Wireless communication devices and measuring systems with wireless communication capabilities

Abstract

This wireless communication device comprises: a substantially square ground conductor (2) provided on a substantially square dielectric substrate (1); and a first antenna (3), a second antenna (4), and a third antenna (5) provided on the dielectric substrate (1). The first antenna (3) is provided along a first side of the dielectric substrate (1), the second antenna (4) is provided along a second side adjacent to the first side of the dielectric substrate (1), and the third antenna (5) is provided along a third side facing the first side of the dielectric substrate (1). The open end of the first antenna (3) faces a direction away from the second side, the open end of the second antenna (4) faces a direction away from the first side, and the open end of the third antenna (5) faces a direction away from the second side.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication device, particularly an antenna device.

Background Art

[0002] When wireless communication is performed in a multipath environment, it is effective to endow a wireless communication device with a diversity function in order to avoid deterioration of communication quality due to multipath fading. In a wireless communication device having a diversity function, it is required to use a plurality of antennas to increase the gain of each antenna and reduce the correlation between the antennas. The correlation between antennas increases when the radiation patterns of the antennas are similar. Also, reducing the coupling amount between antennas is equivalent to reducing the correlation between antennas.

[0003] In a diversity antenna composed of two or more antennas, methods for reducing the correlation between antennas have been studied. For example, the wireless communication device disclosed in Patent Document 1 can receive radio waves in the frequency band of television broadcast (473 MHz - 767 MHz), has a total of four antennas on three sides of a substrate, and arranges the antennas orthogonally or increases the electrical distance between the antennas, thereby increasing the isolation between the antennas and suppressing a decrease in the gain of the antennas. Also, the wireless communication device disclosed in Patent Document 2 can simultaneously and smoothly perform communication using different wireless communication systems (e.g., Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), etc.) in the same frequency band, has a total of four antennas including two 920 MHz band antennas and two 2.4 GHz band antennas on three sides of a substrate, and suppresses interference between the antennas by arranging the antennas of the same frequency orthogonally at diagonal positions on the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] By using the technologies described in Patent Documents 1 and 2, it is possible to reduce the correlation between antennas. However, simply arranging the antennas orthogonally is not sufficient to reduce coupling. Furthermore, as wireless communication devices become smaller, it becomes difficult to increase the electrical distance between antennas. In particular, when the size of the substrate becomes smaller relative to the wavelength of the wireless communication signal, there is a concern that the correlation between antennas will increase, leading to a decrease in communication quality.

[0006] This disclosure is made to solve the above-mentioned problems and aims to provide a wireless communication device that can achieve low correlation and high efficiency in multiple antennas. [Means for solving the problem]

[0007] The wireless communication device related to this disclosure , kidnapping an electrolytic substrate and provided on the dielectric substrate land A conductor, a first antenna provided on the dielectric substrate along a first edge of the dielectric substrate, a second antenna provided on the dielectric substrate along a second edge adjacent to the first edge of the dielectric substrate, and a third antenna provided on the dielectric substrate along a third edge opposite to the first edge of the dielectric substrate. ,of The open end of the first antenna is oriented away from the second side, the open end of the second antenna is oriented away from the first side, and the open end of the third antenna is oriented away from the second side. The first antenna corresponds to a first frequency, the third antenna corresponds to a second frequency, and the second antenna corresponds to both the first and second frequencies. . [Effects of the Invention]

[0008] According to the present disclosure, a plurality of antennas have low correlation and high efficiency, and high communication quality can be obtained.

[0009] The objects, features, aspects, and advantages of the present disclosure will become clearer from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

[0010] [Figure 1] It is a diagram showing the configuration of a wireless communication device according to Embodiment 1. [Figure 2] It is a diagram showing the result of calculating the change in correlation between antennas when the antenna arrangement is changed by electromagnetic field simulation. [Figure 3] It is a diagram showing a modification example of the wireless communication device according to Embodiment 1. [ [Figure 4] It is a diagram showing the configuration of a wireless communication device according to Embodiment 2. [Figure 5] It is a diagram showing the circuit configuration of the wireless communication device according to Embodiment 2. [Figure 6] It is a diagram showing a modification example 1 of the wireless communication device according to Embodiment 2. [Figure 7] It is a diagram showing a modification example 2 of the wireless communication device according to Embodiment 2. [Figure 8] It is a diagram showing a modification example 3 of the wireless communication device according to Embodiment 2. [Figure 9] It is a diagram showing the configuration of a wireless communication device according to Embodiment 3. [Figure 10] It is a diagram showing an example of a decoupling circuit in Embodiment 3. [Figure 11] It is a diagram showing an example of a decoupling circuit in Embodiment 3. [Figure 12] It is a diagram showing the configuration of a wireless communication device according to Embodiment 4. [Figure 13] It is a diagram showing an example of the configuration of a measurement system according to Embodiment 5. [[ID=****]]

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the technology according to the present disclosure will be described with reference to the drawings. In the following embodiments, examples of transmission antennas are mainly shown, but it is needless to say that the same effects can be obtained with reception antennas due to the reversibility of antennas.

[0012] <Embodiment 1> FIG. 1 is a diagram showing the configuration of a wireless communication device according to Embodiment 1. This wireless communication device functions as a transmission antenna or a reception antenna.

[0013] As shown in FIG. 1, the wireless communication device according to Embodiment 1 includes a dielectric substrate 1, a ground conductor 2, a first antenna 3, a second antenna 4, a third antenna 5, a feeding point 6 of the first antenna 3, a feeding point 7 of the second antenna 4, and a feeding point 8 of the third antenna 5.

[0014] The dielectric substrate 1 is substantially square in plan view. A substantially square ground conductor 2 is provided on the dielectric substrate 1. The dielectric substrate 1 and the ground conductor 2 constitute a printed circuit board, but in this specification, for simplicity of explanation, the ground conductor 2 is treated as a conductor provided on one side of the dielectric substrate 1. However, the first antenna 3, the second antenna 4, and the third antenna 5 may be formed on both sides of the dielectric substrate 1. Examples of the material of the dielectric substrate 1 include glass epoxy.

[0015] The first antenna 3, the second antenna 4, and the third antenna 5 are conductor patterns formed on the dielectric substrate 1. In the present embodiment, the first antenna 3, the second antenna 4, and the third antenna 5 are formed by etching a metal film formed on the dielectric substrate 1, but they may be formed of sheet metal, metal wire, or the like.

[0016] The feed point 6 of the first antenna 3 is located between the first antenna 3 and the ground conductor 2. The feed point 7 of the second antenna 4 is located between the second antenna 4 and the ground conductor 2. The feed point 8 of the third antenna 5 is located between the third antenna 5 and the ground conductor 2. Each of the feed points 6, 7, and 8 has the function of exciting a high-frequency signal.

[0017] In the paper shown in Figure 1, we define the x-axis as the horizontal direction, the y-axis as the vertical direction, and the z-axis as the depth direction. We define the right direction as the "+x direction", the left direction as the "-x direction", the upward direction as the "+y direction", and the downward direction as the "-y direction".

[0018] The first antenna 3 is provided along the first edge of the dielectric substrate 1. Specifically, the first antenna 3 extends in the -x direction from the feed point 6 and branches into two. One part of the branched first antenna 3 extends in the -y direction along the first edge of the dielectric substrate 1 from the branching point, and the other part is short-circuited to the ground conductor 2. As a result, the first antenna 3 functions as an inverted F antenna, making impedance matching easy. Note that it is not essential to provide a short-circuit section (the part short-circuited to the ground conductor 2) in the first antenna 3.

[0019] In the description of the first antenna 3, the portion extending in the -x direction from the base end connected to the feed point 6 is sometimes referred to as the "vertical section," and the portion extending in the -y direction from the branching point is sometimes referred to as the "horizontal section."

[0020] The second antenna 4 is provided along the second edge adjacent to the first edge of the dielectric substrate 1, so as to be perpendicular to the first antenna 3. Specifically, the second antenna 4 extends in the +y direction from the feed point 7 and branches into two at the first branching point. One portion of the second antenna 4 that branches at the first branching point extends in the +x direction along the second edge of the dielectric substrate 1, and the other portion extends further in the +y direction. The portion of the second antenna 4 that extends in the +y direction from the first branching point further branches into two at the second branching point. One portion of the second antenna 4 that branches at the second branching point extends in the +x direction along the second edge of the dielectric substrate 1, and the other portion is short-circuited to the ground conductor 2. As a result, the second antenna 4 operates as a multiband inverted F antenna, making impedance matching easy. Note that the short-circuited portion of the second antenna 4 is not essential.

[0021] In the description of the second antenna 4, the portion extending in the +y direction from the base end connected to the feed point 7 is sometimes referred to as the "vertical portion," and the portion extending in the +x direction from the first or second branching point is sometimes referred to as the "horizontal portion."

[0022] The third antenna 5 is provided along the third edge of the dielectric substrate 1 opposite the first edge. Specifically, the third antenna 5 extends in the +x direction from the feed point 8, bends midway, and extends in the -y direction along the third edge of the dielectric substrate 1 from the bend point. As a result, the third antenna 5 operates as an inverted L antenna. In addition, the third antenna 5 may also be provided with a short-circuit section, similar to the first antenna 3 and the second antenna 4.

[0023] In the description of the third antenna 5, the portion extending in the +x direction from the base end connected to the feed point 8 is sometimes referred to as the "vertical portion," and the portion extending in the -y direction from the bending point is sometimes referred to as the "horizontal portion."

[0024] The second antenna 4 is multiband-enabled so as to correspond to the operating frequencies of the first antenna 3 and the third antenna 5. In other words, if the operating frequency of the first antenna 3 is f1 and the operating frequency of the third antenna 5 is f2, then the operating frequencies of the second antenna 4 are f1 and f2.

[0025] The first antenna 3 has a total length equivalent to one-quarter of the wavelength corresponding to the operating frequency f1 of the first antenna 3. That is, in the first antenna 3, the length from the base of the vertical section through the branching point to the tip (open end) of the horizontal section is one-quarter of the wavelength corresponding to the operating frequency f1.

[0026] The second antenna 4 has a total length equivalent to one-quarter of the wavelength corresponding to each of the two operating frequencies f1 and f2 of the second antenna 4. That is, in the second antenna 4, one of the lengths from the base of the vertical section to the tip (open end) of the horizontal section extending from the first branching point, and the other of the lengths from the base of the vertical section to the tip (open end) of the horizontal section extending from the second branching point, is one-quarter of the wavelength corresponding to operating frequency f1, and the other is one-quarter of the wavelength corresponding to operating frequency f2.

[0027] The third antenna 5 has a total length equivalent to one-quarter of the wavelength corresponding to the operating frequency f2 of the third antenna 5. That is, in the third antenna 5, the length from the base of the vertical section through the bend to the tip (open end) of the horizontal section is one-quarter of the wavelength corresponding to the operating frequency f2 of the third antenna 5.

[0028] In this specification, "quarter wavelength length" does not mean only a value exactly equal to a quarter wavelength length, but rather includes an acceptable range in both the positive and negative directions based on the quarter wavelength length.

[0029] Furthermore, as can be seen from Figure 1, the open end of the first antenna 3 is oriented away from the second edge of the dielectric substrate 1 on which the second antenna 4 is mounted. The open end of the second antenna 4 is oriented away from the first edge of the dielectric substrate 1 on which the first antenna 3 is mounted. The open end of the third antenna 5 is oriented away from the second edge of the dielectric substrate 1 on which the second antenna 4 is mounted.

[0030] Figure 2 shows the results of electromagnetic field simulations that calculated the change in correlation between two antennas when their arrangement (position and orientation) was changed.

[0031] As shown in Figure 2(a), two antennas are arranged orthogonally on adjacent sides of a dielectric substrate, with the open end of one antenna oriented away from the side where the other antenna is located, and the open end of the other antenna oriented away from the side where the first antenna is located. The correlation between the antennas in this case is set to 1 and used as the reference.

[0032] As shown in Figure 2(b), when two antennas are arranged orthogonally on adjacent sides of a dielectric substrate, with the open end of one antenna oriented toward the side where the other antenna is located, and the open end of the other antenna oriented toward the side away from the side where the first antenna is located, the correlation between the antennas was 10 (i.e., 10 times that of Figure 2(a)).

[0033] As shown in Figure 2(c), when two antennas are arranged orthogonally on adjacent sides of a dielectric substrate, with the open end of one antenna oriented toward the side where the other antenna is located, and the open end of the other antenna oriented toward the side where the first antenna is located, the correlation between the antennas was 32 (i.e., 32 times that of Figure 2(a)).

[0034] As shown in Figure 2(d), when two antennas were placed parallel to each other on opposite sides of the dielectric substrate, and the open end of one antenna was oriented in the same direction as the open end of the other antenna, the correlation between the antennas was 16 (i.e., 16 times that of Figure 2(a)).

[0035] As shown in Figure 2(e), when two antennas are placed parallel to each other on opposite sides of a dielectric substrate, and the open ends of one antenna are oriented in opposite directions, the correlation between the antennas was 25 (i.e., 25 times that of Figure 2(a)).

[0036] From the results in Figures 2(a) to 2(c), it can be seen that when two antennas are arranged orthogonally on adjacent edges of a dielectric substrate, the arrangement in Figure 2(a) suppresses the correlation between the antennas the most. Furthermore, it can be seen that the arrangement in Figure 2(b) also suppresses the correlation between the antennas to a low degree, although not as much as the arrangement in Figure 2(a).

[0037] Furthermore, the results in Figures 2(d) and 2(e) show that when the two antennas are placed parallel to each other on opposite sides of the dielectric substrate, the antenna correlation is lower in the arrangement in Figure 2(d) than in the arrangement in Figure 2(e).

[0038] In the wireless communication device according to Embodiment 1, the arrangement of the first antenna 3 and the second antenna 4 is as shown in Figure 2(a). This reduces the correlation between the first antenna 3 and the second antenna 4, and the first antenna 3 and the second antenna 4 operate as a diversity antenna at frequency f1. Furthermore, the arrangement of the second antenna 4 and the third antenna 5 is as shown in Figure 2(b). This also reduces the correlation between the second antenna 4 and the third antenna 5, and the second antenna 4 and the third antenna 5 operate as a diversity antenna at frequency f2.

[0039] Thus, by making the second antenna 4 multi-band, the size of the wireless communication device can be reduced. Also, a diversity function corresponding to two wireless communication systems with different operating frequencies can be provided.

[0040] The operating frequencies f1 and f2 may be arbitrary frequencies, but it is preferable that the relationship f1 < f2 is satisfied. As can be seen from FIGS. 2(a) and (b), in the wireless communication device according to Embodiment 1, the correlation between the first antenna 3 and the second antenna 4 is easier to make lower than the correlation between the second antenna 4 and the third antenna 5. Usually, since it is difficult to increase the electrical distance between antennas operating at a low frequency (high wavelength) compared to the electrical distance between antennas operating at a high frequency (short wavelength), it is difficult to make the correlation between antennas operating at a low frequency lower than the correlation between antennas operating at a high frequency. Therefore, by setting the operating frequency f2 assigned to the second antenna 4 and the third antenna 5, for which it is difficult to lower the correlation, higher than the operating frequency f1 assigned to the first antenna 3 and the second antenna 4, for which it is easy to lower the correlation, the correlation between the second antenna 4 and the third antenna 5 can also be easily made lower, and both the correlation between the first antenna 3 and the second antenna 4 and the correlation between the second antenna 4 and the third antenna 5 can be made lower.

[0041] In Embodiment 1, an example is shown in which the first antenna 3 and the second antenna 4 are inverted-F antennas and the third antenna 5 is an inverted-L antenna, but the shapes of the first antenna 3, the second antenna 4, and the third antenna 5 are not limited to this. As long as the above-described actions and effects can be obtained, antennas having other shapes, such as a meander antenna or a folded monopole antenna, may be used.

[0042] If the lowest operating frequency supported by the wireless communication device is f1 and the wavelength of the operating frequency f1 is λ1, the size of the rectangular dielectric substrate 1 is assumed to be 0.25λ1 × 0.25λ1. However, a variation of about ±0.1λ1 is allowed.

[0043] The operation of the wireless communication device according to Embodiment 1 will be described.

[0044] For example, when the first antenna 3 functions as a transmitting antenna, a high-frequency signal is supplied to the feed point 6 of the first antenna 3, and the high-frequency signal is transmitted to the first antenna 3 through the feed point 6. Then, due to the resonance phenomenon that occurs when the high-frequency signal is transmitted through the first antenna 3, electromagnetic waves corresponding to the high-frequency signal are radiated from the first antenna 3 into space. The same applies to the second antenna 4 and the third antenna 5.

[0045] Furthermore, when the first antenna 3 functions as a receiving antenna, electromagnetic waves are received by the first antenna 3, and a high-frequency signal corresponding to the received electromagnetic waves is output from the feed point 6 of the first antenna 3. The same applies to the second antenna 4 and the third antenna 5.

[0046] As described above, the wireless communication device according to Embodiment 1 can configure diversity corresponding to two frequencies (f1 and f2) using three low-correlation antennas, thereby achieving high communication quality.

[0047] [Differentiation] Figure 3 shows a modified example of the wireless communication device according to Embodiment 1. Compared to the configuration in Figure 1, the configuration in Figure 3 adds a non-powered antenna short-circuited to the ground conductor 2 and an antenna element branched from the first antenna 3 to the first antenna 3, and adds a non-powered antenna short-circuited to the ground conductor 2 to the second antenna 4.

[0048] The wireless communication device in Figure 3 can handle operating frequencies f1 and f2, as well as operating frequency f3. That is, the first antenna 3 can handle operating frequency f1, as well as operating frequency f3, and the second antenna 4 can handle operating frequencies f1 and f2, as well as operating frequency f3.

[0049] The operating frequencies f1, f2, and f3 may be arbitrary frequencies, but it is preferable that the relationship f1 < f2 < f3 is satisfied. Since the correlation between the antennas tends to increase as the operating frequencies become closer, the correlation between the first antenna 3 and the second antenna 4 is suppressed by increasing the difference between the corresponding frequencies f1 and f3 for both the first antenna 3 and the second antenna 4.

[0050] In this modification, the first antenna 3 has an overall length corresponding to 1 / 4 of the wavelength corresponding to each of the two operating frequencies f1 and f3 of the first antenna 3. That is, in the first antenna 3, the sum of the length from the base end of the vertical portion to the tip of the horizontal portion extending from the first branch point and the length of the passive antenna added to the first antenna 3 (the length from the base end of the vertical portion through the bending point to the tip of the horizontal portion), and one of the lengths from the base end of the vertical portion to the tip of the horizontal portion extending from the second branch point is 1 / 4 of the wavelength corresponding to the operating frequency f1, and the other is 1 / 4 of the wavelength corresponding to the operating frequency f3.

[0051] The second antenna 4 has an overall length corresponding to 1 / 4 of the wavelength corresponding to each of the three operating frequencies f1, f2, and f3 of the second antenna 4. That is, in the second antenna 4, one of the lengths from the base end of the vertical portion to the tip of the horizontal portion extending from the first branch point and the length from the base end of the vertical portion to the tip of the horizontal portion extending from the second branch point is 1 / 4 of the wavelength corresponding to the operating frequency f1, and the other is 1 / 4 of the wavelength corresponding to the operating frequency f2. And the length of the passive antenna added to the second antenna 4 (the length from the base end of the vertical portion through the bending point to the tip of the horizontal portion) is 1 / 4 of the wavelength corresponding to the operating frequency f3.

[0052] The third antenna 5, as in Figure 1, has a total length equivalent to one-quarter of the wavelength corresponding to the operating frequency f2 of the third antenna 5. That is, in the third antenna 5, the length from the base of the vertical section through the bend to the tip of the horizontal section is one-quarter of the wavelength corresponding to the operating frequency f2 of the third antenna 5.

[0053] As can be seen from Figure 3, in this modified example as well, the open end of the first antenna 3 is oriented away from the second edge of the dielectric substrate 1 on which the second antenna 4 is mounted. The open end of the second antenna 4 is oriented away from the first edge of the dielectric substrate 1 on which the first antenna 3 is mounted. The open end of the third antenna 5 is oriented away from the second edge of the dielectric substrate 1 on which the second antenna 4 is mounted. As a result, the correlation between the first antenna 3 and the second antenna 4 is reduced, and the first antenna 3 and the second antenna 4 operate as diversity antennas at frequencies f1 and f3. Furthermore, the correlation between the second antenna 4 and the third antenna 5 is also kept low, and the second antenna 4 and the third antenna 5 operate as diversity antennas at frequency f2.

[0054] Figure 3 shows an example in which a parasitic antenna and a branched antenna element are added to the first antenna 3, but only one of them may be added. Also, in Figure 3, the parasitic antenna added to the second antenna 4 is connected to the right side of the ground conductor 2, but it may also be connected to the upper side of the ground conductor 2.

[0055] Furthermore, in Figure 3, the tip of the unpowered antenna added to the first antenna 3 is oriented toward the second edge of the dielectric substrate 1 on which the second antenna 4 is mounted, and the tip of the unpowered antenna added to the second antenna 4 is oriented toward the first edge of the dielectric substrate 1 on which the first antenna 3 is mounted. This is to couple the unpowered antenna with the powered antenna.

[0056] If the orientations of these two unpowered antennas are reversed, the correlation between the first antenna 3 and the second antenna 4 can be further reduced. However, it must be noted that this may cause the fed antenna and the unpowered antenna to lose coupling. Conversely, if coupling between the fed antenna and the unpowered antenna can be ensured, the orientations of the two unpowered antennas can be opposite to those in Figure 3.

[0057] According to the wireless communication device of this modified version, diversity corresponding to three frequencies (f1, f2, and f3) can be configured using three low-correlation antennas, and high communication quality can be obtained.

[0058] <Embodiment 2> The wireless communication device according to Embodiment 2 will be described with reference to Figures 4 to 8. In Figures 4 to 8, elements that are the same as or corresponding to the elements described in Embodiment 1 are denoted by the same reference numerals, so redundant explanations of them will be omitted.

[0059] Figure 4 shows the configuration of the wireless communication device according to Embodiment 2. The configuration of the dielectric substrate 1, ground conductor 2, first antenna 3, second antenna 4, and third antenna 5 is the same as in Figure 1.

[0060] As shown in Figure 4, the second antenna 4 is connected to a transmission line 9b provided on the dielectric substrate 1. The transmission line 9b branches into two midway and is connected to the first transceiver module 10 and the second transceiver module 11. However, a phase-adjustable phase shifter 12a is inserted between the branching point of the transmission line 9b and the first transceiver module 10, and a phase-adjustable phase shifter 12b is inserted between the branching point of the transmission line 9b and the second transceiver module 11. The first transceiver module 10 corresponds to frequency f1, and the second transceiver module 11 corresponds to frequency f2. The first transceiver module 10 and the second transceiver module 11 have the function of converting information to be transmitted into a high-frequency signal and the function of extracting information received from the high-frequency signal.

[0061] Furthermore, the first antenna 3 is connected to the first transceiver module 10 via transmission line 9a. The third antenna 5 is connected to the second transceiver module 11 via transmission line 9c.

[0062] Figure 5 shows the circuit configuration of the wireless communication device according to Embodiment 2.

[0063] The second antenna 4 corresponds to two frequencies (f1 and f2). Therefore, if the transmission line 9b is directly connected to the first transmit / receive module 10 and the second transmit / receive module 11, there is a concern that the reflection characteristics may be significantly degraded depending on the reflection phase of the impedance when viewed from the branching point of the transmission line 9b to the first transmit / receive module 10, or the reflection phase of the impedance of the second transmit / receive module 11 when viewed from the branching point of the transmission line 9b. It is desirable that these reflection phases be close to zero.

[0064] Therefore, in Embodiment 2, a phase shifter 12a is inserted between the branching point of the transmission line 9b and the first transceiver module 10, and the amount of phase shift of the phase shifter 12a is determined so that the reflection phase of the impedance when viewed from the branching point of the transmission line 9b to the first transceiver module 10 becomes zero at the operating frequency f2. As a result, the impedance when viewed from the branching point of the transmission line 9b to the first transceiver module 10 becomes electrically open at frequency f2, and reflection from the first transceiver module 10 can be eliminated.

[0065] Furthermore, a phase shifter 12b is inserted between the branching point of the transmission line 9b and the second transceiver module 11, and the phase shift amount of the phase shifter 12b is determined so that the reflection phase of the impedance when viewed from the branching point of the transmission line 9b to the second transceiver module 11 is zero at the operating frequency f1. As a result, the impedance when viewed from the branching point of the transmission line 9b to the second transceiver module 11 becomes electrically open at frequency f1, and reflection from the second transceiver module 11 can be eliminated.

[0066] The phase shifters 12a and 12b may be distributed-parameter lines or lumped-parameter elements such as chip components.

[0067] As described above, by determining the phase shift amount of the phase shifter so that the impedance seen from the branching point of the transmission line 9b connected to the second multiband antenna 4 to the transmit / receive module (first transmit / receive module 10 or second transmit / receive module 11) appears open outside the band, a diplexer-like effect that separates frequencies can be obtained.

[0068] According to the wireless communication device of Embodiment 2, by configuring a simple circuit on the dielectric substrate 1 that can split the signal into two frequencies (f1 and f2) without using a component such as a diplexer to separate the frequencies, the antenna can be shared with low loss between the first transmitting / receiving module 10 and the second transmitting / receiving module 11.

[0069] [Example 1] Figure 6 shows the circuit configuration of a modified example 1 of the wireless communication device according to Embodiment 2.

[0070] The configuration in Figure 6 is the same as the configuration in Figure 5, but with a bandpass filter 13a inserted between the phase shifter 12a and the first transmit / receive module 10, and a bandpass filter 13b inserted between the phase shifter 12b and the second transmit / receive module 11.

[0071] According to this modified example, the reflection amplitude when looking from the branching point of the transmission line 9b to the phase shifter 12a side at frequency f2, and the reflection amplitude when looking from the branching point of the transmission line 9b to the phase shifter 12b side at frequency f1, can both be increased, thereby further reducing the influence of out-of-band reflections.

[0072] [Differentiation 2] Figure 7 shows the circuit configuration of a modified example 2 of the wireless communication device according to Embodiment 2.

[0073] The configuration in Figure 7 is different from the configuration in Figure 6, in which a matching circuit 14a is inserted at the base of the transmission line 9a connected to the first antenna 3 (the connection point with the first antenna 3), a matching circuit 14b is inserted at the base of the transmission line 9b connected to the second antenna 4 (the connection point with the second antenna 4), and a matching circuit 14c is inserted at the base of the transmission line 9c connected to the third antenna 5 (the connection point with the third antenna 5).

[0074] According to this modified example, impedance matching can be achieved by matching circuits 14a, 14b, and 14c. Matching circuits 14a, 14b, and 14c may be distributed constant transmission lines or lumped constant elements such as chip components.

[0075] [Difference 3] In Modification 3, the antenna circuit of Embodiment 2 is applied to the wireless communication device shown in Figure 3, which corresponds to three operating frequencies (f1, f2, and f3). Figure 8 shows Modification 3 of the wireless communication device according to Embodiment 2.

[0076] Even when the wireless communication device has three operating frequencies, the same antenna circuit configuration as in Figure 3 can be used. However, the first transmit / receive module 10 in Figure 8 needs to correspond to two frequencies, f1 and f3. By determining the phase shift amount of the phase shifter 12b so that the reflection phase of the impedance when viewed from the branching point of the transmission line 9b to the second transmit / receive module 11 is zero at frequencies f1 and f3, reflection from the second transmit / receive module 11 can be eliminated.

[0077] <Embodiment 3> Figure 9 shows the configuration of a wireless communication device according to Embodiment 3. In Figure 9, elements that are the same as or corresponding to the elements described in Embodiments 1 and 2 are denoted by the same reference numerals, so redundant explanations for them are omitted.

[0078] In Embodiment 1, the arrangement of the first antenna 3 and the second antenna 4, which are difficult to reduce correlation with because they operate at the lowest frequency f1 of the wireless communication device's operating frequencies, was changed to the arrangement shown in Figure 2(a), which makes it easier to reduce correlation. As a result, the arrangement of the second antenna 4 and the third antenna 5 became the arrangement shown in Figure 2(b). However, it would be ideal if the second antenna 4 and the third antenna 5 could also have their correlation reduced to the same extent as the arrangement in Figure 2(a).

[0079] Therefore, in Embodiment 3, in order to reduce the correlation between the second antenna 4 and the third antenna 5, a decoupling circuit 15 is inserted between the transmission line 9b connected to the second antenna 4 and the transmission line 9c connected to the third antenna 5 to reduce the coupling between the second antenna 4 and the third antenna 5 at frequency f2. An example of the decoupling circuit 15 is shown in Figures 10 and 11.

[0080] Figure 10 shows an example of a decoupling circuit 15 with a matching circuit function corresponding to one frequency. When using this decoupling circuit 15, the phase shift amounts of the phase shifters 12c and 12d are adjusted so that the real part of the admittance Y32 of the second antenna 4 and the third antenna 5 becomes zero at the frequency f2 corresponding to the second antenna 4. Furthermore, the value of the inductor L1 constituting the decoupling circuit 15 is adjusted so that the imaginary part of the admittance Y32 becomes zero at frequency f2. At this time, the value of the capacitor C1 can be obtained from the following equation.

[0081]

number

[0082] However, when the decoupling circuit 15 in Figure 10 is applied to the wireless communication device in Figure 8, the correlation between the second antenna 4 and the third antenna 5 at frequency f2 can be reduced, but the impedance matching deteriorates significantly at frequencies f3 that are far from frequency f2.

[0083] The wireless communication device in Figure 8 requires a decoupling circuit 15 that corresponds to two frequencies. Figure 11 shows the configuration of a decoupling circuit with matching circuit function that corresponds to two frequencies using a parallel resonant circuit.

[0084] In the decoupling circuit 15 of Figure 11, at frequency f2 the decoupling circuit 15 appears as inductor L1, and at frequency f3 the decoupling circuit 15 appears electrically open, with the inductor L of the parallel resonant circuit. p and capacitor C p Determine the value of the inductor L. p and capacitor C p The value of can be calculated using the following formula.

[0085]

number

[0086]

number

[0087]

number

[0088] The decoupling circuit 15 in Figure 11 can reduce the correlation between the second antenna 4 and the third antenna 5 at frequency f2 while maintaining impedance matching of the second antenna 4 at frequency f3.

[0089] Furthermore, as shown in Figure 9, by providing matching circuits 14d and 14e after the decoupling circuit 15 (on the first transmit / receive module 10 or the second transmit / receive module 11 side), adjustments can be made even if there is a slight deviation in impedance matching.

[0090] The phase shifters 12c and 12d may be distributed constant transmission lines or lumped constant elements such as chip components. The decoupling circuit 15 may also be distributed constant transmission lines or lumped constant elements such as chip components.

[0091] In this embodiment, an example is shown in which the decoupling circuit 15 is provided to connect the second antenna 4 and the third antenna 5, but the decoupling circuit 15 may also be provided to connect the first antenna 3 and the second antenna 4.

[0092] According to Embodiment 4, by inserting a decoupling circuit 15 composed of an inductor and a capacitor between antennas to reduce coupling between antennas and lower correlation, a low-correlation diversity antenna can be realized while maintaining a small size for the wireless communication device.

[0093] <Embodiment 4> Figure 12 shows the configuration of a wireless communication device according to Embodiment 4. In Figure 12, elements that are the same as or corresponding to the elements described in Embodiments 1 to 3 are denoted by the same reference numerals, so redundant explanations for them are omitted.

[0094] The wireless communication device in Figure 12 is the same as the configuration in Figure 8, but with the addition of a fourth antenna 16 and its feed point 18, a fifth antenna 17 and its feed point 19, and a third transceiver module 20.

[0095] The fourth antenna 16 and the fifth antenna 17 are formed on the dielectric substrate 1 and are positioned diagonally opposite each other when viewed from the corner between the first side of the dielectric substrate 1 on which the first antenna 3 is located and the second side of the dielectric substrate 1 on which the second antenna 4 is located. The fourth antenna 16 is provided along the third side on which the third antenna 5 is located, and the fifth antenna 17 is provided along the fourth side opposite the second side.

[0096] In this embodiment, the fourth antenna 16 and the fifth antenna 17 are formed by etching a metal film deposited on the dielectric substrate 1, but they may also be formed from sheet metal or metal wire.

[0097] The feed point 18 of the fourth antenna 16 is located between the fourth antenna 16 and the ground conductor 2. The feed point 19 of the fifth antenna 17 is located between the fifth antenna 17 and the ground conductor 2. Each of the feed points 18 and 19 is a part that excites a high-frequency signal.

[0098] The operating frequencies of the fourth antenna 16 and the fifth antenna 17 are both the same frequency f4. The third transceiver module 20 corresponds to the operating frequency f4 of the fourth antenna 16 and the fifth antenna 17. The fourth antenna 16 is connected to the third transceiver module 20 via transmission line 9d, and the fifth antenna 17 is connected to the third transceiver module 20 via transmission line 9e.

[0099] The shape of the fourth antenna 16 will now be described in detail. The fourth antenna 16 extends in the +x direction from the feed point 18, bends midway, and extends in the +y direction from the bend point along the third side of the dielectric substrate 1. As a result, the fourth antenna 16 functions as an inverted L antenna. In addition, the fourth antenna 16 may also be provided with a short-circuit section, similar to the first antenna 3 and the second antenna 4.

[0100] The shape of the fifth antenna 17 will now be described in detail. The fifth antenna 17 is provided along the fourth edge of the dielectric substrate 1 so as to be perpendicular to the fourth antenna 16. The fifth antenna 17 extends in the -y direction from the feed point 19 and branches into two midway. One part of the branched fifth antenna 17 extends in the -x direction along the fourth edge, and the other part extends in the +x direction and is short-circuited to the ground conductor 2. As a result, the fifth antenna 17 operates as an inverted F antenna, making impedance matching easier. Note that providing a short-circuit in the fifth antenna 17 is not essential.

[0101] In FIG. 12, a substantially square dielectric substrate 1 is provided with a convex region that protrudes a part thereof, and a fourth antenna 16 and a fifth antenna 17 are arranged on the convex portion. However, it is not always necessary to provide a convex region on the dielectric substrate 1. That is, the fourth antenna 16 and the fifth antenna 17 may be arranged in a partial region of the dielectric substrate 1 while maintaining the substantially square shape of the dielectric substrate 1.

[0102] Both the fourth antenna 16 and the fifth antenna 17 have a total length that is 1 / 4 of the wavelength corresponding to the operating frequency f4. That is, in each of the fourth antenna 16 and the fifth antenna 17, the length from the base end of the vertical portion to the open end of the horizontal portion via the bending point is 1 / 4 of the wavelength corresponding to the operating frequency f4.

[0103] The fourth antenna 16 and the fifth antenna 17 are arranged as shown in (a) of FIG. 2. Thereby, the correlation between the fourth antenna 16 and the fifth antenna 17 is reduced, and the fourth antenna 16 and the fifth antenna 17 operate as a diversity antenna at the frequency f4.

[0104] The operating frequencies f1, f2, f3, and f4 may be arbitrary frequencies, but it is preferable that the relationship f1 < f2 < f3 < f4 is satisfied. The fourth antenna 16 and the fifth antenna 17 are arranged close to each other, but by increasing the operating frequency f4 of the fourth antenna 16 and the fifth antenna 17, an electrical distance between the fourth antenna 16 and the fifth antenna 17 can be ensured, and the correlation between the fourth antenna 16 and the fifth antenna 17 can be reduced.

[0105] Also, the fourth antenna 16 and the fifth antenna 17 are arranged at diagonal positions when viewed from the corner between the first side of the dielectric substrate 1 where the first antenna 3 is arranged and the second side of the dielectric substrate 1 where the second antenna 4 is arranged. That is, the fourth antenna 16 and the fifth antenna 17 are arranged at positions away from the first antenna 3 and the second antenna 4. The correlation between antennas tends to be higher as the operating frequencies are closer. However, when the relationship f1 < f2 < f3 < f4 is satisfied, the distance between the fourth antenna 16 and the fifth antenna 17 having f4 as the operating frequency and the first antenna 3 and the second antenna 4 having a frequency f3 relatively close to the frequency f4 as the operating frequency is ensured, and the correlation between the first antenna 3 and the second antenna 4 and the fourth antenna 16 and the fifth antenna 17 can be lowered.

[0106] As described above, according to the wireless communication device according to Embodiment 4, diversity corresponding to four frequencies (f1, f2, f3, and f4) can be configured using five low-correlation antennas, and high communication quality can be obtained.

[0107] <Embodiment 5> FIG. 13 is a diagram showing the configuration of a measurement system with a wireless communication function according to Embodiment 5. In FIG. 13, elements that are the same as or corresponding to the elements described in Embodiments 1 to 4 are given the same reference numerals, and redundant descriptions thereof are omitted.

[0108] The measurement system according to Embodiment 5 is a sensor system with a wireless communication function provided in a sensor network. As shown in FIG. 13, the measurement system includes the wireless communication device shown in FIG. 12, a measurement unit 21, and a connection cable 22 that electrically connects the wireless communication device and the measurement unit 21. The wireless communication device included in the measurement system is not limited to the wireless communication device in FIG. 13, and may be, for example, the wireless communication devices shown in FIGS. 3, 4, 8, etc.

[0109] The measurement unit 21 measures data using sensors and transmits the measured data to the outside using radio waves emitted from the wireless communication device. As shown in Figure 13, the measurement unit 21 is positioned close to the underside of the dielectric substrate 1 of the wireless communication device. Conversely, the wireless communication device is positioned on top of the measurement unit 21.

[0110] The connecting cable 22 has a connector 23a at one end for connecting to a wireless communication device and a connector 23b at the other end for connecting to a measurement unit 21. The connector 23a of the connecting cable 22 is connected to the ground conductor 2 at the fourth edge of the dielectric substrate 1 (the lower edge of the dielectric substrate 1 in Figure 12). The connector 23a is connected to the first transceiver module 10 via a transmission line 9f. The connector 23a may also be connected to the second transceiver module 11 or the third transceiver module 20. Furthermore, the signal input from the connector 23a to the dielectric substrate 1 may be shared among the first transceiver module 10, the second transceiver module 11, and the third transceiver module 20 via a dedicated communication line.

[0111] The data measured by the measurement unit 21 is sent to the wireless communication device via the connecting cable 22 and transmitted to the communication partner via radio waves emitted from the wireless communication device. The measurement unit 21 may also transmit to the communication partner, via the wireless communication device, information such as the ID of the measurement unit 21 and the measurement time of the sensor data, in addition to the measured data.

[0112] When a high-frequency signal flows through the surface of the connecting cable 22, which is made of a conductor, the connecting cable 22 may act like an antenna, causing unwanted radio wave radiation, which may affect the antenna characteristics of the wireless communication device. Therefore, it is desirable that the connecting cable 22 not be placed near the antenna and feed point where current is concentrated. In the measurement system according to Embodiment 5, the connector 23a of the connecting cable 22 is mounted in the space on the fourth side of the dielectric substrate 1 where the antenna is not located, thereby preventing the connecting cable 22 from being placed near the antenna and feed point. This prevents a decrease in antenna efficiency and results in a wireless communication measurement system equipped with a highly efficient diversity antenna.

[0113] Furthermore, it is possible to freely combine each embodiment, or to modify or omit each embodiment as appropriate.

[0114] The above description is illustrative in all embodiments, and it should be understood that countless variations not illustrated are conceivable. [Explanation of Symbols]

[0115] 1 Dielectric substrate, 2 Ground conductor, 3 First antenna, 4 Second antenna, 5 Third antenna, 6-8, 18, 19 Feed points, 9a-9f Transmission lines, 10 First transceiver module, 11 Second transceiver module, 12a-12d Phase shifter, 13a, 13b Bandpass filter, 14a-14e Matching circuit, 15 Decoupling circuit, 16 Fourth antenna, 17 Fifth antenna, 20 Third transceiver module, 21 Measurement unit, 22 Connection cable, 23a, 23b Connectors.

Claims

1. Dielectric substrate and A ground conductor provided on the dielectric substrate, A first antenna is provided on the dielectric substrate along the first edge of the dielectric substrate, A second antenna is provided on the dielectric substrate along a second edge adjacent to the first edge of the dielectric substrate, A third antenna is provided on the dielectric substrate along a third edge of the dielectric substrate that is opposite to the first edge of the dielectric substrate, Equipped with, The open end of the first antenna is oriented away from the second side. The open end of the second antenna is oriented away from the first side. The open end of the third antenna is oriented away from the second side. The first antenna corresponds to a first frequency, The third antenna corresponds to the second frequency, The second antenna corresponds to the first frequency and the second frequency, Wireless communication device.

2. The first frequency is f １ , the second frequency is f ２ Then, f １ <f ２ The relationship is satisfied, The wireless communication device according to claim 1.

3. The second antenna is connected to a transmission line provided on the ground conductor. The transmission line has a branching point where it branches into a line connected to a first transmitting / receiving module corresponding to the first frequency and a line connected to a second transmitting / receiving module corresponding to the second frequency. A first phase shifter, which is provided between the branching point and the first transmitting / receiving module and is capable of adjusting the phase, A second phase shifter, which is provided between the branching point and the second transmitting / receiving module and is capable of phase adjustment, Equipped with, The wireless communication device according to claim 1.

4. The first antenna corresponds to the first frequency and the third frequency, The third antenna corresponds to the second frequency, The second antenna corresponds to the first frequency, the second frequency, and the third frequency. The wireless communication device according to claim 1.

5. Let the first frequency be f １ , let the second frequency be f ２ , let the third frequency be f ３ . Then, f １ < f ２ < f ３ and this relationship is satisfied The wireless communication device according to claim 4.

6. The second antenna is connected to a transmission line provided on the ground conductor. The transmission line has a branching point where it branches into a line connected to a first transmitting / receiving module corresponding to the first frequency and the third frequency, and a line connected to a second transmitting / receiving module corresponding to the second frequency. A first phase shifter, which is provided between the branching point and the first transmitting / receiving module and is capable of adjusting the phase, A second phase shifter, which is provided between the branching point and the second transmitting / receiving module and is capable of phase adjustment, Equipped with, The wireless communication device according to claim 4 or claim 5.

7. The device includes a decoupling circuit connected between the second antenna and the third antenna to reduce the correlation between the second antenna and the third antenna at the second frequency. A wireless communication device according to any one of claims 1 to 5.

8. Dielectric substrate and A ground conductor provided on the dielectric substrate, A first antenna is provided on the dielectric substrate along the first edge of the dielectric substrate, A second antenna is provided on the dielectric substrate along a second edge adjacent to the first edge of the dielectric substrate, A third antenna is provided on the dielectric substrate along a third edge of the dielectric substrate that is opposite to the first edge of the dielectric substrate, A fourth antenna is positioned diagonally to the third side of the dielectric substrate, with respect to the corner between the first side and the second side, and is provided along the third side. A fifth antenna is positioned diagonally to the first side and the second side of the dielectric substrate, and is provided along the fourth side of the dielectric substrate opposite to the second side. Equipped with, The first antenna corresponds to a first frequency, The third antenna corresponds to the second frequency, The second antenna corresponds to the first frequency and the second frequency, The fourth antenna and the fifth antenna both correspond to the fourth frequency. The first frequency is f １ , the second frequency is f ２ , the fourth frequency is f ４ Then, f １ <f ２ <f ４ The relationship is satisfied, Wireless communication device.

9. The first antenna corresponds to the first frequency and the third frequency, The second antenna corresponds to the first frequency, the second frequency, and the third frequency. The third frequency is f ３ Then, f １ <f ２ <f ３ <f ４ The relationship is satisfied, The wireless communication device according to claim 8.

10. A wireless communication device according to any one of claims 1 to 5, A measurement unit that measures data transmitted to the outside using radio waves emitted from the aforementioned wireless communication device, The wireless communication device and the measuring unit are connected by a connecting cable. The wireless communication device is placed on top of the measuring unit, The aforementioned connecting cable has one end connected to the measuring unit and the other end connected to the ground conductor of the wireless communication device. The data measured by the measurement unit is transmitted to the outside from the first antenna, the second antenna, or the third antenna via the connecting cable and the transmission line provided on the ground conductor of the wireless communication device. Measurement system with wireless communication capabilities.

11. A wireless communication device according to claim 8 or claim 9, A measurement unit that measures data transmitted to the outside using radio waves emitted from the aforementioned wireless communication device, The wireless communication device and the measuring unit are connected by a connecting cable. The wireless communication device is placed on top of the measuring unit, The aforementioned connecting cable has one end connected to the measuring unit and the other end connected to the ground conductor of the wireless communication device. The data measured by the measurement unit is transmitted to the outside from the first antenna, the second antenna, the third antenna, the fourth antenna, or the fifth antenna via the connecting cable and the transmission line provided on the ground conductor of the wireless communication device. Measurement system with wireless communication capabilities.

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