Wireless communication devices, mobile terminals

Abstract

To realize a wireless communication device and a mobile terminal that can suppress the possibility of unintended radio waves being emitted from an antenna at a lower cost.SOLUTION: Two stubs, ie, a first stub 8 and a second stub 9, are connected on a power supply line 7 that connects an antenna 6 and a communication IC 5 with a distance of 1 / 4 of the wavelength of the blocking frequency (=0.25 λs). Both the first stub 8 and the second stub 9 are linear conductors having a length of approximately 0.25 λs. The first stub 8 and the second stub 9 have shapes bent in a direction approaching each other, and most of each stub is parallel to the power supply line 7.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a technique for suppressing spurious emissions in a device that performs wireless communication. [Background technology]

[0002] Patent Document 1 discloses a configuration in which a stub is provided on a feeder line connecting an antenna and a communication circuit in order to improve impedance matching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-41089 Summary of the Invention [Problem to be solved by the invention]

[0004] In wireless communication devices, in addition to radio waves of the operating frequency, which is the frequency used for communication, unwanted radio waves (so-called spurious signals) may be emitted from the antenna. Furthermore, these spurious signals may occur at levels exceeding the legal upper limit in areas close to the communication frequency. Non-random spurious signals are classified into non-harmonic spurious signals and harmonic spurious signals. Non-harmonic spurious signals originate from the clocks of transmitter / receiver circuits, including analog-to-digital conversion circuits, while harmonic spurious signals are signals equivalent to integer multiples of the operating frequency.

[0005] For spurious signals that have a certain degree of reproducibility and whose intensity can exceed a certain value, a common method is to install a band-stop filter, which is a circuit / chip that blocks signals of the frequency corresponding to the spurious, on the power supply line. However, the method using a band-stop filter has the problem of increased costs due to the band element filter.

[0006] The present disclosure has been made based on the above considerations or points of view, and one of its objectives is to realize wireless communication devices and mobile terminals that can reduce the risk of unintended radiation of radio waves from antennas at lower cost. [Means for solving the problem]

[0007] Disclosed herein 1st The wireless communication device includes an antenna (6) that operates at a working frequency that is a frequency used for communication, a circuit (5) that outputs a signal to be transmitted from the antenna, a feed line (7) for connecting the antenna and the circuit, a first stub (8) that is a linear conductor formed to branch off from the feed line, and a second stub (9) that is a linear conductor connected to the feed line at a second branch point different from a first branch point that is a connection point between the feed line and the first stub, the second branch point being arranged on the feed line closer to the circuit than the first branch point, and the length of the first stub is set to a value within 0.25λs±0.1λs, and the distance between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs, where λs is the wavelength of a rejection frequency that is a frequency to be rejected. In addition to a low-frequency stub set (StL) which is a set of first and second stubs having a length and a branch point interval corresponding to the wavelength of a first stop frequency, the antenna further includes a high-frequency stub set (StH) which is a set of first and second stubs having a length and a branch point interval corresponding to the wavelength of a second stop frequency higher than the first stop frequency, and the high-frequency stub set is arranged closer to the antenna than the low-frequency stub set. . A second wireless communication device included in the present disclosure includes an antenna (6) that operates at a working frequency that is a frequency used for communication, a circuit (5) that outputs a signal to be transmitted from the antenna, a feed line (7) for connecting the antenna and the circuit, a first stub (8) that is a linear conductor formed to branch off from the feed line, and a second stub (9) that is a linear conductor connected to the feed line at a second branch point different from a first branch point that is a connection point between the feed line and the first stub, the second branch point being arranged on the feed line closer to the circuit than the first branch point, and having a wavelength of a blocking frequency that is a frequency to be blocked. where λs is the length of the first stub, the length is set to a value within 0.25λs±0.1λs, and the spacing between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs. The antenna is provided with a low-frequency stub set (StL) which is a set of first and second stubs having a length and spacing between branch points according to the wavelength of the first stop frequency, and a high-frequency stub set (StH) which is a set of first and second stubs having a length and spacing according to the wavelength of a second stop frequency that is higher than the first stop frequency, and the low-frequency stub set is arranged closer to the antenna than the high-frequency stub set.

[0008] According to the above configuration, the second branch point substantially coincides with the high-resistance point formed by the first stub at the rejection frequency. In this case, the second stub provides a path with a relatively lower impedance than the main feeder line leading to the first branch point. Therefore, current at the rejection frequency output from the circuit flows preferentially through the second stub and is less likely to flow into the antenna. As a result, it is possible to suppress radiation of radio waves at the rejection frequency, i.e., spurious emissions, from the antenna.

[0009] In addition, the present disclosure 1stThe mobile terminal is a mobile terminal with a wireless communication function carried by a user, and includes, as a wireless communication module providing the wireless communication function, an antenna (6) operating at a working frequency that is a frequency used for communication, a circuit (5) that outputs a signal to be transmitted from the antenna, a feed line (7) for connecting the antenna and the circuit, a first stub (8) that is a linear conductor formed to branch off from the feed line, and a second stub (9) that is a linear conductor connected to the feed line at a second branch point different from the first branch point that is a connection point between the feed line and the first stub, the second branch point being arranged on the feed line closer to the circuit than the first branch point, and when the wavelength of a rejection frequency that is a frequency to be rejected is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the distance between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs. The antenna includes a low-frequency stub set (StL) which is a set of first and second stubs having a length and a branch point interval corresponding to the wavelength of a first stop frequency, and a high-frequency stub set (StH) which is a set of first and second stubs having a length and an interval corresponding to the wavelength of a second stop frequency higher than the first stop frequency, and the high-frequency stub set is arranged closer to the antenna than the low-frequency stub set. It is equipped with a wireless communication module. A second mobile terminal included in the present disclosure is a mobile terminal with a wireless communication function carried by a user, and includes, as a wireless communication module providing the wireless communication function, an antenna (6) operating at a working frequency that is a frequency used for communication, a circuit (5) that outputs a signal to be transmitted from the antenna, a power feed line (7) for connecting the antenna and the circuit, a first stub (8) that is a linear conductor formed to branch off from the power feed line, and a second stub (9) that is a linear conductor connected to the power feed line at a second branch point different from the first branch point that is a connection point between the power feed line and the first stub, and the second branch point is located on the power feed line closer to the circuit than the first branch point, When the wavelength of the rejection frequency, which is the frequency to be rejected, is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the spacing between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs. The low-frequency stub set (StL) is a set of first and second stubs having a length and branch point spacing according to the wavelength of the first rejection frequency, and a high-frequency stub set (StH) is a set of first and second stubs having a length and spacing according to the wavelength of a second rejection frequency that is higher than the first rejection frequency. The low-frequency stub set is equipped with a wireless communication module that is arranged closer to the antenna than the high-frequency stub set.

[0010] The mobile terminal is a mobile terminal to which the wireless communication device is applied, and by having the same features as the wireless communication device, the same effects can be obtained. Note that the reference numerals in parentheses in the claims indicate a correspondence with specific means described in the embodiments described later as one aspect, and do not limit the technical scope of the present disclosure. Furthermore, the present disclosure does not prohibit the introduction of a band-stop filter configured as a circuit / chip. The present disclosure is also applicable to a wireless communication device that also uses a band-stop filter. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an exploded perspective view showing the configuration of the radio device. [Figure 2] FIG. 2 is a diagram showing a configuration on a circuit board. [Figure 3] FIG. 10 is a diagram for explaining the dimensions of a stub connected to a feeder line. [Figure 4] FIG. 10 is a diagram illustrating a second embodiment. [Figure 5] FIG. 10 is a diagram illustrating a third embodiment. [Figure 6] 10A and 10B are diagrams for explaining the operation and effect of the second embodiment. [Figure 7] FIG. 10 is a diagram illustrating a first comparative configuration. [Figure 8] FIG. 10 is a diagram illustrating a second comparative configuration. [Figure 9] FIG. 10 is a diagram showing the results of simulating the frequency characteristics of insertion loss in the first embodiment and the first and second comparative configurations. [Figure 10] FIG. 10 is a diagram showing the results of simulating the frequency characteristics of insertion loss in the first and second examples. [Figure 11] 10A and 10B are diagrams showing modified shapes of the feed line and the first and second stubs. [Figure 12] 10A and 10B are diagrams showing modified examples of the shapes of the first and second stubs. [Figure 13] 10A and 10B are diagrams showing modified examples of the shapes of the first and second stubs. [Figure 14] FIG. 10 is a diagram showing a configuration in which the second stub is set longer than the first stub. [Figure 15] FIG. 10 is a diagram showing a configuration in which a radio wave blocking section is provided in the upper case. [Figure 16] FIG. 10 is a diagram showing a configuration in which a low-frequency stub set and a high-frequency stub set are provided on a feeder line. [Figure 17] FIG. 16 is a diagram showing the results of a simulation of the frequency characteristics of insertion loss in the configuration shown in FIG. [Figure 18] 10A and 10B are diagrams showing other examples of forming a low-frequency stub set and a high-frequency stub set. [Figure 19] 10A and 10B are diagrams illustrating modified examples of the antenna shape. [Figure 20] FIG. 1 is a diagram illustrating a mobile terminal to which an embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Hereinafter, components having the same functions will be denoted by the same reference numerals, and their description will be omitted. Furthermore, when only a portion of the configuration is mentioned, the configuration of the previously described embodiment can be applied to the other portions.

[0013] In this disclosure, "parallel" does not necessarily mean a completely parallel state. It may also mean tilted by a few degrees to 15 degrees from a completely parallel state. In other words, an expression that a certain member is parallel to another member may include a state in which the two are generally parallel (a so-called substantially parallel state). The expression "perpendicular" in this disclosure is also not limited to a completely perpendicular state, but also includes a state in which the two are tilted by a few degrees to 15 degrees. In this disclosure, "facing" refers to a state in which the two members face each other with a predetermined distance between them. The facing state also includes a state in which the two members generally face each other, such as a state in which the two members are tilted by about 15 degrees from each other.

[0014] Furthermore, if the wavelength of a certain frequency is λ, then in this disclosure, "λ / 2" and "0.5λ" refer to half the wavelength, and "λ / 4" and "0.25λ" refer to one-quarter of the wavelength. In the examples of dimensions of various components constituting the radio device 100, expressions using λ can be interpreted as electrical length. Here, electrical length refers to the effective length taking into account factors such as fringing electric fields and wavelength shortening effects due to dielectrics. Electrical length is sometimes also called effective length. Of course, for portions not affected by wavelength shortening effects, λ can be interpreted as the length in a vacuum or air.

[0015] <Example of use> The wireless device 100 shown in FIG. 1 and other figures is configured to be capable of wireless communication with a communication device (hereinafter, referred to as a mobile terminal) carried by a vehicle user using a predetermined communication method. Examples of the mobile terminal include general-purpose information processing terminals such as smartphones and wearable devices, as well as smart keys, which are electronic keys for vehicles. The wireless device 100 of this embodiment is configured as a communication module for performing ultra-wideband (UWB) communication. More specifically, the wireless device 100 is configured to be capable of transmitting and receiving radio signals (impulse signals) conforming to a so-called UWB-IR (Impulse Radio) communication method, which is capable of performing highly accurate distance measurement. The wireless device 100 may also be configured to be capable of wireless communication using a UWB-FMCW (Frequency Modulated Continuous Wave) communication method.

[0016] The wireless device 100 reports, for example, data indicating the reception strength of a wireless signal from the mobile terminal and the distance from the mobile terminal to the in-vehicle ECU as information indicating the location of the mobile terminal. ECU is an abbreviation for Electronic Control Unit and means an electronic control device. The data indicating the distance is, for example, round-trip time (RTT). The wireless device 100 corresponds to a wireless communication device.

[0017] The wireless device 100 is attached to the interior side of a door-side B-pillar or C-pillar. Here, the B-pillar refers to the second pillar from the front, and the C-pillar refers to the third pillar from the front. The door-side B-pillar refers to the portion of the door window frame that abuts against the B-pillar of the vehicle body. In another embodiment, the wireless device 100 may be configured to be disposed near, for example, an outer door handle for the driver's seat or passenger seat, the roof, a rearview mirror, a side mirror, a rear bumper, or a trunk door handle.

[0018] <Overall configuration overview> Fig. 1 is a diagram showing an example of a schematic configuration of a radio device 100. As shown in Fig. 1, the radio device 100 includes a lower case 1, an upper case 2, a circuit board 3, a connector 4, a communication IC (Integrated Circuit) 5, an antenna 6, a feed line 7, a first stub 8, and a second stub 9.

[0019] In this disclosure, the direction perpendicular to the circuit board 3 is referred to as the up-down direction. The direction from the circuit board 3 toward the lower case 1 corresponds to the downward direction for the radio device 100, and the direction from the circuit board 3 toward the upper case 2 corresponds to the upward direction. The upward direction corresponds to the direction from the lower side, which is the side facing the attachment target, to the upper side, which is the opposite side of the two sides of the circuit board 3. The upper side corresponds to the side on which the antenna 6 is formed.

[0020] Furthermore, in this disclosure, the configuration of radio device 100 will be described by introducing the concept of a right-handed three-dimensional coordinate system having mutually orthogonal X-, Y-, and Z-axes. The X-axis shown in various drawings such as Fig. 1 represents the short-side direction of circuit board 3, the Y-axis represents the long-side direction of circuit board 3, and the Z-axis represents the up-down direction. In another embodiment, if circuit board 3 is square-shaped, the direction along any one of the sides can be set as the X-axis.

[0021] The three-dimensional coordinate system having these X-axis, Y-axis, and Z-axis is a concept for explaining the configuration of the radio device 100. When the radio device 100 is attached to a side portion of the vehicle interior such as a C-pillar, for example, the X-axis corresponds to the front-rear direction of the vehicle, the Y-axis corresponds to the up-down direction of the vehicle, and the Z-axis corresponds to the width direction of the vehicle.

[0022] The lower case 1 is combined with the upper case 2 to form a flat rectangular parallelepiped case (in other words, a housing) as a whole. The lower case 1 is a member that covers the circuit board 3 from below and accommodates and supports the circuit board 3. The lower case 1 corresponds to a member that provides the bottom of the housing of the radio device 100. The lower case 1 plays a role in protecting the underside of the circuit board 3. The lower case 1 is formed using a synthetic resin such as polycarbonate (PC).

[0023] The lower case 1 is formed in a flat (i.e., shallow) box shape with an open upper surface. That is, the lower case 1 includes a bottom surface 11 that faces the circuit board 3 at a predetermined distance, and a lower wall portion 12 that extends upward from the edge of the bottom surface 11. Note that the lower wall portion 12 is an optional element and may be omitted. The bottom surface 11 is formed with through holes 13 for passing screws at positions corresponding to the screw holes 31 formed in the circuit board 3. For example, the through holes 13 for screw fastening are formed in the four corners of the bottom surface 11.

[0024] The lower case 1 may be realized by combining a metal member and a resin. For example, the lower case 1 may have a configuration in which a metal frame is covered with a resin, in other words, a configuration in which a metal frame is embedded inside a resin member that provides the exterior shape.

[0025] The upper case 2 is a member that covers the circuit board 3 from above and houses and protects the circuit board 3. The upper case 2 is made of a resin material such as polycarbonate to allow radio waves to pass through. The upper case 2 is configured to be able to fit into the lower case 1 while housing the circuit board 3.

[0026] The upper case 2 is formed in a generally box-like shape with an open lower surface. Specifically, it includes a ceiling portion 21 that faces the upper surface of the circuit board 3 at a predetermined distance, and a side wall portion 22 that extends downward from the edge of the ceiling portion 21. The ceiling portion 21 corresponds to a configuration that provides the upper surface of the housing of the radio device 100. The side wall portion 22 is formed in a size and shape that allows its lower end to mate with the upper end of the bottom wall portion 12.

[0027] A cutout 23 for exposing the vicinity of the tip of the connector 4 is formed in the side wall 22 of the upper case 2 at a portion corresponding to the connector 4. In addition, a stepped portion or the like with a hole for accommodating a screw is formed on the inside of the upper case 2 at a position corresponding to the screw hole 31. The side wall 22 or the bottom surface 11 may be provided with a metal fitting or the like for attaching the radio device 100 to the vehicle body. A variety of attachment mechanisms can be used to fix the radio device 100 to the vehicle body.

[0028] The circuit board 3 is a plate-like member formed by mounting various electronic components on a printed circuit board. As the printed circuit board, a multilayer board in which a plurality of conductor layers are built up on an insulating layer such as a glass epoxy board (FR4: Flame Retardant Type 4) can be used. Here, as an example, the circuit board 3 is realized using a glass epoxy resin with a relative dielectric constant of approximately 4.3 to 4.9. The circuit board 3 is a single-sided board or a double-sided board without an internal conductor layer. Note that the circuit board 3 may also be realized using a multilayer board with an internal conductor layer, for example.

[0029] The circuit board 3 is formed in a substantially rectangular shape so as to fit the shape of the lower case 1. In the figure, 3xp indicates the edge parallel to the Y-axis that is located relatively closer to the positive X-axis direction of the four edges (sides) of the circuit board 3. In the figure, 3xn indicates the edge parallel to the Y-axis that is located relatively closer to the negative X-axis direction of the circuit board 3. In the figure, yp indicates the edge located relatively closer to the positive Y-axis direction of the two edges parallel to the X-axis that the circuit board 3 has, and yn indicates the edge located relatively closer to the negative Y-axis direction.

[0030] Screw holes 31 are formed in the four corners of the circuit board 3 for screwing the circuit board 3 to the lower case 1 and the upper case 2. The positions of the screw holes 31 can be changed as needed, as long as they are formed in corresponding positions on the lower case 1, the upper case 2, and the circuit board 3. Corresponding positions correspond to overlapping positions in a top view. The screw holes 31, in other words, the fixing portions for fixing the circuit board 3 to the lower case 1 and the upper case 2, may be provided in four or more locations. In addition to screws, various locking structures such as snap fits can be used as a method for maintaining the lower case 1, the upper case 2, and the circuit board 3 in an assembled state. The screw holes 31 are optional elements.

[0031] As shown in FIG. 2, the upper surface of the circuit board 3 is provided with a connector 4, a communication IC 5, an antenna 6, a power supply line 7, a first stub 8, and a second stub 9. The back surface of the circuit board 3 is provided with a ground section, which is a plate-shaped conductor electrically connected to the grounding wire of the power cable via a connector or the like. Here, the plate-shaped section includes a thin film such as copper foil. The ground section does not need to be formed over the entire back surface of the circuit board 3; it only needs to have a size and shape that is necessary and sufficient from the perspective of impedance matching, etc. The ground section for the communication IC 5 and the ground section for the antenna 6 may be formed on different layers. The ground section for the antenna corresponds to an auxiliary element for achieving a mirror effect. The ground section may be formed inside the board. The ground section is also called a base plate or ground layer.

[0032] The connector 4 is a component for connecting various cables, such as a communication cable with an on-board ECU. As an example, the connector 4 is attached to the edge of the circuit board 3 on the negative Y-axis side. The communication IC 5 is a circuit module that performs signal processing related to at least one of signal transmission and signal reception. The communication IC 5 corresponds to a communication circuit.

[0033] The communication IC 5 performs at least one of modulation, demodulation, frequency conversion, amplification, digital-to-analog conversion, and detection. The communication IC 5 has a function of detecting reception strength. The communication IC 5 may also have a function of identifying ToF. Note that the wireless device 100 may also have a power supply circuit and the like in addition to the communication IC 5. The wireless device 100 may also have a microcomputer including a processor and memory as a configuration for performing more advanced arithmetic processing.

[0034] The antenna 6 is configured to transmit and receive radio waves of a predetermined operating frequency. The operating frequency here refers to a frequency used for wireless communication. In UWB communication, multiple channels can be used, as disclosed in IEEE802.15.4a. Here, as an example, the antenna 6 is configured to operate on the fifth channel of UWB communication. That is, the antenna 6 is configured as an antenna for transmitting and receiving radio waves in the 6489.6 MHz (approximately 6.5 GHz) ±250 MHz band, i.e., radio waves from 6240 MHz to 6739 MHz. These frequencies correspond to the operating frequencies in this embodiment. Hereinafter, the wavelength of the frequency located at the center of the operating frequency band (the so-called center frequency) will also be referred to as "λoC." The lowest value of the operating frequency band will also be referred to as the minimum operating frequency, and this wavelength will also be referred to as "λoL." In this embodiment, 6240 MHz corresponds to the minimum operating frequency.

[0035] Of course, the antenna 6 may be an antenna operating on channel 3 or channel 9. Channel 3 refers to the frequency band from 4243 MHz to 4742 MHz (center frequency is 4492 MHz). Channel 9 refers to the frequency band from 7738 MHz to 8237 MHz (center frequency is 7987.2 MHz).

[0036] The antenna 6 may be a dual-purpose antenna for transmission and reception, or a dedicated antenna for reception. In this disclosure, the term "antenna for transmitting and receiving radio signals of a certain frequency band" can include not only an antenna used for both transmission and reception, but also an antenna used only for reception. In other words, the term "transmitting and receiving" can be interpreted as meaning at least one of transmission, reception, or reception. The same applies to the description of the communication IC 5, etc. Because the operation of an antenna is reversible between transmitting and receiving radio waves, an antenna capable of receiving radio waves of a certain frequency can be interpreted as an antenna capable of transmitting the radio waves.

[0037] The antenna 6 is, for example, a plate-like conductor formed in the shape of an isosceles triangle. The antenna 6 is disposed on the circuit board 3 in such a position that the edge corresponding to the base is parallel to the edge yp of the circuit board 3 on the positive side of the Y axis, in other words, the apex angle faces the communication IC 5. The antenna 6 may be formed as a pattern on the surface of the board. Various methods can be used to form the antenna 6 as a pattern on the surface of the board, such as electroplating, metal vapor deposition, or application of conductive paint.

[0038] The vertex of the antenna 6 is connected to the feed line 7. In other words, the feed point of the antenna 6 is formed near the vertex. The feed point may be set at any position where impedance is matched / suitable at the frequency used. The feed point may be set at any position on the antenna 6, and may be located at the center of gravity or the circumcenter, for example.

[0039] If the wavelength of the lowest usable frequency is λoL, the length La of the antenna 6 is designed based on 0.25λoL. For example, La is set to 0.23λoL. The shape and dimensions of the antenna 6 may be appropriately designed so that it is excited at the usable frequency. Antennas for UWB communications generally use planar elements that operate on the same principle as monopole antennas. The wavelength of 6240 MHz in a vacuum and in air, i.e., λoL, is 48 mm, and 0.25λoL is 12 mm.

[0040] The shape of the antenna 6 is not limited to a triangle, but may be a square, pentagon, hexagon, circle, or the like. Circles also include ellipses. Pentagons also include a home base shape. The home base shape refers to a shape used in baseball home bases, where two adjacent corners and one non-adjacent corner are set at right angles.

[0041] The feeder line 7 is a linear conductor for feeding power to the antenna 6. The term "linear" includes shapes with a certain width and thickness. For example, linear shapes include strips or rods whose width and thickness are sufficiently small compared to their longitudinal lengths. The feeder line 7 is configured as, for example, a microstrip line. The feeder line 7 may be formed inside the circuit board 3. One end of the feeder line 7 is connected to the antenna 6, and the other end is electrically connected to a signal terminal of the communication IC 5. Various methods for feeding power to the antenna can be used, including a direct feeding method and an electromagnetic coupling method. The direct feeding method refers to a method in which the feeder line 7 is directly connected to the antenna 6. The electromagnetic coupling method refers to a method that utilizes electromagnetic coupling between the feeder line 7 and the antenna 6. The feeder line 7 is formed parallel to the Y-axis, on the positive side of the Y-axis of the communication IC 5.

[0042] The width of the feeder line 7 is set to, for example, 2 mm, 3 mm, or 1 mm. The width of the feeder line 7 can be designed taking into consideration the magnitude of the current that can flow through the line, the inductance, and the like. The length of the feeder line 7 is set to 0.25 λs or more, where λs is the wavelength of the rejection frequency, which is the frequency to be rejected. For example, the length of the feeder line 7 is set to about 0.3 λs to 0.4 λs.

[0043] The stop frequency in this disclosure is the frequency at which an unacceptable level of spurious is observed. In reality, the stop frequency corresponds to the frequency at which spurious signals with intensities exceeding the legal upper limit or at a level that could affect peripheral devices / circuits are generated. The acceptable level of spurious signals can be determined based on regulations, product characteristics, the expected usage environment, customer requests, etc.

[0044] In this embodiment, as an example, a case will be described in which an unacceptable level of spurious is observed at 6.1 GHz, which is close to the frequency band in use. That is, the rejection frequency in this embodiment is set to 6.1 GHz. Of course, the rejection frequency may be other frequencies. The rejection frequency may vary depending on the configuration of the radio device 100, such as the communication IC 5. Note that a frequency close to the frequency band in use refers to a frequency within 500 MHz of the lower or upper limit of the frequency band in use. Alternatively, a frequency that is within 10% of the center frequency of the lower or upper limit of the frequency band in use may be considered to be a frequency close to the frequency band in use.

[0045] 3, the feeder line 7 is provided with a first branch point 71 which is a connection point with the first stub 8, and a second branch point 72 which is a connection point with the second stub 9. The first branch point 71 is located closer to the antenna 6 than the second branch point 72. For example, the first branch point 71 is located at a position 5 mm to 10 mm away from the antenna 6.

[0046] The second branch point 72 is disposed on the power supply line 7 at a predetermined distance from the first branch point 71, on the communication IC 5 side. A branch point interval Ds, which is the distance between the first branch point 71 and the second branch point 72, is determined according to the wavelength of the rejection frequency.

[0047] The branch point spacing Ds is set to a value within the range of 0.25 λs ± α. α is a predetermined value such as 0.1 λs, 0.125 λs, or 0.05 λs. For example, the branch point spacing Ds is set to 0.2 λs or more and 0.3 λs or less. The specific value of the branch point spacing Ds can be adjusted using simulations, etc., with 0.25 λs as the reference. For example, the branch point spacing Ds is set to 0.23 λs. α is a parameter that defines the limit value of the branch point spacing Ds that achieves the desired spurious suppression effect. The specific value of α can be determined depending on the desired level of spurious suppression. In other aspects, α can also be considered a manufacturing tolerance. Note that the wavelength of 6.1 GHz in vacuum and air, i.e., λs, is approximately 49 mm. Therefore, 0.23 λs corresponds to approximately 11.3 mm.

[0048] The first stub 8 is a linear conductor connected to the feeder line 7 at the first branch point 71. The other end of the first stub 8 is an open end. In other words, the end of the first stub 8 that is not connected to the feeder line 7 is not connected to any other electrical components.

[0049] The width of the first stub 8 is set to, for example, 1 mm or 2 mm. The first stub 8 may be about 0.5 mm to 1.5 mm thicker than the feed line 7. The thicker the first stub 8, the more the inductance per unit length can be reduced, and it can be expected that current will flow more easily through the first stub 8. Of course, the first stub 8 may have the same width as the feed line 7. In addition, the first stub 8 may be about 0.5 mm to 1.5 mm thinner than the feed line 7.

[0050] The length of the first stub 8, that is, the first stub length Ls1, is determined according to the wavelength of the stop frequency, i.e., λs. The first stub length Ls1 is set to a value within the range of 0.25λs±β, where β is a predetermined value such as 0.05λs. Here, β is a parameter indicating the limit value of the first stub length Ls1 at which the desired spurious suppression effect can be obtained. The specific value of β, like α, can be determined depending on the degree to which spurious suppression is desired. In other aspects, β can also be considered as a manufacturing tolerance.

[0051] The first stub 8 is formed in an L-shape by bending a linear element at a right angle. That is, the first stub 8 includes a first lead-out portion 81 extending perpendicularly from the first branch point 71 of the feeder line 7 and a first parallel portion 82 that is a section parallel to the feeder line 7. As an example, the first lead-out portion 81 is formed to extend from the first branch point 71 toward the positive direction of the X-axis. The first parallel portion 82 is formed to extend from the end of the first lead-out portion 81 on the positive side of the X-axis toward the negative direction of the Y-axis. Such a first stub 8 is a conductor element having a shape bent in an L-shape toward the second stub 9, which will be described next. Note that the extension direction of the first stub 8 relative to the feeder line 7 may be toward the negative direction of the X-axis. That is, the first lead-out portion 81 may be formed to extend from the first branch point 71 in the negative direction of the X-axis. Note that the first lead-out portion 81 may be formed obliquely with respect to the feeder line 7. For example, the angle that the first lead-out portion 81 forms with respect to the feeder line 7 may be 45 degrees or 60 degrees. The first stub length Ls1 is the length from the first branch point 71 to the other end. When the first stub 8 has an L-shape as in this embodiment, the sum of the length of the first lead-out portion 81 and the length of the first parallel portion 82 is the first stub length Ls1.

[0052] Because the width of the first stub 8 is sufficiently small compared to the first stub length Ls1, the first separation amount Spf1, which is the separation amount (i.e., distance) between the first parallel portion 82 and the feeder line 7, substantially coincides with the length of the first lead-out portion 81. The value obtained by subtracting the first separation amount Spf1 from the first stub length Ls1 corresponds to the length Lp1 of the first parallel portion 82. The length Lp1 of the first parallel portion 82 corresponds to the bending amount of the first stub 8. The first separation amount Spf1 is set to, for example, 2 mm or 3 mm. The first separation amount Spf1 may be 1 mm. The first separation amount Spf1 may be 5 mm or 10 mm. From the viewpoint of narrowing the stopband, which will be described later, the first separation amount Spf1 is preferably set to 5 mm or less. The first parallel portion 82 is an optional element for obtaining a more suitable stopband. The first stub 8 may be linear.

[0053] The second stub 9 is a linear conductor connected to the feeder line 7 at the second branch point 72. The other end of the second stub 9 is an open end. In other words, the end of the second stub 9 that is not connected to the feeder line 7 is not connected to any other electrical components. The second stub 9 is also formed in an L-shape. The second stub 9 is an element that forms a pair with the first stub 8. The second stub 9 is connected to the feeder line 7 in an orientation obtained by rotating the first stub 8 by 180 degrees.

[0054] That is, the second stub 9 includes a second lead-out portion 91 extending perpendicularly from the second branch point 72 of the feeder line 7 and a second parallel portion 92 that is a section parallel to the feeder line 7. Dimensional parameters of the second stub 9, such as the length and width, can be the same as those of the first stub 8. For example, the second stub length, which is the length of the second stub 9, is set to a value within the range of 0.25λs±β. Furthermore, the second separation amount, which is the distance between the second parallel portion 92 and the feeder line 7, is the same as the first separation amount Spf1. The second stub length is the length from the second branch point 72 to the other end. When the second stub 9 has an L-shape, as in this embodiment, the second stub length refers to the sum of the lengths of the second lead-out portion 91 and the second parallel portion 92. Hereinafter, the second separation amount and the first separation amount Spf1 will be collectively referred to as separation amount Spf. Similarly, the lengths of the second stub 9 and the first stub 8 are also collectively referred to as stub length Ls. In this disclosure, when there is no need to distinguish between the first stub 8 and the second stub 9, they are also collectively referred to as stubs. The first branch point 71 and the second branch point 72 may also be collectively referred to as branch points. If the feeder line 7 is considered to be a main line, the first stub 8 and the second stub 9 correspond to branch lines.

[0055] In this embodiment, the feeder line 7 is formed linearly along the Y-axis. This configuration corresponds to a configuration in which a section from a first branch point 71 to a second branch point 72, which will be described next, is formed linearly. As a modified example, the feeder line 7 may have a shape that is bent at one or more points, as will be described later. For example, the feeder line 7 may have one or more bent portions, such as an L-shape or a meander shape.

[0056] <Supplementary information> As described above as an embodiment, the configuration in which the first stub 8 and the second stub 9 are bent near their bases and formed along the feed line 7 will be referred to as the first example hereinafter. On the other hand, the first stub 8 and the second stub 9 may be linear as shown in Fig. 4. The configuration in which the first stub 8 and the second stub 9 are set linearly as shown in Fig. 4 will be referred to as the second example.

[0057] Furthermore, the first stub 8 and the second stub 9 may be L-shaped, with each stub bent near its midpoint, as shown in Fig. 5. The configuration shown in Fig. 5 is an intermediate configuration between the first and second embodiments, and for convenience, will be referred to as the third embodiment. The third embodiment is conceived as a configuration in which the stubs shown in the first embodiment are bent in directions that approach each other at a point approximately 0.125 λs from the branch point.

[0058] <Effects of the above antenna structure> Here, the effects of the antenna structure of the above embodiment will be explained using Fig. 6. Here, the operating principle of this embodiment will be explained using the second example, but the first and third examples also have the same operation and effects as the second example.

[0059] In the second embodiment, the first stub 8 has a length of approximately 0.25 λs, and therefore the current distribution shown in Fig. 6A is formed in the first stub 8 and the feed line 7 at the stoppage frequency. Here, since the branch point interval Ds is 0.25 λs, the second branch point 72 can correspond to a node of the current distribution formed by the first stub 8. In other words, the second branch point 72 is located at a high resistance point created by the first stub 8.

[0060] Due to the above circumstances, when viewed from the current flowing from the communication IC 5 to the second branch point 72, the impedance of the path from the second branch point 72 to the first branch point 71 appears relatively higher than that of the second stub 9. FIG. 6B conceptually shows the relationship in magnitude of the impedance of each path as viewed from the second branch point 72. Because current flows in the direction of lower resistance, most of the signal at the stop frequency flows toward the second stub 9, as shown in FIG. 6C. In other words, by making the first stub 8 0.25 λs long and providing the second stub 9 at a position 0.25 λs away from the first stub 8, it is possible to prevent the current at the stop frequency from flowing into the antenna 6.

[0061] As described above, according to the configuration of the second embodiment, two stubs, the first stub 8 and the second stub 9, are arranged at a predetermined interval, and due to the interaction between these two stubs, the electrical energy of the stop frequency is consumed in the second stub 9 and its vicinity. This makes it possible to reduce the intensity of spurious radiation. Furthermore, in the first and third embodiments, the first stub 8 and the second stub 9 are arranged at the same length and interval as in the second embodiment, and therefore similar effects are achieved through similar operations.

[0062] Next, the effects of the first embodiment will be explained using first and second comparative configurations. The first comparative configuration is a configuration having only one linear stub, as shown in FIG. 7. The second comparative configuration is a configuration having two linear stubs formed in opposite directions from the same location, as shown in FIG. 8. In the figure, 8x and 9x indicate stubs in the comparative configuration. Stubs 8x and 9x are linear conductor patterns with a length of 0.25 λs. The pattern width itself is set to be the same as that of the first stub 8, etc.

[0063] 9 is a graph showing the results of simulating S21 for each frequency for each of the first embodiment, the first comparative configuration, and the second comparative configuration. S21 is one of the S (Scattering) parameters and is a parameter indicating the transmission coefficient from the input terminal to the output terminal, in other words, the insertion loss. The larger the absolute value of S21, in other words, the further down the graph you go, the greater the loss. Therefore, the larger the absolute value of S21, the better the signal blocking function.

[0064] In the graph shown in FIG. 9, the solid line indicates S21 for each frequency in the first embodiment, and the dashed-dotted line indicates S21 for each frequency in the first comparative configuration. The two-dot-dashed line indicates S21 for each frequency in the second comparative configuration. The target value for S21 is set to, for example, -15 dB. Of course, the target value for S21 may be set to, for example, -10 dB depending on regulations. In this disclosure, the frequency range in which S21 achieves the target level is referred to as the stop band, and its width is referred to as the stop bandwidth. In the figure, Fs indicates the stop frequency, and Foc indicates the center frequency of the frequency band used. The frequency band hatched with a dot pattern corresponds to the fifth channel of UWB communication, i.e., the frequency band used in this embodiment.

[0065] As shown in Figure 9, in all configurations, S21 is -15 dB or less at the target stop frequency (Fs), and the target spurious emissions can be suppressed. However, in the first comparative configuration, which is the simplest configuration, the stop bandwidth is wide (approximately 1 GHz), as shown by the dashed-dotted line in the graph, and it overlaps with the operating frequency band. In other words, in the first comparative configuration, the signal level in the operating frequency band is also suppressed.

[0066] In the second comparative configuration, the stop bandwidth exceeds 2 GHz, as indicated by the two-dot chain line, and the signal level in the operating frequency band is also suppressed. Furthermore, in the second comparative configuration, the peak frequency is shifted approximately 900 MHz higher than the target stop frequency. The peak frequency refers to the frequency at which the best signal level suppression function is achieved. While it is possible to move the peak frequency closer to the stop frequency in the second comparative configuration by lengthening the stubs 8x and 9x, the stop bandwidth itself cannot be narrowed.

[0067] In contrast to the first and second comparative configurations, the configuration of the first embodiment has a loss level of nearly 20 dB for signals at the stop frequency, and a loss level of 10 dB or less for signals in a nearby operating frequency band. That is, the configuration of the first embodiment operates as a narrow-band filter for the target frequency. In this way, the configuration of the first embodiment makes it possible to pass signals in the operating frequency band while blocking signals at stop frequencies close to the operating frequency. In other words, the first embodiment functions as a local band-stop filter circuit. The first embodiment is suitable in cases where unacceptable spurious signals occur near the operating frequency.

[0068] FIG. 10 shows a comparison of S21 at each frequency between the first and second embodiments. The configuration of the second embodiment, as shown in FIG. 10, achieves the blocking effect at the stop frequency, but the stop bandwidth is larger than that of the first embodiment. On the other hand, the third embodiment can achieve a stop bandwidth intermediate between the first and second embodiments. This means that the stop bandwidth can be narrowed (narrowed) by increasing the bending amount of the first stub 8 and the second stub 9. In other words, according to the configuration of the above embodiment, the stop bandwidth can be adjusted by adjusting the bending amount of the first stub 8 and the second stub 9, making it possible to attenuate only signals of the desired frequency (i.e., locally). As a result, it is possible to suppress spurious radiation intensity while maintaining communication performance. The third embodiment corresponds to a configuration in which the stub bending amount is set to 0%, while the first embodiment corresponds to a configuration in which the stub bending amount is set to approximately 95%.

[0069] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, various modifications other than those described below can be implemented without departing from the gist of the present disclosure. For example, the various supplements and modifications described below can be implemented in appropriate combinations as long as no technical contradictions arise. Note that components having the same functions as the components described above are given the same reference numerals, and their description may be omitted. Furthermore, when only a portion of the configuration is mentioned, the above description can be applied to the other portions.

[0070] [Variation (1)] The feeder line 7 may be bent multiple times as shown in FIG. 11 . The first parallel portion 82 and the second parallel portion 92 may also have a bent shape to match the shape of the feeder line 7. The branch point interval Ds in this disclosure is the distance along the feeder line 7. The section of the feeder line 7 from the first branch point 71 to the second branch point 72 may be formed in a meandering, triangular, or sinusoidal wave shape. These configurations make it possible to shorten the distance from the communication IC 5 to the antenna 6 while ensuring the length required to set the branch point interval Ds to 0.25λs. In other words, the wireless device 100 can be made smaller.

[0071] In a configuration in which the bending amount of each stub is set to 51% or more, the branch point distance Ds is also 0.25λs, and therefore at least a portion of the first parallel portion 82 and the second parallel portion 92 face each other with the feed line 7 in between. In other words, the present disclosure also includes a configuration in which the first parallel portion 82 and the second parallel portion 92 are formed to face each other with the feed line 7 in between.

[0072] The first stub 8 and the second stub 9 may be L-shaped and bent in opposite directions, in other words, in directions away from each other, as shown in Fig. 12. Furthermore, the first parallel portion 82 and the second parallel portion 92 may have multiple bends, as shown in Fig. 13. Each stub may be formed in a meandering, triangular, or sinusoidal wave shape.

[0073] The second stub 9 may be set to be longer than the first stub 8 by a predetermined amount, as shown in FIG. 14 . Alternatively, the width of the second stub 9 may be set to be greater than that of the first stub 8. This setting is expected to have the effect of making it easier for current to flow into the second stub 9. Furthermore, the first stub 8 and the second stub 9 may extend in the same direction from the feed line 7. In addition, the first stub 8 and the second stub 9 do not necessarily have to be formed on the same plane as the feed line 7, and may be arranged above and below the feed line 7, respectively.

[0074] [Variation (2)] In the wireless device 100, a radio wave blocking section Rs may be locally formed in a portion covering the filter section on the inner surface of the upper case 2 made of a radio wave transparent material, as shown in FIG. 15 . The filter section here is a section in which the first stub 8 and the second stub 9 are formed, and can also be called a stub-forming section. The section from the first branch point 71 to the second branch point 72 can be understood as the filter section. The radio wave blocking section Rs is configured to block the propagation of radio waves, and can be, for example, a radio wave blocking film, a metal plate, or a metal mesh. The radio wave blocking section Rs can also be called a radio wave absorbing section that absorbs radio waves.

[0075] According to the above configuration, even if the second stub 9 etc. operates as a monopole antenna at the rejection frequency, it is possible to reduce the risk of the radio waves being emitted outside the device. Note that the above embodiment etc. reduces the possibility that a signal at the rejection frequency will propagate to the antenna 6, and ultimately radiate a signal at the rejection frequency from the antenna 6. Furthermore, because the portion of the upper case 2 that covers the antenna 6 is transparent to radio waves, it is also possible to reduce the risk of communication performance degradation.

[0076] The portion of the upper case 2 that covers the antenna 6 may be made of a radio wave-transmitting material (e.g., resin), while the portion that overlaps with the filter section may be made of a radio wave-blocking material (e.g., a metal plate). The metal portion that covers the filter section corresponds to the radio wave blocking section Rs.

[0077] [Variation (3)] The radio device 100 may include a stub set corresponding to each of a plurality of rejection frequencies. A stub set includes one first stub 8 and one second stub 9, each having a length corresponding to the wavelength of the rejection frequency.

[0078] For example, as shown in Fig. 16, the radio device 100 may include a low-frequency stub set StL having a length corresponding to the wavelength of a relatively low first stop frequency and a high-frequency stub set StH having a length corresponding to the wavelength of a relatively high second stop frequency. For example, the first stop frequency is 6.1 GHz and the second stop frequency is 12.2 GHz. Here, as an example, the second stop frequency is set to twice the value of the first stop frequency, but this is not limiting. The second stop frequency may be a frequency that is not an integer multiple of the first stop frequency (i.e., unrelated). The first and second stop frequencies may be determined in consideration of the electrical characteristics of the communication IC 5 and the antenna 6, as well as laws and regulations.

[0079] The high-frequency stub set StH is arranged on the feeder line 7, for example, closer to the antenna 6 than the low-frequency stub set StL. In other words, a signal from the communication IC 5 is configured to reach the antenna 6 through the low-frequency filter section and the high-frequency filter section. The low-frequency filter section is a section where the low-frequency stub set StL is added to the feeder line 7. The high-frequency filter section is a section where the high-frequency stub set StH is added to the feeder line 7.

[0080] The high-frequency stub set StH includes a first high-frequency stub 8H and a second high-frequency stub 9H. The first high-frequency stub 8H and the second high-frequency stub 9H each have a length corresponding to the wavelength of the second stop frequency. For example, the first high-frequency stub 8H and the second high-frequency stub 9H have lengths that are within ±10% of 0.25 times the wavelength of the second stop frequency. The first high-frequency stub 8H and the second high-frequency stub 9H extend in opposite directions from each other with respect to the feed line 7. The first high-frequency stub 8H and the second high-frequency stub 9H each have an L-shape that is bent toward the other. The first high-frequency stub 8H and the second high-frequency stub 9H each have parallel portions 82H and 92H.

[0081] The low frequency stub set StL includes a first low frequency stub 8L and a second low frequency stub 9L. The first low frequency stub 8L and the second low frequency stub 9L each have a length corresponding to the wavelength of the first stop frequency. For example, the first low frequency stub 8L and the second low frequency stub 9L are set to lengths within ±10% of 0.25 times the wavelength of the first stop frequency.

[0082] The first low-frequency stub 8L extends in the same direction as the first high-frequency stub 8H. The second low-frequency stub 9L extends in the same direction as the second high-frequency stub 9H. That is, the first low-frequency stub 8L and the second low-frequency stub 9L also extend in opposite directions relative to the feed line 7. Additionally, the first low-frequency stub 8L and the second low-frequency stub 9L have bent shapes bent toward the other. The first low-frequency stub 8L and the second low-frequency stub 9L have parallel portions 82L and 92L, respectively. The bending amount of each stub included in the low-frequency stub set StL and the high-frequency stub set StH is set to approximately 90 to 95%.

[0083] With the above configuration, the wireless device 100 can suppress the spurious radiation intensity of two frequencies. Fig. 17 is a graph showing the simulation results of S21 for each frequency of the above configuration. In the figure, Fs1 denotes the first stop frequency, and Fs2 denotes the second stop frequency.

[0084] Comparing the graph shape for the 6 GHz band in FIG. 17 with the graph shape for the first embodiment shown in FIG. 9, it can be seen that the two are nearly identical. This means that even if a stub set for a second stop frequency is placed next to a stub set for a first stop frequency, it has almost no effect on the operation of the stub set for the first stop frequency. In other words, this suggests that multiple stub sets can be treated as independent entities. The configuration of the present disclosure has the advantage of being able to flexibly accommodate a variety of stop frequencies.

[0085] 18 , the first high-frequency stub 8H may be formed so as to cover the vicinity of the bent portion of the first low-frequency stub 8L from the outside. This configuration corresponds to a configuration in which a portion of the first low-frequency stub 8L is formed using a region sandwiched between the first high-frequency stub 8H and the feed line 7. Similarly, the second low-frequency stub 9L may be formed so as to cover the vicinity of the bent portion of the second high-frequency stub 9H from the outside. This configuration corresponds to a configuration in which a portion of the second high-frequency stub 9H is formed using a region sandwiched between the second low-frequency stub 9L and the feed line 7. According to the above-described configuration in which the low-frequency stub set StL and the high-frequency stub set StH are formed in a manner in which they partially overlap in the X-axis direction, the length of the feed line 7 in the Y-axis direction can be reduced.

[0086] In the above, the high-frequency stub set StH is arranged closer to the antenna 6 than the low-frequency stub set StL, but this is not limiting. The low-frequency stub set StL may also be arranged closer to the antenna 6 than the high-frequency stub set StH. Simulation results have confirmed that S21 for each frequency does not change even if the arrangement order is changed.

[0087] [Variation (4)] The antenna 6 may be in the shape of a home plate as shown in FIG. 19(A), or in the shape of an ellipse as shown in FIG. 19(B). It may also be in the shape of a combination of a rectangle and a semicircle as shown in FIG. 19(C). The antenna 6 may have a notch on the edge as shown in FIG. 19(D), or may have a slit formed inside as shown in FIG. 19(F). The wireless device 100 may be equipped with an antenna 6 for high frequencies and an antenna 6 for low frequencies. A plurality of antennas 6 corresponding to a plurality of channels to be transmitted and received may be connected to the feeder line 7.

[0088] [Variation (5)] The wireless device 100 may be configured to be capable of transmitting and receiving radio waves in a frequency band used in short-range wireless communication such as Bluetooth (registered trademark) and Wi-Fi (registered trademark). Accordingly, the antenna 6 may be configured to be capable of transmitting and receiving radio waves in a band from 2400 MHz to 2500 MHz (hereinafter referred to as the 2.4 GHz band) or a frequency belonging to the 5 GHz band. In other words, the frequency used may be 2.4 GHz or 5 GHz.

[0089] [Additional remarks] The present disclosure is not limited to communication devices for vehicles, but can also be applied to various devices equipped with wireless communication functions, such as smartphones, tablet terminals, and wireless tags. For example, the configuration of the present disclosure can be applied to a wireless communication module 200 of a portable terminal carried by a user. Note that the portable terminal here refers to a general-purpose information processing terminal equipped with wireless communication functions, such as a smartphone. As shown in FIG. 20 , the portable terminal can include a display 300, an operation unit 400, and the like, in addition to the wireless communication module 200. The operation unit 400 is a touch panel, a switch, or the like. [Explanation of symbols]

[0090] 100 radio, 1 lower case, 2 upper case, 3 circuit board, 5 communication IC (communication circuit), 6 antenna, 7 power supply line, 8 first stub, 8L low frequency first stub, 8H high frequency first stub, 9L low frequency second stub, 9H high frequency second stub, 9 second stub, 71 first branch point, 72 second branch point, 81 first lead-out portion, 82 first parallel portion, 91 second lead-out portion, 92 second parallel portion, StH high frequency stub set, StL low frequency stub set

Claims

1. an antenna (6) that operates at a working frequency that is a frequency used for communication; a circuit (5) for outputting a signal to be transmitted from the antenna; a feeder line (7) for connecting the antenna and the circuit; a first stub (8) which is a linear conductor formed so as to branch off from the power supply line; a second stub (9) which is a linear conductor connected to the power supply line at a second branch point different from a first branch point which is a connection point between the power supply line and the first stub; the second branch point is disposed on the power supply line closer to the circuit than the first branch point, When the wavelength of a stop frequency, which is a frequency to be stopped, is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the interval between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs, In addition to a low-frequency stub set (StL) which is a set of the first stub and the second stub having a length and a branch point interval according to the wavelength of the first stop frequency, a high-frequency stub set (StH) that is a set of the first stub and the second stub, the set having a length and an interval corresponding to a wavelength of the second stop frequency that is higher than the first stop frequency; The wireless communication device, wherein the high-frequency stub set is disposed closer to the antenna than the low-frequency stub set.

2. 2. The wireless communication device according to claim 1, The wireless communication device, wherein the first stub and the second stub extend in opposite directions from the feed line.

3. 3. The wireless communication device according to claim 1, A wireless communication device in which the section of the power supply line from the first branch point to the second branch point is formed in a straight line.

4. 4. The wireless communication device according to claim 1, The wireless communication device, wherein the first stub and the second stub each have a bent shape so as to have a portion parallel to the feed line.

5. 5. The wireless communication device according to claim 4, a first parallel portion (82) of the first stub, which is a section parallel to the feed line, is spaced apart from the feed line by a distance of 5 mm or less; A wireless communication device in which a distance between a second parallel portion (92), which is a section of the second stub that is parallel to the feed line, and the feed line is set to 5 mm or less.

6. 6. The wireless communication device according to claim 1, A wireless communication device, wherein the distance between the first branch point and the second branch point is set to be equal to or greater than 0.2 λs and less than 0.3 λs.

7. 7. The wireless communication device according to claim 1, a first low-frequency stub (8L) which is the first stub constituting the low-frequency stub set and a second low-frequency stub (9L) which is the second stub constituting the low-frequency stub set extend in opposite directions to each other with respect to the feed line, a high-frequency first stub (8H) which is the first stub constituting the high-frequency stub set extends in the same direction as the low-frequency first stub with respect to the feed line, a high-frequency second stub (9H) which is the second stub constituting the high-frequency stub set extends in the same direction as the low-frequency second stub with respect to the feed line, the first stub for low frequency and the first stub for high frequency have an L-shape bent in a direction in which the circuit exists, the second stub for low frequency and the second stub for high frequency have an L-shape bent toward the direction in which the antenna is present, a portion of the second high-frequency stub is formed in a region sandwiched between the second low-frequency stub and the feed line, A wireless communication device, wherein a portion of the first low-frequency stub is formed using a region sandwiched between the first high-frequency stub and the feed line.

8. 8. The wireless communication device according to claim 1, for implementing ultra-wideband wireless communication in which the width of one channel is 450 MHz or more.

9. 9. The wireless communication device according to claim 1, The operating frequency includes 6.5 GHz or 8.0 GHz, The wireless communication device, wherein the rejection frequency includes 6.1 GHz or 12.2 GHz.

10. an antenna (6) that operates at a working frequency that is a frequency used for communication; a circuit (5) for outputting a signal to be transmitted from the antenna; a feeder line (7) for connecting the antenna and the circuit; a first stub (8) which is a linear conductor formed so as to branch off from the power supply line; a second stub (9) which is a linear conductor connected to the power supply line at a second branch point different from a first branch point which is a connection point between the power supply line and the first stub; the second branch point is disposed on the power supply line closer to the circuit than the first branch point, When the wavelength of a stop frequency, which is a frequency to be stopped, is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the interval between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs, a low-frequency stub set (StL) that is a set of the first stub and the second stub, the set having a length and a branch point interval corresponding to the wavelength of the first stop frequency; a high-frequency stub set (StH) which is a set of the first stub and the second stub, the set having a length and an interval corresponding to a wavelength of a second stop frequency which is higher than the first stop frequency, The wireless communication device, wherein the low-frequency stub set is disposed closer to the antenna than the high-frequency stub set.

11. A mobile terminal with a wireless communication function carried by a user, As a wireless communication module that provides the wireless communication function, an antenna (6) that operates at a working frequency that is a frequency used for communication; a circuit (5) for outputting a signal to be transmitted from the antenna; a feeder line (7) for connecting the antenna and the circuit; a first stub (8) which is a linear conductor formed so as to branch off from the power supply line; a second stub (9) which is a linear conductor connected to the power supply line at a second branch point different from a first branch point which is a connection point between the power supply line and the first stub; the second branch point is disposed on the power supply line closer to the circuit than the first branch point, When the wavelength of a stop frequency, which is a frequency to be stopped, is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the interval between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs, a low-frequency stub set (StL) that is a set of the first stub and the second stub, the set having a length and a branch point interval corresponding to the wavelength of the first stop frequency; a high-frequency stub set (StH) which is a set of the first stub and the second stub, the set having a length and an interval corresponding to a wavelength of a second stop frequency which is higher than the first stop frequency, A mobile terminal including the wireless communication module, wherein the high-frequency stub set is arranged closer to the antenna than the low-frequency stub set.

12. A mobile terminal with a wireless communication function carried by a user, As a wireless communication module that provides the wireless communication function, an antenna (6) that operates at a working frequency that is a frequency used for communication; a circuit (5) for outputting a signal to be transmitted from the antenna; a feeder line (7) for connecting the antenna and the circuit; a first stub (8) which is a linear conductor formed so as to branch off from the power supply line; a second stub (9) which is a linear conductor connected to the power supply line at a second branch point different from a first branch point which is a connection point between the power supply line and the first stub; the second branch point is disposed on the power supply line closer to the circuit than the first branch point, When the wavelength of a stop frequency, which is a frequency to be stopped, is λs, the length of the first stub is set to a value within 0.25λs±0.1λs, and the interval between the first branch point and the second branch point is set to a value within 0.25λs±0.1λs, a low-frequency stub set (StL) that is a set of the first stub and the second stub, the set having a length and a branch point interval corresponding to the wavelength of the first stop frequency; a high-frequency stub set (StH) which is a set of the first stub and the second stub, the set having a length and an interval corresponding to a wavelength of a second stop frequency which is higher than the first stop frequency, A mobile terminal including the wireless communication module, wherein the low-frequency stub set is disposed closer to the antenna than the high-frequency stub set.

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