JP2022148624A - antenna device - Google Patents

Abstract

To improve communication reliability, and also to make it possible to achieve a higher degree of freedom in wiring pattern design while an antenna is miniaturized.SOLUTION: An antenna device includes a substrate 10 formed of dielectric, an antenna 30 disposed on the substrate 10, and a GND 20 provided on the substrate 10. For the one antenna 30, a plurality of feeding points 50L and 50R and a grounding line 40 for grounding to the GND 20 are provided. The antenna device also includes a switch that switches between the feeding points 50L and 50R to be used from among the plurality of feeding points 50L and 50R, and a transmission/reception circuit that controls switching of the switch.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to antenna devices.

Demands on signal quality, reliability, and transmission speed in wireless communications are increasing. For example, in mobile devices, if there is a null in the antenna directivity, there is a risk that the communication reliability will decrease. Therefore, null interpolation has become important in wireless communication in mobile devices. On the other hand, a diversity antenna is known in which a plurality of antennas with different polarizations or directivities are installed to complement the null characteristics of the respective antennas, thereby improving communication reliability.

However, when multiple antennas are used, the installation space for the antennas increases. In particular, the degree of freedom in design is reduced in portable devices that are small and have a limited installation space for the antenna. Further, when the distances between a plurality of antennas are shortened in order to make the antennas smaller, mutual coupling occurs between the antennas, the isolation is lowered, and a problem arises that the impedance matching is deviated.

As a technique for solving such a problem, for example, in Patent Document 1, parasitic elements such as a first coupling gap and a second coupling gap are provided near the first antenna unit and the second antenna unit, respectively, and the antennas are connected to each other. Techniques for suppressing mutual coupling are disclosed.

JP 2013-214953 A

However, in the technique disclosed in Patent Document 1, since the number of parasitic elements to be installed increases, there arises a problem that the degree of freedom in designing the wiring pattern decreases. Further miniaturization of the antenna is required in order to improve the degree of freedom in design.

One object of the present disclosure is to provide an antenna device that improves communication reliability and makes it possible to reduce the size of the antenna while increasing the degree of freedom in designing the wiring pattern.

The above objects are achieved by the combination of features stated in the independent claims, and the subclaims define further advantageous embodiments of the disclosure. The symbols in parentheses described in the claims indicate the corresponding relationship with specific means described in the embodiments described later as one aspect, and do not limit the technical scope of the present disclosure. .

To achieve the above object, the antenna device of the present disclosure includes a substrate (10) made of a dielectric, an antenna (30) arranged on the substrate, and grounds (20, 20c) provided on the substrate. ), wherein a plurality of feeding points (50, 50L, 50R) and grounding lines (40, 40a, 40b) for grounding are provided for one antenna, and a plurality of A switch (70) for switching a feeding point to be used from among the feeding points and a control circuit (80) for controlling switching of the switch are provided.

According to this, it is possible to obtain different polarizations or directivities by switching which one of the plurality of feeding points for one antenna is used. Therefore, null complement can be performed, and communication reliability can be improved. Also, by switching which one of a plurality of feeding points for one antenna is used, it is possible to supplement nulls, so it is possible to reduce the number of antennas to be used. Therefore, the number of antennas to be used can be reduced, and the size of the antennas can be reduced. In addition, since the number of antennas to be used can be reduced, it is not necessary to increase the number of parasitic elements, so the degree of freedom in wiring pattern design can be increased. As a result, it is possible to increase the degree of freedom in designing the wiring pattern while improving communication reliability and miniaturizing the antenna.

1 is a plan view for explaining an example of a schematic configuration of an antenna device 1; FIG. 1 is a diagram for explaining an example of a schematic configuration of an antenna device 1; FIG. 4 is a Smith chart showing simulation results of antenna characteristics in Embodiment 1. FIG. FIG. 4 is a VSWR diagram showing a simulation result of antenna characteristics in Embodiment 1; FIG. 4 is a diagram of antenna directivity showing simulation results of antenna characteristics in Embodiment 1; 1 is a plan view for explaining an example of a schematic configuration of an antenna device 1a; FIG. FIG. 10 is an antenna directivity diagram showing a simulation result of antenna characteristics in Embodiment 2; It is a top view for demonstrating an example of a schematic structure of the antenna apparatus 1b. FIG. 11 is a diagram of antenna directivity showing a simulation result of antenna characteristics in Embodiment 3; It is a top view for demonstrating an example of a schematic structure of the antenna device 1c. FIG. 11 is a diagram of antenna directivity showing simulation results of antenna characteristics in Embodiment 4;

A number of embodiments for the disclosure are described with reference to the drawings. For convenience of explanation, in some embodiments, parts having the same functions as the parts shown in the drawings used in the explanation so far are denoted by the same reference numerals, and the explanation thereof may be omitted. be. The description in the other embodiments can be referred to for the parts with the same reference numerals.

(Embodiment 1)
<Schematic Configuration of Antenna Device 1>
Hereinafter, this embodiment will be described with reference to the drawings. An example of a schematic configuration of the antenna device 1 will be described below with reference to FIGS. 1 and 2. FIG. In FIG. 1, a schematic plan view of the antenna device 1 is shown. FIG. 2 shows a diagram for explaining the configuration omitted in FIG.

The antenna device 1 includes a substrate 10 , a ground (hereinafter referred to as GND) 20 , an antenna 30 , a ground wire 40 , a feeding point 50 , an impedance circuit 60 , an RF switch 70 and a transmission/reception circuit 80 . The antenna device 1 may be used, for example, in mobile equipment.

Substrate 10 is formed of a dielectric. The board 10 is a circuit board. The substrate 10 is, for example, a printed circuit board. The substrate 10 may have a planar shape. The substrate 10 has a predetermined wiring pattern formed on the surface of an insulating base material.

A GND 20 is provided on the substrate 10 . The GND 20 is provided on part of the surface of the substrate 10, as shown in FIG. The GND 20 is a solid pattern (that is, a solid ground pattern) extending in the surface direction of the substrate 10 . The GND 20 may be configured to be formed of copper foil or the like, for example.

The antenna 30 is arranged on the substrate 10 as shown in FIG. The antenna 30 may be a pattern antenna formed on the substrate 10 by printing or etching. Note that the antenna 30 may be a chip antenna. Below, the case where the antenna 30 is a pattern antenna is mentioned as an example, and description is continued. A plurality of antennas 30 may be arranged on the substrate 10, but a configuration in which one antenna is arranged on the substrate 10 is preferable. This is because the antenna device 1 can be made more compact. Below, the case where one antenna 30 is arranged on the board|substrate 10 is mentioned as an example, and description is continued.

As shown in FIG. 1, the antenna 30 may have a shape in which two inverted F-shaped antennas are connected back-to-back so that the F-shapes are mirror images of each other. In other words, the antenna 30 has a symmetrical shape with a certain axis as a line of symmetry. In the example of FIG. 1, the line of symmetry of the antenna 30 is indicated by Sl. In FIG. 1, the antenna 30 has a symmetrical shape with respect to the line of symmetry Sl.

Ground line 40 is a line that grounds antenna 30 to GND 20 . The ground line 40 may be a pattern line. In the example of FIG. 1, the ground line 40 has a symmetrical shape with respect to the line of symmetry Sl. In addition, in the example of FIG. 1, the grounding position of the grounding line 40 to the GND 20 is not biased to the left or right with respect to the line of symmetry Sl. In other words, the ground line 40 is provided so as to pass through the center of the line of symmetry Sl. Further, the solid pattern of the GND 20 is also symmetrical with respect to the line of symmetry Sl. Although a plurality of grounding wires 40 may be provided for one antenna 30, one grounding wire 40 is preferable. This is because the fewer the number of ground lines 40, the higher the degree of freedom in designing the wiring pattern.

The feeding point 50 is a point that electrically connects the antenna 30 and the feeding line. A plurality of feeding points 50 are provided for one antenna 30 . In the example of FIG. 1, a feeding point 50L and a feeding point 50R are provided at symmetrical positions with respect to the line of symmetry Sl. On the left side of the line of symmetry Sl, the length from the feeding point 50L to the left end of the antenna 30 where the feeding point 50L is not provided is approximately the wavelength λ of the radio wave. On the right side of the line of symmetry Sl, the length from the feeding point 50R to the right end of the antenna 30 where the feeding point 50R is not provided is approximately the wavelength λ of the radio wave. In the example of FIG. 1, the case where two feeding points 50 are provided on one antenna 30 is shown as an example, but the present invention is not necessarily limited to this. For example, one antenna 30 may be configured to have three or more feeding points 50 . In addition, it is preferable that the feeding point 50 is provided symmetrically with respect to one antenna 30 .

The impedance circuit 60 is a lumped-constant circuit for impedance matching (that is, matching). A lumped constant circuit may be used as the impedance circuit 60 . An impedance circuit 60 is provided near the feed point 50 for matching. An impedance circuit 60 is provided for each of the plurality of feeding points 50 . In the example of FIG. 1, an impedance circuit 60L is provided for the feeding point 50L, and an impedance circuit 60R is provided for the feeding point 50R. The plurality of impedance circuits 60 are preferably provided symmetrically with respect to the line of symmetry Sl. This is to facilitate impedance matching. In the example of FIG. 1, an impedance circuit 60L and an impedance circuit 60R are provided at symmetrical positions with respect to the line of symmetry Sl. Moreover, it is preferable that the constants of the plurality of impedance circuits 60 are symmetrical with respect to the line of symmetry Sl. In the example of FIG. 1, it is preferable that the constants of the impedance circuit 60L and the impedance circuit 60R are bilaterally symmetrical with respect to the line of symmetry Sl. This is to facilitate impedance matching.

The switch 70 is a switch that switches the feeding point 50 to be used from among the plurality of feeding points 50 . In the example of FIG. 1, switching is made between the feeding point 50L and the feeding point 50R. An RF switch, for example, may be used as the switch 70 . Switch 70 may be an electronic RF switch. The switch 70, as shown in FIG. 2, may be configured to be connected to the power supply lines of the power supply points 50L and 50R. The switch 70 may be provided on the surface of the substrate 10 on which the antenna 30 is arranged (hereinafter referred to as the front surface), or may be provided on the back surface opposite to that surface.

The transmitting/receiving circuit 80 controls the switch 70 . The transmission/reception circuit 80 corresponds to the control circuit. The transmission/reception circuit 80 may control the switch 70 by outputting a control signal to the switch 70 . The transmitting/receiving circuit 80 switches the feeding point 50 to be used from among the plurality of feeding points 50 by controlling the switch 70 . Transmitting/receiving circuit 80 is electrically connected to feeding point 50 via switch 70 . The transmitting/receiving circuit 80 also includes a modulation circuit for wirelessly transmitting a signal, a demodulation circuit for demodulating the signal from the radio wave received by the antenna 30, a circuit for specifying the reception sensitivity from the radio wave received by the antenna 30, and the like. Just do it.

The transmitting/receiving circuit 80 may switch the feeding point 50 to be used among the plurality of feeding points 50 periodically, for example. Further, when all the reception sensitivities of the plurality of feeding points 50 have been specified, the transmission/reception circuit 80 may switch the switch 70 so as to use the feeding point 50 with the highest reception sensitivity.

<Results of simulation of antenna characteristics>
Next, an example of simulation results of antenna characteristics of the antenna 30 shown in FIGS. 1 and 2 will be described with reference to FIGS. 3 to 5. FIG. The examples of FIGS. 3 to 5 show simulation results of antenna characteristics for radio waves of 2.4 GHz used for communication conforming to Bluetooth (registered trademark). FIG. 3 is a Smith chart showing simulation results of the antenna characteristics of the antenna 30. As shown in FIG. The horizontal axis of the circle in FIG. 3 represents the real part of the complex reflection coefficient, and the vertical axis represents the imaginary part. FIG. 4 is a diagram of a voltage standing wave ratio (hereinafter referred to as VSWR) showing simulation results of the antenna characteristics of the antenna 30. As shown in FIG. The vertical axis in FIG. 4 represents VSWR, and the horizontal axis represents frequency. FIG. 5 is an antenna directivity diagram showing a simulation result of the antenna characteristics of the antenna 30. In FIG. A and B of FIGS. 3 to 5 show examples of using the feeding points 50L and 50R, respectively.

As shown in FIG. 3, in the Smith chart, the trajectory is drawn near the center in both examples A and B. FIG. Therefore, it can be said that impedance matching is achieved near 2.4 GHz. Moreover, as shown in FIG. 4, in both examples A and B, the VSWR takes a small value near 2.4 GHz. Therefore, in this respect as well, it can be said that impedance matching is achieved near 2.4 GHz. Furthermore, as shown in FIG. 6, the directivity in each example of A and B can complement each other's directivity nulls. Therefore, the directivity null of the antenna 30 can be complemented, and the single antenna 30 can sufficiently perform the same role as a diversity antenna.

<Summary of Embodiment 1>
According to the configuration of Embodiment 1, it is possible to obtain different polarized waves or directivities by switching which one of the plurality of feeding points 50L and 50R for one antenna 30 is used. Therefore, null complement can be performed, and communication reliability can be improved. Further, by switching which one of the plurality of feeding points 50L and 50R for one antenna 30 is used, it is possible to supplement nulls, so it is possible to reduce the number of antennas 30 to be used. Therefore, the size of the antennas 30 can be reduced to the extent that the number of antennas 30 to be used can be reduced. That is, it becomes possible to reduce the installation area of the antenna 30 . In addition, since the number of antennas 30 to be used can be reduced, there is no need to increase the number of parasitic elements, so the degree of freedom in wiring pattern design can be increased. As a result, it is possible to increase the degree of freedom in designing the wiring pattern while improving communication reliability and miniaturizing the antenna. In mobile devices that are small and have a limited installation space for antennas, miniaturization of antennas is desired. Therefore, it is more preferable to apply the configuration of the first embodiment to mobile devices.

In the first embodiment, the case where the antenna device 1 is provided with one antenna 30 has been described as an example. Compared to a configuration in which only one antenna is provided, it is possible to make the antenna smaller while complementing the null. Therefore, compared to a configuration in which only one feed point is provided for one antenna, it is possible to increase the degree of freedom in wiring pattern design while improving communication reliability and reducing the size of the antenna.

Further, although the antenna device 1 shown in Embodiment 1 has a plurality of feeding points 50, the antenna 30 is not independent for each feeding point 50. FIG. Therefore, compared to a diversity antenna in which the antenna 30 is independent for each feeding point 50, impedance matching tends to be difficult. However, in the configuration of Embodiment 1, the shape of the pattern of the antenna 30, the shape of the impedance circuit 60, and the constants of the impedance circuit are symmetrical with respect to the line of symmetry of the antenna 30, so impedance matching can be easily performed. be possible. As a result, it becomes possible to reduce the transmission loss of the energy transmitted through the antenna 30. FIG.

(Embodiment 2)
In the first embodiment, the grounding wire 40 has a symmetrical shape with respect to the line of symmetry Sl, but the configuration is not necessarily limited to this. For example, the configuration of Embodiment 2 below may be used. An example of the second embodiment will be described below with reference to the drawings.

The antenna device 1a of Embodiment 2 includes a substrate 10, a GND 20, an antenna 30, a ground line 40a, a feeding point 50, an impedance circuit 60, an RF switch 70, and a transmission/reception circuit 80. The antenna device 1a of the second embodiment is the same as the antenna device 1 of the first embodiment except that the grounding wire 40a is replaced with the grounding wire 40a. The ground wire 40a is the same as the ground wire 40 of the first embodiment, except that the ground wire 40a has a left-right asymmetrical shape with respect to the line of symmetry Sl, as shown in FIG.

According to the configuration of the second embodiment, the impedance matching and the degree of deviation of the directivity of the antenna 30 are adjusted according to the extent to which the shape of the ground line 40a is deformed into a left-right asymmetrical shape with respect to the symmetry line Sl. becomes possible. This allows further null completion.

Here, an example of a simulation result of the antenna characteristics of the antenna 30 in Embodiment 2 is shown. FIG. 7 is an antenna directivity diagram showing simulation results of the antenna characteristics of the antenna 30 according to the second embodiment. FIGS. 7A and 7B show examples in which feeding points 50L and 50R are used, respectively.

As shown in FIG. 7, according to the configuration of the second embodiment, the directivity in each example of A and B can complement each other's directivity nulls. According to the configuration of the second embodiment, although it does not greatly improve null complementation as compared to the configuration of the first embodiment, it does not change the installation area of the antenna 30 and does not affect the impedance matching. , it is possible to shift the directivity bias.

(Embodiment 3)
In the first embodiment, the grounding position of the grounding wire 40 to the GND 20 is not biased to either the left or the right with respect to the line of symmetry Sl, but this is not necessarily the case. For example, the configuration of Embodiment 3 below may be used. An example of the third embodiment will be described below with reference to the drawings.

The antenna device 1b of Embodiment 3 includes a substrate 10, a GND 20, an antenna 30, a ground line 40b, a feeding point 50, an impedance circuit 60, an RF switch 70, and a transmission/reception circuit 80. The antenna device 1b of the third embodiment is the same as the antenna device 1 of the first embodiment except that a ground wire 40b is provided instead of the ground wire 40. FIG. The ground line 40b is biased to the left or right with respect to the line of symmetry Sl at the position where it is grounded to the GND 20 . In the example of FIG. 8, the position where the ground line 40b is grounded to the GND 20 is biased to the right with respect to the line of symmetry Sl. The ground line 40b is the same as the ground line 40 of the first embodiment, except that the ground line 40b is grounded to the GND 20 at a left or right side with respect to the line of symmetry Sl.

According to the configuration of the third embodiment, according to the degree to which the grounding position of the grounding wire 40b to the GND 20 is biased to the left or right with respect to the line of symmetry Sl, the degree of deviation of the impedance matching and the bias of the directivity of the antenna 30 can be adjusted. This allows further null completion.

Here, an example of a simulation result of the antenna characteristics of the antenna 30 in Embodiment 3 is shown. FIG. 9 is an antenna directivity diagram showing simulation results of the antenna characteristics of the antenna 30 according to the third embodiment. FIGS. 9A and 9B show examples in which feeding points 50L and 50R are used, respectively.

As shown in FIG. 9, according to the configuration of the third embodiment, the directivity in each example of A and B can complement each other's directivity nulls. According to the configuration of the third embodiment, although it does not significantly improve null complementation as compared to the configuration of the first embodiment, it does not change the installation area of the antenna 30 and does not affect the impedance matching. , it is possible to shift the directivity bias. Further, according to the configuration of the third embodiment, by shifting the position of the grounding wire 40b to be grounded to the GND 20 by about 1 mm to the left or right with respect to the line of symmetry Sl, the directivity is more biased than the configuration of the second embodiment. It becomes possible to

(Embodiment 4)
Although the solid pattern of the GND 20 has a shape symmetrical with respect to the line of symmetry Sl in the first embodiment, it is not necessarily limited to this. For example, the configuration of Embodiment 4 below may be used. An example of the fourth embodiment will be described below with reference to the drawings.

An antenna device 1c of Embodiment 4 includes a substrate 10, a GND 20c, an antenna 30, a ground line 40, a feeding point 50, an impedance circuit 60, an RF switch 70, and a transmission/reception circuit 80. The antenna device 1c of Embodiment 4 is the same as the antenna device 1 of Embodiment 1, except that GND 20c is provided instead of GND 20. FIG. The GND 20c is the same as the GND 20 of the first embodiment, except that the solid pattern has a laterally asymmetrical shape with respect to the line of symmetry Sl, as shown in FIG.

According to the configuration of the fourth embodiment, it is possible to adjust the degree of impedance matching and deviation of the directivity bias of the antenna 30 according to the degree to which the solid pattern of the GND 20c is deformed into a left-right asymmetrical shape with respect to the line of symmetry Sl. be possible. This allows further null completion.

Here, an example of the simulation result of the antenna characteristics of the antenna 30 in Embodiment 4 is shown. FIG. 11 is an antenna directivity diagram showing simulation results of the antenna characteristics of the antenna 30 according to the fourth embodiment. FIGS. 11A and 11B show examples of using feeding points 50L and 50R, respectively.

As shown in FIG. 11, according to the configuration of the fourth embodiment, the directivity in each example of A and B can complement each other's directivity nulls. According to the configuration of the fourth embodiment, although it does not significantly improve null complementation as compared to the configuration of the first embodiment, it does not change the installation area of the antenna 30 and does not affect the impedance matching. , it is possible to shift the directivity bias. The configuration of the fourth embodiment has less influence on impedance matching than the configurations of the second and third embodiments. Also, the configuration of the fourth embodiment can be easily adopted according to the convenience of the circuit patterns other than the antenna 30 on the substrate 10 .

It should be noted that the present disclosure is not limited to the above-described embodiments, and can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Embodiments are also included in the technical scope of the present disclosure.

1 antenna device, 10 substrate, 20, 20c GND (ground), 30 antenna, 40, 40a, 40b ground wire, 50, 50L, 50R feeding point, 60, 60L, 60R impedance circuit, 70 switch, 80 transmission/reception circuit (control circuit)

Claims (8)

a substrate (10) formed of a dielectric;
an antenna (30) disposed on the substrate;
An antenna device comprising grounds (20, 20c) provided on the substrate,
A plurality of feeding points (50, 50L, 50R) and ground lines (40, 40a, 40b) connected to the ground are provided for one antenna,
a switch (70) for switching the feeding point to be used from among the plurality of feeding points;
and a control circuit (80) for controlling switching of the switch. The antenna device according to claim 1,
An antenna device, wherein the number of antennas arranged on the substrate is one. The antenna device according to claim 1 or 2,
The antenna device has a symmetrical shape with a certain axis as a line of symmetry. The antenna device according to claim 3,
The antenna device, wherein the ground line (40a) has a left-right asymmetrical shape with respect to the line of symmetry. The antenna device according to claim 3 or 4,
The antenna device according to claim 1, wherein the ground line (40b) has a grounded position that is biased to the left or right with respect to the line of symmetry. The antenna device according to any one of claims 3 to 5,
The ground (20c) is an antenna device having a left-right asymmetrical shape with respect to the line of symmetry. The antenna device according to any one of claims 3 to 6,
An impedance circuit (60, 60L, 60R) is provided for each of the plurality of feeding points,
The antenna device, wherein the plurality of impedance circuits are provided symmetrically with respect to the line of symmetry. The antenna device according to any one of claims 3 to 7,
An impedance circuit (60, 60L, 60R) is provided for each of the plurality of feeding points,
The antenna device according to claim 1, wherein the plurality of impedance circuits have symmetrical constants with respect to the line of symmetry.

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