side.

[0026] However, as explained in Figure 2(b), a large current flows through the bypass circuit when the fundamental wave resonates. Therefore, if the excitation electrode 40 and electromagnetic coupling element 50 are provided on the capacitor 60 on the bypass circuit side, a large current will flow through the electromagnetic coupling element 50 when the fundamental wave resonates, resulting in a large current loss. For this reason, in the antenna device 100, instead of providing the excitation electrode 40 and electromagnetic coupling element 50 on the capacitor 60 on the bypass circuit side, the excitation electrode 40 and electromagnetic coupling element 50 are provided on the signal line 20a on the power supply circuit side.

[0027] As a result, the antenna device 100 can obtain the required double-resonance characteristics without losing the large amount of current flowing through the capacitor 60 on the bypass circuit side in the electromagnetic field coupling element 50 during fundamental wave resonance. Furthermore, the antenna device 100 excites the aperture 10a by passing current through the signal line 20a, and by making the excitation electrode 40 function as a passive antenna via the electromagnetic field coupling element 50, it generates two resonances in the harmonics and broadens the frequency band.

[0028] Figure 3 shows the frequency characteristics of the reflection coefficient of the antenna device 100 in the embodiment. In Figure 3, the horizontal axis represents frequency and the vertical axis represents the reflection coefficient. Graph A (solid line) shows the frequency characteristics of the reflection coefficient of the antenna device 100, and graph B (dashed line) shows the frequency characteristics of the reflection coefficient of a comparison antenna device. The comparison antenna device is configured by removing the excitation electrode 40 and the electromagnetic field coupling element 50 from the antenna device 100.

[0029] As can be seen from Graph A, antenna device 100 generates two resonances in the frequency band including approximately 5 GHz to approximately 7 GHz. On the other hand, as can be seen from Graph B, the comparison antenna device generates only one resonance in the frequency band including approximately 5 GHz to approximately 7 GHz.

[0030] Furthermore, Figure 4 shows the frequency characteristics of the radiation efficiency of the antenna device 100 in the embodiment. In Figure 4, the horizontal axis represents frequency, and the vertical axis represents radiation efficiency. Graph C (solid line) shows the frequency characteristics of the radiation efficiency of the antenna device 100, and graph D (dashed line) shows the frequency characteristics of the radiation efficiency of a comparison antenna device.

[0031] When comparing graph C, which shows the radiation efficiency of antenna device 100, with graph D, which shows the radiation efficiency of a comparison antenna device, they show approximately the same radiation efficiency at all frequencies. In particular, in the band including the fundamental wave of approximately 2.5 GHz, graph C, which shows the radiation efficiency of antenna device 100, and graph D, which shows the radiation efficiency of the comparison antenna device, are in agreement. In other words, from graphs C and D shown in Figure 4, it can be seen that although antenna device 100 is equipped with an excitation electrode 40 and an electromagnetic field coupling element 50 to obtain double resonance characteristics, there is no current loss due to the provision of the electromagnetic field coupling element 50.

[0032] As described above, in the antenna device 100, as shown in Figure 1, by providing an electromagnetic field coupling element 50 in the middle of the signal line 20a on the feed circuit side, current loss due to the electromagnetic field coupling element 50 is suppressed, and the excitation electrode 40 functions as a powerless antenna, thereby obtaining the required double-resonance characteristics. Therefore, the antenna device 100 can broaden its frequency bandwidth, for example, in the band including approximately 5 GHz to approximately 7 GHz.

[0033] The connection configuration of the excitation electrode 40 and the electromagnetic field coupling element 50 provided on the signal line 20a on the power supply circuit side is not limited to the connection configuration shown in Figure 1. Below, variations of the connection configuration of the excitation electrode 40 and the electromagnetic field coupling element 50 will be described. Note that the variations described below are examples, and the connection configurations described in each variation may be combined as appropriate.

[0034] (Modification 1) Figure 5 is a schematic diagram of the antenna device 100A in Modification 1. In the antenna device 100A shown in Figure 5, the same reference numerals are used for components that are the same as those in the antenna device 100 shown in Figure 1, and detailed explanations will not be repeated. The antenna device 100A is a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0035] The antenna device 100A electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 of the opening 10a on the left side of Figure 5. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which coil L1 and coil L2 are magnetically coupled.

[0036] Coil L1 is located in the middle of the signal line 20a. Coil L1 shown in Figure 5 has both ends electrically connected to the signal line 20a. One end of coil L2 is electrically connected to the excitation electrode 40, and the other end of coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a.

[0037] Furthermore, the antenna device 100A is further provided with a capacitor 60 (bypass circuit) on the right side of Figure 5 to bypass the opening 10a.

[0038] The excitation electrode 40 is a strip-shaped electrode that extends in the positive X direction (arrow direction) along the long side of the opening 10a, and is positioned in the part of the opening 10a on the side where the capacitor 60 is connected (the right-hand opening 10a in the figure) when the opening 10a is viewed from above, with the coil L1 as the boundary. In the antenna device 100A, which is designed to excite the resonance of harmonics in a band including approximately 5 GHz to approximately 7 GHz at the left end of the opening 10a, the required double-resonance characteristics can be obtained even if the excitation electrode 40 is positioned in the center of the opening 10a as shown in Figure 5. The antenna device 100A can change the resonance frequency compared to the antenna device 100 shown in Figure 1.

[0039] (Modification 2) Figure 6 is a schematic diagram of the antenna device 100B in Modification 2. In the antenna device 100B shown in Figure 6, the same reference numerals are used for components that are the same as those in the antenna device 100 shown in Figure 1, and detailed explanations will not be repeated. The antenna device 100B is a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0040] The antenna device 100B electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 of the opening 10a on the left side of Figure 6. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which coil L1 and coil L2 are magnetically coupled.

[0041] Coil L1 is provided in the middle of the signal line 20a. Coil L1 shown in Figure 6 has both ends electrically connected to the signal line 20a. One end of coil L2 is electrically connected to the excitation electrode 40 (first excitation electrode), and the other end of coil L2 is electrically connected to the excitation electrode 42 (second excitation electrode). In other words, in the antenna device 100B, excitation electrodes 40 and 42 are provided at both ends of coil L2 to configure a parasitic antenna as a dipole antenna.

[0042] In the antenna device 100 shown in Figure 1, the other end of the coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a. On the other hand, in the antenna device 100B shown in Figure 6, the other end of the coil L2 is electrically coupled to the conductor 10 on the lower side 10a2 of the opening 10a via the excitation electrode 42. In other words, the other end of the coil L2 is electrically connected to the excitation electrode 42 in order to indirectly connect to the conductor 10 on the lower side 10a2 of the opening 10a.

[0043] Antenna device 100B improves radiation efficiency in the bandwidth including approximately 5 GHz to approximately 7 GHz by providing excitation electrodes 40 and 42 at both ends of the coil L2, thereby converting the unpowered antenna into a dipole. Furthermore, when viewing the aperture 10a from above, antenna device 100B increases the area of ​​the excitation electrodes 40 and 42 that overlap with the aperture 10a, thus increasing the excitation current of the unpowered antenna.

[0044] (Modification 3) Figure 7 is a schematic diagram of the antenna device 100C in Modification 3. In the antenna device 100C shown in Figure 7, the same reference numerals are used for components that are the same as those in the antenna device 100 shown in Figure 1, and detailed explanations will not be repeated. The antenna device 100C is a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0045] In the antenna device 100C, on the left side of FIG. 7, a signal line 20a that supplies a signal from a power feeding circuit 30 is electrically connected to the conductor 10 on the upper side 10a1 side of the opening 10a. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which a coil L1 and a coil L2 are magnetically coupled.

[0046] The coil L1 is provided in the middle of the signal line 20a. Both ends of the coil L1 shown in FIG. 7 are electrically connected to the signal line 20a. One end of the coil L2 is electrically connected to an excitation electrode 40, and the other end of the coil L2 is electrically connected to the conductor 10 on the lower side 10a2 side of the opening 10a.

[0047] Furthermore, in the antenna device 100C, a capacitor 70 is connected in parallel to the electromagnetic field coupling element 50. Note that the element connected in parallel to the electromagnetic field coupling element 50 is not limited to a capacitor, and may be any passive element such as an inductor. By connecting the capacitor 70 in parallel to the electromagnetic field coupling element 50, the antenna device 100C can be adjusted to an optimal circuit with improved matching at a specific resonance frequency. The capacitor 70 is shunt-connected to the electromagnetic field coupling element 50, with one end connected to the signal line 20a and the other end connected to the conductor 10 on the lower side 10a2 side of the opening 10a, respectively. However, the connection method of the capacitor 70 is not limited to this, and the capacitor 70 may be connected in series to the electromagnetic field coupling element 50.

[0048] (Modification 4) FIG. 8 is a schematic diagram of an antenna device 100D according to Modification 4. Note that in the antenna device 100D shown in FIG. 8, the same reference numerals are assigned to the same configurations as those of the antenna device 100 shown in FIG. 1, and detailed description will not be repeated. The antenna device 100D constitutes a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0049] The antenna device 100D electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 of the opening 10a on the left side of Figure 8. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which coil L1 and coil L2 are magnetically coupled.

[0050] Coil L1 is located in the middle of the signal line 20a. Coil L1 shown in Figure 8 has both ends electrically connected to the signal line 20a. One end of coil L2 is electrically connected to the excitation electrode 40, and the other end of coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a.

[0051] The excitation electrode 40 is a strip-shaped electrode that extends in the negative X direction (arrow direction) along the long side of the opening 10a, and is electrically connected to the conductor 10 on the upper side 10a1 of the opening 10a by wiring 80. In other words, the excitation electrode 40 is electrically connected to the conductor 10 on the upper side 10a1 of the opening 10a, not by electric field coupling. Therefore, in the antenna device 100D, the unpowered antenna using the excitation electrode 40 becomes a current-excited type, and the length of the excitation electrode 40 (length in the X direction) needs to be half the wavelength of the resonant frequency, rather than one-quarter of the wavelength of the resonant frequency.

[0052] In the antenna device 100D shown in Figure 8, the length of the excitation electrode 40 is longer compared to the antenna device 100 shown in Figure 1. The antenna device 100D can reduce manufacturing variations due to misalignment of the excitation electrode 40 by electrically connecting the excitation electrode 40 to the conductor 10 on the upper side 10a1 of the opening 10a with wiring 80.

[0053] (Modification 5) Figure 9 is a schematic diagram of the antenna device 100E in Modification 5. In the antenna device 100E shown in Figure 9, the same reference numerals are used for components that are the same as those in the antenna device 100 shown in Figure 1, and detailed explanations will not be repeated. The antenna device 100E is a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0054] The antenna device 100E electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 of the opening 10a on the left side of Figure 9. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which coil L1 and coil L2 are magnetically coupled.

[0055] Coil L1 is located in the middle of the signal line 20a. Coil L1 shown in Figure 9 has both ends electrically connected to the signal line 20a. One end of coil L2 is electrically connected to the excitation electrode 40, and the other end of coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a.

[0056] Furthermore, the antenna device 100E is further provided with at least one capacitor to bypass the opening 10a on the right side of Figure 9. Specifically, the opening 10a is provided with capacitor 60 (first bypass circuit) and capacitor 62 (second bypass circuit). In the antenna device 100E, a configuration in which capacitors 60 and 62 are provided as bypass circuits has been described, but the device is not limited to this, and passive elements such as inductors may also be used. Also, in the antenna device 100E, a configuration in which two capacitors 60 and 62 are provided as bypass circuits has been described, but the device is not limited to this, and three or more passive elements such as capacitors and inductors may be provided in combination.

[0057] (Modification 6) Figure 10 is a schematic diagram of the antenna device 100F in Modification 6. In the antenna device 100F shown in Figure 10, the same reference numerals are used for components that are the same as those in the antenna device 100 shown in Figure 1, and detailed explanations will not be repeated. The antenna device 100F is a slot antenna, and an opening 10a (slot) is formed in the conductor 10.

[0058] The antenna device 100F electrically connects a signal line 20a, which supplies signals from the power supply circuit 30, to the conductor 10 on the upper side 10a1 of the opening 10a on the left side of Figure 10. An electromagnetic field coupling element 50 is provided in the middle of the signal line 20a. The electromagnetic field coupling element 50 constitutes a transformer in which coil L1 and coil L2 are magnetically coupled.

[0059] Coil L1 is located in the middle of the signal line 20a. Coil L1 shown in Figure 10 has both ends electrically connected to the signal line 20a. One end of coil L2 is electrically connected to the excitation electrode 40, and the other end of coil L2 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a.

[0060] Furthermore, the antenna device 100F is provided with an electromagnetic field coupling element 52 in the capacitor 64 that bypasses the opening 10a on the right side of Figure 10. The electromagnetic field coupling element 52 is a rectangular parallelepiped chip component that contains two coils L3 (third coil) and L4 (fourth coil), and constitutes a transformer in which coils L3 and L4 are magnetically coupled. The electromagnetic field coupling element 52 is made of an insulator (ceramic element) of a ceramic layer formed by stacking multiple substrates (ceramic green sheets) on which the coil wiring is formed.

[0061] One end of coil L3 is electrically connected to the excitation electrode 44 (excitation electrode for bypass circuit), and the other end of coil L3 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a. The excitation electrode 44 (also called the excitation conductor, feed line, or simply microstrip line) is positioned so as to overlap with the opening 10a when viewed from above. Furthermore, the excitation electrode 44 is a strip shape extending in the positive X direction (arrow direction) along the long side of the opening 10a, and is positioned in the part of the opening 10a on the side where the signal line 20a is not connected (the right side of the opening 10a in the figure) when viewed from above, with the coil L3 as the boundary. In the antenna device 100F, the excitation electrode 44 acts as a capacitive feeding element for the opening 10a, functioning as a passive antenna in a slot antenna.

[0062] One end of the coil L4 is electrically connected to one end of the capacitor 64, and the other end of the coil L4 is electrically connected to the conductor 10 on the lower side 10a2 of the opening 10a. The other end of the capacitor 64 is electrically connected to the conductor 10 on the upper side 10a1 of the opening 10a. Therefore, one end of the coil L4 is indirectly connected to the conductor 10 on the upper side 10a1 of the opening 10a. In other words, one end of the coil L4 is connected to the conductor 10 on the upper side 10a1 of the opening 10a via the capacitor 64, which is another circuit element. Note that the other circuit element provided between one end of the coil L4 and the conductor 10 on the upper side 10a1 of the opening 10a is not limited to the capacitor 64, but may be a passive element such as an inductor.

[0063] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope of the claims are intended to be included.

[0064] 10 Conductor, 10a Aperture, 20 Coaxial cable, 20a Signal line, 20b Insulator, 20c GND line, 20d Fixing part, 30 Power supply circuit, 40, 42, 44 Excitation electrodes, 50, 52 Electromagnetic field coupling elements, 60, 62, 64, 70 Capacitors, 80 Wiring, 100, 100A-100F Antenna device.

Claims

1. An antenna device comprising: a plate-shaped conductor having an opening; a signal line for supplying a signal from a power supply circuit; a first coil electrically connected or indirectly connected to the signal line; a GND line electrically connected to the conductor on the second side of the opening opposite to the first side to which the signal line is electrically connected or indirectly connected; an excitation electrode positioned to overlap the opening when the opening is viewed from above; a second coil having one end electrically connected to the excitation electrode and the other end electrically connected or indirectly connected to the conductor on the second side; and at least one capacitor capacitively coupling the conductor on the first side and the conductor on the second side, wherein the first coil and the second coil are positioned to be magnetically coupled.

2. The antenna device according to claim 1, further comprising a passive element connected in parallel with the first coil.

3. The antenna device according to claim 1 or claim 2, wherein, when the opening is viewed from above, the excitation electrode is positioned on the side of the first coil where the capacitor is not provided.

4. The antenna device according to claim 1 or claim 2, wherein, when the opening is viewed from above, the excitation electrode is positioned on the side of the first coil where the capacitor is provided.

5. The antenna device according to any one of claims 1 to 4, wherein the excitation electrode includes a first excitation electrode and a second excitation electrode, and the second coil has one end electrically connected to the first excitation electrode and the other end electrically connected to the second excitation electrode.

6. The antenna device according to any one of claims 1 to 5, wherein the excitation electrode is electrically connected to the conductor via wiring.

7. The antenna device according to any one of claims 1 to 6, wherein the signal line and the GND line constitute a coaxial cable.

8. The antenna device according to any one of claims 1 to 7, further comprising: an excitation electrode for a bypass circuit positioned to overlap with the opening when the opening is viewed from above; a third coil having one end electrically connected to the excitation electrode for the bypass circuit and the other end electrically connected or indirectly connected to the conductor on the second side; and a fourth coil positioned between one end of the capacitor and the conductor on the second side, having one end electrically connected or indirectly connected to the capacitor and the other end electrically connected or indirectly connected to the conductor on the second side, wherein the third coil and the fourth coil are positioned to be magnetically coupled.

9. An electronic device comprising the power supply circuit and the antenna device according to any one of claims 1 to 8.

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