Three-way divider includes first transmission line, second transmission line, and third transmission line. First transmission line includes first input-side line and first output-side line, which are connected at first connection point. Second transmission line includes second input-side line and second output-side line, which are connected at second connection point. Third transmission line includes third input-side line and third output-side line, which are connected at third connection point. Each of first transmission line, second transmission line, and third transmission line has an electrical length that is ¼ a wavelength of a second frequency. The first connection point and the second connection point, the third connection point and the second connection point, the first output terminal and the second output terminal, and the third output terminal and the second output terminal are respectively connected via corresponding resistors.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is the U.S. National Phase under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2020/002037, filed on Jan. 22, 2020, which in turn claims the benefit of Japanese Application No. 2019-100276, filed on May 29, 2019, the entire disclosures of which Applications are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a three-way divider.

BACKGROUND ART

In recent years, wireless terminals based on standards such as wireless LAN (Local Area Network) and Bluetooth (registered trademark) are being installed in household appliances such as televisions and audio devices, for example, beyond just information devices such as personal computers. As such, household appliances sometimes communicate wirelessly in a plurality of frequency bands, each corresponding to one of a plurality of standards. Additionally, techniques are known in which an array antenna is used as an antenna used for wireless communication in order to achieve a desired directionality. When such an array antenna is used, it is necessary to divide signals in a plurality of frequency bands for a plurality of antennas. PTL 1, for example, discloses a Wilkinson-type three-way divider capable of three-way division of signals in two frequency bands.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

Technical Problem

There is demand for miniaturization in wireless terminals, and as such, there is demand for miniaturization in dividers provided in wireless terminals.

Accordingly, the present disclosure provides a small three-way divider capable of three-way distribution of signals in two frequency bands.

Solution to Problem

A three-way divider according to one aspect of the present disclosure is a three-way divider that divides a signal three ways. The three-way divider includes: an input terminal into which the signal is input; a first output terminal, a second output terminal, and a third output terminal, each of which outputs a corresponding one of three divided signals obtained by the signal having been divided three ways; a first transmission line, a second transmission line, and a third transmission line that connect the input terminal to the first output terminal, the second output terminal, and the third output terminal, respectively; and a first resistor, a second resistor, a third resistor, and a fourth resistor. The first transmission line includes, in order from a side on which the input terminal is located, a first input-side line and a first output-side line connected in series at a first connection point. The second transmission line includes, in order from the side on which the input terminal is located, a second input-side line and a second output-side line connected in series at a second connection point. The third transmission line includes, in order from the side on which the input terminal is located, a third input-side line and a third output-side line connected in series at a third connection point. Each of the first input-side line, the second input-side line, and the third input-side line has an electrical length that is ¼ a wavelength of a first frequency. Each of the first transmission line, the second transmission line, and the third transmission line has an electrical length that is ¼ a wavelength of a second frequency that is lower than the first frequency. The first connection point and the second connection point are connected via the first resistor, the third connection point and the second connection point are connected via the second resistor, the first output terminal and the second output terminal are connected via the third resistor, and the third output terminal and the second output terminal are connected via the fourth resistor.

Advantageous Effect of Invention

According to the present disclosure, a small three-way divider capable of three-way division of signals in two frequency bands can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the present disclosure will be described hereinafter with reference to the drawings.

Note that the following embodiments describe comprehensive or specific examples of the present disclosure. The numerical values, shapes, materials, constituent elements, arrangements and connection states of constituent elements, steps, orders of steps, and the like in the following embodiments are merely examples, and are not intended to limit the present disclosure.

Additionally, the drawings are schematic diagrams, and are not necessarily exact illustrations. In the drawings, constituent elements which are the same are given the same reference signs.

A three-way divider according to Embodiment 1 will be described.

First, the configuration of a three-way divider according to the present embodiment will be described with reference toFIG. 1.FIG. 1is a schematic diagram illustrating the configuration of three-way divider6according to the present embodiment.

Three-way divider6according to the present embodiment is a divider which divides signals in a first frequency band and a second frequency band three ways.

As illustrated inFIG. 1, three-way divider6includes input terminal T0, first output terminal T1, second output terminal T2, third output terminal T3, first transmission line L1, second transmission line L2, third transmission line L3, first resistor R1, second resistor R2, third resistor R3, and fourth resistor R4.

Input terminal T0is a terminal into which a signal is input. In the present embodiment, a signal in a first frequency band including a first frequency, and a signal in a second frequency band including a second frequency which is lower than the first frequency, are input to input terminal T0. The first frequency band and the second frequency band are not particularly limited. In the present embodiment, the first frequency band and the second frequency band are 5 GHz and 2.4 GHz bands, respectively.

First output terminal T1, second output terminal T2, and third output terminal T3are terminals which output three divided signals obtained by a signal input from input terminal T0being divided three ways. In the present embodiment, the three divided signals, which have the same phase, are output from first output terminal T1, second output terminal T2, and third output terminal T3, respectively.

First transmission line L1, second transmission line L2, and third transmission line L3are lines which connect input terminal T0to first output terminal T1, second output terminal T2, and third output terminal T3, respectively.

First transmission line L1includes, from the input terminal T0side, first input-side line L11and first output-side line L12, which are connected in series by first connection point CP1. Second transmission line L2includes, from the input terminal T0side, second input-side line L21and second output-side line L22, which are connected in series by second connection point CP2. Third transmission line L3includes, from the input terminal T0side, third input-side line L31and third output-side line L32, which are connected in series by third connection point CP3.

The electrical length of each of first input-side line L11, second input-side line L21, and third input-side line L31is ¼ the wavelength of the first frequency (Λa/4). The electrical length of each of first transmission line L1, second transmission line L2, and third transmission line L3is ¼ the wavelength of the second frequency, which is lower than the first frequency (Λb/4).

First resistor R1is connected between first connection point CP1and second connection point CP2; second resistor R2, between third connection point CP3and second connection point CP2; third resistor R3, between first output terminal T1and second output terminal T2; and fourth resistor R4, between third output terminal T3and second output terminal T2. First resistor R1, second resistor R2, third resistor R3, and fourth resistor R4are absorption resistors. For example, when an impedance on an output side of three-way divider6is 50Ω, resistance values of third resistor R3and fourth resistor R4are twice the outside-side impedance, namely 100Ω, and resistance values of first resistor R1and second resistor R2are greater than or equal to twice and less than or equal to four times the output-side impedance, namely greater than or equal to 100Ω and less than or equal to 200Ω. In the present embodiment, the resistance values of first resistor R1, second resistor R2, third resistor R3, and fourth resistor R4are the same, each being 100Ω.

Each transmission line can be formed, for example, from a conductive member or the like patterned on a main surface of an insulated substrate. Each transmission line is formed, for example, from a metal film such as copper film.

By having the configuration described thus far, three-way divider6according to the present embodiment can divide signals in a first frequency band and a second frequency band three ways.

1-2. Actions and Effects

Actions and effects of three-way divider6according to the present embodiment will be described next with reference toFIG. 2, in comparison with a three-way divider according to a comparative example.FIG. 2is a schematic diagram illustrating the configuration of three-way divider1006according to the comparative example. Three-way divider1006according to the comparative example is a Wilkinson-type three-way divider. As illustrated inFIG. 2, like three-way divider6according to the present embodiment, three-way divider1006includes input terminal Ta0, first output terminal Ta1, second output terminal Ta2, third output terminal Ta3, first transmission line La1, second transmission line La2, and third transmission line La3.

First transmission line La1includes, from the input terminal Ta0side, first input-side line La11and first output-side line La12, which are connected in series by first connection point CPa1. Second transmission line La1includes, from the input terminal Ta0side, second input-side line La21and second output-side line La22, which are connected in series by second connection point CPa2. Third transmission line La3includes, from the input terminal Ta0side, third input-side line La31and third output-side line La32, which are connected in series by third connection point CPa3. Here, the electrical length of each of first input-side line La11, second input-side line La21, and third input-side line La31is ¼ the wavelength of the first frequency (Λa/4).

However, in three-way divider1006according to the comparative example, the electrical length of each of first output-side line La12, second output-side line La22, and third output-side line La32is ¼ the wavelength of the second frequency (Λb/4), which is different from the transmission lines in three-way divider6according to the present embodiment.

Additionally, three-way divider1006according to the comparative example includes two absorption resistors R0, which are respectively connected between first output terminal Ta1and second output terminal Ta2and between third output terminal Ta3and second output terminal Ta2. Absorption resistors are connected neither between first connection point CPa1and second connection point CPa2, nor between third connection point CPa3and second connection point CPa2.

In this manner, in the Wilkinson-type three-way divider1006, it is necessary to set the electrical length of each of first output-side line La12, second output-side line La22, and third output-side line La32, which respectively correspond to first output-side line L12, second output-side line L22, and third output-side line L32of three-way divider6according to the present embodiment, to a wavelength ¼ the second frequency. However, with three-way divider6according to the present embodiment, the electrical length of each of first transmission line L1, second transmission line L2, and third transmission line L3can be set to ¼ the wavelength of the second frequency by connecting absorption resistors between first connection point CP1and second connection point CP2and between third connection point CP3and second connection point CP2. Accordingly, with three-way divider6according to the present embodiment, the electrical lengths of first transmission line L1, second transmission line L2, and third transmission line L3can be made smaller than those in the Wilkinson-type three-way divider1006by ¼ the wavelength of the first frequency.

As described thus far, with three-way divider6according to the present embodiment, a three-way divider which can divide signals in two frequency bands three ways and which is smaller than past three-way dividers can be realized.

An antenna module according to Embodiment 2 will be described. The antenna module according to the present embodiment is an application example of three-way divider6according to Embodiment 1.

First, the configuration of the antenna module according to the present embodiment will be described with reference toFIGS. 3 and 4.FIGS. 3 and 4are first and second plan views illustrating the configuration of antenna module100according to the present embodiment.FIG. 3is a plan view illustrating one main surface141of board140of antenna module100in plan view.FIG. 4is a plan view of constituent elements disposed on a main surface of board140on the opposite side from main surface141, which also indicates edges of board140with dotted lines. Note that inFIGS. 3 and 4, a direction perpendicular to main surface141of board140of antenna module100is assumed to be a Z-axis direction, and two directions which are both perpendicular to the Z-axis direction and to each other are assumed to be an X-axis direction and a Y-axis direction, respectively.

Antenna module100according to the present embodiment is a module including array antenna101and a divider which divides a signal for each of multiband antennas constituting array antenna101. In the present embodiment, antenna module100is a module which communicates wirelessly on the basis of the wireless LAN standard, and transmits and receives signals in the 5 GHz and 2.4 GHz bands, which are the first frequency band and the second frequency band, respectively. Antenna module100includes three-way divider106as a divider. Antenna module100further includes ground electrode190, lines61,62,63,71,72, and73, phase shifter80, grounding interconnects71g,72g, and73g, connector Cn, and control terminal Ts.

Array antenna101is an antenna including a plurality of multiband antennas. In the present embodiment, array antenna101includes three multiband antennas1a,1b, and1c. The three multiband antennas1a,1b, and1cshare board140. The three multiband antennas1a,1b, and1care arranged in the X-axis direction perpendicular to the Y-axis direction of each of currents.

The three multiband antennas1a,1b, and1chave the same configuration. The configuration of multiband antenna1awill be described next with reference toFIG. 5as a representative example of the three multiband antennas1a,1b, and1c.FIG. 5is a plan view illustrating the configuration of multiband antenna1aaccording to the present embodiment.

Multiband antenna1ais an antenna which transmits and receives signals in two frequency bands. In the present embodiment, multiband antenna1atransmits and receives a signal in a first frequency band including a first frequency, and a signal in a second frequency band including a second frequency which is lower than the first frequency. Although the first frequency band and the second frequency band are not particularly limited, in the present embodiment, 5 GHz and 2.4 GHz are used for the first frequency band and the second frequency band, respectively. As such, multiband antenna1acan be used as a dual-band antenna for 5 GHz and 2.4 GHz bands, based on the wireless LAN standard. As illustrated inFIG. 5, multiband antenna1aincludes board140, input terminal16, antenna part10, and grounding part20. In the present embodiment, multiband antenna1afurther includes grounding terminals26.

Board140is a member serving as a base of multiband antenna1a. Note that multiband antennas1a,1b, and1cshare board140. Other constituent elements of antenna module100are also disposed on board140. Board140is a circuit board, and antenna part10and grounding part20are disposed on one main surface141of board140. In the present embodiment, board140is a rectangular plate-shaped dielectric body. Board140is a glass epoxy board, for example.

Input terminal16is a terminal which is disposed on board140into which a signal is input. In the present embodiment, a high-frequency signal transmitted by multiband antenna1ais input to input terminal16. Input terminal16also functions as an output terminal which outputs a high-frequency signal received by multiband antenna1a. In the present embodiment, a signal is input to input terminal16through a via interconnect passing through board140from the main surface on the side of board140opposite from main surface141. Input terminal16is connected to antenna part10.

Grounding terminals26are terminals which are disposed on board140and are grounded. In the present embodiment, grounding terminals26are disposed on main surface141of board140and are connected to grounding part20. In the present embodiment, grounding terminals26are grounded through a via interconnect passing through board140. Although the number of grounding terminals26is not particularly limited, the number is two in the present embodiment.

Antenna part10is a conductive member which is disposed on board140and connected to input terminal16. In the present embodiment, a signal in the first frequency band and a signal in the second frequency band resonate in antenna part10. Radio waves are radiated from antenna part10as a result. Antenna part10includes, in order from the input terminal16side, first low-inductance part11, first high-inductance part12, and first tip part13, which are connected in series. The sum of the electrical lengths of first low-inductance part11, first high-inductance part12, and first tip part13is ¼ the wavelength of the second frequency. As a result, a signal in the second frequency band including the second frequency resonates in antenna part10.

The position where antenna part10is connected to input terminal16is not particularly limited, but in the present embodiment, input terminal16is connected to a grounding part20-side end of first low-inductance part11. To be more specific, input terminal16is disposed only on the grounding part20-side end of first low-inductance part11, and is not provided for first high-inductance part12and first tip part13. Note that the end of first low-inductance part11means, for example, a region corresponding to a range of no greater than 10% of a length in the Y-axis direction of first low-inductance part11from the grounding part20-side end of first low-inductance part11.

In the present embodiment, antenna part10is a conductive member patterned on main surface141of board140, and is formed, for example, from a metal film such as copper film. Additionally, first low-inductance part11, first high-inductance part12, and first tip part13are arranged in the Y-axis direction inFIG. 5. Accordingly, the Y-axis direction inFIG. 5corresponds to a lengthwise direction of antenna part10and a resonation direction of signals in antenna part10. As illustrated inFIG. 5, the widths of first low-inductance part11, first high-inductance part12, and first tip part13(i.e., the dimensions in the direction perpendicular to the resonation direction and in a direction parallel to main surface141of board140) are the same.

First low-inductance part11is a part of antenna part10which is connected to input terminal16. One end of first low-inductance part11is connected to input terminal16, and another end is connected to first high-inductance part12. The electrical length of first low-inductance part11is ¼ the wavelength of the first frequency. First low-inductance part11has a lower inductance than first high-inductance part12. In the present embodiment, first low-inductance part11has a meandering shape, as illustrated inFIG. 5, but has an inductance low enough so that first low-inductance part11does not act as a choke coil with respect to signals in the first frequency band and the second frequency band (e.g., does not inhibit the signals). Providing first low-inductance part11with a meandering shape in this manner makes it possible to reduce the dimension of first low-inductance part11in the resonation direction (i.e., the Y-axis direction inFIG. 5).

First high-inductance part12is a part of antenna part10which is disposed between first low-inductance part11and first tip part13, and has a meandering shape. First high-inductance part12has a higher inductance than first low-inductance part11. In the present embodiment, the meandering shape of first high-inductance part12has a smaller line width and smaller intervals than the meandering shape of first low-inductance part11. This makes the inductance of first high-inductance part12higher than first low-inductance part11. In the present embodiment, first high-inductance part12has a meandering shape in which the line width is 0.1 mm, the intervals are 0.1 mm, the length (the dimension in the Y-axis direction inFIG. 5) is 2.1 mm, and the width (the dimension in the X-axis direction inFIG. 5) is 3 mm. First high-inductance part12acts as a choke coil with respect to signals in the first frequency band. In other words, the effective electrical length of antenna part10with respect to signals in the first frequency band input from input terminal16connected to first low-inductance part11is the electrical length of first low-inductance part11(¼ the wavelength of the first frequency). As a result, a signal in the first frequency band resonates in antenna part10. Note that first high-inductance part12has an inductance low enough so that first high-inductance part12does not act as a choke coil with respect to signals in the second frequency band. Accordingly, first high-inductance part12does not inhibit signals in the second frequency band. As such, signals in the second frequency band resonate in a channel constituted by first low-inductance part11, first high-inductance part12, and first tip part13of antenna part10.

First tip part13is a part of antenna part10located at an end furthest from input terminal16in the resonation direction. Although the shape of first tip part13is not particularly limited, first tip part13is rectangular in the present embodiment. This makes it possible to increase the current density of first tip part13more than if first tip part13has a meandering shape, and the radiation efficiency of radio waves from first tip part13can be increased as a result.

Grounding part20is a conductive member which is disposed on board140and insulated from input terminal16. Grounding part20is disposed at a predetermined distance from antenna part10in the resonation direction. An interval between antenna part10and grounding part20is, for example, greater than 0 and less than or equal to approximately 1 mm. The interval between antenna part10and grounding part20is 0.5 mm in the present embodiment. Additionally, the width of grounding part20(e.g., the dimension in a direction perpendicular to the resonation direction and in a direction parallel to main surface141of board140) is greater than the width of antenna part10.

Grounding part20includes second low-inductance part21, second high-inductance part22, and second tip part23, which are connected in series in order from the input terminal16side. In the present embodiment, grounding part20is a conductive member patterned on main surface141of board140, and is formed, for example, from a metal film such as copper film. Additionally, second low-inductance part21, second high-inductance part22, and second tip part23are arranged in the Y-axis direction inFIG. 5.

The total electrical length of second low-inductance part21, second high-inductance part22, and second tip part23is set so that the directionality of radio waves in the second frequency, radiated from antenna part10, broadens along a plane parallel to the lengthwise direction of antenna part10(i.e., the Y-axis direction inFIG. 5) (in other words, a plane parallel to a ZX plane inFIG. 5). A relationship between that total electrical length and the directionality of radio waves in the second frequency can be found through simulations or the like, for example.

Grounding part20is connected to grounding terminals26. The positions where grounding terminals26are disposed are not particularly limited, but in the present embodiment, grounding terminals26are disposed on an antenna part10-side (i.e., an input terminal16-side) end of second low-inductance part21. To be more specific, the two grounding terminals26are disposed only on the antenna part10-side end of second low-inductance part21, and are not provided for second high-inductance part22and second tip part23. Note that the end of second low-inductance part21means, for example, a region corresponding to a range of no greater than 10% of a length in the resonation direction of second low-inductance part21(the Y-axis direction inFIG. 5) from the antenna part10-side end of second low-inductance part21.

Second low-inductance part21is a part of grounding part20which is disposed at a location closest to antenna part10. One end of second low-inductance part21is connected to grounding terminals26, and another end is connected to second high-inductance part22. The electrical length of second low-inductance part21is set so that the directionality of radio waves in the first frequency, radiated from antenna part10, broadens along a plane perpendicular to the lengthwise direction of antenna part10. A relationship between the electrical length of second low-inductance part21and the directionality of radio waves in the first frequency can be found through simulations or the like, for example. Additionally, a line width and pitch of meandering-shaped parts of two high-inductance elements22aand22bmay be the same as a line width and pitch of meandering-shaped parts of first high-inductance part12of antenna part10. This makes it possible to simplify the design of multiband antenna1a.

Second low-inductance part21has a lower inductance than second high-inductance part22. In the present embodiment, as illustrated inFIG. 5, second low-inductance part21is rectangular, but the shape of second low-inductance part21is not limited thereto. Second low-inductance part21may be designed with any shape as long as the inductance of second low-inductance part21is low enough so that second low-inductance part21does not act as a choke coil with respect to signals in the first frequency and the second frequency.

Second high-inductance part22is a part of grounding part20which is disposed between second low-inductance part21and second tip part23, and has a meandering shape. Second high-inductance part22has a higher inductance than second low-inductance part21. Second high-inductance part22acts as a choke coil with respect to signals in the first frequency band. In other words, the effective electrical length of grounding part20with respect to signals in the first frequency band induced by second low-inductance part21is the electrical length of second low-inductance part21. Additionally, second high-inductance part22has an inductance low enough so that second high-inductance part22does not act as a choke coil with respect to signals in the second frequency band. Accordingly, second high-inductance part22does not inhibit signals in the second frequency band. As such, the effective electrical length of grounding part20with respect to signals in the second frequency band includes the electrical length of a channel including second high-inductance part22of grounding part20.

Second high-inductance part22includes the two high-inductance elements22aand22b, which are connected to both ends of second low-inductance part21in the width direction thereof (the X-axis direction inFIG. 5). Opening22cis formed between the two high-inductance elements22aand22b. In other words, a region in which a conductive member is not disposed is formed between the two high-inductance elements22aand22b. Note that it is acceptable for no opening to be provided in a region of board140corresponding to opening22c. Each of the two high-inductance elements22aand22bhas a meandering shape. The two high-inductance elements22aand22bhave structures which are inverted horizontally with respect to each other. As such, the two high-inductance elements22aand22bhave the same electrical length. Note that in the present embodiment, the electrical length of second high-inductance part22of multiband antenna1ais defined by the electrical length of one of the two high-inductance elements22aand22b.

In second low-inductance part21, current corresponding to transmitted and received radio waves flows mainly along edges of second low-inductance part21, as indicated by the broken line arrows inFIG. 5. Thus by disposing the two high-inductance elements22aand22bat the ends of grounding part20in the width direction, the current indicated by the broken line arrows inFIG. 5passes through one of high-inductance element22aand high-inductance element22b.

Second tip part23is a part of grounding part20located at an end furthest from antenna part10in the resonation direction. Although the shape of second tip part23is not particularly limited, second tip part23is rectangular in the present embodiment. Additionally, second tip part23connects the two high-inductance elements22aand22bof second high-inductance part22. As such, in second tip part23, a current component flowing to second tip part23from the two high-inductance elements22aand22bcan be canceled out, and thus radio wave radiation broadening in the resonation direction, produced by that current component, can be suppressed.

Here, actions and effects of multiband antenna1aaccording to the present embodiment will be described with reference toFIGS. 6 to 8, in comparison with a multiband antenna according to a comparative example.FIG. 6is a plan view illustrating the configuration of multiband antenna1001according to the comparative example.FIG. 6is a plan view illustrating board140of multiband antenna1001according to the comparative example in plan view.FIGS. 7 and 8are diagrams illustrating an overview of directionality for a first frequency of the multiband antennas according to the present embodiment and the comparative example.

Multiband antenna1001according to the comparative example, illustrated inFIG. 6, includes board140, input terminal16, grounding terminals26, antenna part10, and grounding part1020, like multiband antenna1aaccording to the present embodiment. Multiband antenna1001according to the comparative example is the same as multiband antenna1aaccording to the present embodiment with the exception of the configuration of grounding part1020. Grounding part1020according to the comparative example has the same electrical length as the overall electrical length of grounding part20according to the present embodiment. However, grounding part1020according to the comparative example has a flat plate shape. In other words, the entirety of grounding part1020according to the comparative example has the same configuration as second low-inductance part21of grounding part20according to the present embodiment.

With respect to signals in the second frequency, in multiband antenna1aaccording to the present embodiment, the overall electrical length of grounding part20is set so that the directionality of radio waves in the second frequency, radiated from antenna part10, broadens along a plane perpendicular to the lengthwise direction of antenna part10. Because grounding part1020according to the comparative example has the same electrical length as grounding part20according to the present embodiment, the directionality of radio waves in the second frequency, radiated from antenna part10, broadens along a plane perpendicular to the lengthwise direction of antenna part10in multiband antenna1001according to the comparative example as well.

However, with respect to signals in the first frequency, multiband antenna1aaccording to the present embodiment includes second high-inductance part22, which acts as a choke coil with respect to signals in the first frequency, and thus the effective electrical length of grounding part20with respect to signals in the first frequency band induced by second low-inductance part21is equivalent to the electrical length of second low-inductance part21. Additionally, the electrical length of second low-inductance part21is set so that the directionality of radio waves in the first frequency, radiated from antenna part10, broadens along a plane perpendicular to the lengthwise direction of antenna part10. Thus as illustrated inFIG. 7, the directionality of radio waves in the first frequency broadens along a plane perpendicular to the lengthwise direction of antenna part10.

As opposed to this, multiband antenna1001according to the comparative example does not include second high-inductance part22, and thus the electrical length with respect to signals in the first frequency is equal to the overall electrical length of grounding part1020, as is the case with the electrical length with respect to the second frequency. As illustrated inFIG. 8, in multiband antenna1001having such a configuration, the directionality of radio waves in the first frequency broadens in a direction tilted toward grounding part20(i.e., the downward diagonal direction inFIG. 8), relative to a plane perpendicular to the lengthwise direction of antenna part10. AlthoughFIG. 8illustrates only the directionality in a plane parallel to an XY plane, the directionality of multiband antenna1001is the same as the directionality illustrated inFIG. 8in all planes passing through input terminal16of multiband antenna1001and parallel to the Y axis. This is thought to be because in multiband antenna1001according to the comparative example, the effective electrical length of grounding part1020with respect to signals in the first frequency is longer than in multiband antenna1aaccording to the present embodiment, and thus an electrical field component produced by current flowing to the tip end of grounding part1020is stronger than an electrical length component produced by antenna part10.

As described above, in multiband antenna1aaccording to the present embodiment, grounding part20includes second high-inductance part22, which has a meandering shape, and thus the effective electrical length of grounding part20with respect to the first frequency can be made shorter than the effective electrical length with respect to signals in the second frequency. The effective electrical length of grounding part20can therefore be set appropriately with respect to both signals in the first frequency and the second frequency, which makes it possible to achieve directionality perpendicular to the resonation direction in frequency bands including those frequencies.

This multiband antenna1ais particularly useful when used in array antenna101according to the present embodiment, for example. In other words, multiband antennas1a,1b, and1chave directionality which is perpendicular to the resonation direction, and thus when array antenna101is configured by disposing multiband antennas1a,1b, and1cin a direction perpendicular to the resonation direction as in the present embodiment, the reciprocal effects of radio waves radiated by the multiband antennas can be increased.

Ground electrode190is an electrode which is grounded. Ground electrode190is disposed on main surface141of board140. In the present embodiment, ground electrode190is disposed in a position adjacent to grounding part20of each multiband antenna in array antenna101. Ground electrode190also acts as shield wiring for each line disposed on the main surface of board140on the opposite side from main surface141. Ground electrode190is, for example, a conductive member patterned on main surface141of board140, and is formed, for example, from a metal film such as copper film. Ground electrode190is connected, by terminals196ato196c,197,198, and199, to each conductive member disposed on the main surface of board140on the side opposite from main surface141, through via interconnects passing through board140.

Three-way divider106is a divider which divides signals in the first frequency band and the second frequency band three ways. Three-way divider106according to the present embodiment will be described below with reference toFIG. 9.FIG. 9is a plan view illustrating the configuration of three-way divider106according to the present embodiment.FIG. 9is an enlargement of the part ofFIG. 4within the broken line box.

As illustrated inFIG. 9, three-way divider106includes input terminal T0, first output terminal T1, second output terminal T2, third output terminal T3, first transmission line L1, second transmission line L2, third transmission line L3, first resistor R1, second resistor R2, third resistor R3, and fourth resistor R4, like three-way divider6according to Embodiment 1.

Three-way divider106according to the present embodiment can, like three-way divider6according to Embodiment 1, be made smaller than a Wilkinson-type divider, and thus antenna module100can be made smaller as well.

Additionally, as illustrated inFIG. 9, the width of second input-side line L21is narrower than the widths of first input-side line L11and third input-side line L31. By reducing the width of second input-side line L21in this manner, second input-side line L21can be bent, which makes it easy to fit second input-side line L21into a region interposed between first input-side line L11and third input-side line L31while maintaining the electrical length of second input-side line L21.

Additionally, the width of second output-side line L22is narrower than the widths of first output-side line L12and third output-side line L32. By reducing the width of second output-side line L22in this manner, second output-side line L22can be bent, which makes it easy to fit second output-side line L22into a region interposed between first output-side line L12and third output-side line L32while maintaining the electrical length of second output-side line L22.

Connector Cn is a connecting member for inputting signals to antenna module100from the exterior. Although the configuration of connector Cn is not particularly limited, in the present embodiment, connector Cn is a coaxial connector. A signal interconnect of connector Cn is connected to input terminal T0of three-way divider106. Accordingly, signals can be input to three-way divider106from the exterior via connector Cn. Connector Cn has connector ground Cg which is grounded. Shield wiring of connector Cn is connected to connector ground Cg. Connector ground Cg is connected to terminal198of ground electrode190through a via interconnect passing through board140.

Line61is a conductive member which connects line71to first output terminal T1of three-way divider106. The electrical length of line61is set on the basis of a phase difference between divided signals distributed to lines71to73and the electrical lengths of lines62and63. Note that line61is connected to phase shifter80, and a phase delay amount in line61changes depending on a state of phase shifter80.

Line62is a conductive member which connects line72to second output terminal T2of three-way divider106. The electrical length of line62is set on the basis of a phase difference between divided signals distributed to lines71to73and the electrical lengths of lines61and63.

Line63is a conductive member which connects line73to third output terminal T3of three-way divider106. The electrical length of line63is set on the basis of a phase difference between divided signals distributed to lines71to73and the electrical lengths of lines61and62.

Phase shifter80is a device which is connected to line61and which changes a phase delay amount of the divided signal in line61. Phase shifter80is a loaded line-type phase shifter. Phase shifter80includes lines81and82, capacitors83and84, PIN diodes86and87, and ground electrode85.

Line81is a line coupled to line61by capacitor83. One end of line81is connected to capacitor83, and another end is connected to PIN diode86.

Line82is a line coupled to line61by capacitor84. Line82is coupled to line61at a position different from the position at which line81is coupled. One end of line82is connected to capacitor84, and another end is connected to PIN diode87.

Capacitors83and84are elements for coupling line61to lines81and82, respectively. In other words, phase shifter80and line61are coupled by capacitors83and84. By coupling lines81and82to line61via capacitors83and84, high-frequency signals can be exchanged between lines81and82and line61while suppressing the flow of DC current between lines81and82and line61.

Ground electrode85is an electrode which is grounded. In the present embodiment, ground electrode85is connected to terminal197of ground electrode190through a via interconnect passing through board140.

PIN diodes86and87are switches which switch a connection state between lines81and82and ground electrode85to an open state or a closed state. PIN diodes86and87are controlled by control signals input to control terminal Ts. In phase shifter80, the phase delay amount of the divided signal in line61is switched by setting the states of both PIN diodes86and87to the open state or the closed state.

2-1-7. Control Terminal

Control terminal Ts is a terminal into which the control signals for controlling the states of PIN diodes86and87of phase shifter80are input. Control terminal Ts includes a ground terminal, and the ground terminal is connected to terminal191on board140, and to terminal199of ground electrode190through a via interconnect passing through board140.

Each of lines71,72, and73is a long conductive member into which a divided signal obtained from three-way divider106is input and which extends in the Y-axis direction inFIG. 4(i.e., the resonation direction of each multiband antenna).

In the present embodiment, one end of line71is connected to line61. Terminal74is provided at another end of line71. Terminal74is connected to input terminal16of multiband antenna1athrough a via interconnect passing through board140. Accordingly, the divided signal from first output terminal T1of three-way divider106is input to line71via line61, and line71outputs the divided signal to multiband antenna1a.

One end of line72is connected to line62. Terminal76is provided at another end of line72. Terminal76is connected to input terminal16of multiband antenna1bthrough a via interconnect passing through board140. Accordingly, the divided signal from second output terminal T2of three-way divider106is input to line72via line62, and line72outputs the divided signal to multiband antenna1b.

One end of line73is connected to line63. Terminal78is provided at another end of line73. Terminal78is connected to input terminal16of multiband antenna1cthrough a via interconnect passing through board140. Accordingly, the divided signal from third output terminal T3of three-way divider106is input to line73via line63, and line73outputs the divided signal to multiband antenna1c.

Two ground lines71gare long conductive members which are disposed along line71and which extend in the Y-axis direction inFIG. 4. The two ground lines71gare arranged in the X-axis direction inFIG. 4, and line71is disposed between the two ground lines71g. The two ground lines71gand line71are disposed with gaps therebetween. Terminal75gis disposed at one end, and terminal74gis disposed at another end, of each of the two ground lines71g. Terminals75gare connected to terminals196aof ground electrode190through via interconnects passing through board140. Terminals74gare connected to grounding terminals26of grounding part20of multiband antenna1athrough via interconnects passing through board140.

Two ground lines72gare long conductive members which are disposed along line72and which extend in the Y-axis direction inFIG. 4. The two ground lines72gare arranged in the X-axis direction inFIG. 4, and line72is disposed between the two ground lines72g. The two ground lines72gand line72are disposed with gaps therebetween. Terminal77gis disposed at one end, and terminal76gis disposed at another end, of each of the two ground lines72g. Terminals77gare connected to terminals196bof ground electrode190through via interconnects passing through board140. Terminals76gare connected to grounding terminals26of grounding part20of multiband antenna1bthrough via interconnects passing through board140.

Two ground lines73gare long conductive members which are disposed along line73and which extend in the Y-axis direction inFIG. 4. The two ground lines73gare arranged in the X-axis direction inFIG. 4, and line73is disposed between the two ground lines73g. The two ground lines73gand line73are disposed with gaps therebetween. Terminal79gis disposed at one end, and terminal78gis disposed at another end, of each of the two ground lines73g. Terminals79gare connected to terminals196cof ground electrode190through via interconnects passing through board140. Terminals78gare connected to grounding terminals26of grounding part20of multiband antenna1cthrough via interconnects passing through board140.

The transmission lines, lines61,62,63,71to73,81, and82, and grounding interconnects71g,72g, and73gof three-way divider106according to the present embodiment are, for example, conductive members patterned on the main surface of board140on the side opposite from main surface141, and are formed, for example, from a metal film such as copper film.

The transmission lines and lines61,62, and63of three-way divider106according to the present embodiment, and lines81and82of phase shifter80, are disposed in positions opposite ground electrode190with board140interposed therebetween. As such, the lines and ground electrode190form microstrip lines.

Line71and ground lines71gillustrated inFIG. 4are disposed in positions opposite grounding part20of multiband antenna1aillustrated inFIG. 3. The width (dimension in the X-axis direction) of grounding part20is greater than a distance, in the X-axis direction, between outer edges of parts of the two ground lines71gdisposed along line71(i.e., in the example illustrated inFIG. 4, the parts of ground lines71gexcluding the periphery of terminals75g). In other words, grounding part20extends further outward, in the X-axis direction, than the two ground lines71g. In the present embodiment, the width of grounding part20is 7 mm, and the distance, in the X-axis direction, between outer edges of parts of the two ground lines71gdisposed along line71is 3 mm. Accordingly, a situation where radio waves produced by current flowing in the ends, in the X-axis direction, of grounding part20(see the broken line arrows inFIG. 5) are blocked by the two ground lines71gcan be suppressed. A worsening of the directionality in the Z-axis direction of multiband antenna1acan therefore be suppressed. Like the width of grounding part20of multiband antenna1a, the widths of grounding parts20of multiband antennas1band1care greater than the distances, in the X-axis direction, between outer edges of parts of the two opposing ground lines disposed along lines72and73.

2-2. Actions and Effects

Actions and effects of antenna module100according to the present embodiment will be described next. As described above, in antenna module100according to the present embodiment, appropriately setting the electrical lengths of lines61,62, and63makes it possible to adjust the phases of the signals input to the multiband antennas constituting array antenna101. This makes it possible to adjust the directionality of array antenna101. For example, when an antenna which transmits and receives signals in frequency band near the frequency band handled by antenna module100is present near antenna module100, lowering the directionality of array antenna101of antenna module100in a direction facing from array antenna101toward that other antenna makes it possible to reduce radio wave interference between antenna module100and the other antenna. Such directionality of array antenna101will be described with reference toFIG. 10.FIG. 10is a graph illustrating directionality of array antenna101according to the present embodiment. Note thatFIG. 10illustrates the directionality when both PIN diodes86and87in phase shifter80of antenna module100are off. Note also that angle θzx inFIG. 10indicates an angle of inclination from the Z-axis direction toward the X-axis direction in each drawing.

In the example illustrated inFIG. 10, directionality is reduced with respect to the positive side of the X-axis direction. Accordingly, when another antenna is present on the positive side, in the X-axis direction, of array antenna101having such directionality, interference between array antenna101and the other antenna can be reduced.

Additionally, in antenna module100according to the present embodiment, the phase of the signal input to multiband antenna1acan be switched by phase shifter80. The phase of the signal input to multiband antenna1acan be changed by approximately 50° by phase shifter80according to the present embodiment, when both PIN diodes86and87are off, and when the PIN diodes are on. Effects provided by phase shifter80will be described here with reference toFIG. 11.

FIG. 11is a graph illustrating directionality of array antenna101according to the present embodiment when the state of phase shifter80has been changed.FIG. 11illustrates the directionality when both PIN diodes86and87in phase shifter80are turned on. Note also that angle θzx inFIG. 11indicates an angle of inclination from the Z-axis direction toward the X-axis direction in each drawing. As can be seen from the directionalities illustrated inFIGS. 10 and 11, the directionality of array antenna101can be changed greatly by phase shifter80. This effect of phase shifter80is useful when there is a shifting radio wave environment around antenna module100. For example, when the positions of antenna module100and the other antenna have been changed, the relative positions of antenna module100and the other antenna can change as well. Additionally, if antenna module100and the other antenna are moved, even if the relative positions of antenna module100and the other antenna have not changed, the relative positions of surrounding structures and antenna module100can change. In this case, radio waves radiated from the other antenna are reflected by the surrounding structures, and thus in array antenna101of antenna module100, interference from those reflected waves can become problematic. By changing the directionality of array antenna101using phase shifter80in situations where the radio wave environment changes in this manner, interference with other radio waves can be suppressed.

2-3. Application Example

An application example of antenna module100according to the present embodiment will be described next with reference toFIG. 12.FIG. 12is a perspective view illustrating the configuration of audio device103including antenna module100according to the present embodiment.

Audio device103illustrated inFIG. 12mainly includes housing103c, antenna modules100,100a, and104, and speakers Sp0to Sp4. Note that inFIG. 12, only the contours of housing103care indicated, using dotted lines, in order to show the locations of the respective constituent elements.

Antenna module100ais a module which communicates wirelessly on the basis of the same wireless LAN standard as antenna module100, and transmits and receives signals in the 5 GHz and 2.4 GHz bands. Antenna module100ais the same as antenna module100, with the exception of the structures and locations of the constituent elements being flipped horizontally with respect to antenna module100. As such, the directionality of the array antenna included in antenna module100ais flipped horizontally with respect to the directionality of array antenna101in antenna module100(i.e., the graphs illustrated inFIGS. 10 and 11are inverted horizontally).

Antenna module104is a module which communicates wirelessly with another device. In the present embodiment, antenna module104transmits signals in the 2.4 GHz band to another audio device, on the basis of a standard different from the wireless LAN standard. Here, the other audio device is a subwoofer or the like, for example.

As described above, audio device103includes the three antenna modules100,100a, and104, which handle signals in the 2.4 GHz band, and thus radio wave interference can arise among these modules. However, array antenna101of antenna module100according to the present embodiment has low directionality on the positive side of the X-axis direction, as illustrated inFIG. 10, and thus radio wave interference with other modules can be reduced.

Additionally, antenna module100ahas a structure which is flipped horizontally with respect to antenna module100, and thus the array antenna in antenna module100ahas low directionality on the negative side of the X-axis direction. Radio wave interference with another antenna module disposed on the negative side, in the X-axis direction, of antenna module100acan therefore be reduced.

Depending on the positional relationship between audio device103and surrounding structures, radio waves radiated from antenna module104may be reflected by the structures and reach antenna modules100and100a. In such a state, if interference from the reflected radio waves is a problem in antenna modules100and100a, interference with those reflected radio waves can be reduced by changing the settings of the phase shifters in antenna modules100and100ato change the directionality of each array antenna.

A three-way divider according to the present disclosure has been described based on embodiments. However, the present disclosure is not limited to the foregoing embodiments. Various conceivable variations made on the embodiments by one skilled in the art also fall within the scope of the present disclosure as long as those variations do not depart from the essential spirit of the present disclosure.

For example, Embodiment 2 described an example in which antenna module100is used in audio device103, but antenna module100can be used in another device instead. For example, antenna module100may be used in a television receiver or the like.

Additionally, although a dual-band antenna which transmits and receives signals in two frequency bands was described as an example of multiband antenna1a, the multiband antenna according to the present disclosure may transmit and receive in three or more frequency bands. For example, a multiband antenna can be implemented which, in addition to the first frequency band and the second frequency band, transmits and receives in a third frequency band including a third frequency which is lower than the first frequency and higher than the second frequency. For example, in multiband antenna1aaccording to Embodiment 2, by inserting a first mid-inductance part between first low-inductance part11and first high-inductance part12, and inserting a second mid-inductance part between second low-inductance part21and second high-inductance part22, a multiband antenna which can transmit and receive signals in three frequency bands, namely the first frequency band to the third frequency band, can be realized.

Here, the first mid-inductance part has a higher inductance than first low-inductance part11and a lower inductance than first high-inductance part12. Likewise, the second mid-inductance part has a higher inductance than second low-inductance part21and a lower inductance than second high-inductance part22. First low-inductance part11and second low-inductance part21do not act as choke coils with respect to signals in the third frequency. First mid-inductance part and second mid-inductance part act as choke coils with respect to signals in the first frequency, but do not act as choke coils with respect to signals in the second frequency and the third frequency. First high-inductance part12and second high-inductance part22act as choke coils with respect to signals in the third frequency. The sum of the electrical lengths of first low-inductance part11and the first mid-inductance part is ¼ the wavelength of the third frequency.

Additionally, embodiments achieved by combining constituent elements and functions from the embodiments as desired within a scope which does not depart from the spirit of the present disclosure, and the like are also included in the present disclosure.

INDUSTRIAL APPLICABILITY

The three-way divider according to the present disclosure can be used as a three-way divider for an antenna module used in an audio device or the like, for example.