JP7471835B2 - Antennas and Radio Equipment - Google Patents

Description

The present invention relates primarily to antennas and wireless devices.

There is an antenna design method in which an antenna element is placed on a wide ground surface, giving it directivity perpendicular to the ground surface. This has the advantage that it does not radiate to the opposite side of the ground surface, and because it is separated by the ground surface, the structure on the opposite side of the antenna element does not affect the radiation characteristics. In addition, taking advantage of the above advantages, wireless communication systems have been proposed that can be used even when placed close to the human body or on a metal surface, and various use cases, such as wearable wireless systems worn on the human body, are being considered.

JP 2014-27416 A JP 2016-208223 A

The antenna described in Patent Document 1 is composed of a substrate equipped with a power distribution circuit and multiple elements (antenna elements) arranged in a line at a distance from the substrate, and the radiation direction is in the direction between the substrate and the elements. When the antenna described in Patent Document 1 is attached to the human body, there are cases where the elements are attached so that they face the human body, and not only does the proximity of the dielectric deteriorate the radiation characteristics of the elements, but the electromagnetic waves themselves are shielded by the human body, so they do not radiate in a direction away from the body.

The antenna described in Patent Document 2 is composed of multiple inverted F-shaped antenna elements surrounding a ground, which are integrated into a substrate, and the radiation direction is vertical, penetrating the substrate. If the antenna described in Patent Document 2 is placed on a metal desk parallel to the top, the radiation characteristics of the antenna elements will deteriorate due to the proximity of conductors, and so it will not radiate in a direction directly facing the top.

In this way, the proximity of conductors or dielectrics can shorten the communication distance of wireless devices, and improving the radiation performance of antennas in such cases has been a challenge.

The present invention aims to provide an antenna whose radiation performance is less likely to deteriorate even when a dielectric or conductor is located near a wireless device.

In order to solve the above-mentioned problems, one aspect of the antenna according to the present invention is an antenna comprising: an input/output point for inputting and outputting a radio signal; a first region composed of a first ground and a first radiating means; a second region composed of a second ground and a second radiating means and arranged to overlap with the first region when viewed from a direction perpendicular to a plane on which the first ground is arranged; a conductor connecting the ground of the first region to the ground of the second region ; and switching means capable of switching whether the first radiating means or the second radiating means is connected to the input/output point , wherein at least one of the first radiating means and the second radiating means has a plurality of antenna elements, and either the first radiating means or the second radiating means that is not connected to the input/output point functions as a ground.

Moreover, in order to solve the above-mentioned problems, one aspect of a wireless device according to the present invention is a wireless device including: a transmitting/receiving means for transmitting and receiving wireless signals; a first region composed of a first ground and a first radiating means ; a second region composed of a second ground and a second radiating means and overlapping with the first region when viewed from a direction perpendicular to a plane on which the first ground is arranged ; a conductor connecting the ground of the first region to the ground of the second region ; switching means capable of switching whether the first antenna or the second antenna is connected to the transmitting/receiving means; and control means for controlling the switching means based on predetermined conditions, wherein at least one of the first radiating means and the second radiating means has a plurality of antenna elements, and either the first radiating means or the second radiating means that is not connected to the transmitting/receiving means functions as a ground.

The present invention provides an antenna whose radiation performance is less likely to deteriorate even when a dielectric or conductive material is located near the wireless device.

FIG. 2 is a diagram showing an example of an antenna according to the first embodiment; 3 shows functional blocks of the antenna according to the first embodiment. 3A and 3B are top and bottom views of a substrate A of the antenna according to the first embodiment. 4A and 4B are top and bottom views of substrate B of the antenna according to the first embodiment. FIG. 4 is an operation sequence diagram of the antenna according to the first embodiment. 5A to 5C are diagrams showing an example of the operation of the antenna according to the first embodiment. 7 is a diagram showing radiation characteristics of an antenna in the operation example shown in FIG. 6; 5A and 5B are diagrams showing another embodiment of the substrate A and the substrate B shown in FIGS. 3 and 4 . FIG. 3 is a diagram showing another embodiment of the functional blocks shown in FIG. 2 . 10A and 10B are top and bottom views of substrates C and D of the antenna shown in FIG. 9 . FIG. 11 is a diagram showing an example of an antenna according to a second embodiment. 12 is a top view of the antenna substrate E shown in FIG. 11 .

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

Example 1
The configuration of a wireless device 1 that operates as an antenna in this embodiment is shown in Fig. 1. Hereinafter, parts with the same filled-in pattern in the figure have the same function unless otherwise specified. Furthermore, even if the functions or mounted parts are not shown, all configurations that provide the same effect are included in this embodiment.

The wireless device includes substrates 101 and 102, which are stacked approximately parallel to the Z-axis direction, which is the thickness direction of the substrates. Substrates 101 and 102 each have ground 103 and ground 104 in their central portions, and grounds 103 and 104 are at the same potential via multiple conductive parts (conductors) 105. Note that in the example of FIG. 1, substrates 101 and 102 are described as being different substrates, but they may be mounted on different layers of a multi-layer substrate.

The substrate 101 has four antenna elements (radiating parts) 106 arranged to surround the ground 103. The ground end (ground point) of the inverted-F antenna is electrically connected to the ground 103, and the power feed end (power feed point) that transmits and receives signals is electrically connected to the power feed part 107. The antenna elements 106 extend in the +X direction, +Y direction, -X direction, and -Y direction, respectively, and are arranged so that the orientation of the open ends differs by 90 degrees.

Similarly, the substrate 102 has four antenna elements 108 arranged to surround the ground 104, and the four antenna elements 108 are inverted-F antennas of the same shape. The ground end of the inverted-F antenna is conductive with the ground 104, and the power feed end for transmitting and receiving signals is connected to the power feed unit 109. The antenna elements 108 extend in the +X direction, +Y direction, -X direction, and -Y direction, respectively, and are arranged so that the orientation of the open ends differs by 90 degrees. Note that the extension direction of the antenna elements 106 and 108 may be reversed, that is, the antenna in FIG. 1 may be arranged by flipping it left to right.

In this embodiment, the substrates 101 and 102 are spaced apart by a distance of λ/4 or less, for example, λ/8 or less. This allows the size of the wireless device 1 in the Z direction to be reduced. However, in another example, the substrates may be spaced apart by a distance of, for example, λ/4 or more. This prevents the antenna element of the substrate 101 from coupling with the antenna element of the substrate 102, making it easier to design the antenna. In this embodiment, the antenna elements 106 and 108 are described as being inverted F-shaped antennas of the same shape, but at least one of a monopole antenna, a patch antenna, a waveguide antenna, and a slot antenna may also be used.

Functional blocks of the wireless device 1 according to this embodiment are shown in Figure 2. In the figure, board 101 shown in Figure 1 corresponds to board A, and board 102 corresponds to board B. Furthermore, solid lines indicate paths through which RF signals in the frequency band in which the antenna radiates electromagnetic waves pass, dotted lines indicate paths through which signals that control specific functions or signals that exchange information pass, and dashed lines indicate specific functions or names.

When an RF signal is transmitted from wireless device 1, the RF signal transmitted from transceiver unit 201 is output to either path a or path b by switching unit 202. When the RF signal is output to path a, the RF signal is distributed into four by phase shift unit 203, and the phases of the four distributed RF signals are rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively, and output to antenna elements 205, which are substrate A antennas 1, 2, 3, and 4.

Similarly, when an RF signal is output to path b, the RF signal is split into four in phase shift section 204, and the phases of the four split RF signals are rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively, and output to antenna elements 206, which are substrate B antennas 1, 2, 3, and 4.

The detection unit 207 monitors the characteristic impedance of paths a and b, and when the amount of change in the characteristic impedance of the monitored path exceeds a threshold, it transmits a signal to the control unit 208 notifying the proximity of a dielectric or conductor. Here, the characteristic impedance of path a is the characteristic impedance including path a and the antenna connected to path a. Since the characteristic impedance increases or decreases when a dielectric or conductor approaches the antenna element 205 or antenna element 206, the amount of change can be determined by measuring the power of the reflected wave (reflected power) using a directional coupler or the like. That is, the detection unit 207 detects the proximity of a dielectric or conductor based on the reflected power and notifies the control unit 208.

In one example, the detection unit 207 may transmit to the control unit 208 a signal indicating which of the change in characteristic impedance of path a and the change in characteristic impedance of path b is smaller. Alternatively, the signal may indicate which path should be used based on the change in characteristic impedance of paths a and b. In another example, the detection unit 207 may transmit to the control unit 208 a signal indicating the value of the characteristic impedance or the change in characteristic impedance of at least one of paths a and b, and the control unit 208 may determine which path to use.

In one example, the detection unit 207 may have sensors including at least an illuminance sensor, a gravity sensor, a geomagnetic sensor, an acceleration sensor, and a capacitance sensor, and may notify the control unit of a signal notifying the proximity of an object based on values acquired from the sensors. For example, if the illuminance sensors arranged on boards A and B indicate that the illuminance on the board A side is lower, and the gravity sensor determines that board A faces the ground, the detection unit 207 may detect that the wireless device is placed with the board A side facing down. This allows the control unit 208 to transmit and receive wireless signals using board B, which does not face the ground, and prevents degradation of radiation performance.

The control unit 208 controls the switching unit 202 based on the signal received from the detection unit 207, and also writes the control result in the storage unit 209. The control process of the switching unit 202 will be described later with reference to FIG. 5. When the wireless device 1 receives electromagnetic waves, the function of each block does not change, except that the route through which the RF signal passes is reversed from that during transmission. That is, the RF signal received by the antenna element 205 or antenna element 206 is input to the transceiver unit 201 through at least one of route a and route b selected by the control unit 208.

Next, an embodiment of the substrate A shown in FIG. 2 is shown in FIG. 3. The surface layer 301 of the substrate A includes a ground 302, an antenna element 303, and an RF line 304. The ground end of the antenna element 303 is connected to the ground 302, and the power supply end of the antenna element 303 is connected to the RF line 304 and connection points (denoted as α, β, γ, and δ). The connection points α, β, γ, and δ function as input and output points of an RF signal for the antenna element 303. The RF line 304 operates as a microstrip line together with the ground 302, as well as a ground 308 and a via 309 described later. Note that in FIG. 3, the connection points are used to facilitate the explanation of the antenna element 303 and the RF line 304, but since the connection points are points on a conductor, they do not need to be confirmed in reality.

The back layer 307 of the substrate A includes a ground 308, an RF line 304, and mounted components 310 to 312, and the ground 308 is connected to the ground 302 by a via 309. The RF switch 310 has a SPDT (single-pole double-throw) structure, with a wireless IC 311 that transmits and receives RF signals connected to the pole side, an RF line 313 connected to one side of the throw side, and an RF connector 312 connected to the other side. A connection point 306 (referred to as ξ) on the surface layer 301 of the substrate A and a connection point 314 on the back layer 307 of the substrate A are connected by a via. The RF line 313 connects the wireless IC 311 to the connection point 314. The RF switch 310 is switched by a detection unit (not shown) and a control unit (not shown) to connect the wireless IC 311 to either the via 306 or the RF connector 312.

The RF line 304 electrically connects each connection point (α, β, γ, δ) and the connection point 306 (ξ). The line length of the RF line 304 can be expressed as L ₀ + λ/4 (between ξ-β), L ₀ + 2λ/4 (between ξ-γ), and L ₀ + 3λ/4 (between ξ-δ) using the wavelength λ of the RF signal at the design frequency of the wireless device and the line length L ₀ between ξ-α. When an RF signal at the design frequency propagates through a signal line with a line length of λ/4, the phase of the signal rotates 90 degrees, so that in the transmission operation of the wireless device, the RF signal input to ξ is output after rotating 0 degrees, 90 degrees, 180 degrees, and 270 degrees at each connection point (α, β, γ, δ). Therefore, the composite (composite wave) of the electromagnetic waves radiated from the four antenna elements 303 has a circular polarization characteristic.

The order of the phase differences given to the RF signal by the phase shifter 305 does not matter. In the case of reverse rotation, the RF signal input to the connection point ξ is rotated by 0 degrees, 270 degrees, 180 degrees, and 90 degrees at each connection point (α, β, γ, δ) and output. In this case too, the composite wave from the four antenna elements 303 has circular polarization characteristics.

In addition, in this embodiment, the antenna 303 has been described as being disposed on the surface layer of the substrate 301, but in the example of FIG. 3, the antenna 303 may be disposed on the back layer of the substrate 301. Also, although substrate A is shown as a two-layer substrate, it may be mounted on different layers of a multi-layer substrate, and the phase shifter 305 may be provided on any layer of the multi-layer substrate.

Next, FIG. 4 shows an example of the substrate B of the wireless device of FIG. 2. As with substrate A, the surface layer 401 of substrate B includes a ground 402, an antenna element 403, and an RF line 404, with the ground end of the antenna element 403 connected to the ground 402 and the feed end of the antenna element 403 connected to the RF line 404. In the phase shift section 405, the RF line 404 connecting the antenna element 403 and the connection point 406 has its line length increased by λ/4 in the counterclockwise direction.

The back layer 407 of the substrate B includes a ground 408, an RF line 404, and an RF connector 410 which is a mounted component, and the ground 408 is connected to the ground 402 by a via 409. The RF line 411 connects the RF connector 410 to the connection point 406. The RF connector 312 of the substrate A and the RF connector 410 of the substrate B are connected by a coaxial cable (not shown).

When the wireless device 1 transmits a wireless signal, the RF signal input from the connection point 406 to the phase shifter 405 is rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees by the RF line 404 and input to the antenna element 403. Therefore, the composite wave from the four antenna elements 403 has a circular polarization characteristic similar to that described with reference to FIG. 3. Note that, as with the substrate A, the order of the phase difference provided by the phase shifter 405 does not matter. Also, as with the example of FIG. 3, in the example of FIG. 4, the antenna 403 has been described as being placed on the surface layer of the substrate 401, but the antenna 403 may be placed on the back layer of the substrate 401. Also, although the substrate B is shown as a two-layer substrate, the phase shifter 405 may be provided on an inner layer of the multi-layer substrate.

Next, the flowchart of the wireless device shown in FIG. 2 is shown in FIG. 5. The flowchart shown in FIG. 5 is executed by the control unit 208 or the detection unit 207 when power is applied to the wireless processing. When the wireless device starts operation, the control unit 208 reads the initial settings from the storage unit 209 and controls the switching unit 202 (S501). The initial settings include at least one of the following: setting information for the initial path of the switching unit 202, and information on the amount of change in characteristic impedance of the path used by the control unit 208 to determine that a dielectric or conductor is in proximity to the substrate. Next, when the transmitting/receiving unit 201 starts transmitting and receiving a signal, the following steps S502 to S509 of proximity detection and switching control are repeatedly executed until the transmission and reception is completed.

In S502, the control unit 208 determines whether or not a dielectric or a conductor is in proximity to the substrate A based on the signal acquired from the detection unit 207. The proximity detection in S502 is one of the predetermined conditions for the control unit 208 to control the switching unit 202 to switch. If the control unit 208 determines that a dielectric or a conductor is not in proximity to the substrate A (N in S502), the control unit 208 proceeds to S505 and controls the switching unit 202 to set the output destination of the RF signal to the path a. If the control unit 208 determines that a dielectric or a conductor is in proximity to the substrate A (Y in S502), the control unit 208 proceeds to S504 and determines whether or not a dielectric or a conductor is in proximity to the substrate B based on the signal acquired from the detection unit 207. If the control unit 208 determines that a dielectric or a conductor is not in proximity to the substrate A (N in S504), the control unit 208 proceeds to S507 and controls the switching unit 202 to set the output destination of the RF signal to the path b.

If the control unit 208 determines that both board A and board B are in proximity (Y in S504), the control unit 208 proceeds to S508 and compares the proximity of board A and board B. In one example, the proximity may be the amount of change in the characteristic impedance of each of paths a and b. If the control unit 208 determines that the proximity of board A is not greater than the proximity of board B (N in S506), the control unit 208 controls the switching unit 202 to set the output destination of the RF signal to path a (S507). On the other hand, if the control unit 208 determines that the proximity of board A is greater than the proximity of board B (Y in S506), the control unit 208 controls the switching unit 202 to set the output destination of the RF signal to path b (S508).

After the processing of S503, S505, S507, or S508, the control unit 208 advances the process to S509 and determines whether or not the transmission and reception are complete. If the control unit 208 determines that the transmission and reception are not complete (N in S509), the control unit 208 returns the process to S502. On the other hand, if the control unit 208 determines that the transmission and reception are complete (Y in S509), the control unit 208 writes the connection settings for the last set route to the storage unit 209 (S510), and ends the operation of FIG. 5.

Note that this operation sequence is just an example, and it is also possible to perform only S502, S504, or S506, or to change the order of the processes.

An example of the operation of the wireless device of FIG. 1 that operates according to the flowchart of FIG. 5 is shown in FIG. 6. FIG. 6(A) shows a state in which the dielectric 601 is close to the -Z direction, that is, below the substrate 102. In this case, as explained in S503 and S507 of FIG. 5, the output destination of the RF signal is set to the substrate A (+Z direction). In S503 and S507, the power feed point of the antenna element 106 is connected to the power feed section 107, but the power feed end of the antenna element 108 is open, and the ground 104 and the antenna element 108 are at approximately the same potential due to the ground end. For this reason, in addition to the ground 103, the ground 104 and the antenna element 108 connected by the conductive section 105 function as grounds for the antenna element 106. By sandwiching the ground between the antenna element 106 and the dielectric 601 when viewed in the Z-axis direction, it is possible to suppress the influence of the dielectric 601 on the radiation performance of the antenna element 106, and to maintain the circular polarization characteristics while directing the directivity of the antenna element 106 in the +Z direction.

Figure 6 (B) shows the +Z direction, that is, the state where the dielectric 602 is close to the upper part of the substrate 101. In this case, as explained in S505 and S508 of Figure 5, the output destination of the RF signal is set to substrate B (-Z direction). In S505 and S508, the power supply end of the antenna element 108 is connected to the power supply section 109, but the power supply end of the antenna element 106 is open, and the ground 103 and the antenna element 106 are at approximately the same potential due to the ground end. Therefore, in addition to the ground 104, the ground 103 and the antenna element 106 connected by the conductive section 105 function as a ground surface for the antenna element 108. By sandwiching the ground surface between the antenna element 108 and the dielectric 602 when viewed in the Z-axis direction, it is possible to suppress the influence of the dielectric 602 on the radiation performance of the antenna element 108 and maintain the circular polarization characteristics while directing the directivity of the antenna element 108 in the -Z direction.

As a result, for example, even when this wireless device is worn on the human body, it is possible to radiate in a direction away from the human body regardless of the proximity of a dielectric. Also, when this antenna is placed on a metal desk so that it is parallel to the top, it is possible to radiate in a direction away from the top regardless of the proximity of a conductor. Here, dielectrics 601 and 602 are assumed to be the human body, but they can be any material that affects the characteristic impedance, and can function in the same way with conductors such as metals.

The radiation characteristics at 920 MHz of Figures 6(A) and 6(B) are shown in Figures 7(A) and 7(B). Here, the substrates 101 and 102 have a substrate thickness of 1 mm and a relative dielectric constant of 4.3, the distance between the substrates 101 and 102 is 10 mm, the dielectrics 601 and 602 have a thickness of 200 mm and a relative dielectric constant of 40, and the element length of the inverted F-shaped antenna is approximately λ/4. In addition, in Figure 7(A), the distance between the substrate 102 and the dielectric 601 is 3 mm, and in Figure 7(B), the distance between the substrate 101 and the dielectric 602 is 3 mm.

In FIG. 7(A), the electric field intensity is strongest in the +Z direction, and in FIG. 7(B), the electric field intensity is strongest in the -Z direction. In other words, the main lobe (main beam) is directed in the +Z direction in FIG. 7(A) and in the -Z direction in FIG. 7(B). From this, it can be seen that the electromagnetic wave is radiated in a direction away from the dielectric. Also, since the horizontally polarized component and the vertically polarized component are radiated to the same extent in FIG. 7(A) and FIG. 7(B), it can be seen that either arrangement has a circular polarization characteristic. Note that the shape, material, and antenna size of the substrate shown here are examples, and all modified examples that can obtain the same effect, such as the inclusion of a high dielectric around the antenna element, integral molding with resin, and sharing of the support member and conductive part between the substrates, are included in this embodiment. For example, when the support member and conductive part between the substrates are shared, the conductive part 105 is a metal column and also functions as a fixing member between the substrates. Also, instead of separating the substrates 101 and 102, components such as antenna element 106, antenna element 108, ground 103, and ground 104 may be provided in a multi-layer substrate. In this case, the conductive portion 105 may be formed by a via that connects the layers.

Next, another example of the configuration of the substrate A and the substrate B is shown in FIG. 8. The surface layer 801 of the substrate A and the substrate B includes a ground 802, an antenna element 803, and an RF line 804.

The ground end of the antenna element 803 is connected to the ground 802, which has a via 805 that is conductive to the back layer (not shown), and the feed end of the antenna element 803 is connected to the RF line 804 at connection points (denoted as α, β, γ, and δ). The RF line 804 operates as a coplanar line or a coplanar line with a ground.

The phase shifter 806 is a mounting component capable of imparting a phase difference of n×π/2 degrees (n is an integer) to the RF signal passing through it, and is connected to a connection point 807 (referred to as ξ) that is conductive to the back layer (not shown) through a via and each connection point (α, β, γ, δ) through an RF line 804. When the wireless device radiates electromagnetic waves, the RF signal input to the connection point ξ is rotated 0 degrees, 90 degrees, 180 degrees, and 270 degrees at each connection point (α, β, γ, δ) and output. As a result, the composite wave of the electromagnetic waves radiated from the four antenna elements 803 has a circular polarization characteristic. Note that the order of the phase differences imparted by the phase shifter 806 may be changed. For example, the RF signal input to the connection point ξ may be rotated 0 degrees, 270 degrees, 180 degrees, and 90 degrees at each connection point (α, β, γ, δ) and output, and in this case, the composite wave from the four antenna elements 803 also has a circular polarization characteristic.

This wireless device can also be applied to wireless communication systems such as RFID (Radio Frequency Identifier), GPS (Global Positioning System), Wi-Fi, and LTE (Long Term Evolution).

As described above, when a dielectric or conductor is located near a substrate, the wireless device according to the first embodiment determines which side of the substrate the device is closer to, and determines the substrate for transmitting and receiving electromagnetic waves based on the determination. This makes it possible to suppress degradation of radiation performance even when a dielectric or conductor is located near the wireless device.

Example 2
In the first embodiment, a configuration was described in which an RF signal output from a transmitting/receiving unit is output to one of the boards by a switching unit, and the RF signal is phase-shifted for each board. In the second embodiment, a configuration will be described in which an RF signal output from a transmitting/receiving unit is divided into four, each of the divided RF signals is phase-shifted by a phase shifter, and then the output of each of the four phase-shifted RF signals is switched to one of the boards by a switching unit. Note that the same reference numerals are used for configurations, functions, or processes as those in the first embodiment, and descriptions thereof will be omitted.

The functional blocks of the wireless device in this embodiment are shown in FIG. 9. In the figure, the explanation will be made assuming that the substrate 101 shown in FIG. 1 corresponds to substrate C, and the substrate 102 corresponds to substrate D. That is, substrate C is disposed above substrate D in the Z-axis direction and approximately parallel to substrate D. When an RF signal is transmitted from the wireless device, the RF signal output from the transceiver unit 901 passes through the phase shift unit 902, is distributed into four, and is input to each of the four switching units 903. The phase shift unit 902 distributes the input RF signal into four, rotates the phase by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, and outputs the signal to the four switching units 903.

The switching unit 903 switches whether the input RF signal is output to path c or path d. Path c is an RF line for outputting the output signal from the phase shift unit 902 to the antenna elements 904, that is, substrate C antenna 1, substrate C antenna 2, substrate C antenna 3, and substrate C antenna 4. On the other hand, path d is an RF line for outputting the output signal from the phase shift unit 902 to the antenna elements 905, that is, substrate D antenna 1, substrate D antenna 2, substrate D antenna 3, and substrate D antenna 4.

The detection unit 906 monitors the characteristic impedance of paths c and d, and when the change in the characteristic impedance of the monitored path exceeds a threshold value, it notifies the control/storage unit 907 of a signal notifying the proximity of a dielectric or conductor. Here, the characteristic impedance of path c is the characteristic impedance including path c and the antenna connected to path c. The detection unit 906 monitors the characteristic impedance of at least one of antennas 1 to 4 of substrate C, and at least one of antennas 1 to 4 of substrate D. The control/storage unit 907 controls the switching unit 903 based on the information notified by the detection unit 906, and holds the control results.

Next, FIG. 10(A) shows a top view of substrate C, and FIG. 10(B) shows a top view of substrate D. A ground 1002, an antenna element 1003, and an RF line 1004 are arranged on the surface layer 1001 of substrate C. The ground end of antenna element 1003 is connected to ground 1002, and ground 1002 has a via 1005 that is conductive to the back layer (not shown), and the feed end of antenna element 1003 is connected to RF line 1004.

The phase shifter 1006 is a mounting component that can split an input RF signal and give a phase difference of n x 90 degrees (n is an integer). In the example of FIG. 10(A), the input RF signal is split into four, and a phase shift of 0 degrees, 90 degrees, 180 degrees, and 270 degrees is given to each of them. When the four output signals from the phase shifter 1006 are input to the four antenna elements 1003, the composite wave has a circular polarization characteristic. In one example, the phase shifter 1006 may be a variable phase shifter. Each RF line 1004 has a one-input, two-output switching unit 1008 between the phase shifter 1006 and the antenna element 1003, and the input side of the switching unit 1008 is connected to the RF line 1004. One output of the switching unit 1008 is connected to the antenna element 1003, and the other output is connected to the RF connector 1009.

The surface layer 1010 of the substrate D includes a ground 1011, an antenna element 1012, and an RF line 1013. The ground end of the antenna element 1012 is connected to the ground 1011, the ground 1011 includes a via 1014 that is conductive to the back layer (not shown), and the power supply end of the antenna element 1012 is connected to the RF connector 1015 through the RF line 1013. In this embodiment, the RF connector 1009 of the substrate C and the RF connector 1015 of the substrate D are described as being connected by a coaxial cable (not shown), but other configurations may be adopted as long as the RF connectors 1009 and 1015 are electrically connected. In one example, when the substrates C and D are implemented as a multilayer substrate, the RF connectors 1009 and 1015 may be connection points connected by vias.

The flowchart for radiation switching in Example 1 described with reference to FIG. 5 can also be applied to this example, so a description thereof will be omitted.

When a dielectric or conductor is located nearby below the substrate D in the -Z direction, the switching unit 1008 connects the RF line 1004 to the antenna element 1003, and leaves the RF connector 1009 side open. In this case, the antenna element 1012 on the substrate D is at approximately the same potential as the ground 1011 and ground 1002 due to the ground end, and functions as a ground surface with respect to the antenna element 1003. This makes it possible to orient the directivity of the antenna element 1003 in the +Z direction while maintaining circular polarization characteristics regardless of the presence or absence of a dielectric or conductor located nearby in the -Z direction.

On the other hand, when a dielectric or conductor is located nearby above the substrate C in the +Z direction, the switching unit 1008 connects the RF line 1004 to the RF connector 1009 and opens the antenna element 1003. The ground end of the antenna element 1003 makes it approximately equal in potential to the grounds 1002 and 1011, and it functions as a ground surface with respect to the antenna element 1012. This makes it possible to orient the directivity of the antenna element 1012 in the -Z direction while maintaining the circular polarization characteristics regardless of the presence or absence of a dielectric or conductor located nearby in the +Z direction.

As described above, the wireless device according to the second embodiment switches to which board the RF signal is output after being phase-shifted. This eliminates the need to prepare a phase shifter for each board, and reduces the circuit scale or cost associated with the phase shifter.

Example 3
In the present embodiment, the switching unit 202 has been described as switching between electrically connecting and disconnecting either of the paths a and b to the transceiver unit 201. In one example, the switching unit 202 may operate to electrically connect either of the paths a and b to the transceiver unit 201 and electrically connect the other to ground. In this case, even if the antenna element 205 and the antenna element 206 do not have a connection point to ground, they can function as ground when connected to ground by the switching unit 202. This makes it possible to realize the wireless device 1 using an antenna that does not have a connection point to ground.

In Example 3, a configuration example will be described in which the switching unit and phase shift unit are arranged on different substrates from the antenna element. A functional block diagram of the wireless device according to this example is shown in FIG. 11. Note that descriptions of the same configuration, processing, and functions as those in Examples 1 and 2 will be omitted.

The wireless device is configured by stacking board 1101 (board E), board 1102 (board F), and board 1103 (board G) in the Z-axis direction, which is the thickness direction of the boards, with board G sandwiched between boards E and F, and board G having ground 1104 in the center.

Substrate E has four antenna elements 1105 arranged to surround ground 1104 when viewed from the Z-axis direction, and the four antenna elements 1105 are inverted-F antennas of the same shape. The ground end of the inverted-F antenna is conductive to ground 1104 through conductive part 1106, and the power supply end that transmits and receives signals is connected to power supply part 1108 through conductive part 1107. The antenna elements 1105 extend in the +X direction, +Y direction, -X direction, and -Y direction, respectively, and are arranged so that the orientation of the open ends differs by 90 degrees.

Similarly, substrate F has four antenna elements 1109 arranged to surround ground 1104 when viewed from the Z-axis direction, and the four antenna elements 1109 are inverted-F antennas of the same shape. The ground end of the inverted-F antenna is conductive with ground 1104 through conductive part 1110, and the power supply end for transmitting and receiving signals is connected to power supply part 1108 through conductive part 1111. The antenna elements 1109 extend in the +X direction, +Y direction, -X direction, and -Y direction, respectively, and are arranged so that the orientation of the open ends differs by 90 degrees.

An example of the configuration of substrate G is shown in FIG. 12. In FIG. 12, the surface layer 1201 of substrate G includes a ground 1202 and an RF line 1203, and the ground 1202 includes a via 1204 that is conductive to the back surface (not shown). The RF line 1203 connects the via 1205 to four switching units 1207, branches the RF signal from the transmitting/receiving unit 901 into four, and operates as a phase shift unit 1206 that shifts the phase of the four branched RF signals.

In the phase shift unit 1206, the input RF signal is branched into four, and a phase difference of n×90 degrees (n is an integer) is given to each of the branched RF signals. In the example of FIG. 12, the input RF signal is branched into four, and a phase shift of 0 degrees, 90 degrees, 180 degrees, and 270 degrees is given to each of the branched RF signals. The phase-shifted RF signal is input to the switching unit 1207. The switching unit 1207 has two outputs (not shown), one of which is connected to a coaxial cable (not shown) connected to the connection point 1107 of the substrate E, and the other is connected to a coaxial cable (not shown) connected to the connection point 1111 of the substrate F. The four switching units 1207 are controlled so that the output destination of the RF signal is the same for the four switching units 1207. In other words, the switching unit 1207 switches whether the RF signal is output to the four antennas 1105 of the substrate E or the four antennas 1109 of the substrate F. As a result, the composite wave from the antenna element (not shown) has circular polarization characteristics. Note that the conductive part 1110 shown in FIG. 11 can be connected anywhere on the ground 1202, and the connection method does not require a mounted component such as a coaxial cable, but can utilize a support member between boards, such as a metal pole.

In this embodiment, the operation of the flowchart is the same as in the first and second embodiments, so the description will be omitted. That is, when a dielectric or conductor is located close to the bottom of the substrate F in the -Z direction, the antenna element 1105 is connected to the power supply 1108, and the antenna element 1109 is connected to the ground 1104. Therefore, while the directivity of the antenna element 1105 is oriented in the +Z direction, it is possible to maintain the circular polarization characteristics regardless of the presence or absence of a dielectric in the -Z direction. On the other hand, when a dielectric or conductor is located close to the top of the substrate E in the +Z direction, the antenna element 1109 is connected to the power supply 1108, and the antenna element 1105 is connected to the ground 1104. Therefore, while the directivity of the antenna element 1109 is oriented in the -Z direction, it is possible to maintain the circular polarization characteristics regardless of the presence or absence of a dielectric in the +Z direction.

As described above, in the wireless device according to the third embodiment, the switching unit and the phase shift unit are arranged on a different substrate from the antenna. This reduces the influence of the switching unit and the phase shift unit on the antenna, making it easier to design the antenna.

<Other embodiments>
Although the wireless device according to the present embodiment has been described as controlling the switching unit 202 based on the program stored in the storage unit 209 and the detection result of the detection unit 207, the switching unit 202 may be controlled based on a control signal received by the transmission/reception unit 201. In other words, the control unit 208 may control the switching unit 202 based on a control signal received by at least one of the antenna element 106 and the antenna element 108.

The substrate of the wireless device according to this embodiment has been described as having four antenna elements, but the number of antenna elements is not limited to this. For example, the substrate may have n antenna elements (n is an integer equal to or greater than 1) arranged in a circle, and the n antenna elements may be fed with power in a clockwise direction for every i-th antenna element with a phase difference of i times (integer multiple) 360/n degrees. This makes it possible to transmit and receive elliptically polarized electromagnetic waves regardless of the number of antenna elements.

The wireless device according to the present embodiment has been described using an example in which, when a dielectric or conductor is located nearby, the wireless device radiates electromagnetic waves in a direction away from the dielectric or conductor. In one example, the wireless device according to the present embodiment can also be applied to an example in which, when a dielectric or conductor is located nearby, the wireless device radiates radio waves in a direction away from the dielectric or conductor. For example, in a wireless device that is placed near the human body and communicates with a capsule-type small intestine endoscope inside the body, when the wireless device is placed near a dielectric such as the human body, it is necessary to radiate electromagnetic waves toward the inside of the human body. Therefore, when the wireless device is placed near the human body, the change in the characteristic impedance of the antenna is larger than when a dielectric or conductor is not located near the wireless device, and the wireless device can communicate with a communication device inside the body by radiating electromagnetic waves to the board side. In this case, the antenna provided in the wireless device may be designed to match the relative dielectric constant of the human body.

The above-mentioned embodiment can also be implemented by executing the following process. That is, a recording medium on which the program code of the software that realizes the functions of the above-mentioned embodiment is recorded is supplied to a system or device. Then, the computer (or CPU or MPU) of the system or device reads and executes the program code stored in the recording medium. This makes it possible to achieve the above-mentioned object. In this case, the program code itself read from the storage medium realizes the functions of the above-mentioned embodiment, and the storage medium storing the program code constitutes the present invention. Examples of storage media for supplying the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, DVDs, etc. can be used.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

101, 102: Substrate, 103, 104: Ground, 105: Conduction section, 106, 108: Antenna element, 107, 109: Power supply section, 201: Transmitter/receiver section, 202: Switching section, 203, 204: Phase shift section, 207: Detector section, 208: Control section, 209: Memory section

Claims (20)

An antenna,
an input/output point for inputting and outputting a wireless signal;
a first region comprising a first ground and a first radiating means;
a second region including a second ground and a second radiating means, the second region being arranged to overlap with the first region when viewed from a direction perpendicular to a plane on which the first ground is arranged ;
a conductor connecting a ground of the first region and a ground of the second region ;
a switching means capable of switching whether the first radiating means or the second radiating means is connected to the input/output point;
Equipped with
At least one of the first radiating means and the second radiating means has a plurality of antenna elements;
13. The antenna according to claim 12, wherein either the first radiating means or the second radiating means that is not electrically connected to the input/output point functions as a ground. the first radiating means, when connected to the input/output point, radiates an electromagnetic wave having a main lobe from the first radiating means in a direction different from a direction of the second region ;
2. The antenna according to claim 1, wherein the second radiating means, when connected to the input/output point, radiates an electromagnetic wave having a main lobe from the second radiating means in a direction different from a direction of the first region . 3. The antenna according to claim 1 , wherein the first region is disposed on a first substrate, and the second region is disposed on a second substrate . 4. The antenna according to claim 1 , wherein the plurality of antenna elements are arranged so as to surround at least one of the first ground and the second ground. At least one of the plurality of antenna elements
a ground point connected to the first ground or the second ground;
A power supply point connected to the switching means;
having
5. The antenna according to claim 1, wherein the feeding points of the plurality of antenna elements of either the first radiating means or the second radiating means that is not connected to the input/output point are open . the first radiating means and the second radiating means include the same number of antenna elements;
a branching means arranged between the first radiating means and the second radiating means and the switching means, the branching means branching a radio signal from the switching means into a number equal to the number of the plurality of antenna elements;
6. An antenna as claimed in claim 1, further comprising phase shifting means arranged between said branching means and at least one of said plurality of antenna elements, said phase shifting means providing a phase shift to at least one of said branches equal in number to said plurality of antenna elements. the first radiating means and the second radiating means include the same number of antenna elements;
a branching means arranged between the input/output point and the switching means, for branching a radio signal from the input/output point into a number equal to the number of the plurality of antenna elements;
phase shifting means disposed between said branching means and said input/output point for imparting a phase shift to at least one of said branches, the number of which corresponds to the number of said plurality of antenna elements;
6. The antenna according to claim 1, further comprising: An antenna according to claim 6 or 7, characterized in that the phase shifting means provides a phase shift such that the phase difference between each of the plurality of antenna elements and the input/output point is an integer multiple of 360/n degrees, where n is the number of the plurality of antenna elements. 9. An antenna according to claim 1, wherein the switching means is arranged in the first region . 9. An antenna as claimed in claim 1, further comprising a third substrate arranged between the first region and the second region , on which the switching means is arranged. 11. The antenna according to claim 1, wherein the first region and the second region are spaced apart at a distance of λ/8 or less, where λ is the wavelength of a design frequency. 12. The antenna according to claim 1, wherein the first region and the second region are disposed on different layers of a multi-layer substrate. 13. The antenna according to claim 1, wherein either the first radiating means or the second radiating means that is not connected to the input/output point functions as a ground by being connected to the first ground and the second ground. 1. A wireless device, comprising:
A transmitting/receiving unit for transmitting and receiving a radio signal;
a first region comprising a first ground and a first radiating means ;
a second region including a second ground and a second radiating means , the second region being arranged to overlap with the first region when viewed from a direction perpendicular to a plane on which the first ground is arranged ;
a conductor connecting a ground of the first region and a ground of the second region ;
a switching means capable of switching whether the first radiating means or the second radiating means is connected to the transmitting/receiving means;
A control means for controlling the switching means based on a predetermined condition;
Including,
At least one of the first radiating means and the second radiating means has a plurality of antenna elements;
2. A wireless device comprising: a first radiating means and a second radiating means that are not connected to the transmitting/receiving means; a detection means for detecting a value corresponding to a magnitude of reflected power when a radio signal is input to the first radiating means and the second radiating means ,
The wireless device according to claim 14, characterized in that the predetermined condition includes that the value when a wireless signal is input to either the first radiating means or the second radiating means connected to the transmitting/receiving means exceeds a threshold value. The wireless device according to claim 15, characterized in that the predetermined condition further includes that the value when a wireless signal is input to either the first radiating means or the second radiating means connected to the transmitting/receiving means does not exceed a threshold value. The predetermined condition is:
The predetermined condition is that the value detected by the detection means exceeds a threshold when a wireless signal is input to either the first emission means or the second emission means connected to the transmission/reception means;
The wireless device according to claim 15 or 16, characterized in that the value corresponding to either the first radiating means or the second radiating means connected to the transmitting/receiving means is smaller than the value corresponding to either the first radiating means or the second radiating means connected to the transmitting/receiving means. the wireless device further comprises a sensor for detecting an object located in the vicinity of either the first emitting means or the second emitting means ;
18. The wireless device according to claim 14, wherein the predetermined condition includes that the object is detected by the sensor. a memory for storing a connection setting indicating whether the transmitting/receiving means is connected to the first radiating means or the second radiating means ;
The control means
reading the connection setting from the memory before transmission by the transmitting/receiving means;
19. The wireless device according to claim 14, wherein the connection settings are written to the memory after transmission by the transmitting/receiving means. 20. The wireless device according to claim 14, wherein the control means controls the switching means based on a control signal received via at least one of the first radiating means and the second radiating means .

Images