Wireless communication circuit, antenna module, and industrial remote controller
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-05
- Publication Date
- 2026-08-13
Smart Images
Figure JP2026004171_13082026_PF_FP_ABST
Abstract
Description
Wireless communication circuit, antenna module, and industrial remote controller
[0001] The present disclosure relates to a wireless communication circuit compatible with a plurality of frequency bands, an antenna module equipped with the wireless communication circuit, and an industrial remote controller including the antenna module.
[0002] In Japan, specific low-power radio that can be used without a license or qualification is widely used for remote control of industrial equipment, cranes, conveyors, etc. (for example, Patent Document 1). Specific low-power radio has frequency bands and technical standards defined according to the application, and is operated based on, for example, the specific low-power radio standard defined by the Association of Radio Industries and Businesses (ARIB).
[0003] Specific low-power radio communication is wireless communication that performs transmission with an output limited to the milliwatt level (for example, 10 mW or less, 20 mW or less, 1 mW or less, etc.) in a predetermined frequency band defined by a specific specific low-power radio standard (STD-T93 (315 MHz band), STD-T67 (400 MHz band and 1200 MHz band), STD-T108 (920 MHz band), STD-92 (433 MHz band), STD-30 (426 MHz band), etc.). Due to this low-output limitation, specific low-power radio communication is generally used for short-distance communication (although strongly dependent on environmental and antenna conditions, with a rough guide of several tens of meters to several hundreds of meters). Another prior art related to specific low-power radio communication is Patent Document 2.
[0004] Japanese Patent Application Laid-Open No. 2019-064817, Japanese Patent Application Laid-Open No. 10-2715{{71}}
[0005] Conventional communication systems or devices used for specific low-power radio communication communicate in one frequency band (for example, the 400 MHz band) defined by the standard based on a specific communication standard (for example, STD-T67). For this reason, wireless communication circuits and antennas corresponding to each communication standard have been designed and manufactured.
[0006] Furthermore, in specified low-power radio standards, multiple communication channels are defined within the frequency band used for communication, and the communication channel used is switched or changed based on the communication status. For example, in specified low-power radio communication, if there is interference or jamming, the communication channel is switched within the frequency band corresponding to that communication standard. However, if all communication channels are in use, such switching cannot be performed. Moreover, in specified low-power radio communication, there is always a risk of interference occurring between adjacent communication channels.
[0007] This disclosure is made in view of the above circumstances and aims to provide a wireless communication circuit suitable for wireless communication in multiple frequency bands included in the ISM band or the range of several hundred MHz to several GHz, and is used for selectively performing wireless communication in any of the frequency bands of said multiple frequency bands.
[0008] Another objective of this disclosure is to provide an industrial remote controller that allows for flexible selection of the frequency band used for communication, in order to reduce problems caused by interference and other issues in environments where a large number of remote controllers are used, such as within a factory.
[0009] The wireless communication circuit of this disclosure is a wireless communication circuit that performs wireless communication in any of a plurality of frequency bands, comprising: a loop antenna; a plurality of antenna circuits corresponding to each of the plurality of frequency bands; a first high-frequency switch for selectively connecting any of the plurality of antenna circuits to the loop antenna; and a second high-frequency switch for selectively connecting any of the plurality of antenna circuits to a subsequent circuit, wherein each of the plurality of antenna circuits has a first terminal connected to the first high-frequency switch and a second terminal connected to the second high-frequency switch, and the equivalent electrical lengths between the first terminal and the second terminal are set to be different from each other according to the frequency band each corresponds to.
[0010] In the wireless communication circuit of this disclosure, the first high-frequency switch and the second high-frequency switch may be switched in conjunction with each other so that the same antenna circuit is connected to the loop antenna and the subsequent circuit.
[0011] In the wireless communication circuit of this disclosure, the equivalent electrical length may be determined based on the phase delay amount or group delay in the transmission characteristics from the first terminal to the second terminal.
[0012] In the wireless communication circuit of this disclosure, the antenna circuit may include: a first capacitor and a first coil interposed in series between a first terminal and a second terminal, one of which is an input terminal and the other is an output terminal; a second capacitor with one end grounded and the other end connected to the first terminal; a third capacitor with one end connected to a common connection point between the first capacitor and the first coil and the other end grounded; a second coil with one end connected to the common connection point and the other end grounded; and a third coil with one end connected to the second terminal and the other end grounded.
[0013] In the wireless communication circuit of this disclosure, the plurality of antenna circuits may include at least a first antenna circuit corresponding to the 1200 MHz band, a second antenna circuit corresponding to the 920 MHz band, the 915 MHz band and the 868 MHz band, a third antenna circuit corresponding to the 433 MHz band, the 429 MHz band and the 426 MHz band, and a fourth antenna circuit corresponding to the 315 MHz band and a frequency band lower than 315 MHz.
[0014] The antenna module of the present disclosure is an antenna module comprising a wireless communication circuit of the present disclosure, comprising: a substrate; an RF shield portion provided on one main surface of the substrate and housing at least a part of the wireless communication circuit; and the loop antenna provided on the substrate and disposed outside the RF shield portion, wherein the substrate may have wiring patterns that electrically connect the circuit elements in the RF shield portion and components such as operating portions disposed in other areas of the substrate.
[0015] The industrial remote controller of this disclosure is an industrial remote controller that performs wireless communication in any of a plurality of frequency bands, and comprises: an operating unit; a control unit that generates a control signal in response to the operation of the operating unit; a transmitting unit that wirelessly transmits the control signal; and a receiving unit that wirelessly receives a received signal, and a wireless communication unit having the antenna module of this disclosure, wherein each of the plurality of frequency bands may be an ISM band or may be included in the ISM band.
[0016] In the industrial remote controller of this disclosure, the control unit may detect interference based on a communication error, carrier sense result, or received signal strength, and may change the operating frequency band by switching the first high-frequency switch and the second high-frequency switch when interference is detected.
[0017] The wireless communication circuit of this disclosure includes multiple antenna circuits (hereinafter also referred to as tuning circuits or resonant circuits) used for tuning a single loop antenna, and these antenna circuits are provided for each frequency band and operate selectively. Therefore, according to this disclosure, it is possible to provide a wireless communication circuit that can handle multiple frequency bands included in the ISM band or the range of several hundred MHz to several GHz, and consequently, an antenna module and an industrial remote controller.
[0018] Furthermore, according to this disclosure, by enabling the selection of multiple frequency bands, it becomes possible to switch to a less congested band / channel even in environments where interference is a concern, thereby contributing to the reduction of interference problems.
[0019] In this disclosure, the plurality of antenna circuits are configured such that the equivalent electrical lengths between the first terminal on the first high-frequency switch side (e.g., terminal T1 in Figure 4) and the second terminal on the second high-frequency switch side (e.g., terminal T2 in Figure 4) are different, depending on the corresponding frequency band. For example, the equivalent electrical length is defined as the electrical length of a transmission line that gives the same phase delay amount (phase shift amount) based on the phase delay amount (phase shift amount) of the transmission characteristics (e.g., S21) between the first terminal and the second terminal.
[0020] This disclosure uses a loop antenna (magnetic field antenna), more specifically a miniature loop antenna. Since loop antennas primarily utilize the magnetic field component for transmission and reception, they are more susceptible to characteristic variations (such as fluctuations in resonant frequency, deterioration of matching, and disturbances in directivity) caused by the presence of surrounding metal objects or their placement within the enclosure, compared to antennas that primarily utilize the electric field component.
[0021] In industrial facilities, metal structures such as cranes, conveying equipment, and machine frames are often located near wireless communication circuits or industrial remote controllers that utilize them. Furthermore, electromagnetic noise is easily generated by peripheral equipment such as inverters, motors, relays, and switching power supplies. From the perspective of ensuring a stable wireless link under these environmental factors, loop antennas are suitable for wireless communication circuits that communicate in multiple frequency bands, including the ISM band or the range of several hundred MHz to several GHz.
[0022] Since a loop antenna behaves as a coil (inductance) when its circumference is shorter than its wavelength, it is desirable to tune (resonate) it using an external capacitor or the like. The aforementioned multiple antenna circuits can function as tuning circuits to resonate the loop antenna in a desired frequency band.
[0023] An example of an industrial remote control system to which this disclosure can be applied is shown. This is a perspective view of an antenna module constituting a remote controller. This is a diagram showing an example configuration of a radio station including a wireless communication circuit according to one embodiment of this disclosure. This is a diagram showing an example configuration of an antenna circuit (tuning circuit) included in the wireless communication circuit.
[0024] The embodiments described below are subject to various technically preferred limitations. However, this disclosure is not limited to the embodiments described below.
[0025] In this specification, "electrical length" or "equivalent electrical length" in relation to circuit configurations such as antenna circuits refers to the equivalent electrical length defined not as the physical length of the transmission path from a specific point (first point) to another specific point (second point) in a high-frequency circuit, but based on the phase delay or group delay in the transmission characteristics from the first point to the second point. Not limited to distributed constant lines, even for circuit networks including lumped constant elements such as coils and capacitors, the equivalent electrical length can be determined as the electrical length of an ideal transmission line that gives the same phase delay or group delay, based on the phase φ(ω) (ω: angular frequency of the signal) of the scattering parameter, so-called S-parameter (e.g., S21: forward transmission coefficient), from the first point to the second point on the circuit network, or based on the phase delay at the reference frequency (e.g., the center frequency of the target band) or the group delay evaluated within the target band. The equivalent electrical length may be calculated by setting the measurement target to the first and second points (e.g., the first terminal T1 and the second terminal T2 in Figure 4, or corresponding measurement points) and measuring the S-parameter with a vector network analyzer or the like. Furthermore, the evaluation range for equivalent electrical length is not limited to the tuning circuit alone, but may be set as a system including a loop antenna and / or a high-frequency switch.
[0026] The present disclosure will be described below with reference to the figures. Figure 1 shows an example of an industrial remote control system to which the present disclosure can be applied. Gantry cranes 5a and 5b are installed in the factory, and each gantry crane 5a and 5b is remotely controlled by corresponding remote controllers 1a and 1b, respectively. Gantry crane 5a includes legs 51, wheels 52 for traveling along rails 7, a lifting mechanism 53, a trolley 54, lifting equipment 55 such as hooks, and a control unit 56. The control unit 56 includes a receiver, a transmitter, a control circuit and an antenna 56a, and communicates wirelessly with the remote controller 1a via the antenna 56a, controlling gantry crane 5a in accordance with the operation of the remote controller 1a. Gantry crane 5b is configured similarly and is remotely controlled by the remote controller 1b.
[0027] Remote controllers 1a and 1b are examples of industrial remote controllers in this disclosure. In this disclosure, an industrial remote controller is a wireless device used for operation in factories, plants, warehouses, construction sites, power generation and transmission / distribution facilities, water and sewage facilities, transportation infrastructure and other business facilities and infrastructure (hereinafter referred to as "industrial facilities, etc.") and for the purpose of operation, monitoring, maintenance, inspection, control, or information management related thereto, and is equipped with at least wireless communication capabilities and transmits and receives data with external devices (e.g., control devices, sensors, actuators, higher-level systems, mobile terminals, other wireless devices).
[0028] Communication between the remote controller 1a and the control unit 56 of the gantry crane 5a can be performed, for example, based on the specified low-power radio standard described above. The specified low-power radio standard includes standards for multiple bands, such as the 315 MHz band, 429 MHz band, 920 MHz band, and 1200 MHz band, which can be selected according to the application and operating environment. Within the factory, there may be gantry cranes (not shown in the illustration) and other remote controllers for remotely controlling those gantry cranes. Conventionally, when operation relied on a specific frequency band, there was a risk of interference problems occurring due to the proximity of these cranes and controllers operating. However, by using the multi-frequency compatible industrial remote controllers (remote controllers 1a, 1b) according to this disclosure, it is possible to switch to a band / channel with less interference, and a reduction in interference problems can be expected.
[0029] Although not shown in detail in Figure 1, each of the remote controllers 1a and 1b includes an operation unit that receives user input and is equipped with various operation buttons, a control unit that generates control signals in response to the operation of the operation unit, and a wireless communication unit that includes a transmission unit that wirelessly transmits control signals and a reception unit that wirelessly receives received signals. Furthermore, each of the remote controllers 1a and 1b is equipped with the antenna module 200 of this disclosure.
[0030] Figure 2 shows an example of an antenna module 200 provided in the remote controller 1a. The antenna module 200 includes a circuit board 210, an RF shield section 220 provided on one main surface of the circuit board 210, and a loop antenna 150, etc. At least a part of the radio station 10 shown in Figure 3 (for example, a radio IC 11, a balun circuit 12, filters 14L, 14M, 14H, multiple high-frequency switches, multiple antenna circuits, etc.) can be housed inside the RF shield section 220. The circuit board 210 is provided with wiring patterns, etc., for electrically connecting components such as an operating section (not shown in Figure 3) and components inside the RF shield section 220.
[0031] The loop antenna 150 is a small loop antenna with a circumference shorter than the wavelength. The small loop antenna operates as a "magnetic field antenna" that captures magnetic field components by electromagnetic induction and can exhibit directivity with a sharp null point in the axial direction of the loop. Furthermore, due to its loop shape, it has high inductive reactance, and it is desirable to resonate (tune) it in combination with external parts (such as a capacitor). Therefore, the multiple antenna circuits described later can be used to supplement the electrical length (equivalent electrical length) of the loop antenna 150 according to the frequency band and tune it to the desired band.
[0032] Figure 3 shows an example configuration of the radio station 10 provided by the antenna module 200. The remote controllers 1a and 1b mentioned above are examples of the radio station 10. The radio station 10 is a low-power radio station and is a multiband radio station capable of supporting, for example, the 1200 MHz band, 920 MHz band, 915 MHz band, 868 MHz band, 433 MHz band, 429 MHz band, 426 MHz band, 315 MHz band, and a weak frequency band lower than 315 MHz.
[0033] As shown in Figure 3, the radio station 10 includes a radio IC (Integrated Circuit) 11, a balun circuit 12 (or matching circuit), a high-frequency switch 13, filters 14L, 14M and 14H, a high-frequency switch 15, an RF connector 16, and a wireless communication circuit 100. The wireless communication circuit 100 includes a high-frequency switch 110, a high-frequency switch 120, an RF connector 160, a high-frequency switch 140, a plurality of antenna circuits 130(1) to 130(4), and a loop antenna 150. These may be housed, for example, within the RF shield section 220 of the antenna module 200.
[0034] The wireless IC 11 is a circuit that generates a high-frequency signal (hereinafter simply referred to as "signal" in this specification) with information to be transmitted wirelessly superimposed on it, or extracts information from a received signal, under the control of a control device (not shown in Figure 3; in the case of the remote controller 1a) which is in charge of the overall control of the wireless station 10. A balun circuit 12 (or matching circuit) that performs balanced-to-unbalanced conversion is connected to the wireless IC 11. When the wireless station 10 is a transmitting station, the balun circuit 12 (or matching circuit) performs balanced-to-unbalanced conversion on the input signal from the wireless IC 11 and outputs the converted signal to the high-frequency switch 13.
[0035] The high-frequency switch 13 is a switch for switching the signal path, and may be mechanical or electronic (the same applies to other high-frequency switches). Under the control of the control device described above, the high-frequency switch 13 selectively connects the balun circuit 12 (or matching circuit) to one of the filters 14L, 14M, and 14H. Filter 14L is a low-pass filter that allows signals with frequencies below 500 MHz to pass through. Therefore, signals in the 433 MHz, 429 MHz, 426 MHz, 315 MHz, and weak bands pass through filter 14L, while signals in the 1200 MHz, 920 MHz, 915 MHz, and 868 MHz bands do not pass through filter 14L. Signals in the 868 MHz, 915 MHz, and 920 MHz bands pass through filter 14M. Filter 14M is a bandpass filter (BPF) that allows signals in the frequency band of 860 MHz to 930 MHz to pass through. Filter 14H is a lowpass filter that allows signals with frequencies below 1200 MHz to pass through.
[0036] When performing wireless communication in the 1200 MHz band, the aforementioned control device connects the balun circuit 12 (or matching circuit) to filter 14H by switching the high-frequency switch 13. In contrast, when performing wireless communication in the 868 MHz, 915 MHz, and 920 MHz bands, the control device connects the balun circuit 12 (or matching circuit) to filter 14M by switching the high-frequency switch 13. When performing wireless communication in the 433 MHz, 429 MHz, 426 MHz, 315 MHz, and low-power bands, the control device connects the balun circuit 12 (or matching circuit) to filter 14L by switching the high-frequency switch 13.
[0037] The high-frequency switch 15, under the control of the aforementioned control device, selectively connects one of filters 14L, 14M, or 14H to the RF connector 16. The switching of the high-frequency switch 15 is performed in synchronization with the switching of the high-frequency switch 13. That is, when the balun circuit 12 (or matching circuit) is connected to filter 14H by the switching of the high-frequency switch 13, the filter 14H is connected to the RF connector 16 by the switching of the high-frequency switch 15. Conversely, when the balun circuit 12 (or matching circuit) is connected to either filter 14M or filter 14L by the switching of the high-frequency switch 13, the filter (filter 14M or filter 14L) connected to the balun circuit 12 (or matching circuit) is connected to the RF connector 16 by the switching of the high-frequency switch 15.
[0038] As shown in Figure 3, the RF connector 16 is connected to the high-frequency switch 110 of the wireless communication circuit 100. Under the control of the control device described above, the high-frequency switch 110 selectively connects the RF connector 16 to either the RF connector 160 or the internal antenna. The internal antenna is formed from the high-frequency switch 120, antenna circuits 130(1) to 130(4), high-frequency switch 140, and antenna 150. An external antenna (not shown in Figure 1) is connected to the RF connector 160 as needed. The external antenna is attached to the radio station 10, for example, when the product specifications require an external antenna, or when wireless communication is hindered due to the antenna layout or other factors.
[0039] The high-frequency switch 120, under the control of the aforementioned control device, selectively connects the high-frequency switch 110 to one of the antenna circuits 130(1) to 130(4). As a result, the downstream circuits from the high-frequency switch 110 (wireless IC (Integrated Circuit) 11 to RF connector 16) are selectively connected to one of the antenna circuits 130(1) to 130(4). The high-frequency switch 120 is an example of a second high-frequency switch in this disclosure.
[0040] In this embodiment, each of the antenna circuits 130(1) to 130(4) corresponds to a different frequency band. Specifically, antenna circuit 130(1) corresponds to the 1200 MHz band. Antenna circuit 130(1) is an example of the first antenna circuit in this disclosure. Antenna circuit 130(2) corresponds to the 920 MHz band, the 915 MHz band and the 868 MHz band. Antenna circuit 130(2) is an example of the second antenna circuit in this disclosure. Antenna circuit 130(3) corresponds to the 433 MHz band, the 429 MHz band and the 426 MHz band. Antenna circuit 130(3) is an example of the third antenna circuit in this disclosure. Antenna circuit 130(4) corresponds to the 315 MHz band and the low-power band. Antenna circuit 130(4) is an example of the fourth antenna circuit in this disclosure.
[0041] During operation, when performing wireless communication in the 1200 MHz band, the control device connects the high-frequency switch 110 to the antenna circuit 130(1) by switching the high-frequency switch 120. When performing wireless communication in any of the 920 MHz, 915 MHz, or 868 MHz frequency bands, the control device connects the high-frequency switch 110 to the antenna circuit 130(2) by switching the high-frequency switch 120. When performing wireless communication in any of the 433 MHz, 429 MHz, or 426 MHz frequency bands, the control device connects the high-frequency switch 110 to the antenna circuit 130(3) by switching the high-frequency switch 120. When performing wireless communication in any of the 315 MHz band or low-power band frequency bands, the control device connects the high-frequency switch 110 to the antenna circuit 130(4) by switching the high-frequency switch 120.
[0042] The high-frequency switch 140 selectively connects one of the antenna circuits 130(1) to 130(4) to the antenna 150 under the control of the control device described above. The high-frequency switch 140 is an example of the first high-frequency switch in this disclosure.
[0043] In operation, for example, when performing wireless communication in the 1200 MHz band, the control device connects the antenna circuit 130(1) to the antenna 150 by switching the high-frequency switch 140. Also, when performing wireless communication in any frequency band of the 920 MHz band, 915 MHz band, or 868 MHz band, the control device connects the antenna circuit 130(2) to the antenna 150 by switching the high-frequency switch 140. Also, when performing wireless communication in any frequency band of the 433 MHz band, 429 MHz band, or 426 MHz band, the control device connects the antenna circuit 130(3) to the antenna 150 by switching the high-frequency switch 140. Also, when performing wireless communication in the 315 MHz band or a weak frequency band, the control device connects the antenna circuit 130(4) to the antenna 150 by switching the high-frequency switch 140.
[0044] As described above, the loop antenna 150 is a micro loop antenna. Since it is desirable to resonate (tune) the micro loop antenna in combination with an external capacitor or the like, each of the antenna circuits 130(n) (n = 1 to 4) can function as a tuning circuit (resonance circuit) for the loop antenna 150.
[0045] In this embodiment, although the antenna circuits 130(1) to 130(4) respectively correspond to different frequency bands, their configurations are common. FIG. 4 is a diagram showing a configuration example of the antenna circuit 130(n). In FIG. 4, in addition to the antenna circuit 130(n), a high-frequency switch 120 and a high-frequency switch 140 respectively connected to the antenna circuit 130(n) are shown. As shown in FIG. 4, the antenna circuit 130(n) includes a first terminal T1, a second terminal T2, coils 1310a, 1310b, and 1310c, and capacitors 1320a, 1320b, and 1320c.
[0046] In this embodiment, the first terminal T1 is connected to the high-frequency switch 140, and the second terminal T2 is connected to the high-frequency switch 120. When a transmitter is configured using the wireless communication circuit 100, the transmission signal is input to the antenna circuit 130(n) via the second terminal T2, and a signal is output from the first terminal T1. That is, when a transmitter is configured using the wireless communication circuit 100, the first terminal T1 serves as the signal output terminal, and the second terminal T2 serves as the signal input terminal. When a receiver is configured using the wireless communication circuit 100, the first terminal T1 serves as the signal input terminal, and the second terminal T2 serves as the signal output terminal.
[0047] As shown in FIG. 4, the coil 1310a and the capacitor 1320a are inserted in series between the first terminal T1 and the second terminal T2. As shown in FIG. 4, one end of the capacitor 1320b is grounded, and the other end is connected to the first terminal T1. One end of the capacitor 1320c is connected to the common connection point of the coil 1310a and the capacitor 1320a, and the other end is grounded.
[0048] One end of the coil 1310b is connected to the common connection point of the coil 1310a and the capacitor 1320a, and the other end is grounded. In other words, one end of the coil 1310b is connected to the first terminal T1 via the coil 1310a and the capacitor 1320a. The coil 1310b is an example of the first coil in the present disclosure. One end of the coil 1310c is connected to the second terminal T2, and the other end is grounded. The coil 1310c is an example of the second coil in the present disclosure.
[0049] The antenna circuit 130(n) may include a circuit configuration such as a π-type, but is not limited thereto. For example, the capacitance of each capacitor and the inductance of each coil can be set so that the loop antenna 150 resonates in a desired band, and impedance matching and gain (radiation efficiency) can be improved.
[0050] Although the configurations of antenna circuits 130(1) to 130(4) are common, each antenna circuit is adjusted so that the equivalent electrical length between the first terminal T1 and the second terminal T2 differs from that of the corresponding frequency band. For example, the capacitance of each capacitor and the inductance of each coil are set so that the phase delay amount of S21 at the center frequency f0 of the frequency band becomes a desired value for each antenna circuit. This allows the tuning conditions (resonant frequency, bandwidth, etc.) of the loop antenna 150 to be appropriately realized for each frequency band. The equivalent electrical length and phase delay amount may be evaluated for the antenna circuit alone, or for the entire system including the loop antenna 150. For example, the equivalent electrical length can be determined by measuring the S-parameters between terminals T1 and T2 (or equivalent measurement points) using a vector network analyzer and calculating the phase delay amount or group delay.
[0051] As mentioned above, during operation, the control device connects the desired antenna circuit 130(n) to the antenna 150 and subsequent circuits by switching the high-frequency switch 140 and high-frequency switch 120 according to the frequency band to be used. However, if interference is detected, the control device may change the band / channel being used based on the received signal strength, carrier sense results, communication error rate, etc. For example, if the 429 MHz band is congested, interference problems can be reduced by switching to the 920 MHz band.
[0052] The embodiments described above are illustrative, and those skilled in the art can make various modifications or substitutions without departing from the spirit of this disclosure. For example, the specific circuit configuration of the antenna circuit, the switch configuration, the combination of corresponding frequency bands, and the shape of the antenna can be changed as appropriate.
[0053] Although the above embodiment was an example of applying the disclosure to the remote control of a gantry crane, the disclosure may also be applied to the remote control of equipment other than gantry cranes.
[0054] The scope of application of this disclosure is not limited to low-power radio communications, but may also be applied to communication devices that communicate in the ISM (Industrial, Scientific, and Medical) band. Here, the ISM band refers to the frequency band designated for ISM use, which is listed in the footnote to Article 5 (Frequency Allocation) of the ITU (International Telecommunication Union) Radio Regulations (RR). Furthermore, this disclosure may be used in Europe for wireless communications based on communication standards such as EN 300 220 (868 MHz band) and ETSI EN 300 220 LPD433 (433 MHz band) established by ETSI (European Telecommunications Standards Institute), as well as for wireless communications based on provisions §15.231, §15.247, §15.249, etc., established by the FCC (Federal Communications Commission) in the United States.
[0055] At least one embodiment of this disclosure can be described or presented in view of the following clauses:
[0056] <Clause 1> An antenna circuit characterized by comprising: a first capacitor and a first coil interposed in series between a first terminal and a second terminal, one of which is an input terminal and the other is an output terminal; a second capacitor with one end grounded and the other end connected to the first terminal; a third capacitor with one end connected to the common connection point of the first capacitor and the first coil and the other end grounded; a second coil with one end connected to the common connection point and the other end grounded; and a third coil with one end connected to the second terminal and the other end grounded.
[0057] <Clause 2> A wireless communication circuit comprising a plurality of antenna circuits as described in Clause 1, further comprising: an antenna; a first high-frequency switch for selectively connecting one of the first terminals in each of the plurality of antenna circuits to the antenna; and a second high-frequency switch for selectively connecting one of the second terminals in each of the plurality of antenna circuits to a subsequent circuit, wherein the capacitances of the first capacitor, the second capacitor, and the third capacitor in each of the plurality of antenna circuits, and the inductances of the first coil, the second coil, and the third coil are set so that the electrical lengths of the plurality of antenna circuits are different from each other.
[0058] <Clause 3> The wireless communication circuit according to Clause 2, wherein the plurality of antenna circuits include at least a first antenna circuit corresponding to the 1200 MHz band, a second antenna circuit corresponding to the 920 MHz band, the 915 MHz band and the 868 MHz band, a third antenna circuit corresponding to the 433 MHz band, the 429 MHz band and the 426 MHz band, and a fourth antenna circuit corresponding to the 315 MHz and lower frequency bands.
[0059] <Clause 4> A loop antenna, a plurality of antenna circuits, a first high-frequency switch, and a second high-frequency switch, each of the plurality of antenna circuits comprising: a first capacitor and a first coil interposed in series between a first terminal and a second terminal, one of which is an input terminal and the other is an output terminal; a second capacitor with one end grounded and the other end connected to the first terminal; a third capacitor with one end connected to the common connection point of the first capacitor and the first coil and the other end grounded; a second coil with one end connected to the common connection point and the other end grounded; and a third coil with one end connected to the second terminal and the other end grounded, the first high-frequency switch selectively connects one of the first terminals in each of the plurality of antenna circuits to the loop antenna, and the second high-frequency switch selectively connects one of the second terminals in each of the plurality of antenna circuits to a subsequent circuit. A wireless communication circuit characterized in that, each of the multiple paths from the first high-frequency switch to the second high-frequency switch via any of the multiple antenna circuits is a path that allows signals of different frequency bands to pass through, the capacitances of the first capacitor, the second capacitor, and the third capacitor in each of the multiple antenna circuits, and the inductances of the first coil, the second coil, and the third coil in each of the multiple antenna circuits are set according to the frequency band to which the antenna circuit corresponds.
[0060] <Clause 5> The wireless communication circuit according to Clause 4, wherein the plurality of antenna circuits include at least two of the following: a first antenna circuit corresponding to the 1200 MHz band; a second antenna circuit corresponding to the 920 MHz band, the 915 MHz band and the 868 MHz band; a third antenna circuit corresponding to the 433 MHz band, the 429 MHz band and the 426 MHz band; and a fourth antenna circuit corresponding to the 315 MHz band and a frequency band lower than 315 MHz.
[0061] <Clause 6> A specified low-power radio station comprising: a wireless communication circuit as described in Clause 4; an RF connector connected to the second high-frequency switch; a wireless IC connected to the RF connector via a balun circuit or matching circuit; and a control device for controlling the switching of the first high-frequency switch and the second high-frequency switch.
[0062] <Clause 7> A specified low-power radio station comprising: a wireless communication circuit according to Clause 4; an RF connector connected to the second high-frequency switch; a radio IC connected to the RF connector via a balun circuit or matching circuit; a control device for controlling the switching of the first high-frequency switch and the second high-frequency switch; and a third high-frequency switch, a fourth high-frequency switch, and a third filter disposed between the balun circuit or matching circuit and the RF connector, wherein the plurality of antenna circuits in the wireless communication circuit include a first antenna circuit corresponding to the 1200 MHz band, a second antenna circuit corresponding to the 920 MHz band, the 915 MHz band and the 868 MHz band, a third antenna circuit corresponding to the 433 MHz band, the 429 MHz band and the 426 MHz band, and a fourth antenna circuit corresponding to the 315 MHz band and a frequency band lower than 315 MHz, and the control device is When performing wireless communication in the 1200 MHz band, the RF connector and the loop antenna are connected to the first antenna circuit by switching the first and second high-frequency switches, while the balun circuit or matching circuit is connected to the RF connector via the third filter by switching the third and fourth high-frequency switches. When performing wireless communication in any of the 920 MHz, 915 MHz, or 868 MHz frequency bands, the RF connector and the loop antenna are connected to the second antenna circuit by switching the first and second high-frequency switches. When performing wireless communication in any of the 433 MHz, 429 MHz, or 426 MHz frequency bands, the RF connector and the loop antenna are connected to the third antenna circuit by switching the first and second high-frequency switches. When performing wireless communication in the 315 MHz band or a frequency band lower than 315 MHz, the control device connects the RF connector and the loop antenna to the fourth antenna circuit by switching the first high-frequency switch and the second high-frequency switch, for a specified low-power radio station.
[0063] 1a, 1b Remote controller 5a, 5b Gantry crane 51 Legs 52 Wheels 53 Lifting mechanism 54 Trolley 55 Lifting device (hook) 56 Control unit 56a Antenna 7 Rail 10 Radio station 11 Radio IC 12 Balun circuit (or matching circuit) 13, 15, 110, 120, 140 High-frequency switch 14L, 14M, 14H Filter 16, 160 RF connector 100 Wireless communication circuit 130(n) (n=1-4) Antenna circuit (tuning circuit) 150 Loop antenna T1 First terminal T2 Second terminal 1310a-c Coil 1320a-c Capacitor 200 Antenna module 210 Circuit board 220 RF shield section
Claims
1. A wireless communication circuit for performing wireless communication in any of a plurality of frequency bands, comprising: a loop antenna; a plurality of antenna circuits corresponding to each of the plurality of frequency bands; a first high-frequency switch for selectively connecting any of the plurality of antenna circuits to the loop antenna; and a second high-frequency switch for selectively connecting any of the plurality of antenna circuits to a subsequent circuit, wherein each of the plurality of antenna circuits has a first terminal connected to the first high-frequency switch and a second terminal connected to the second high-frequency switch, and the equivalent electrical lengths between the first terminal and the second terminal are set to be different from each other according to the frequency band each corresponds to.
2. The wireless communication circuit according to claim 1, wherein the first high-frequency switch and the second high-frequency switch are switched in conjunction so that the same antenna circuit is connected to the loop antenna and the subsequent circuit.
3. The wireless communication circuit according to claim 2, wherein the equivalent electrical length is determined based on the phase delay amount or group delay in the transmission characteristics from the first terminal to the second terminal.
4. The wireless communication circuit according to claim 3, comprising: a first capacitor and a first coil interposed in series between a first terminal and a second terminal, one of which is an input terminal and the other is an output terminal; a second capacitor with one end grounded and the other end connected to the first terminal; a third capacitor with one end connected to the common connection point of the first capacitor and the first coil and the other end grounded; a second coil with one end connected to the common connection point and the other end grounded; and a third coil with one end connected to the second terminal and the other end grounded.
5. The wireless communication circuit according to any one of claims 1 to 4, wherein the plurality of antenna circuits include at least a first antenna circuit corresponding to the 1200 MHz band, a second antenna circuit corresponding to the 920 MHz band, the 915 MHz band and the 868 MHz band, a third antenna circuit corresponding to the 433 MHz band, the 429 MHz band and the 426 MHz band, and a fourth antenna circuit corresponding to the 315 MHz band and a frequency band lower than 315 MHz.
6. An antenna module comprising a wireless communication circuit according to any one of claims 1 to 5, the antenna module comprising: a substrate; an RF shield portion provided on one main surface of the substrate and housing at least a part of the wireless communication circuit; and a loop antenna provided on the substrate and disposed outside the RF shield portion, wherein the substrate has a wiring pattern that electrically connects the circuit elements in the RF shield portion and components such as an operating portion disposed in other areas of the substrate.
7. An industrial remote controller that performs wireless communication in any of a plurality of frequency bands, comprising: an operating unit; a control unit that generates a control signal in response to the operation of the operating unit; a transmitting unit that wirelessly transmits the control signal; and a receiving unit that wirelessly receives a received signal, the wireless communication unit having the antenna module described in claim 6, wherein each of the plurality of frequency bands is an ISM band or is included in the ISM band.
8. The control unit detects interference based on a communication error, carrier sense result, or received signal strength, and changes the operating frequency band by switching the first high-frequency switch and the second high-frequency switch when interference is detected, as described in claim 7.