Wireless communication device and measurement system with wireless communication function

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

Wireless communication device and measurement system with wireless communication function

[0001] The present disclosure relates to wireless communication devices, and more particularly to antenna devices.

[0002] When wireless communication is performed in a multipath environment, it is effective to provide a wireless communication device with a diversity function in order to avoid degradation of communication quality due to multipath fading. Wireless communication devices with a diversity function use multiple 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. Furthermore, reducing the amount of coupling between antennas is equivalent to reducing the correlation between antennas.

[0003] Methods for reducing correlation between antennas in diversity antennas consisting of two or more antennas have been studied. For example, a wireless communication device disclosed in Patent Document 1 is capable of receiving radio waves in the television broadcast frequency band (473 MHz-767 MHz), and is provided with a total of four antennas on three sides of a substrate. By arranging the antennas orthogonally and increasing the electrical distance between the antennas, isolation between the antennas is increased and a decrease in antenna gain is suppressed. Furthermore, a wireless communication device disclosed in Patent Document 2 is capable of simultaneously and smoothly communicating using different wireless communication methods (e.g., Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), etc.) in the same frequency band. The device is provided with a total of four antennas, including two 920 MHz band antennas and two 2.4 GHz band antennas, on three sides of the substrate, and by orthogonally arranging the antennas of the same frequency at diagonal positions on the substrate, interference between the antennas is suppressed.

[0004] International Publication No. WO 2013 / 114840 International Publication No. WO 2018 / 043207

[0005] By using the techniques of Patent Document 1 and Patent Document 2, it is possible to reduce the correlation between antennas. However, simply arranging the antennas orthogonally is not enough to sufficiently reduce the coupling. Furthermore, as wireless communication devices become smaller, it becomes more difficult to increase the electrical distance between antennas. In particular, as the size of the board becomes smaller relative to the wavelength of the wireless communication signal, the correlation between antennas increases, raising concerns about a decline in communication quality.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a wireless communication device that can achieve low correlation and high efficiency in multiple antennas.

[0007] A wireless communication device according to the present disclosure includes a substantially rectangular dielectric substrate, a substantially rectangular ground conductor provided on the dielectric substrate, a first antenna provided on the dielectric substrate along a first side of the dielectric substrate, a second antenna provided on the dielectric substrate along a second side adjacent to the first side of the dielectric substrate, a third antenna provided on the dielectric substrate along a third side opposite to the first side of the dielectric substrate, and a third antenna provided between the ground conductor and the first antenna. The antenna includes a first feed point that feeds power to a first antenna, a second feed point that is provided between the ground conductor and the second antenna and feeds power to the second antenna, and a third feed point that is provided between the ground conductor and the third antenna and feeds power to the third antenna, wherein the open end of the first antenna faces away from the second side, the open end of the second antenna faces away from the first side, and the open end of the third antenna faces away from the second side.

[0008] According to the present disclosure, multiple antennas have low correlation and high efficiency, resulting in high communication quality.

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

[0010] FIG. 1 is a diagram showing a configuration of a wireless communication device according to a first embodiment. FIG. 2 is a diagram showing the results of calculation, by electromagnetic field simulation, of changes in correlation between antennas when the arrangement of the antennas is changed. FIG. 3 is a diagram showing a modified example of a wireless communication device according to the first embodiment. FIG. 4 is a diagram showing a configuration of a wireless communication device according to a second embodiment. FIG. 5 is a diagram showing a circuit configuration of a wireless communication device according to the second embodiment. FIG. 6 is a diagram showing a first modified example of a wireless communication device according to the second embodiment. FIG. 7 is a diagram showing a second modified example of a wireless communication device according to the second embodiment. FIG. 8 is a diagram showing a third modified example of a wireless communication device according to the second embodiment. FIG. 9 is a diagram showing a configuration of a wireless communication device according to a third embodiment. FIG. 10 is a diagram showing an example of a decoupling circuit in the third embodiment. FIG. 11 is a diagram showing an example of a decoupling circuit in the third embodiment. FIG. 12 is a diagram showing a configuration of a wireless communication device according to a fourth embodiment. FIG. 13 is a diagram showing an example of the configuration of a measurement system according to a fifth embodiment.

[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 a transmitting antenna will be mainly shown, but it goes without saying that the same effect can be obtained with a receiving antenna due to the reversibility of the antenna.

[0012] 1 is a diagram showing the configuration of a wireless communication device according to embodiment 1. This wireless communication device functions as a transmitting antenna or a receiving antenna.

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

[0014] The dielectric substrate 1 is substantially rectangular in plan view. A ground conductor 2, which is also substantially rectangular, is provided on the dielectric substrate 1. The dielectric substrate 1 and the ground conductor 2 form a printed circuit board, but for the sake of simplicity, the present specification will treat the ground conductor 2 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. The dielectric substrate 1 may be made of, for example, 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 this 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 also be formed from sheet metal, metal wire, or the like.

[0016] A feed point 6 of the first antenna 3 is provided between the first antenna 3 and the ground conductor 2. A feed point 7 of the second antenna 4 is provided between the second antenna 4 and the ground conductor 2. A feed point 8 of the third antenna 5 is provided 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] Here, on the paper surface of Figure 1, the x-axis is taken horizontally, the y-axis is taken vertically, and the z-axis is taken depthwise, and the right direction is defined as the "+x direction," the left direction as the "-x direction," the up direction as the "+y direction," and the down direction as the "-y direction."

[0018] The first antenna 3 is provided along the first side 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 portion of the first antenna 3 branches into two and extends from the branch point in the -y direction along the first side of the dielectric substrate 1, while the other portion is shorted to the ground conductor 2. This allows the first antenna 3 to function as an inverted F antenna, making it easy to perform impedance matching. It is not essential to provide the first antenna 3 with a short-circuit portion (the portion shorted to the ground conductor 2).

[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 portion,” and the portion extending in the −y direction from the branch point is sometimes referred to as the “horizontal portion.”

[0020] The second antenna 4 is disposed along a second side adjacent to the first side of the dielectric substrate 1, 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 a first branching point. One portion of the second antenna 4 branched at the first branching point extends in the +x direction along the second side of the dielectric substrate 1, and the other portion further extends in the +y direction. The portion of the second antenna 4 extending in the +y direction from the first branching point further branches into two at a second branching point. One portion of the second antenna 4 branched at the second branching point extends in the +x direction along the second side of the dielectric substrate 1, and the other portion is short-circuited to the ground conductor 2. This allows the second antenna 4 to function as a multi-band inverted-F antenna, facilitating impedance matching. 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 branch point or the second branch point is sometimes referred to as the "horizontal portion."

[0022] The third antenna 5 is provided along a third side of the dielectric substrate 1 that faces the first side. Specifically, the third antenna 5 extends from the feed point 8 in the +x direction, bends midway, and extends from the bend in the -y direction along the third side of the dielectric substrate 1. This allows the third antenna 5 to operate as an inverted L antenna. Note that the third antenna 5 may also be provided with a short-circuit portion, 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 multi-band so as to correspond to the operating frequency of the first antenna 3 and the operating frequency of the third antenna 5. That is, the operating frequency of the first antenna 3 is f １ , the operating frequency of the third antenna 5 is f ２ Then, the operating frequency of the second antenna 4 is f１ and f ２ is.

[0025] The first antenna 3 operates at an operating frequency f １ That is, in the first antenna 3, the length from the base end of the vertical part through the branch point to the tip (open end) of the horizontal part is equal to ¼ of the wavelength corresponding to the operating frequency f １ The wavelength is 1 / 4 of the wavelength corresponding to the

[0026] The second antenna 4 is connected to the two operating frequencies f １ and f ２ That is, in the second antenna 4, one of the length from the base end of the vertical portion to the tip (open end) of the horizontal portion extending from the first branch point and the length from the base end of the vertical portion to the tip (open end) of the horizontal portion extending from the second branch point has a total length corresponding to ¼ of the wavelength of the operating frequency f １ The other is the length of a quarter of the wavelength corresponding to the operating frequency f ２ The wavelength is 1 / 4 of the wavelength corresponding to the

[0027] The third antenna 5 operates at an operating frequency f ２ That is, in the third antenna 5, the length from the base end of the vertical portion through the bending point to the tip (open end) of the horizontal portion is equal to the operating frequency f of the third antenna 5. ２ The wavelength is 1 / 4 of the wavelength corresponding to the

[0028] It should be noted that the term "quarter wavelength length" as used in this specification does not mean only a value that is strictly equal to the quarter wavelength length, but also includes an allowable range in both positive and negative directions based on the quarter wavelength length.

[0029] 1 , the open end of the first antenna 3 faces away from the second side of the dielectric substrate 1 on which the second antenna 4 is provided. The open end of the second antenna 4 faces away from the first side of the dielectric substrate 1 on which the first antenna 3 is provided. The open end of the third antenna 5 faces away from the second side of the dielectric substrate 1 on which the second antenna 4 is provided.

[0030] FIG. 2 is a diagram showing the results of calculations performed by electromagnetic field simulation on the change in correlation between two antennas when the arrangement (position and orientation) of the antennas is changed.

[0031] As shown in Figure 2(a), when two antennas are arranged orthogonally on adjacent sides of a dielectric substrate, with the open end of one antenna facing away from the side on which the other antenna is provided and the open end of the other antenna facing away from the side on which the first antenna is provided, the correlation between the antennas is set to 1, and this is 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 facing toward the side on which the other antenna is provided and the open end of the other antenna facing away from the side on which the first antenna is provided, the correlation between the antennas is 10 (i.e., 10 times that in the case 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 facing in a direction approaching the side on which the other antenna is provided, and the open end of the other antenna facing in a direction approaching the side on which the first antenna is provided, the correlation between the antennas is 32 (i.e., 32 times that in the case of Figure 2(a)).

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

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

[0036] From the results of Figures 2(a) to 2(c), it can be seen that when two antennas are arranged orthogonally on adjacent sides of a dielectric substrate, the arrangement of Figure 2(a) can best suppress the correlation between the antennas. Also, it can be seen that the arrangement of Figure 2(b) can also suppress the correlation between the antennas to a low level, although not as low as the arrangement of Figure 2(a).

[0037] Furthermore, from the results of Figures 2(d) and (e), it can be seen that when two antennas are arranged parallel to opposite sides of a dielectric substrate, the correlation between the antennas is lower in the arrangement of Figure 2(d) than in the arrangement of Figure 2(e).

[0038] In the wireless communication device according to the first embodiment, the first antenna 3 and the second antenna 4 are arranged as shown in FIG. 2A. This reduces the correlation between the first antenna 3 and the second antenna 4, and the first antenna 3 and the second antenna 4 are separated by a frequency f １ The second antenna 4 and the third antenna 5 are arranged as shown in FIG. 2B. This 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 the frequency f ２ It operates as a diversity antenna in

[0039] In this way, the second antenna 4 is multi-band, which allows the wireless communication device to be miniaturized and also provides a diversity function that supports two wireless communication methods with different operating frequencies.

[0040] Operating frequency f １ and f ２ can be any frequency, but f １ <f ２2A and 2B, in the wireless communication device according to the first embodiment, the correlation between the first antenna 3 and the second antenna 4 is easier to lower than the correlation between the second antenna 4 and the third antenna 5. Normally, it is more difficult to increase the electrical distance between antennas operating at low frequencies (high wavelengths) than between antennas operating at high frequencies (shorter wavelengths). Therefore, it is more difficult to lower the correlation between antennas operating at low frequencies than between antennas operating at high frequencies. Therefore, the operating frequency f assigned to the second antenna 4 and the third antenna 5, which is difficult to lower the correlation between, is set to 0. ２ The operating frequency f is assigned to the first antenna 3 and the second antenna 4, which is easy to lower the correlation. １ By making it higher than , it becomes easier to lower the correlation between the second antenna 4 and the third antenna 5, and it is possible to lower 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.

[0041] In the first embodiment, 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 these. As long as the above-described functions and effects can be obtained, antennas of other shapes, such as meander antennas and folded monopole antennas, may be used.

[0042] The lowest operating frequency supported by the wireless communication device is f １ and the operating frequency f １ The wavelength of λ １ Then, the size of the rectangular dielectric substrate 1 is 0.25λ １ ×0.25λ １ However, it is assumed that ±0.1λ １ Some degree of variation is acceptable.

[0043] The operation of the wireless communication device according to the first embodiment 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 a 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 into space from the first antenna 3. 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, according to the wireless communication device of the first embodiment, two frequencies (f １ and f ２ ) can be configured, thereby achieving high communication quality.

[0047] [Modification] Fig. 3 is a diagram showing a modification of the wireless communication device according to embodiment 1. The configuration in Fig. 3 is different from the configuration in Fig. 1 in that a parasitic antenna shorted to the ground conductor 2 and an antenna element branched from the first antenna 3 are added to the first antenna 3, and a parasitic antenna shorted to the ground conductor 2 is added to the second antenna 4.

[0048] The wireless communication device of FIG. １ and f ２ In addition, the operating frequency f ３ That is, the first antenna 3 can correspond to the operating frequency f １ In addition, the operating frequency f ３ and the second antenna 4 can correspond to an operating frequency f １ and f ２ In addition, the operating frequency f ３ It can respond to.

[0049] Operating frequency f １ , f ２ and f ３ can be any frequency, but f１ <f ２ <f ３ It is preferable that the following relationship is satisfied. Since the correlation between antennas tends to be higher as the operating frequencies are closer, the frequency f １ and f ３ This is because by increasing the difference between the first antenna 3 and the second antenna 4, the correlation between the first antenna 3 and the second antenna 4 is suppressed.

[0050] In this modification, the first antenna 3 has two operating frequencies f １ and f ３ That is, in the first antenna 3, one of the total length of the length from the base end of the vertical section to the tip of the horizontal section extending from the first branch point and the length of the parasitic antenna added to the first antenna 3 (the length from the base end of the vertical section through the bending point to the tip of the horizontal section) and the length from the base end of the vertical section to the tip of the horizontal section extending from the second branch point is set to be ¼ of the wavelength corresponding to the operating frequency f １ The other is the length of a quarter of the wavelength corresponding to the operating frequency f ３ The wavelength is 1 / 4 of the wavelength corresponding to the

[0051] The second antenna 4 is connected to the three operating frequencies f １ , f ２ and f ３ That is, in the second antenna 4, one 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 from the base end of the vertical portion to the tip of the horizontal portion extending from the second branch point has a total length corresponding to ¼ of the wavelength corresponding to the operating frequency f １ The other is the length of a quarter of the wavelength corresponding to the operating frequency f ２ The length of the parasitic antenna added to the second antenna 4 (the length from the base end of the vertical part through the bending point to the tip of the horizontal part) is ¼ of the wavelength corresponding to the operating frequency f ３ The wavelength is 1 / 4 of the wavelength corresponding to the

[0052] The third antenna 5 has an operating frequency f ２ That is, in the third antenna 5, the length from the base end of the vertical part through the bending point to the tip of the horizontal part is equal to the operating frequency f ２ The wavelength is 1 / 4 of the wavelength corresponding to the

[0053] 3, in this modification as well, the open end of the first antenna 3 faces away from the second side of the dielectric substrate 1 on which the second antenna 4 is provided. The open end of the second antenna 4 faces away from the first side of the dielectric substrate 1 on which the first antenna 3 is provided. The open end of the third antenna 5 faces away from the second side of the dielectric substrate 1 on which the second antenna 4 is provided. This reduces the correlation between the first antenna 3 and the second antenna 4, and the first antenna 3 and the second antenna 4 can be connected to each other at the frequency f １ and f ３ The second antenna 4 and the third antenna 5 operate as a diversity antenna at a frequency f ２ It operates as a diversity antenna in

[0054] 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 FIG. 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] 3, the tip of the parasitic antenna added to the first antenna 3 faces in a direction approaching the second side of the dielectric substrate 1 on which the second antenna 4 is provided, and the tip of the parasitic antenna added to the second antenna 4 faces in a direction approaching the first side of the dielectric substrate 1 on which the first antenna 3 is provided. This is to couple the parasitic antenna with the powered antenna.

[0056] If the orientations of these two parasitic antennas are reversed, the correlation between the first antenna 3 and the second antenna 4 can be further reduced. However, it should be noted that there is a risk that the powered antenna and the parasitic antenna will not be coupled. Conversely, the orientations of the two parasitic antennas may be opposite to that shown in Figure 3, as long as coupling between the powered antenna and the parasitic antenna can be ensured.

[0057] According to the wireless communication device of this modification, three low-correlation antennas are used to transmit three frequencies (f １ , f ２ and f ３ It is possible to configure diversity corresponding to the above three conditions, thereby achieving high communication quality.

[0058] <Embodiment 2> A 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 correspond to elements described in embodiment 1 are given the same reference numerals, and therefore redundant description of those elements will be omitted.

[0059] 4 is a diagram showing the configuration of a wireless communication device according to embodiment 2. The configurations of the dielectric substrate 1, the ground conductor 2, the first antenna 3, the second antenna 4, and the third antenna 5 are the same as those in FIG.

[0060] As shown in Fig. 4, the second antenna 4 is connected to a transmission line 9b provided on a dielectric substrate 1. The transmission line 9b branches into two at some midpoint and is connected to a first transmitter / receiver module 10 and a second transmitter / receiver module 11. However, a phase-adjustable phase shifter 12a is inserted between the branch point of the transmission line 9b and the first transmitter / receiver module 10, and a phase-adjustable phase shifter 12b is inserted between the branch point of the transmission line 9b and the second transmitter / receiver module 11. The first transmitter / receiver module 10 receives a signal at a frequency f １ and the second transceiver module 11 corresponds to frequency f ２ The first transmitting / receiving module 10 and the second transmitting / receiving module 11 have the function of converting information to be transmitted into a high frequency signal and the function of extracting received information from the high frequency signal.

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

[0062] FIG. 5 is a diagram showing a circuit configuration of a wireless communication device according to the second embodiment.

[0063] The second antenna 4 receives two frequencies (f １ and f ２ ). Therefore, if the transmission line 9b is directly connected to the first transceiver module 10 and the second transceiver module 11, there is a concern that the reflection characteristics may be significantly degraded depending on the reflection phase of the impedance of the first transceiver module 10 as viewed from the branch point of the transmission line 9b, or the reflection phase of the impedance of the second transceiver module 11 as viewed from the branch point of the transmission line 9b. It is desirable that these reflection phases be close to zero.

[0064] Therefore, in the second embodiment, a phase shifter 12a is inserted between the branch point of the transmission line 9b and the first transmitting / receiving module 10, and the reflection phase of the impedance when the first transmitting / receiving module 10 is viewed from the branch point of the transmission line 9b is adjusted to the operating frequency f ２ The phase shift amount of the phase shifter 12a is determined so that the impedance when the first transmitting / receiving module 10 is viewed from the branch point of the transmission line 9b becomes zero at the frequency f ２ , and reflection from the first transceiver module 10 can be eliminated.

[0065] Furthermore, a phase shifter 12b is inserted between the branch point of the transmission line 9b and the second transmitting / receiving module 11, and the reflection phase of the impedance when the second transmitting / receiving module 11 is viewed from the branch point of the transmission line 9b is set to be equal to or smaller than the operating frequency f １ The amount of phase shift of the phase shifter 12b is determined so that it becomes zero at frequency f. As a result, the impedance of the second transmitting / receiving module 11 as seen from the branch point of the transmission line 9b becomes １ , and the reflection from the second transceiver module 11 can be eliminated.

[0066] The phase shifters 12a and 12b may be either distributed constant lines or lumped constant 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 branch point of the transmission line 9b connected to the multi-band compatible second antenna 4 to the transceiver module (first transceiver module 10 or second transceiver module 11) appears open outside the band, an effect similar to that of a diplexer that separates frequencies can be achieved.

[0068] According to the wireless communication device of the second embodiment, two frequencies (f １ and f ２ ) is configured on the dielectric substrate 1, the first transmitting / receiving module 10 and the second transmitting / receiving module 11 can share the same antenna with low loss.

[0069] [Modification 1] FIG. 6 is a diagram showing a circuit configuration of Modification 1 of the wireless communication device according to the second embodiment.

[0070] The configuration of Figure 6 differs from the configuration of Figure 5 in that a bandpass filter 13a is inserted between the phase shifter 12a and the first transceiver module 10, and a bandpass filter 13b is inserted between the phase shifter 12b and the second transceiver module 11.

[0071] According to this modification, the frequency f ２ The reflection amplitude when looking at the phase shifter 12a side from the branch point of the transmission line 9b and the frequency f １ and the reflection amplitude when looking at the phase shifter 12b side from the branch point of the transmission line 9b, respectively, can be increased, and the influence of the reflected wave outside the band can be further reduced.

[0072] [Modification 2] FIG. 7 is a diagram showing a circuit configuration of Modification 2 of the wireless communication device according to the second embodiment.

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

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

[0075] [Modification 3] In Modification 3, three operating frequencies (f １ , f ２ and f ３ 8 is a diagram showing a third modification of the wireless communication device according to the second embodiment.

[0076] Even when the wireless communication device has three operating frequencies, the antenna circuit configuration can be the same as that shown in FIG. 3. However, the first transceiver module 10 shown in FIG. 8 operates at the frequency f １ and f ３ The reflection phase of the impedance when the second transceiver module 11 is viewed from the branch point of the transmission line 9b is equal to the frequency f １ and f ３ By determining the phase shift amount of the phase shifter 12b so that the reflection from the second transceiver module 11 is zero at

[0077] <Embodiment 3> Fig. 9 is a diagram showing the configuration of a wireless communication device according to embodiment 3. In Fig. 9, elements that are the same as or correspond to elements described in embodiments 1 and 2 are given the same reference numerals, and therefore redundant description of those elements will be omitted.

[0078] In the first embodiment, the lowest frequency f １Since the first antenna 3 and the second antenna 4 operate at a frequency where it is difficult to reduce the correlation, the arrangement of the first antenna 3 and the second antenna 4 was changed to the arrangement of Fig. 2(a) which makes it easier to reduce the correlation, and therefore the arrangement of the second antenna 4 and the third antenna 5 was changed to the arrangement of Fig. 2(b). However, it would be ideal if the correlation between the second antenna 4 and the third antenna 5 could also be reduced to the same extent as in the arrangement of Fig. 2(a).

[0079] Therefore, in the third embodiment, in order to reduce the correlation between the second antenna 4 and the third antenna 5, a frequency f ２ A decoupling circuit 15 is inserted to reduce coupling between the second antenna 4 and the third antenna 5. Examples of the decoupling circuit 15 are shown in FIGS.

[0080] 10 shows an example of a decoupling circuit 15 with a matching circuit function corresponding to one frequency. When this decoupling circuit 15 is used, the frequency f ２ The phase shift amounts of the phase shifters 12c and 12d are adjusted so that the real parts of the admittances Y32 of the second antenna 4 and the third antenna 5 become zero at frequency f ２ Inductor L constituting the decoupling circuit 15 is connected so that the imaginary part of admittance Y32 becomes zero at １ At this time, the value of the capacitor C １ The value of can be calculated using the following formula:

[0081]

[0082] However, when the decoupling circuit 15 of FIG. 10 is applied to the wireless communication device of FIG. 8, the frequency f ２ The correlation between the second antenna 4 and the third antenna 5 at frequency f ２ Frequency f away from ３ The impedance matching is significantly degraded.

[0083] The wireless communication device shown in Fig. 8 requires a decoupling circuit 15 that supports two frequencies. Fig. 11 is a diagram showing the configuration of a decoupling circuit with a matching circuit function that supports two frequencies using a parallel resonant circuit.

[0084] In the decoupling circuit 15 of FIG. ２ Then, the decoupling circuit 15 is connected to the inductor L １ appears to be at frequency f ３ Now, let us consider the inductor L of the parallel resonant circuit so that the decoupling circuit 15 appears electrically open. ｐ and capacitor C ｐ At this time, the value of the inductor L ｐ and capacitor C ｐ The value of can be calculated from the following formula:

[0085]

[0086]

[0087]

[0088] The decoupling circuit 15 of FIG. ２ While reducing the correlation between the second antenna 4 and the third antenna 5 at frequency f ３ Therefore, the impedance matching of the second antenna 4 can be maintained.

[0089] Furthermore, as shown in Figure 9, by providing matching circuits 14d and 14e in the subsequent stage of the decoupling circuit 15 (on the first transceiver module 10 or second transceiver module 11 side), it is possible to adjust even if a slight deviation occurs in the impedance matching.

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

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

[0092] According to the fourth embodiment, in order to reduce the coupling between the antennas and lower the correlation, a decoupling circuit 15 consisting of an inductor and a capacitor is inserted between the antennas, thereby realizing a low-correlation diversity antenna while maintaining a small size of the wireless communication device.

[0093] <Fourth Embodiment> Fig. 12 is a diagram showing the configuration of a wireless communication device according to a fourth embodiment. In Fig. 12, elements that are the same as or correspond to elements described in the first to third embodiments are given the same reference numerals, and therefore redundant description thereof will be omitted.

[0094] The wireless communication device of FIG. 12 is obtained by adding a fourth antenna 16 and its feed point 18, a fifth antenna 17 and its feed point 19, and a third transceiver module 20 to the configuration of FIG.

[0095] The fourth antenna 16 and the fifth antenna 17 are formed on the dielectric substrate 1, and are disposed at diagonal positions viewed from the corner between the first side of the dielectric substrate 1 on which the first antenna 3 is disposed and the second side of the dielectric substrate 1 on which the second antenna 4 is disposed. The fourth antenna 16 is provided along the third side on which the third antenna 5 is disposed, 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 formed on the dielectric substrate 1, but they may also be formed from sheet metal, metal wire, etc.

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

[0098] The fourth antenna 16 and the fifth antenna 17 operate at the same frequency f ４ The third transceiver module 20 transmits the fourth antenna 16 and the fifth antenna 17 at the operating frequency f ４The fourth antenna 16 is connected to the third transceiver module 20 via a transmission line 9d, and the fifth antenna 17 is connected to the third transceiver module 20 via a transmission line 9e.

[0099] The shape of the fourth antenna 16 will be specifically described. The fourth antenna 16 extends from the feed point 18 in the +x direction, bends midway, and extends from the bend in the +y direction along the third side of the dielectric substrate 1. This allows the fourth antenna 16 to function as an inverted L antenna. Note that the fourth antenna 16 may also be provided with a short circuit portion, similar to the first antenna 3 and the second antenna 4.

[0100] The shape of the fifth antenna 17 will be specifically described. The fifth antenna 17 is provided along the fourth side of the dielectric substrate 1 so as to be perpendicular to the fourth antenna 16. The fifth antenna 17 extends from the feed point 19 in the -y direction and branches into two branches along the way. One part of the branched fifth antenna 17 extends in the -x direction along the fourth side, and the other part extends in the +x direction and is then short-circuited to the ground conductor 2. This allows the fifth antenna 17 to function as an inverted-F antenna, making impedance matching easier. It is not essential to provide a short-circuit portion in the fifth antenna 17.

[0101] 12, a convex region is provided on a substantially rectangular dielectric substrate 1, and the fourth antenna 16 and the fifth antenna 17 are disposed on the convex region. However, it is not necessary to provide a convex region on the dielectric substrate 1. In other words, the fourth antenna 16 and the fifth antenna 17 may be disposed on a partial region of the dielectric substrate 1 while maintaining the substantially rectangular shape of the dielectric substrate 1.

[0102] The fourth antenna 16 and the fifth antenna 17 both operate at an operating frequency f ４ That is, in each of the fourth antenna 16 and the fifth antenna 17, the length from the base end of the vertical portion through the bending point to the open end of the horizontal portion is ¼ of the wavelength corresponding to the operating frequency f ４ The wavelength is 1 / 4 of the wavelength corresponding to the

[0103] The fourth antenna 16 and the fifth antenna 17 are arranged as shown in Fig. 2A. This reduces the correlation between the fourth antenna 16 and the fifth antenna 17, and the fourth antenna 16 and the fifth antenna 17 are connected to each other at a frequency f ４ It operates as a diversity antenna in

[0104] Operating frequency f １ , f ２ , f ３ and f ４ can be any frequency, but f １ <f ２ <f ３ <f ４ It is preferable that the relationship of the fourth antenna 16 and the fifth antenna 17 is satisfied. Although the fourth antenna 16 and the fifth antenna 17 are arranged close to each other, the operating frequency f ４ By increasing the value of , the electrical distance between the fourth antenna 16 and the fifth antenna 17 is ensured, and the correlation between the fourth antenna 16 and the fifth antenna 17 can be reduced.

[0105] The fourth antenna 16 and the fifth antenna 17 are disposed at diagonal positions when viewed from the corner between the first side of the dielectric substrate 1 on which the first antenna 3 is disposed and the second side of the dielectric substrate 1 on which the second antenna 4 is disposed. In other words, the fourth antenna 16 and the fifth antenna 17 are disposed at positions away from the first antenna 3 and the second antenna 4. The correlation between the antennas tends to be higher as the operating frequencies are closer, but f １ <f ２ <f ３ <f ４ If the relationship ４ a fourth antenna 16 and a fifth antenna 17 having an operating frequency of f ４ A frequency f relatively close to ３ The distance between the first antenna 3 and the second antenna 4, which have an operating frequency of 100 MHz, is secured, 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 reduced.

[0106] As described above, according to the wireless communication device of the fourth embodiment, four frequencies (f １ , f ２ , f ３ and f ４ ) can be configured, thereby achieving high communication quality.

[0107] <Embodiment 5> Fig. 13 is a diagram showing the configuration of a measurement system with wireless communication function according to embodiment 5. In Fig. 13, elements that are the same as or correspond to elements described in embodiments 1 to 4 are given the same reference numerals, and therefore redundant description of those elements will be omitted.

[0108] The measurement system according to the fifth embodiment 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 shown in Fig. 13 , and may be, for example, the wireless communication device shown in Fig. 3 , Fig. 4 , Fig. 8 , etc.

[0109] The measuring unit 21 measures data using a sensor and transmits the measured data to the outside by radio waves emitted from the wireless communication device. As shown in Fig. 13, the measuring unit 21 is disposed close to the lower side of the dielectric substrate 1 of the wireless communication device. Conversely, the wireless communication device is disposed on top of the measuring unit 21.

[0110] The connection cable 22 has a connector 23a at one end for connection to a wireless communication device and a connector 23b at the other end for connection to the measurement unit 21. The connector 23a of the connection cable 22 is connected to the ground conductor 2 on the fourth side of the dielectric substrate 1 (the bottom side of the dielectric substrate 1 in FIG. 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 measuring unit 21 is sent to the wireless communication device via the connection cable 22 and transmitted to the communication partner by radio waves emitted from the wireless communication device. The measuring unit 21 may transmit not only the measured data but also the ID of the measuring unit 21 and information on the measurement time of the sensor data to the communication partner via the wireless communication device.

[0112] If a high-frequency signal flows on the surface of the connection cable 22, which is made of a conductor, the connection cable 22 may act as an antenna, radiating unwanted radio waves, which may affect the antenna characteristics of the wireless communication device. Therefore, it is desirable to avoid placing the connection cable 22 near the antenna and the feed point, where current is concentrated. In the measurement system according to the fifth embodiment, the connector 23 a of the connection cable 22 is mounted in a space on the fourth side of the dielectric substrate 1 where no antenna is located, thereby preventing the connection cable 22 from being placed near the antenna and the feed point. This prevents a decrease in antenna efficiency, resulting in a measurement system with wireless communication capabilities and a highly efficient diversity antenna.

[0113] It is possible to freely combine the embodiments, and to modify or omit the embodiments as appropriate.

[0114] The above description is illustrative in all respects, and it is understood that countless variations not illustrated can be envisioned.

[0115] 1 dielectric substrate, 2 ground conductor, 3 first antenna, 4 second antenna, 5 third antenna, 6 to 8, 18, 19 feed point, 9a to 9f transmission line, 10 first transmitting / receiving module, 11 second transmitting / receiving module, 12a to 12d phase shifter, 13a, 13b bandpass filter, 14a to 14e matching circuit, 15 decoupling circuit, 16 fourth antenna, 17 fifth antenna, 20 third transmitting / receiving module, 21 measurement unit, 22 connection cable, 23a, 23b connector.

Claims

1. A dielectric substrate; a ground conductor provided on the dielectric substrate; a first antenna provided on the dielectric substrate along a first side of the dielectric substrate; a second antenna provided on the dielectric substrate along a second side adjacent to the first side of the dielectric substrate; a third antenna provided on the dielectric substrate along a third side of the dielectric substrate opposite to the first side; Equipped with an open end of the first antenna facing away from the second side; an open end of the second antenna facing away from the first side; an open end of the third antenna facing away from the second side; the first antenna responds to a first frequency; the third antenna corresponds to a 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 of claim 1 .

3. the second antenna is connected to a transmission line provided on the ground conductor, the transmission line has a branch point at which it branches into a line connected to a first transceiver module corresponding to the first frequency and a line connected to a second transceiver module corresponding to the second frequency; a first phase shifter that is provided between the branch point and the first transceiver module and is capable of adjusting a phase; a second phase shifter that is provided between the branch point and the second transceiver module and is capable of adjusting a phase; Equipped with The wireless communication device of claim 1 .

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

5. The first frequency is f １ , the second frequency is f ２ , the third frequency is f ３ Then, f １ <f ２ <f ３ The relationship is satisfied, 5. 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 branch point at which the transmission line branches into a line connected to a first transceiver module corresponding to the first frequency and the third frequency, and a line connected to a second transceiver module corresponding to the second frequency; a first phase shifter that is provided between the branch point and the first transceiver module and is capable of adjusting a phase; a second phase shifter that is provided between the branch point and the second transceiver module and is capable of adjusting a phase; Equipped with 6. The wireless communication device according to claim 4 or 5.

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

8. A dielectric substrate; a ground conductor provided on the dielectric substrate; a first antenna provided on the dielectric substrate along a first side of the dielectric substrate; a second antenna provided on the dielectric substrate along a second side adjacent to the first side of the dielectric substrate; a third antenna provided on the dielectric substrate along a third side of the dielectric substrate opposite to the first side; a fourth antenna disposed at a diagonal position viewed from a corner between the first side and the second side on the dielectric substrate and provided along the third side; a fifth antenna disposed at a diagonal position viewed from a corner between the first side and the second side on the dielectric substrate and provided along a fourth side of the dielectric substrate opposite the second side; Equipped with the first antenna responds to a first frequency; the third antenna corresponds to a second frequency; the second antenna corresponds to the first frequency and the second frequency; the fourth antenna and the fifth antenna both correspond to a fourth frequency; When the first frequency is f 1 , the second frequency is f 2 , and the fourth frequency is f 4 , the relationship f 1 < f 2 < f 4 is satisfied. Wireless communication device.

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

10. A wireless communication device according to any one of claims 1 to 5 and claims 8 to 9; a measurement unit that measures data transmitted to the outside by radio waves emitted from the wireless communication device using a sensor; a connection cable that connects the wireless communication device and the measurement unit; the wireless communication device is disposed over the measurement unit, one end of the connection cable is connected to the measurement unit, and the other end is connected to the ground conductor of the wireless communication device; Measurement system with wireless communication function.