JP7211543B2 - Antenna device and electronic equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an antenna device provided in an electronic device, and more particularly to an antenna device provided with a radiation element having a conductor loop portion and an electronic device provided with the antenna device.

2. Description of the Related Art In electronic devices such as smartphones and mobile communication terminals, part of the housing may be used as part of the radiation element of the antenna device.

In smartphones, mobile communication terminals, and the like, antenna devices that can be used over a wide band are required in order to be applicable to communication frequency bands ranging from several hundred MHz to several GHz, for example.

One of the important factors in widening the bandwidth of the antenna device is impedance matching between the feeding circuit and the radiating element. A transformer type matching circuit suitable for impedance matching between such a feeding circuit and a radiating element and capable of performing predetermined impedance conversion over a wide band is disclosed in, for example, Patent Document 1.

Japanese Patent No. 6048593

In an electronic device such as a smart phone or a mobile communication terminal, if a part of the housing is used as a part of the radiating element, the occupancy rate of the antenna device in the electronic device can be reduced, which is advantageous for miniaturization.

FIG. 42 is a schematic configuration diagram of a loop antenna configured on a circuit board. The circuit board has a ground area GND in which a ground conductor is formed and a non-ground area NGA in which no ground conductor is formed, and a loop conductor pattern PL is formed in this non-ground area NGA. A feeder circuit FS connected to the loop conductor pattern PL is provided on the circuit board.

However, when trying to apply the transformer type matching circuit to a loop antenna having a loop-shaped radiating element, the loop antenna itself has an inductance (hereinafter referred to as "L characteristic") due to its structure. Because of its large size, the impedance conversion effect of the transformer matching circuit is limited. In other words, there arises a problem to be solved that the frequency band in which a predetermined impedance conversion ratio can be obtained is narrowed. The detailed action of this will be described later.

Although it is possible to construct the radiation element with a metal frame, the antenna space is increased. Also, when trying to apply it to a MIMO (multiple-input and multiple-output) antenna in 5G (5th Generation), etc., it is necessary to arrange a plurality of radiating elements in the housing of a smartphone or the like, which is difficult to realize.

The above-mentioned problems are not limited to an antenna device that constitutes a typical loop antenna and an electronic device including the same, but are not limited to an antenna device having a loop portion that forms a loop from a feeding portion to a ground portion as a radiating element, and an antenna device that includes the same. The same is true for electronic equipment.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an antenna device having wideband characteristics while including a radiation element having a loop portion, and an electric device including the antenna device. be.

An antenna device as an example of the present disclosure is an antenna device configured in an electronic device including a housing having a conductive frame, and a first feeding circuit and a circuit board housed in the housing, a first radiating element; and an impedance matching circuit connected between the first feeding circuit and the first radiating element for matching impedances of the first feeding circuit and the first radiating element. The impedance matching circuit has a transformer type matching circuit including a first coil and a second coil magnetically coupled to each other, the circuit board has a ground conductor, and the frame has a first conductor portion and a second conductor portion. wherein the first radiating element includes the first conductor portion and the ground conductor, the second conductor portion is electrically connected to the ground conductor, and the first conductor portion has a first end and a second end. , the first feeding circuit, the impedance matching circuit, the first conductor and the ground conductor form a loop, and a capacitive section is formed between the second end and the second conductor.

An electronic device as an example of the present disclosure includes a radiating element, a feeding circuit, a circuit board, an impedance matching circuit connected between the radiating element and the feeding circuit, the radiating element, the impedance matching circuit, and and a housing containing the power supply circuit, wherein the impedance matching circuit has a transformer type matching circuit composed of a first coil and a second coil that are magnetically coupled to each other; The body has a conductive frame, the circuit board has a ground conductor, the frame has a first conductor portion and a second conductor portion, and the radiating element connects the first conductor portion and the ground conductor. wherein the second conductor is conductive to the ground conductor, the first conductor has a first end and a second end, the feeding circuit, the impedance matching circuit, the first conductor and the ground conductor The feeder circuit is connected to the first conductor portion via the impedance matching circuit, the second end is adjacent to the second conductor portion, and the second end and the second A capacitive section is formed between the conductor section.

Further, an electronic device as an example of the present disclosure includes: a first radiation element; a feed circuit; a circuit board; an impedance matching circuit connected between the first radiation element and the feed circuit; An electronic device comprising a housing containing a radiating element, the impedance matching circuit, and the feeding circuit, wherein the impedance matching circuit is a transformer type configured by a first coil and a second coil magnetically coupled to each other. a matching circuit, the circuit board having a ground conductor, the frame having a first conductor portion and a second conductor portion, the first radiation element including the first conductor portion and the ground conductor; The second conductor is electrically connected to the ground conductor, the first conductor has a first end and a second end, and is looped by the feeding circuit, the impedance matching circuit, the first conductor and the ground conductor. is configured, the feeder circuit is connected to the first conductor via the impedance matching circuit, the second end is adjacent to the second conductor, and the second end and the second conductor are connected A capacitor is formed between

ADVANTAGE OF THE INVENTION According to this invention, the antenna device which has a wideband characteristic, and an electric equipment provided with the antenna device are obtained, although it is equipped with the antenna element which has a loop part. In addition, since the capacitive portion generated between the second end of the first conductor and the second conductor is added, the length of the first radiation element required to obtain a predetermined frequency characteristic can be shortened.

FIG. 1 is a plan view of an antenna device 101 and an electronic device 201 including the antenna device 101 of the first embodiment. FIG. 2 is a cross-sectional view of the electronic device 201 shown in FIG. 1, taken along line YY. FIG. 3 is a plan view of the antenna device 101 portion of the electronic device. FIG. 4 is an equivalent circuit diagram of the antenna device 101. As shown in FIG. FIG. 5 is a diagram showing the electric field intensity distribution at the fundamental wave resonance of the half-wave loop antenna. FIG. 6A is a circuit diagram of the transformer matching circuit 31, and FIG. 6B is its equivalent circuit diagram. FIG. 7A is a circuit diagram of the transformer type matching circuit 31, and FIGS. 7B and 7C are impedance matching circuits as comparative examples. FIG. 8(A) shows the reflection coefficient (S11) of the antenna element with a large L characteristic as viewed from the feeding circuit, and FIG. 8(B) shows the impedance of the antenna viewed from the feeding circuit on a Smith chart. It is the figure which expressed. FIG. 9(A) shows the reflection coefficient (S11) of an antenna element with a small L characteristic as viewed from the feeding circuit, and FIG. 9(B) shows the impedance of the antenna viewed from the feeding circuit on a Smith chart. It is the figure which expressed. FIG. 10 is a circuit diagram of another transformer-type matching circuit 32 according to the first embodiment. FIG. 11 is a plan view of the antenna device 102 portion of the electronic device according to the second embodiment. FIG. 12 is an equivalent circuit diagram of the antenna device 102. As shown in FIG. 13A is a plan view of the antenna device 103A portion of the electronic device according to the third embodiment, and FIG. 13B is a plan view of the antenna device 103B portion of the electronic device according to the third embodiment. be. 14A and 14B schematically show the action of the impedance matching circuit 30. FIG. FIG. 15A is a diagram showing the configuration of the impedance matching circuit, in particular, of the antenna device according to the third embodiment. FIG. 15(B) is a diagram showing the configuration of an antenna device in which the input side and the output side of the transformer type matching circuit 31 shown in FIG. 15(A) are connected in an opposite relationship. FIG. 15(C) is a diagram showing modifications and specific examples of the matching circuits 41, 42, and 43 in FIGS. 15(A) and 15(B). FIG. 16 is a diagram showing the configuration of another impedance matching circuit of the antenna device according to the third embodiment. FIG. 17 is a plan view of the antenna device 104 portion of the electronic device according to the fourth embodiment. FIG. 18 is an equivalent circuit diagram of the antenna device 104. As shown in FIG. FIG. 19 is a plan view of the antenna device 105A portion of the electronic device according to the fifth embodiment. FIG. 20 is a plan view of another antenna device 105B portion of the electronic device according to the fifth embodiment. FIG. 21 is a plan view of the antenna device 106A portion of the electronic device according to the sixth embodiment. FIG. 22 is a plan view of another antenna device 106B portion of the electronic device according to the sixth embodiment. FIG. 23 is a plan view of the antenna device 107 portion of the electronic device according to the seventh embodiment. FIG. 24 is an equivalent circuit diagram of the impedance matching circuit 30 in FIG. FIG. 25 is a diagram showing the frequency characteristics of the insertion loss of the antenna device 107 and the frequency characteristics of the insertion loss of the antenna device of the comparative example. FIG. 26 is a diagram showing the configuration of the antenna device 108 according to the eighth embodiment. FIG. 27 is a plan view of the antenna device 108. FIG. FIG. 28 is a plan view of the antenna device 108 and an electronic device 208 including it. FIG. 29 is a diagram showing the frequency characteristics of the reflection coefficient of the antenna device 108 according to the eighth embodiment viewed from the first feeding circuit 1 and the second feeding circuit 2. FIG. FIG. 30 is a diagram showing the configuration of an antenna device 109A according to the ninth embodiment. FIG. 31 is a plan view of the antenna device 109A. FIG. 32A is a diagram showing the frequency characteristics of the reflection coefficient viewed from the first feeding circuit 1 of the antenna device 109A according to the ninth embodiment. FIG. 32B is a diagram showing the frequency characteristics of the reflection coefficient of the antenna device 108 shown in the eighth embodiment as a comparative example, viewed from the first feeding circuit 1 and the second feeding circuit 2. FIG. FIG. 33 is a diagram showing the configuration of another antenna device 109B according to the ninth embodiment. FIG. 34 is a plan view of the antenna device 109B. FIG. 35 is a diagram showing the configuration of an antenna device 110A according to the tenth embodiment. FIG. 36 is a diagram showing the configuration of another antenna device 110B according to the tenth embodiment. FIG. 37 is a diagram showing the configuration of yet another antenna device 110C according to the tenth embodiment. FIG. 38 shows a switch circuit for selecting reactance elements. FIG. 39 is a plan view particularly showing the structure of the first conductor portion 11 and the second conductor portion 12 of the antenna device according to the eleventh embodiment. FIG. 40A is a plan view of another antenna device according to the eleventh embodiment. FIG. 40(B) is a cross-sectional view taken along line YY in FIG. 40(A). FIG. 41(A) is a plan view of still another antenna device according to the eleventh embodiment. FIG. 41(B) is a plan view with the circuit board 20 of FIG. 41(A) removed. FIG. 41(C) is a cross-sectional view taken along line YY in FIG. 41(A). FIG. 42 is a schematic configuration diagram of a loop antenna configured on a circuit board.

<<1st Embodiment>>
FIG. 1 is a plan view of an antenna device 101 and an electronic device 201 including the antenna device 101 of the first embodiment. However, it shows a state in which the upper half of the housing is removed. This electronic device 201 comprises a circuit board 20 and a housing 100 enclosing it. Housing 100 has a conductive frame 10 . The antenna device 101 is composed of part of the frame 10 and part of the circuit board 20 . A power supply circuit, which will be described later, is configured on the circuit board 20 .

FIG. 2 is a cross-sectional view of the electronic device 201 shown in FIG. 1, taken along line YY. A ground conductor 20G is formed on the upper surface of the circuit board 20 . This ground conductor 20G is electrically connected to the conductor portion of the housing 100 . The circuit board 20 is a multilayer board, but the internal layers are omitted in FIG.

FIG. 3 is a plan view of the antenna device 101 portion of the electronic device. However, for convenience of explanation, it is a plan view in which the frame 10 is laid down and the circuit board 20 and the frame 10 are arranged on the same plane as indicated by the two-dot chain line in FIG.

The circuit board 20 has a region where the ground conductor 20G is formed and a non-ground portion 20N where the ground conductor 20G is not formed.

In this example, the frame 10 is made of a metal plate. A first conductor portion 11 and a second conductor portion 12 are formed in a portion of the frame 10 . A capacitive portion CP is formed at a position where the first conductor portion 11 and the second conductor portion 12 are adjacent to each other. In this example, a slit-like gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms the capacitance portion CP.

The second conductor portion 12 is electrically connected to the ground conductor 20G of the circuit board 20 . The first conductor portion 11 has a first end FE and a second end SE, and the second end SE is adjacent to the second conductor portion 12 . More specifically, the second end SE is closer to the second conductor portion 12 than the first end FE.

The first conductor portion 11 is located opposite the non-ground portion 20N of the circuit board 20 and is separated from the ground conductor 20G. The second conductor portion 12 is electrically connected to the ground conductor 20G of the circuit board 20 .

The first power supply circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit including a transformer type matching circuit 31 . In this example, the first power supply circuit 1 is connected to the second end SE of the first conductor portion 11 or its vicinity via an impedance matching circuit. More specifically, the position where the first power supply circuit 1 is connected to the first conductor portion 11 via the impedance matching circuit is closer to the second end SE than to the first end FE.

A loop is configured by the first feeder circuit 1, the impedance matching circuit including the transformer type matching circuit 31, the first conductor portion 11, and the ground conductor 20G. That is, the antenna element is composed of a part of the frame 10 and the ground conductor 20G of the circuit board 20. As shown in FIG.

FIG. 4 is an equivalent circuit diagram in the vicinity of the fundamental resonance frequency, corresponding to the portion of the antenna device 101 from the transformer type matching circuit 31 to the ground conductor 20G via the first conductor portion 11. As shown in FIG. The antenna element of this antenna device 101 is a kind of loop antenna. A loop antenna with fewer slits is suitable for a housing with a metal frame because of its design and strength. An inductor component Lant1 is formed between the transformer matching circuit 31 and the capacitive part CP generated in the slit-shaped gap GAP1, and the inductance components Lant2, Lant3 and the capacitive component Cm of the antenna element are formed by the first conductor part 11 and the ground conductor 20G. is configured. Note that resistance components are omitted in the equivalent circuit.

Since the loop antenna generally resonates at λ/2 from the feed point to the ground point, the antenna length for realizing the same resonance frequency is longer than that of a monopole antenna that resonates at λ/4. Therefore, the antenna has a high L characteristic. However, in this embodiment, the effect of lowering the resonance frequency is produced by the CP of FIG.

FIG. 5 is a diagram showing the electric field intensity distribution at the fundamental wave resonance of the half-wave loop antenna. It shows the distribution from the output part of the transformer type matching circuit 31 shown in FIG. The capacitive part CP is near the maximum position of the electric field distribution.

Since the slit-like gap GAP1 between the first conductor portion 11 and the second conductor portion 12 is formed in the metal frame 10, the facing area of the gap GAP1 can be easily increased. A larger capacitance can be obtained than a capacitor formed by a formed conductor pattern or LDS (Laser Direct Structuring) conductor pattern.

FIG. 6A is a circuit diagram of the transformer matching circuit 31, and FIG. 6B is its equivalent circuit diagram. As shown in FIG. 6A, the transformer matching circuit 31 includes a first coil L1 connected to the first power supply circuit 1 and a second coil L2 coupled to the first coil L1. The transformer type matching circuit 31 has a first coil L1 and a second coil L2 connected in series. It is an autotransformer having both ends as second input/output ports. In FIG. 6A, the terminal (P1-G) is the first input/output port, and the terminal (P2-G) is the second input/output port.

The transformer-type matching circuit 31 is a transformer-type circuit in which the first coil L1 and the second coil L2 are tightly coupled via a mutual inductance M. This transformer-type matching circuit 31 can be equivalently converted to a T-type circuit with three inductance elements Z1, Z2, and Z3, as shown in FIG. 6(B).

If the inductance of the first coil L1 shown in FIG. 6A is L1, the inductance of the second coil L2 is L2, and the mutual inductance is M, the inductance of the first inductance element Z1 in FIG. 6B is L1+M , the inductance of the second inductance element Z2 is −M, and the inductance of the third inductance element Z3 is L2+M. Therefore, the impedance transformation ratio is (L1+L2+2M):L2. For example, when the first feeding circuit 1 side is 50Ω and the antenna side is 5Ω, impedance conversion of 10:1 is performed. Since a loop antenna generally has a lower antenna impedance than a feeder circuit, it is easy to match the impedance by using the transformer type matching circuit 31 capable of obtaining such a large impedance conversion ratio.

Since the inductance between the terminals (P1-G) is L1+L2+2M, a high impedance conversion ratio can be realized with the first coil L1 and the second coil having a small number of turns. Therefore, the resistance component of the transformer matching circuit 31 can be suppressed, and the insertion loss can be suppressed.

Here, the difference in characteristics between the transformer type matching circuit 31 and the impedance matching circuit using the LC circuit will be described. FIG. 7A is a circuit diagram of the transformer type matching circuit 31, and FIGS. 7B and 7C are impedance matching circuits as comparative examples.

FIG. 8(A) shows the reflection coefficient (S11) of the antenna element with a large L characteristic as viewed from the feeding circuit, and FIG. 8(B) shows the impedance of the antenna viewed from the feeding circuit on a Smith chart. It is the figure which expressed. Further, FIG. 9A shows the reflection coefficient (S11) of the antenna element with small L-characteristic as viewed from the feeding circuit, and FIG. Figure 3 is the diagram presented above. Lines A, B, and C in FIGS. 8A, 8B, 9A, and 9B correspond to the It corresponds to the characteristics of each impedance matching circuit. Lines D in FIGS. 8A, 8B, 9A, and 9B are the characteristics without the impedance matching circuit.

The impedance of the antenna element with a large L-characteristic is displaced from point Dp1 to point Dp2 along line D in FIG. 8(B) as the frequency rises. For example, the reactance at point Dp1 is −100Ω, and the reactance at point Dp2 is +100Ω. This difference of 200Ω corresponds to the magnitude of the L characteristic of the antenna element.

For an antenna element with a large L characteristic, in the impedance matching circuit by the LC circuit shown in FIGS. Moreover, the frequency band for impedance matching is narrow. Also, even if the impedance conversion is performed by the transformer type matching circuit 31 shown in FIG. 7A, the impedance matching frequency band is narrow as indicated by line A in FIGS. 8A and 8B. In other words, although it is a transformer-type matching circuit, it is not much different from an impedance matching circuit using an LC circuit.

In an antenna element with a small L characteristic, in the impedance matching circuit by the LC circuit shown in FIGS. , the impedance matching frequency band expands a little, but the locus on the Smith chart extends under the influence of the frequency characteristics of the LC, so the characteristics are still narrow. In the case of impedance conversion by the transformer-type matching circuit 31 shown in FIG. 7(A), the impedance matching frequency band is wide as indicated by line A in FIGS. 9(A) and 9(B). In the example shown in FIG. 9A, impedance matching is achieved from 3 GHz to 5 GHz or more.

Thus, in order to perform impedance conversion between the first feeding circuit 1 and the antenna element using the transformer matching circuit 31, it is important that the L characteristic of the antenna element is small. According to this embodiment, as shown in FIGS. 3 and 4, the capacitive component C of the antenna element is increased by the capacitive part CP, and the L characteristic of the entire antenna element including this capacitive component C is small. Therefore, impedance conversion by the transformer-type matching circuit 31 enables impedance matching between the first feeding circuit 1 and the antenna element over a wide band.

FIG. 10 is a circuit diagram of another transformer type matching circuit 32 according to this embodiment. As shown in FIG. 10, the transformer matching circuit 32 includes a first coil L1 connected to the first power supply circuit 1 and a second coil L2 coupled to the first coil L1. A transformer is composed of the first coil L1 and the second coil L2. In FIG. 10, the terminal (P1-G) is the first input/output port, and the terminal (P2-G) is the second input/output port.

The transformer-type matching circuit 31 is a transformer in which a first coil L1 and a second coil L2 are tightly coupled via a mutual inductance M.

Thus, the transformer type matching circuit 32 having a structure in which the first coil L1 and the second coil L2 that are magnetically coupled to each other are separated may be used.

<<Second embodiment>>
In the second embodiment, an antenna device in which the feeding position for the first conductor portion 11 is different from the example shown in the first embodiment will be described.

FIG. 11 is a plan view of the antenna device 102 portion of the electronic device according to the second embodiment. FIG. 3 is a plan view showing a state in which the frame 10 shown in FIG. 2 is laid down and the circuit board 20 and the frame 10 are arranged on the same plane, like the example shown in FIG. 3 in the first embodiment.

The circuit board 20 has a region where the ground conductor 20G is formed and a non-ground portion 20N where the ground conductor 20G is not formed. The frame 10 is made of a metal plate. A first conductor portion 11 and a second conductor portion 12 are formed in a portion of the frame 10 . A capacitive portion CP is formed at a position where the first conductor portion 11 and the second conductor portion 12 are adjacent to each other. In this example, a slit-like gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms the capacitance portion CP.

The second conductor portion 12 is electrically connected to the ground conductor 20G of the circuit board 20 . The first conductor portion 11 has a first end FE and a second end SE, and the second end SE is adjacent to the second conductor portion 12 .

The first conductor portion 11 is located opposite the non-ground portion 20N of the circuit board 20 and is separated from the ground conductor 20G. The second conductor portion 12 is electrically connected to the ground conductor 20G of the circuit board 20 .

The first power supply circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit including a transformer type matching circuit 31 . In this example, the first power supply circuit 1 is connected via an impedance matching circuit to the power supply position Pf, which is a distance P from the second end SE of the first conductor portion 11 toward the first end FE. That is, the first conductor portion 11 protrudes toward the second conductor portion 12 by the distance P from the feeding position Pf with respect to the first conductor portion 11 . The capacitive part CP is at or near a quarter wavelength away from the feed position Pf for the first conductor part 11 (with respect to the loop). Other configurations are as shown in the first embodiment.

FIG. 12 is an equivalent circuit diagram in the vicinity of the fundamental resonance frequency corresponding to the portion of the antenna device 102 from the transformer type matching circuit 31 to the ground conductor 20G via the first conductor portion 11. FIG. The antenna element of this antenna device 102 is a kind of loop antenna. An inductor component Lant1 is formed between the transformer matching circuit 31 and the capacitive part CP generated in the slit-shaped gap GAP1, and the inductance components Lant2, Lant3 and the capacitive component Cm of the antenna element are formed by the first conductor part 11 and the ground conductor 20G. is configured. Note that resistance components are omitted in the equivalent circuit.

According to the present embodiment, since the conductor portion spreads from the power feeding position Pf to the second end SE with respect to the first conductor portion 11, the current in the conductor portion from the power feeding position Pf to the second end SE becomes small and the voltage ( The maximum point of the electric field can be concentrated near the bulge at a distance P. As a result, the capacity of the capacitive part CP can be added to the portion where the voltage (electric field) intensity is high, and the effect of adding this capacity is enhanced.

As in this example, the feeding position Pf for the first conductor portion 11 is not limited to the second end SE of the first conductor portion 11 or its vicinity.

<<Third embodiment>>
In the third embodiment, an antenna device having an impedance matching circuit different from the configuration shown so far will be shown.

13A is a plan view of the antenna device 103A portion of the electronic device according to the third embodiment, and FIG. 13B is a plan view of the antenna device 103B portion of the electronic device according to the third embodiment. be. In both cases, the first power supply circuit 1 is connected to the first conductor portion 11 via the impedance matching circuit 30 . In this example, the impedance matching circuit 30 is composed of a transformer type matching circuit 31, a matching circuit 41 provided in the front stage thereof, and a matching circuit 42 provided in the rear stage thereof. Other configurations are as shown in the first and second embodiments.

The matching circuits 41 and 42 are, for example, an LC circuit including a series-connected inductor and a grounded capacitor shunt-connected, or an LC circuit including a series-connected capacitor and a grounded shunt-connected inductor. The matching circuit 42 may include reactance elements (L, C) that adjust the resonance frequency of the antenna.

In the example of the antenna device 103A, the transformer type matching circuit 31 and the matching circuits 41 and 42 are provided in the non-ground portion 20N, but they may be provided in the portion where the ground conductor 20G is formed. Further, like the antenna device 103B, the matching circuit 42 including the element for adjusting the resonance frequency of the antenna is arranged in the non-ground portion 20N, and the matching circuit 41 including the transformer type matching circuit 31 and the shunt connection is formed on the ground conductor 20G. can be placed in the department.

14A and 14B schematically show the action of the impedance matching circuit 30. FIG. In FIG. 14, trajectories S0, S1, and S2 represent impedance trajectories viewed from the first feeding circuit 1 when the frequency is swept over the operating frequency band of the antenna element on the Smith chart. A locus S0 represents the displacement of the impedance when the impedance is matched by the matching circuit 42. FIG. A locus S1 represents the displacement of the impedance in a state of being impedance-converted by the transformer-type matching circuit 31 . Thus, the arc of the impedance locus is reduced by the transformer matching circuit 31 . Furthermore, a locus S2 represents the impedance displacement in a state in which the impedance is matched by the matching circuit 41. FIG. In this example, the matching circuit 41 is composed of a shunt-connected capacitor and a series-connected inductor, and is impedance-matched as shown in FIG. This causes the impedance locus to shrink and transition to the center of the Smith chart.

In the example shown above, the LC circuits are provided at the front and rear stages of the transformer matching circuit 31, but the LC circuits may be provided only at the front and rear stages. As a result, compared to the characteristics of the transformer type matching circuit 31 alone, it is possible to widen the band of impedance matching.

In this manner, the LC circuit may be provided before, after, or before and after the transformer matching circuit 31 .

FIG. 15A is a diagram showing the configuration of the impedance matching circuit, in particular, of the antenna device according to the third embodiment. The first radiation element 11R is a radiation element composed of the first conductor portion 11 and the ground conductor 20G. The first feeding circuit 1 is connected to the first radiating element 11R via an impedance matching circuit 30. As shown in FIG. In this example, the impedance matching circuit 30 includes a transformer type matching circuit 31, a matching circuit 41 provided in the preceding stage, a matching circuit 42 provided in the subsequent stage, and a transformer type matching circuit 31 connected between the ground and the ground. It is composed of a matching circuit 43 .

A matching circuit 41 in FIG. 15A is composed of an inductor connected in series and a capacitor connected to a shunt. The matching circuits 42 and 43 are also composed of inductors, capacitors, or inductors and capacitors.

Although the matching circuit 42 is shunt-connected to the ground in the example shown in FIG. In addition, in the example shown in FIG. 15A, the matching circuit 43 has two terminals connected to the ground. Circuits connected in series may also be used. When the matching circuit 43 is composed of an inductor connected between the transformer type matching circuit 31 and the ground, the inductor is not magnetically coupled with the first coil L1 and the second coil L2. Ratios and impedance matching can be fine-tuned.

FIG. 15(B) is an example in which the input side and the output side of the transformer type matching circuit 31 shown in FIG. 15(A) are connected in a reverse relationship. When the impedance of the first radiating element 11R is higher than the impedance of the first feeding circuit 1, or due to the influence of the wiring from the transformer matching circuit 31 to the first radiating element 11R, the side from the transformer matching circuit 31 to the first radiating element 11R In the case that the impedance when viewed is equivalently high, an impedance matching circuit that increases the impedance may be configured in this way.

FIG. 15(C) shows a specific example of the matching circuits 42 and 43 in FIGS. 15(A) and 15(B). 15C shows an example of a matching circuit 41 different from the matching circuit 41 shown in FIGS. 15A and 15B. Thus, the matching circuit 42 may constitute a circuit for adjusting the resonance frequency of the first radiating element 11R. Also, the matching circuit 41 in the preceding stage of the transformer type matching circuit 31 may be provided with a shunt-connected inductor.

FIG. 16 is a diagram showing the configuration of another impedance matching circuit of the antenna device according to the third embodiment. A first feeding circuit 1 is connected to the first radiating element 11R via an impedance matching circuit 30 . In this example, the impedance matching circuit 30 includes a transformer type matching circuit 32, a matching circuit 41 provided in the front stage thereof, a matching circuit 42 provided in the rear stage, and a transformer type matching circuit 32 connected between the ground and the ground. It is composed of a matching circuit 43 .

As shown in this embodiment, the impedance matching circuit may be composed of the transformer type matching circuits 31 and 32 and the LC circuit.

<<Fourth embodiment>>
In the fourth embodiment, an antenna device in which the structure of the first conductor portion 11 provided on the frame 10 is different from the examples shown so far will be described.

FIG. 17 is a plan view of the antenna device 104 portion of the electronic device according to the fourth embodiment. A first feeder circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit 30 . In this example, the impedance matching circuit 30 is composed of a transformer type matching circuit 31, a matching circuit 41 provided in the front stage thereof, and a matching circuit 42 provided in the rear stage thereof.

A notch portion 11N is formed between the first end FE of the first conductor portion 11 and the third conductor portion 13 . Other configurations are as shown in the third embodiment.

FIG. 18 is an equivalent circuit diagram in the vicinity of the fundamental resonance frequency, corresponding to the portion of the antenna device 104 from the impedance matching circuit 30 to the ground conductor 20G via the first conductor portion 11. FIG. The antenna element of this antenna device 104 is a kind of loop antenna. An inductor component Lant1 is formed between the impedance matching circuit 30 and the capacitive part CP generated in the slit-shaped gap GAP1, and the inductance components Lant2, Lant3 and the capacitive component Cm of the antenna element are formed by the first conductor part 11 and the ground conductor 20G. Configured. Note that resistance components are omitted in the equivalent circuit.

In this embodiment, since the notch portion 11N is formed between the first end FE of the first conductor portion 11 and the third conductor portion 13, the first conductor portion 11 and the circuit board 20 are not grounded. A connection point (short point) SP with the periphery of the portion 20N is defined in a narrow area. Therefore, even if part of another antenna element is provided in the third conductor part 13, the first conductor part 11 can be separated from the other antenna element. In other words, the frame 10 can be used as part of the antenna elements of other antenna devices without dedicating the frame 10 to the antenna device 104 .

<<Fifth Embodiment>>
In the fifth embodiment, an antenna device including a reactance circuit in the loop of the loop antenna is illustrated.

FIG. 19 is a plan view of the antenna device 105A portion of the electronic device according to the fifth embodiment. A first feeder circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit 30 . In this example, the impedance matching circuit 30 is composed of a transformer type matching circuit 31, a matching circuit 41 provided in the front stage thereof, and a matching circuit 42 provided in the rear stage thereof.

A gap GAP1 is formed between the second end SE of the first conductor portion 11 and the second conductor portion 12, and a gap GAP2 is formed between the first end FE of the first conductor portion 11 and the third conductor portion 13. is formed. A reactance circuit 51 is connected between the first end FE of the first conductor portion 11 and the ground. That is, reactance circuit 51 is inserted in the loop of the loop antenna.

The reactance circuit 51 is composed of a plurality of reactance elements X and a switch SW for selecting one of them. In this example, the reactance element X is selected by a control signal for the switch SW to shift the resonance frequency of the antenna, thereby configuring an antenna device that covers a wider band.

FIG. 20 is a plan view of another antenna device 105B portion of the electronic device according to the fifth embodiment. This antenna device 105B includes a variable reactance element 52 in place of the reactance circuit 51 shown in FIG. The variable reactance element 52 is, for example, a variable capacitance element whose capacitance is determined by an applied voltage. In this example, the resonance frequency of the antenna is shifted by the applied voltage to configure an antenna device that covers a wider band.

<<Sixth embodiment>>
In the sixth embodiment, an antenna device in which a reactance circuit is added to the loop antenna will be illustrated.

FIG. 21 is a plan view of the antenna device 106A portion of the electronic device according to the sixth embodiment. A first feeder circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit 30 .

A gap GAP1 is formed between the second end SE of the first conductor portion 11 and the second conductor portion 12 . A reactance circuit 51 is connected between the first end FE and the second end SE of the first conductor portion 11 and between the ground. That is, the reactance circuit 51 is connected between a predetermined position of the loop of the loop antenna and the ground.

The reactance circuit 51 is composed of a plurality of reactance elements X and a switch SW for selecting one of them. In this example, the reactance element X is selected by a control signal for the switch SW to shift the resonance frequency of the antenna, thereby configuring an antenna device that covers a wider band.

FIG. 22 is a plan view of another antenna device 106B portion of the electronic device according to the sixth embodiment. This antenna device 106B includes a variable reactance element 52 in place of the reactance circuit 51 shown in FIG. The variable reactance element 52 is, for example, a variable capacitance element whose capacitance is determined by an applied voltage. In this example, the resonance frequency of the antenna is shifted by the applied voltage to configure an antenna device that covers a wider band.

<<Seventh embodiment>>
In the seventh embodiment, an antenna device including an impedance matching circuit having a shunt-connected inductor is illustrated.

FIG. 23 is a plan view of the antenna device 107 portion of the electronic device according to the seventh embodiment. FIG. 24 is an equivalent circuit diagram of the impedance matching circuit 30 in FIG. A first feeder circuit 1 is connected to the first conductor portion 11 via an impedance matching circuit 30 . In this example, the impedance matching circuit 30 is composed of a transformer matching circuit 31 and an inductor L0. Other configurations are as shown in the first and second embodiments.

The transformer-type matching circuit 31 is an autotransformer in which a first coil L1 and a second coil L2 are connected in series, and the impedance matching circuit 30 has an inductor L0 connected in series with the second coil L2. That is, the impedance matching circuit 30 connects both ends of the series connection circuit of the first coil L1, the second coil L2, and the inductor L0 to the first input/output port, and connects both ends of the series connection circuit of the second coil L2, and the inductor L0 to the second input port. This circuit is used as an output port.

If the impedance matching circuit 30 is composed only of an autotransformer consisting of the first coil L1 and the second coil L2, the antenna element (the radiation element including a part of the frame 10 and the ground conductor 20G of the circuit board 20) In the frequency region where the impedance of is high, the inductance component of the second coil L2 is effective, and the impedance matching circuit may operate like a high-pass filter. In this embodiment, by connecting the inductor L0 in series with the second coil L2 shunt-connected to the ground, the impedance of the shunt path can be increased in the frequency region where the impedance of the antenna element is high. As a result, the high-pass filter-like operation can be suppressed.

FIG. 25 is a diagram showing frequency characteristics of insertion loss IL not including loss due to reflection of antenna device 107 and frequency characteristics of insertion loss IL not including loss due to reflection of the antenna device of the comparative example. In FIG. 25, line A is the characteristic of the antenna device 107, and line B is the characteristic of the antenna device when the inductor L0 shown in FIG. 23 is not provided.

In the example shown in line B of FIG. 25, without the inductor L0, the above-described high-pass filter operation causes a large insertion loss in the frequency range lower than 3.5 GHz. On the other hand, in this embodiment, as indicated by line A in FIG. 25, it is possible to suppress an increase in insertion loss in a region where the impedance of the antenna element is high.

Since the impedance matching circuit 30 of this embodiment is equivalently represented as shown in FIG. 24, the impedance transformation ratio of the impedance matching circuit 30 is (L1+L2+2M+L0):(L2+L0). Therefore, the impedance conversion ratio of the impedance matching circuit 30 can be adjusted by appropriately determining the inductance of the inductor L0.

The transformer type matching circuit 31 and the inductor L0 may be separate elements, or may be integrally formed in the same element.

<<Eighth embodiment>>
The eighth embodiment exemplifies an antenna device and an electronic device including a second radiation element.

FIG. 26 is a diagram showing the configuration of the antenna device 108 according to the eighth embodiment. The antenna device 108 is composed of a first antenna device 108A and a second antenna device 108B. The first antenna device 108A is composed of a first radiation element 11R, a capacitor CP and an impedance matching circuit 30. As shown in FIG. The second antenna device 108B is composed of the second radiating element 12R.

In addition, in FIG. 26, the characteristics of the antenna may be adjusted by inserting a reactance element at the position indicated by the two-dot chain line.

FIG. 27 is a plan view of the antenna device 108. FIG. This figure is a plan view in which the circuit board 20 and the frame 10 are arranged on the same plane, in the same way as the notation method shown in FIG. 3 and the like in the first embodiment. FIG. 28 is a plan view of the antenna device 108 and an electronic device 208 including it. The electronic device 208 includes a housing 100 having a conductive frame 10 , and a first power supply circuit 1 , a second power supply circuit 2 and a circuit board 20 housed in the housing 100 . Also, the antenna device 108 includes a first conductor portion 11 , a second conductor portion 12 and an impedance matching circuit 30 .

The circuit board 20 has a region in which the ground conductor 20G is formed, and non-ground portions 20N1 and 20N2 in which the ground conductor 20G is not formed.

In this example, the frame 10 is made of a metal plate. A first conductor portion 11 , a second conductor portion 12 and a fourth conductor portion 14 are formed in a portion of the frame 10 . A capacitance portion CP is formed at a position adjacent to the first conductor portion 11 and the second conductor portion 12 . In this example, a slit-like gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms the capacitance portion CP.

The first radiation element 11R shown in FIG. 26 includes the first conductor portion 11 and the ground conductor 20G shown in FIG. 27, and the second radiation element 12R includes the second conductor portion 12. In FIG. More specifically, the first radiation element 11R is composed of the first conductor portion 11 and the ground conductor 20G. A second radiation element 12R is configured by the second conductor portion 12 and the ground conductor 20G.

A loop is formed by the first feeding circuit 1, the impedance matching circuit 30, the first conductor portion 11 and the ground conductor 20G, and the first radiation element 11R forms a loop antenna. The configuration of the first radiating element 11R is similar to that of the antenna device 101 and the like shown in the first embodiment. In the eighth embodiment, the second feeding circuit 2, the second conductor portion 12 and the ground conductor 20G form a loop, and the second radiation element 12R forms a loop antenna.

FIG. 29 is a diagram showing the frequency characteristics of the reflection coefficient of the antenna device 108 according to the eighth embodiment viewed from the first feeding circuit 1 and the second feeding circuit 2. FIG. In FIG. 29, A1 indicates the characteristics of the first radiation element 11R, and A2 indicates the characteristics of the second radiation element 12R. In this example, the first radiation element 11R and the impedance matching circuit 30 provide high radiation efficiency characteristics over a wide band on the low frequency side. In addition, the second radiation element 12R provides a characteristic of high radiation efficiency even on the high frequency side.

In the example shown in FIG. 29, the antenna formed by the first radiating element 11R and the impedance matching circuit 30 is made to act as an antenna on the low band side, and the antenna by the second radiating element 12R is made to act as an antenna on the high band side. may have an inverse relationship.

Also, in the example shown in FIG. 29, the frequency bands with high radiation efficiency are separated into the low-frequency side and the high-frequency side, but these two frequency bands may partially overlap.

According to this embodiment, since the second conductor portion 12 is used as part of the second radiation element, [antenna bandwidth/length of conductor such as occupied metal frame] can be increased. In other words, a compact wideband antenna device can be realized.

<<Ninth Embodiment>>
The ninth embodiment illustrates an antenna device including a second radiation element.

FIG. 30 is a diagram showing the configuration of an antenna device 109A according to the ninth embodiment. The antenna device 109A is composed of a first radiation element 11R, a second radiation element 12R, a capacitance section CP and an impedance matching circuit 30. FIG.

In addition, in FIG. 30, the characteristics of the antenna may be adjusted by inserting a reactance element at the position indicated by the two-dot chain line.

FIG. 31 is a plan view of the antenna device 109A. This figure is a plan view in which the circuit board 20 and the frame 10 are arranged on the same plane, in the same way as the notation method shown in FIG. 3 and the like in the first embodiment. The antenna device 109A includes a first conductor section 11, a second conductor section 12, and an impedance matching circuit 30. As shown in FIG.

The circuit board 20 has a region in which the ground conductor 20G is formed, and non-ground portions 20N1 and 20N2 in which the ground conductor 20G is not formed.

In this example, the frame 10 is made of a metal plate, and a first conductor portion 11, a second conductor portion 12 and a fourth conductor portion 14 are formed in a portion of the frame 10. As shown in FIG. A slit-shaped gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms a capacitance portion CP.

Unlike the antenna device shown in the eighth embodiment, the second radiation element 12R composed of the second conductor portion 12 and the ground conductor 20G is a parasitic radiation element.

FIG. 32A is a diagram showing the frequency characteristics of the reflection coefficient viewed from the first feeding circuit 1 of the antenna device 109A according to the ninth embodiment. FIG. 32(B) is a diagram showing the frequency characteristics of the reflection coefficient viewed from the first feeder circuit 1 of the antenna apparatus of the comparative example when the second radiating element 12R, which is a parasitic radiating element, is not provided.

As is clear from a comparison between the characteristics shown in FIG. 32A and the characteristics A1 shown in FIG. properties are obtained.

FIG. 33 is a diagram showing the configuration of another antenna device 109B according to the ninth embodiment. The antenna device 109B is composed of a first radiation element 11R, a second radiation element 12R, a capacitance section CP, and an impedance matching circuit 30. As shown in FIG.

FIG. 34 is a plan view of the antenna device 109B. This figure is a plan view in which the circuit board 20 and the frame 10 are arranged on the same plane, in the same way as the notation method shown in FIG. 3 and the like in the first embodiment. The antenna device 109B includes a first conductor section 11, a second conductor section 12 and an impedance matching circuit 30. FIG.

The circuit board 20 has a region in which the ground conductor 20G is formed, and non-ground portions 20N1 and 20N2 in which the ground conductor 20G is not formed.

A first conductor portion 11 and a second conductor portion 12 are formed in a portion of the frame 10 . A slit-shaped gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms a capacitance portion CP.

Both ends of the second conductor portion 12 are electrically connected to the ground conductor 20G, and the second conductor portion 12 and the ground conductor 20G constitute a parasitic loop antenna. Thus, the parasitic radiating element may be a loop antenna.

<<Tenth Embodiment>>
The tenth embodiment illustrates an antenna device including a second radiating element and a switch.

FIG. 35 is a diagram showing the configuration of an antenna device 110A according to the tenth embodiment. The antenna device 110A is composed of a first radiation element 11R, a second radiation element 12R, a capacitor CP, an impedance matching circuit 30 and a switch SW. The switch SW switches between connecting the first feeding circuit 1 to the impedance matching circuit 30 and connecting it to the second radiation element 12R according to the control signal.

This antenna device 110A does not include the second feeding circuit 2 in the antenna device 108 shown in FIG. have. The resonant frequency bands of the first radiating element 11R and the second radiating element 12R are different, and by selecting the switch SW according to the desired communication frequency band, the antenna device 110A can be used over a wide band.

Note that the switch SW in FIG. 35 may be replaced with a diplexer. With the switch SW, one of them is connected for a certain period of time, but with the diplexer, simultaneous connection is possible while suppressing interference between the first radiating element 11R and the second radiating element 12R. It is effective for carrier aggregation in the frequency band covered by one radiating element.

FIG. 36 is a diagram showing the configuration of another antenna device 110B according to the tenth embodiment. The antenna device 110B is composed of a first radiation element 11R, a second radiation element 12R, a capacitor CP, an impedance matching circuit 30 and a switch SW.

A second feeding circuit 2 is connected to a first end of the second radiating element 12R, and a switch SW is inserted between the second end of the second radiating element 12R and the ground.

The switch SW becomes conductive/open state according to the control signal. That is, switching is made between grounding and opening the second end of the second radiating element 12R.

FIG. 37 is a diagram showing the configuration of yet another antenna device 110C according to the tenth embodiment. This antenna device 110C is also composed of a first radiation element 11R, a second radiation element 12R, a capacitance section CP, an impedance matching circuit 30, and a switch SW.

The second feeding circuit 2 is connected to the first end of the second radiation element 12R, the second end of the second radiation element 12R is grounded, and the first end and the second end of the second radiation element 12R are connected to each other. A switch SW is connected between the terminal and the ground.

The switch SW becomes conductive/open state according to the control signal. That is, switching is made between grounding and opening a predetermined point between the first end and the second end of the second radiation element 12R.

In both of the antenna devices 110B and 110C, the frequency band with high radiation efficiency of the second radiation element 12R shifts according to the conductive/open state of the switch SW. Therefore, by selecting the switch SW according to the desired communication frequency band, the antenna devices 110B and 110C can be used over a wide band.

In addition, in FIGS. 36 and 37, an example including a switch SW for switching conduction/opening is shown in the circuit diagram, but a switch circuit that selects a reactance element other than switching between conduction/opening may be configured. FIG. 38 is one example. In the example of FIG. 38, reactance elements X1 and X2 are connected between the switch SW and the ground. The reactance elements X1 and X2 are inductors and capacitors. By switching the reactance in this manner, the frequency band in which the radiation efficiency of the antenna is high may be shifted.

Also, in FIGS. 36 and 37, the characteristics of the antenna may be adjusted by inserting a reactance element at the position indicated by the two-dot chain line.

<<11th embodiment>>
In the eleventh embodiment, several structures of the capacitive section formed between the second end of the first conductor section 11 and the second conductor section 12 are illustrated.

FIG. 39 is a plan view particularly showing the structure of the first conductor portion 11 and the second conductor portion 12 of the antenna device according to the eleventh embodiment. FIG. 39 is a plan view of the circuit board 20 and the frame 10 arranged on the same plane. A slit-shaped gap GAP1 is formed between the first conductor portion 11 and the second conductor portion 12, and the gap GAP1 forms a capacitance portion CP. In this way, the capacitance of the capacitor CP may be set not only by the gap GAP1 but also by the dimension of the frame 10 in the height direction.

FIG. 40A is a plan view of another antenna device according to the eleventh embodiment. FIG. 40(B) is a cross-sectional view taken along line YY in FIG. 40(A). The frame 10 is composed of a metal frame 10M and an insulating resin film 10R covering its outer surface. The lower end of metal frame 10M is electrically connected to metal pad 10P. Wiring patterns 20W are formed on the circuit board 20, and these wiring patterns 20W are electrically connected to the metal pads 10P via spring pins 20P. In the example shown in FIG. 40B, the display panel 60 is arranged below.

In the example shown in FIGS. 40A and 40B, a capacitance section CP is formed between two wiring patterns 20W formed on the circuit board 20. In the example shown in FIGS. Thus, the capacitance of the capacitor CP may be set according to the interval and length of the wiring pattern 20W.

FIG. 41(A) is a plan view of still another antenna device according to the eleventh embodiment. FIG. 41(B) is a plan view with the circuit board 20 of FIG. 41(A) removed. FIG. 41(C) is a cross-sectional view taken along line YY in FIG. 41(A). This cross-sectional structure is the same as the example shown in FIG. That is, the frame 10 is composed of a metal frame 10M and an insulating resin film 10R coated on the outer surface thereof, and the lower end of the metal frame 10M is electrically connected to the metal pad 10P. Further, wiring patterns 20W are formed on the circuit board 20, and these wiring patterns 20W are electrically connected to the metal pads 10P via spring pins 20P.

In the examples shown in FIGS. 41(A), 41(B) and 41(C), a capacitive portion CP is formed between two metal pads 10P to which the metal frame 10M conducts. In this manner, the capacitance of the capacitor CP may be set according to the interval and length of the metal pads 10P.

Finally, the invention is not limited to the embodiments described above. Appropriate modifications and changes can be made by those skilled in the art. The scope of the invention is indicated by the claims rather than the above-described embodiments. Furthermore, the scope of the present invention includes modifications and changes from the embodiments within the scope of claims and equivalents.

For example, the features shown in each embodiment may be combined and implemented.

In addition, in the above examples, the antenna device having the loop antenna as the basic component is shown. the present invention can be applied.

C: Capacitance component CP: Capacitance part FE: First ends of the first conductor GAP1, GAP2: Gap GND: Ground area L0: Inductor L1: First coil L2: Second coil Lant1, Lant2, Lant3: Antenna inductance component M Mutual inductance NGA Non-ground area Pf Feed position PL Loop conductor pattern P1 First input/output port terminal P2 Second input/output port terminal S0, S1, S2 Trajectory SE First conductor portion Second end SW Switch X Reactance element Z1 First inductance element Z2 Second inductance element Z3 Third inductance element 1 First feeding circuit 2 Second feeding circuit 10 Frame 10M Metal frame 10P Metal Pad 10R...Insulating resin film 11...First conductor part 11N...Notch shape part 11R...First radiation element 12R...Second radiation element 12...Second conductor part 13...Third conductor part 14...Fourth conductor part 20 . Circuit board 20G . Variable reactance element 60 Display panel 100 Housings 101, 102, 103A, 103B, 104, 105A, 105B, 106A, 106B, 108, 109A, 109B, 110A, 110B, 110C Antenna device 201, 208 Electronic device

Claims (16)

An antenna device configured in an electronic device including a housing having a conductive frame, and a first feeding circuit and a circuit board housed in the housing,
a first radiating element;
an impedance matching circuit connected between the first feeding circuit and the first radiating element for matching impedances of the first feeding circuit and the first radiating element;
with
The impedance matching circuit has a transformer type matching circuit including a first coil and a second coil magnetically coupled to each other,
The circuit board has a ground conductor,
the frame has a first conductor , a second conductor , and a third conductor ;
the first radiation element includes the first conductor portion and the ground conductor;
the second conductor is electrically connected to the ground conductor;
the first conductor portion has a first end and a second end;
A loop is configured by the first feeding circuit, the impedance matching circuit, the first conductor and the ground conductor,
A capacitance section is formed between the second end and the second conductor section ,
A notch-shaped portion is formed between the first end of the first conductor and the third conductor,
antenna device. An antenna device configured in an electronic device including a housing having a conductive frame, and a first feeding circuit and a circuit board housed in the housing,
a first radiating element;
an impedance matching circuit connected between the first feeding circuit and the first radiating element for matching impedances of the first feeding circuit and the first radiating element;
with
The impedance matching circuit has a transformer type matching circuit including a first coil and a second coil magnetically coupled to each other,
The circuit board has a ground conductor,
the frame has a first conductor, a second conductor, and a third conductor;
the first radiation element includes the first conductor portion and the ground conductor;
the second conductor is electrically connected to the ground conductor;
the first conductor portion has a first end and a second end;
A loop is configured by the first feeding circuit, the impedance matching circuit, the first conductor and the ground conductor,
A capacitance section is formed between the second end and the second conductor section,
A gap is formed between the first end of the first conductor and the third conductor,
A reactance circuit is connected between the first end of the first conductor and ground,
antenna device. The reactance circuit is composed of a switch selected by an external control signal and a plurality of reactance elements connected to the switch,
The antenna device according to claim 2 . The reactance circuit is a variable reactance element whose reactance value is controlled by an external control signal,
The antenna device according to claim 2 . a second radiating element connected to a second feeding circuit included in the electronic device and acting as a feeding radiating element;
The antenna device according to any one of claims 1 to 4 . a second radiating element acting as a parasitic radiating element coupled with the first radiating element;
The antenna device according to any one of claims 1 to 4 . The capacitive section is a slit-shaped gap formed between the first conductor section and the second conductor section,
The antenna device according to any one of claims 1 to 6 . A position where the first power supply circuit is connected to the first conductor via an impedance matching circuit is closer to the second end than the first end,
The antenna device according to any one of claims 1 to 7 . A position where the first feeding circuit is connected to the first conductor via an impedance matching circuit is between the first end and the second end of the first conductor,
The antenna device according to any one of claims 1 to 7 . The impedance matching circuit includes an LC circuit connected to at least one of the front stage and the rear stage of the transformer type matching circuit,
The antenna device according to any one of claims 1 to 9 . In the transformer type matching circuit, the first coil and the second coil are connected in series. An autotransformer with both ends as second input/output ports,
The antenna device according to any one of claims 1 to 10 . The transformer type matching circuit is an autotransformer in which the first coil and the second coil are connected in series,
The impedance matching circuit has an inductor connected in series with the second coil,
The impedance matching circuit connects both ends of the series connection circuit of the first coil, the second coil and the inductor as a first input/output port, and connects both ends of the series connection circuit of the second coil and the inductor as a second input/output port. is a circuit with
The antenna device according to any one of claims 1 to 10 . The capacitive section is at or near the maximum position of the voltage distribution occurring in the loop,
An antenna device according to any one of claims 1 to 12 . The capacitive section is at or near a quarter wavelength away from the feed position for the loop,
14. The antenna device according to any one of claims 1 to 13 . a radiating element, a feeding circuit, a circuit board, an impedance matching circuit connected between the radiating element and the feeding circuit, a housing containing the radiating element, the impedance matching circuit and the feeding circuit; An electronic device comprising
The impedance matching circuit has a transformer type matching circuit composed of a first coil and a second coil magnetically coupled to each other,
the housing has a conductive frame,
The circuit board has a ground conductor,
the frame has a first conductor , a second conductor , and a third conductor ;
the radiating element includes the first conductor and the ground conductor;
the second conductor is electrically connected to the ground conductor;
the first conductor portion has a first end and a second end;
A loop is configured by the feeding circuit, the impedance matching circuit, the first conductor and the ground conductor,
The power supply circuit is connected to the first conductor through the impedance matching circuit,
the second end is adjacent to the second conductor portion, and a capacitance portion is formed between the second end and the second conductor portion ;
A notch-shaped portion is formed between the first end of the first conductor and the third conductor,
Electronics. a radiating element, a feeding circuit, a circuit board, an impedance matching circuit connected between the radiating element and the feeding circuit, a housing enclosing the radiating element, the impedance matching circuit and the feeding circuit; An electronic device comprising
The impedance matching circuit has a transformer type matching circuit composed of a first coil and a second coil magnetically coupled to each other,
the housing has a conductive frame,
The circuit board has a ground conductor,
the frame has a first conductor, a second conductor, and a third conductor;
the radiating element includes the first conductor and the ground conductor;
the second conductor is electrically connected to the ground conductor;
the first conductor portion has a first end and a second end;
A loop is configured by the feeding circuit, the impedance matching circuit, the first conductor and the ground conductor,
The power supply circuit is connected to the first conductor through the impedance matching circuit,
the second end is adjacent to the second conductor portion, and a capacitance portion is formed between the second end and the second conductor portion;
A gap is formed between the first end of the first conductor and the third conductor,
A reactance circuit is connected between the first end of the first conductor and ground,
Electronics.

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