ANTENNA MODULE AND RADIO EQUIPMENT

Provided is an antenna module in which an antenna element configured to perform wireless communication of a first frequency band and an antenna pattern configured to perform wireless communication of a second frequency band can be arranged in a space-saving manner, and radio equipment that can achieve a small size as constituted by the antenna module. An antenna module includes a substrate, an antenna element mounted on the substrate, where the antenna element is configured to perform wireless communication using a wireless signal of a first frequency band, and an antenna pattern formed on the substrate and surrounding the antenna element, where the antenna pattern is configured to perform wireless communication using a wireless signal of a second frequency band.

The contents of the following Japanese patent application(s) are incorporated herein by reference: NO. 2017-221186 filed in JP on Nov. 16, 2017.

BACKGROUND

1. Technical Field

The present invention relates to an antenna module and radio equipment.

2. Related Art

Antennas used in portable wireless communication terminals such as mobile phones are, for example, structured in such a manner that antenna elements are mounted on substrates or antenna patterns are formed on substrates. The antenna elements to be mounted on the substrates include, for example, a chip antenna element that is structured in such a manner that a spiral or zigzag conductive pattern is formed on the surface of a base made of a dielectric or magnetic substance, or a dielectric and magnetic substance (see, for example, Patent Document 1). The antenna patterns to be formed on the substrates include, for example, a loop antenna used in a Radio Frequency IDentifier (RFID) tag (see, for example, Patent Document 2).

Generally speaking, the antenna characteristics of the antenna element are degraded if metal structures approach the antenna element. Therefore, when mounted on the substrate, the chip antenna element is surrounded by an antenna formed region in which no patterns or parts are provided except for the minimum constituents required to operate the chip antenna element (for example, the power feeding conductor for the chip antenna element, the impedance matching circuit). In addition, since the chip antenna element needs to be positioned away from the ground pattern formed in a part arranged region in which parts are arranged, the chip antenna element is often mounted near the edge of the substrate. For this reason, when the chip antenna element is employed, it needs to be ensured that the substrate has the part arranged region and the antenna formed region that is spaced away from the part arranged region and positioned near the edge of the substrate, which means that the substrate requires a reasonably large area.

As for the loop antenna used in the RFID tag, one of the ends of the loop antenna is connected to one of the ends of the RFID tag integrated circuit (IC), and the other end is connected to the other end of the RFID tag IC. When magnetic flux generated by a loop antenna included in an external device (for example, an RFID reader/writer) passes through the loop antenna of the RFID tag, induced electromotive force is generated in the loop antenna of the RFID tag. This induced electromotive force operates the RFID tag IC and enables the RFID tag IC to perform data transmission.

Patent document 2: Japanese Patent Application Publication No. 10-224277

Radio equipment uses a chip antenna element to transmit sensor data via a wireless network and uses contactless communication based on infrared communication to perform provisioning. Here, “provisioning” represents a process of performing settings necessary to allow the radio equipment to participate in a wireless network. In recent years, during the provisioning process for the radio equipment, the settings may be performed using smartphones, tablet terminals and the like. If such is the case, it may be desired to perform the settings through contactless communication using a loop antenna embedded in the smartphones, tablet terminals and the like.

To do so, the radio equipment needs to include both a chip antenna element and a loop antenna. As previously stated, however, the chip antenna element requires the antenna formed region near the edge of the substrate in the region excluding the part arranged region. Therefore, the chip antenna element, parts and loop antenna are arranged away from each other, which requires a large substrate. As a result, there are difficulties in reducing the size of the equipment. It may be suggested to form the loop antenna in a different substrate. Since more substrates are required, however, this suggestion does not solve the size-reduction issues and obstructs the attempts to lower the costs.

The present invention is made in light of the above-described problems and aims to provide an antenna module having a chip antenna element configured to perform wireless communication in a first frequency band and an antenna pattern configured to perform wireless communication in a second frequency band arranged in a space-saving manner and radio equipment that can achieve a reduced size by including the antenna module.

SUMMARY

To achieve the above-mentioned objective, an antenna module (1) relating to one aspect of the present invention includes a substrate (11), an antenna element (chip antenna element21) mounted on the substrate, where the antenna element is configured to perform wireless communication using a wireless signal of a first frequency band, and an antenna pattern (loop antenna31, loop antenna931) formed on the substrate and surrounding the antenna element, where the antenna pattern is configured to perform wireless communication using a wireless signal of a second frequency band.

Such configurations can reduce the size of the antenna module that is configured to transmit and receive a wireless signal in the first frequency band used by the first antenna for communication and in the second frequency band used by the second antenna for communication.

In the antenna module relating to the one aspect of the present invention, the substrate may include at least two layers in which the antenna pattern is formed, the antenna pattern may include a first loop pattern that is formed like a loop in a first layer of the two layers, a second loop pattern that is formed like a loop in a second layer of the two layers, where the second loop pattern at least partially overlaps the first loop pattern in a thickness direction of the substrate, and a connecting portion (314) connecting the first loop pattern and the second loop pattern to each other.

With such configurations, the antenna module can achieve a reduced size while it can be ensured to have a reasonable region in which the antenna element is arranged.

In the antenna module relating to the one aspect of the present invention, the antenna element may be positioned in a vicinity of a center of the antenna pattern.

With such configurations, a reasonable distance can be provided to separate the antenna pattern and the antenna element from each other. This can reduce the degradation of the antenna characteristics of the antenna element caused by the antenna pattern. Here, the vicinity of the center of the antenna pattern includes the midpoint of the inside region of the loop pattern and includes such a region that the distance from the inner edge of the loop pattern to each of the upper, lower, right and left outer edges of the antenna element is equal to or more than a predetermined value.

In the antenna module relating to the one aspect of the present invention, the substrate may include an antenna formed region in which no conductor or circuit is formed except for a power feeding conductor for the antenna element and an impedance matching circuit (23) constituted by a passive element, and the antenna element and the antenna pattern may be formed in the antenna formed region.

In the antenna module relating to the one aspect of the present invention, the antenna element may be operated by power fed through the power feeding conductor, and the antenna pattern may be operated by power fed in a contactless manner from outside.

In the antenna module relating to the one aspect of the present invention, the antenna pattern (loop antenna931) may be a loop pattern that is wound at least twice.

With such configurations, the antenna module can achieve a reduced size while it can be ensured to have a reasonable region in which the antenna element is arranged.

To achieve the above-mentioned objective, radio equipment (100) relating to a different one aspect of the present invention includes any of the above-described antenna modules (1), a battery (7) configured to feed power to the antenna module, and an electrical circuit (RF switch2, transceiver3, RFID tag controller4, controller6) configured to perform wireless communication with outside using the antenna module.

With such configurations, a small size can be achieved while wireless signals are transmitted and received in the first frequency band used by the first antenna for communication and in the second frequency band used by the second antenna for communication.

In the radio equipment relating to the different one aspect of the present invention, the battery may be positioned near the substrate so as not to overlap a direction in which communication is performed by the antenna element.

Such configurations can reduce the degradation of the antenna characteristics of the chip antenna element caused by the battery.

In the radio equipment relating to the different one aspect of the present invention, the electrical circuit may include a controller (6), and the controller may perform such a control that a period of transmission performed by the antenna element does not overlap a period of transmission performed by the antenna pattern.

With such configurations, the communications are controlled in such a manner that, while one of the antenna element and the antenna pattern is performing communication, the other does not perform communication. Accordingly, the antenna characteristics of the antenna element and the antenna pattern can be prevented from degrading while they are performing communication.

The radio equipment relating to the different one aspect of the present invention may further include a sensor (5), a battery case (105) housing therein the battery, a body chassis (102) supporting the sensor and the battery case, and a body cover (104) attached to the body chassis and covering the sensor and the battery case.

Such configurations can reduce the size of the antenna module that is configured to transmit and receive a wireless signal in the first frequency band used by the first antenna for communication and in the second frequency band used by the second antenna for communication, and can also reduce the size of the radio communication equipment including the antenna module.

According to the present invention, it is possible to arrange the antenna element configured to perform wireless communication in a first frequency band and an antenna pattern configured to perform wireless communication in a second frequency band in a space-saving manner. It is also possible to reduce the size of radio equipment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following describes some embodiments of the present invention with reference to the drawings. The embodiments do not limit the invention according to the claims, and all the combinations of the features described in the embodiments are not necessarily essential to means provided by aspects of the invention. Note that, in the drawings referred to in the following description, the individual components are drawn to different scales, if necessary, in order to allow the individual components to have recognizable sizes.

FIG. 1shows an exemplary structure of radio equipment100relating to an embodiment of the present invention.

As shown inFIG. 1, the radio equipment100includes an antenna module1, an RF switch2(an electrical circuit), a transceiver3(an electrical circuit), an RFID tag controller4(an electrical circuit), a sensor5, a controller6(an electrical circuit) and a battery7. The antenna module1has a chip antenna element21and a loop antenna31(an antenna pattern).

The radio equipment100transmits and receives a wireless signal in a first frequency band to/from a wireless gateway, which is not shown. The first frequency band is, for example, the frequency band used by the LoRa communication scheme, which is the communication standard proposed by the LoRa (registered trademark) Alliance and is one type of Low Power Wide Area Network (LPWAN). The radio equipment100transmits and receives a wireless signal in a second frequency band to/from a terminal, which is not shown. The second frequency band is, for example, the frequency band used for the communication by an RFID tag. The not-shown terminal is, for example, a smartphone, a tablet or notebook personal computer and the like having RFID reader/writer functions.

The chip antenna element21transmits and receives a wireless signal in the first frequency band. The chip antenna element21outputs the received wireless signal of the first frequency band to the RF switch2. The chip antenna element21transmits a wireless signal of the first frequency band output from the RF switch2. Note that the chip antenna element21operates in a self-feeding manner. To be specific, the chip antenna element21operates by receiving the delivery of the power that is obtained by converting the power output from the battery7into the power used for the transmission by the transceiver3. The following description is made taking, as an exemplary antenna element, a chip antenna element in which the antenna is a chip part, but the antenna element may be an antenna having a different structure. In addition, the chip antenna element21may be mounted on the surface of a substrate11(seeFIG. 2) or embedded in the substrate11.

The loop antenna31transmits and receives a wireless signal in the second frequency band. The loop antenna31outputs the received wireless signal of the second frequency band to the RFID tag controller4. The loop antenna31transmits a wireless signal of the second frequency band output from the RFID tag controller4. Note that the loop antenna31operates on the power fed in a contactless manner from outside.

The RF switch2is a switch used to switch the wireless signal paths. The RF switch2outputs, to the transceiver3, the wireless signal of the first frequency band output from the chip antenna element21. The RF switch2outputs, to the chip antenna element21, the wireless signal of the first frequency band output from the transceiver3.

The transceiver3performs predetermined signal processing on the wireless signal of the first frequency band output from the RF switch2to extract information. The transceiver3outputs the extracted information to the controller6. The transceiver3performs predetermined signal processing on the information output from the controller6to generate a wireless signal of the first frequency band. The transceiver3outputs the generated wireless signal of the first frequency band to the RF switch2. The information output from the controller6is, for example, measurement information obtained by the measurement performed by the sensor5.

The RFID tag controller4operates on the power fed in a contactless manner from outside and performs predetermined signal processing on the wireless signal of the second frequency band output from the loop antenna31to extract information. For example, when the not-shown terminal transmits information for provisioning to the radio equipment100, the RFID tag controller4extracts the information for provisioning. The RFID tag controller4outputs the extracted information to the controller6. The RFID tag controller4performs predetermined signal processing on the information output from the controller6to generate a wireless signal of the second frequency band. The RFID tag controller4outputs the generated wireless signal of the second frequency band to the loop antenna31.

The sensor5is, for example, a temperature sensor, a humidity sensor, an atmospheric pressure sensor, a vibration sensor or the like. The sensor5outputs, to the controller6, the measurement information obtained by the measurement performed by it.

The controller6outputs the measurement information output from the sensor5to the transceiver3in, for example, predetermined cycles. The controller6obtains the information output from the transceiver3. Here, the information output from the transceiver3includes, for example, a request received from the not-shown wireless gateway, and the like. The controller6obtains the information output from the RFID tag controller4. The information output from the RFID tag controller4includes, for example, the above-mentioned information for provisioning. The controller6performs settings (provisioning) to realize wireless communication through the chip antenna element21based, for example, on the information output from the RFID tag controller4.

The battery7feeds power to all the constituents of the radio equipment100except for the loop antenna31. The battery7is a primary or secondary battery.

FIG. 2shows an exemplary structure of the antenna module1relating to the embodiment of the present invention. InFIG. 2, the y-axis, x-axis and z-axis directions respectively indicate the lengthwise, widthwise and thickness directions of the substrate11.

As seen fromFIG. 2, in the antenna module1, an antenna formed region41is defined along one of the edges of the substrate11that oppose each other in the y-axis direction and a part arranged region12occupies the region excluding the antenna formed region41. Note that the substrate11is a multilayer substrate made up by at least two layers.

On the surface of the antenna formed region41, the chip antenna element21is attached. In the two layers of the antenna formed region41, the loop antenna31is formed. In the part arranged region12, a power feeding section25is formed. In the antenna formed region41, no conductors are formed except for the power feeding conductor for the chip antenna element21, and no conductor circuits are formed except for an impedance matching circuit23.

In the part arranged region12, for example, the RF switch2, the transceiver3, the RFID tag controller4and the controller6, which are shown inFIG. 1, are arranged. The chip antenna element21and the power feeding section25are connected to each other via a power feeding pattern24. Between the chip antenna element21and the power feeding section25, the impedance matching circuit23is formed. The impedance matching circuit23is constituted by, for example, passive elements such as an inductor and a capacitor and can achieve a match between the impedance of the chip antenna element21and that of the transceiver3. The power output from the battery7is converted into the power for the transmission from the transceiver3. The power obtained by the conversion is fed to the chip antenna element21through the RF switch2, the power feeding pattern24and the impedance matching circuit23, so that the power is transmitted in the form of a wireless signal. The impedance matching circuit23is mounted on or formed in the surface of the substrate in the antenna formed region41. Alternatively, the impedance matching circuit23may be formed in the substrate in the antenna formed region41.

Here, the power feeding pattern24is formed in a different layer than the layer in which the loop antenna31is formed.

In other words, the antenna module1of the present embodiment is structured such that the chip antenna element21is attached to the substrate11in the antenna formed region41and the loop antenna31is formed in the same substrate11in the antenna formed region41.

The following describes an exemplary structure of the loop antenna31.

FIG. 3is a plan view showing an exemplary structure of the loop antenna31relating to the embodiment of the present invention.FIG. 4is a perspective view showing an exemplary structure of the loop antenna31relating to the embodiment of the present invention.

InFIGS. 3 and 4, the x-axis, y-axis and z-axis directions respectively indicate the lengthwise, widthwise and thickness directions of the loop antenna31.

As shown inFIGS. 3 and 4, the loop antenna31includes an antenna pattern311(the first turn, a first loop pattern), an antenna pattern312(the second turn, a second loop pattern) and the connecting portion314. The antenna pattern311is connected to a power feeding pattern315and the antenna pattern312through a connecting portion313and a connecting portion314. The antenna pattern312is connected to the antenna pattern311through the connecting portion314. The other end312bof the antenna pattern312is connected to a power feeding pattern316. As shown inFIG. 4, the other end312bof the antenna pattern312may be continuous with the power feeding pattern316. Furthermore, the antenna patterns311and312are connected to the RFID tag controller4through the power feeding patterns315and316.

The antenna pattern311is the first turn and formed by, for example, a copper foil pattern in a first layer of the substrate11(seeFIG. 2). One end311aof the antenna pattern311is connected through the connecting portion313to the power feeding pattern315, which is formed in a second layer of the substrate11. The other end311bof the antenna pattern311is connected through the connecting portion314to one end312aof the antenna pattern312, which is formed in the second layer of the substrate11. The antenna pattern311and the antenna pattern312each have a width of, for example, 0.7 mm in the x-axis and y-axis directions and a thickness of, for example, 35 μm in the z-axis direction.

The antenna pattern312is the second turn and formed by, for example, a copper foil pattern in the second layer of the substrate11. The one end312aof the antenna pattern312is connected through the connecting portion314to the antenna pattern311, which is formed in the first layer of the substrate11. The other end312bof the antenna pattern312is connected to the power feeding pattern316, which is formed in the second layer of the substrate11. The antenna pattern312has a width of, for example, 0.7 mm in the x-axis and y-axis directions and a thickness of, for example, 35 μm in the z-axis direction.

The connecting portions313and314are each a via, for example

As shown inFIG. 5, in the substrate11, an insulation layer111bis formed under the first layer111a, and the second layer111cis formed under the insulation layer111bin the z-axis direction.

In the first layer111a, the antenna pattern311or the first turn is formed. In the second layer111c, the antenna pattern312or the second turn is formed. In this manner, the antenna pattern311and the antenna pattern312are formed so as to at least partially overlap each other in the z-axis direction (when seen in the z-axis direction).

With the above-described configurations, the present embodiment can leave a sufficient region to have the chip antenna element21arranged therein while reducing the size of the antenna module1.

The following describes the size of the space enclosed within the loop antenna31.

FIG. 6shows, as an example, the space enclosed within the loop antenna31relating to the embodiment of the present invention.FIG. 6does not show the chip antenna element21. InFIG. 6, the x-axis and y-axis directions respectively indicate the lengthwise and widthwise directions of the loop antenna31. As described above, the two turns constituting the loop antenna31are formed in the two layers in the antenna formed region41.

Here, the loop antenna31has a width L3in the x-axis and y-axis directions. An inside region41aof the loop antenna31has a length L1in the x-axis direction. Here, the inside region41aof the loop antenna31has a length L2in the y-axis direction.

FIG. 6shows an exemplary case where, as indicated by a reference numeral51, the connecting portion between the first turn and the second turn is bent within the x-y plane, in the y-axis direction and toward the inside region41aof the loop antenna31, but the present invention is not limited to such. The connecting portion indicated by the reference numeral51may be shaped as a straight line. In this case, the connecting portion between the first turn and the second turn may be positioned in the region indicated by a reference numeral52, for example

FIG. 7shows, as an example, the space enclosed within a loop antenna931having a different exemplary structure in accordance with the embodiment of the present invention. The coordinates ofFIG. 7are similar to those ofFIG. 6. According to this different exemplary structure, the loop antenna31is replaced with a loop antenna931that have two turns formed in a single layer in an antenna formed region941. Here, the loop antenna931is a loop pattern that is wound at least twice on the surface, in the same layer, or inside of the substrate11in the antenna formed region941. Here, the antenna formed region941relating to the different exemplary structure has the same length as the antenna formed region41in the x-axis and y-axis directions.

Here, the loop antenna931has a width L3in the x-axis and y-axis directions. There is a gap L4between the first turn and the second turn.

In this case, an inside region941aof the loop antenna931has a length L901in the x-axis direction, where L901=L1−(L3+L4)×2. Likewise, the inside region941aof the loop antenna931has a length L902in the y-axis direction, where L902=L2−(L3+L4)×2.

In the present embodiment shown inFIG. 6and the like, the two turns of the loop antenna31are formed so as to at least partially overlap each other in the z-axis direction. Therefore, when compared with the different exemplary structure shown inFIG. 7in which the two turns are formed in the single layer, the lengths of the space enclosed within the loop antenna31in the x-axis and y-axis directions are longer by (L3+L4)×2. For the reasons described above, the inside region41aof the loop antenna31of the present embodiment has a larger area than the inside region941aof the different exemplary structure at least by M1+M2×2=(L3+L4)×L1+[(L3+L4)×{L2−(L3+L4)×2}]×2 at the top, left and right.

In the present embodiment, the chip antenna element21is arranged in the inside region41aof the loop antenna31.

FIG. 8shows an exemplary manner of arranging the chip antenna element21in the inside region41aenclosed within the loop antenna31relating to the embodiment of the present invention. The coordinates ofFIG. 8are similar to those ofFIG. 6. The chip antenna element21is sized such that the length in the x-axis direction is 3 mm and the length in the y-axis direction is 10.5 mm. The loop antenna31has a width of 0.7 mm in the x-axis and y-axis directions.

The width (gap) L21between the upper edge of the chip antenna element21and the loop antenna31is 3.95 mm. Regarding the width between the lower edge of the chip antenna element21and the loop antenna31, the narrowest width L22is 9.55 mm and the wide width L23is 10.95 mm. In addition, the width L11defined between each of the right and left side surfaces of the chip antenna element21and the loop antenna31is 7.4 mm.

With the above-described configurations, the present embodiment can reduce the degradation in the antenna characteristics of the chip antenna element caused by the antenna pattern.

FIG. 9shows an exemplary manner of arranging the chip antenna element21in the inside region941aenclosed within the loop antenna931having the different exemplary structure in accordance with the present embodiment. Here, the loop antenna931ofFIG. 9is formed, for example, in a region having the same area as the antenna formed region41in which the loop antenna31ofFIG. 8is formed. The coordinates ofFIG. 9are similar to those ofFIG. 8. The chip antenna element21has the same size as inFIG. 8.

The width L921between the upper edge of the chip antenna element21and the loop antenna931is 2.55 mm. The width L922between the lower edge of the chip antenna element21and the loop antenna931is 9.55 mm. In addition, the width L911defined between each of the right and left side surfaces of the chip antenna element21and the loop antenna931is 6 mm.

As can be seen from above, the present embodiment shown inFIG. 8can ensure that a longer gap is provided between the chip antenna element21and the loop antenna31when compared with the different exemplary structure shown inFIG. 9. Note that the different exemplary structure shown inFIG. 9can also realize a reduced size since the chip antenna element21is enclosed within the loop antenna931as is shown inFIG. 8, although the antenna characteristics achieved by the structure shown inFIG. 9are poorer than those achieved by the structure shown inFIG. 8.

The positioning shown inFIG. 8is illustrative and the present invention is not limited to such. The chip antenna element21is positioned such that the width L23is longer than the width L21as shown inFIG. 8in order to reduce the influence on the communication that may be caused by the battery7when the antenna module1is incorporated into the radio equipment100, which will be described later with reference toFIGS. 10A and 10B. Therefore, the chip antenna element21is desirably positioned in the vicinity of the center of the inside region41aof the loop antenna31if the battery7has a small height. Here, the vicinity of the center of the inside region41aof the loop antenna31includes the midpoint of the inside region41aof the loop antenna31and includes such a region that the distance from the inner edge of the loop antenna31to each of the upper, lower, right and left outer edges of the chip antenna element21is equal to or more than a predetermined value.

The following describes an exemplary manner of arranging the parts of the radio equipment100including the antenna module1.

FIGS. 10A and 10Bare respectively a front view and a side view showing an exemplary manner of arranging the parts of the radio equipment100including the antenna module1relating to the present embodiment.FIG. 10Ais a front view of the radio equipment100.FIG. 10Bis a side view of the radio equipment100.

As shown inFIG. 10A, the substrate11is attached to a body chassis102through an attachment member103, which serves as a support. Here, the body chassis102is integrated with the attachment member103. The substrate11has the part arranged region and the antenna formed region. In the antenna formed region, the antenna module1is formed. The antenna module1includes the chip antenna element21and the loop antenna31. In the inside region of the loop antenna31, the chip antenna element21is attached. In the part arranged region, for example, the RF switch2, the transceiver3, the RFID tag controller4and the controller6, which are shown inFIG. 1, are arranged. A reference numeral104represents a body cover.FIGS. 10A and 10Bonly show the shape of the body cover104since they are used to describe the inside of the body cover104.

As shown inFIG. 10B, the sensor5is attached to the body chassis102integrated with the attachment member103. The battery7is held in a battery case105that is positioned in the vicinity of the substrate11. The battery case105is attached to the body chassis102integrated with the attachment member103. The body cover104is attached to the body chassis102and covers the sensor5, the battery7, the battery case105and the substrate11. As described above, the battery7is positioned near the substrate11within the body cover. Here, “near the substrate11” means the vicinity of the substrate11and may include contacting the substrate11. Here, in the x-y plane, the chip antenna element21exhibits the characteristics of a horizontally polarized antenna in terms of the horizontal direction that is defined by treating the x-y plane as the horizontal plane. Also, in the y-z plane, the chip antenna element21exhibits the characteristics of a horizontally polarized antenna in terms of the horizontal direction that is defined by treating the y-z plane as the horizontal plane. Also, in the z-x plane, the chip antenna element21exhibits the characteristics of a vertically polarized antenna in terms of the horizontal direction that is defined by treating the z-x plane as the horizontal plane. The following studies the case where the chip antenna element21performs wireless communication in, for example, the −z-axis direction and +z-axis direction. In this case, it is preferable that, on the back of the substrate11having the chip antenna element21attached thereto, that is, on the surface of the substrate11facing the battery7, the wireless communication of the chip antenna element21performed through the vertically polarized wave on the z-x plane with respect to the horizontal direction that is defined by treating the z-x plane as the horizontal plane and through the horizontally polarized wave on the y-z plane with respect to the horizontal direction that is defined by treating the y-z plane as the horizontal plane may not be blocked. Therefore, in the present embodiment, the battery7is arranged at such a position and a height that the battery7does not block the radio direction of the chip antenna element21. In this manner, in the present embodiment, the battery7can be prevented from blocking the wireless signal, and the battery7can be arranged so as not to overlap the chip antenna element21, that is to say, at such a height in the y-axis direction that the battery7does not obstruct the communication performed by the chip antenna element21. With such configurations, the present embodiment can reduce the degradation in the characteristics of the chip antenna element21that may be caused by the battery7.

The following describes the simulated characteristics. As a comparative example, an antenna module including a chip antenna element only, which is shown inFIG. 11, was also simulated.

FIG. 11shows an exemplary structure of radio equipment including the chip antenna element relating to the comparative example

As shown inFIG. 11, an antenna module911of the radio equipment relating to the comparative example has a chip antenna element912arranged in the antenna formed region.

Note that the chip antenna element receives the frequency of 924 MHz, which is used by the LoRa communication scheme.

FIG. 12shows the simulated antenna characteristics of the antenna module911relating to the comparative example and the simulated antenna characteristics of the antenna module1relating to the embodiment of the present invention. The graph indicated by the reference sign g11indicates the simulated antenna characteristics relating to the antenna module911of the comparative example. The graph indicated by the reference sign g12indicates the simulated antenna characteristics of the antenna module1relating to the present embodiment. InFIG. 12, the horizontal axis represents the frequency and the vertical axis represents the magnitude of the S11(return loss), which is one of the S-parameters.

As shown by the graph indicated by the reference sign g11, the chip antenna element912relating to the comparative example in which no loop antenna is formed in the antenna formed region exhibited an S11of −32.85 dB at the frequency of 924 MHz.

On the other hand, as shown by the graph indicated by the reference sign g12, the antenna module1relating to the present embodiment exhibited an S11of −21.60 dB at the frequency of 924 MHz.

As mentioned above, although the chip antenna element21is attached in the inside region of the loop antenna31in the present embodiment, the magnitude of the S11can be −21.60 db at the frequency of 924 MHz.

Here, as shown by the graph indicated by the reference sign g12, the present embodiment can reduce the influence on the frequencies other than 924 MHz, which is the frequency utilized by the chip antenna element21.

FIG. 13shows the simulated antenna directivity of the antenna module911relating to the comparative example and the simulated antenna directivity of the antenna module1relating to the embodiment of the present invention. The graph indicated by the reference sign g21shows the simulated antenna directivity of the antenna module911relating to the comparative example. The graph indicated by the reference sign g22shows the simulated antenna directivity of the antenna module1of the present embodiment. Note thatFIG. 13shows the directivity of the antennas in terms of the polarized waves in the horizontal and vertical planes at the frequency of 924 MHz. InFIG. 13, the vertical axis represents the gain, and the numbers “0,” “90,” “180,” “270,” and −90” indicate the angles.

As shown inFIG. 13, the antenna module1of the the present embodiment can achieve the directivity equal to that of the comparative example

As described above, in the present embodiment, the loop antenna31is formed in two layers and formed in the antenna formed region in such a manner that the first turn and the second turn at least partially overlap each other in the z-axis direction. In the present embodiment, the chip antenna element21is arranged in the inside region41aenclosed within the loop antenna31. In other words, in the antenna module1of the the present embodiment, the antenna pattern constituting the loop antenna31is formed around the chip antenna element21. In order to increase the distance between the chip antenna element21and the loop antenna31, the present embodiment employs a multilayer substrate structure to realize the winding structure, according to which the first turn of the antenna pattern is formed in a different layer than the second turn of the antenna pattern. In this manner, the present embodiment can increase the distance between the chip antenna element21and the antenna pattern constituting the loop antenna31, thereby reducing the degradation of the characteristics of the chip antenna element21.

In the above-described manner, the present embodiment can reduce the area occupied by the two antennas by efficiently arranging the two antennas in a single substrate. In addition, the present embodiment can realize an efficient antenna pattern that can reduce the degradation of the antenna characteristics of the chip antenna element21as much as possible. As a consequence, the present embodiment can reduce the degradation of the characteristics of the chip antenna element21as much as possible with it being possible to reduce the area of the antenna formed region.

The following describes, as an example, the timings of the communications performed using the two antennas (the chip antenna element21and the loop antenna31) with reference toFIGS. 14 to 16. InFIGS. 14 to 16, the horizontal axis represents the time and the vertical axis represents the voltage. Note that the radio equipment100has the structure shown inFIG. 1. The first frequency band is the frequency band used by the chip antenna element21to perform communication. The second frequency band is the frequency band used by the loop antenna31to perform communication. InFIGS. 14 to 16, the reference sign g101denotes the state of the wireless communication in the first frequency band and the reference sign g102denotes the state of the wireless communication in the second frequency band.

The chip antenna element21performs the wireless communication in the first frequency band in cycles of a period T1. The timing of the communication performed by the chip antenna element21is controlled by the controller6(seeFIG. 1).

The loop antenna31performs the communication when the user places a not-shown terminal close to the loop antenna31.

FIG. 14shows an exemplary case where the communication in the first frequency band does not overlap the communication in the second frequency band in timing in the radio equipment100relating to the embodiment of the present invention. InFIG. 14, the horizontal axis represents the time.

The chip antenna element21transmits information during the period from a timing t1to a timing t2, the period from a timing t5to a timing t6, the period from a timing t9to a timing t10, and the period from a timing t11to a timing t12.

The loop antenna31performs the wireless communication in the second frequency band during the period from a timing t3to a timing t4and the period from a timing t7to a timing t8. In the exemplary case shown inFIG. 14, the period of the communication performed by the chip antenna element21does not overlap the period of the communication performed by the loop antenna31as seen from the drawing.

Accordingly, the communication by the chip antenna element21and the communication by the loop antenna31can be both performed in accordance with the timings shown inFIG. 14.

FIG. 15shows an exemplary case where the communication in the first frequency band overlaps the communication in the second frequency band in timing in the radio equipment100relating to the embodiment of the present invention. InFIG. 15, the horizontal axis represents the time.

In the exemplary case shown inFIG. 15, the chip antenna element21first transmits information in the first frequency band during the period from a timing t101to a timing t102, and the loop antenna31then performs wireless communication in the second frequency band during the period from a timing t103to a timing t104.

Since the user places a not-shown terminal close to the loop antenna31, the loop antenna31performs wireless communication in the second frequency band during the period from a timing t105to a timing t108. Here, the period from the timing t105to the timing t108overlaps the period from a timing t106to a timing t107, during which the chip antenna element21is scheduled to perform communication. In this case, the controller6controls the timings of the communications in such a manner that the communication using the chip antenna element21is not performed at the scheduled timings and information is alternatively transmitted by the chip antenna element21when a predetermined period T2has elapsed after the end of the communication using the loop antenna31, during the period from a timing t109to a timing t110.

In addition, the controller6controls the timings of the communications such that the next round of communication using the chip antenna element21is performed when the period T1has elapsed after the timing t109, during the period from a timing t111to a timing t112.

In other words, when the scheduled timing of the wireless communication in the first frequency band is reached while the wireless communication is in progress in the second frequency band, the controller6controls the timings of the communications in such a manner that the wireless communication in the first frequency band is not performed while the wireless communication is in progress in the second frequency band. The controller6controls the timings of the communications in such a manner that the wireless communication in the first frequency band can be alternatively started when the period T2has elapsed after the detection of the end of the wireless communication in the second frequency band.

FIG. 16shows an exemplary case where an attempt is made to perform the communication in the second frequency band while communication is being performed in the first frequency band in the radio equipment100relating to the embodiment of the present invention. InFIG. 16, the horizontal axis represents the time.

In the exemplary case shown inFIG. 16, the chip antenna element21first transmits information in the first frequency band during the period from a timing t201to a timing t202, and the loop antenna31then performs wireless communication in the second frequency band during the period from a timing t203to a timing t204. The controller6controls the timings of the communications such that the communication in the first frequency band is performed during the period from a timing t205to a timing t206, which starts when the period T1has elapsed after the timing t201.

If the user places a not-shown terminal close to the loop antenna31during the period from the timing t205to the timing t206(the period T3), the controller6controls the timings of the communications in such a manner that the communication by the loop antenna31is performed during the period from a timing t206to a timing t207, which is placed after the end of the communication by the chip antenna element21.

In other words, when an attempt is made to perform the wireless communication in the second frequency band while the wireless communication is in progress in the first frequency band, the controller6does not allow the wireless communication in the second frequency band to be performed while the wireless communication in the first frequency band is being performed. In this manner, the wireless communication in the second frequency band is prohibited until the wireless communication in the first frequency band ends. The controller6controls the timings of the communications in such a manner that the wireless communication in the second frequency band is allowed when the wireless communication in the first frequency band ends. Here, the controller6may control the RFID tag controller4for the second frequency band to remain in the low power consumption mode during the communication-prohibited period.

It should be noted that the timings of the communications shown inFIGS. 14 to 16are only illustrative and the present invention is not limited to such. For example, with reference toFIG. 15, the controller6may control the timings of the communications in such a manner that the chip antenna element21may start the communication before the period T2has elapsed after the timing t108at which the loop antenna31ends the communication.

As seen from the exemplary cases shown inFIGS. 14 to 16, the timings of the communications are controlled in such a manner that the transmission by the chip antenna element21does not overlap the transmission by the loop antenna31in timing in the present embodiment.

With such configurations, while one of the chip antenna element21and the loop antenna31performs communication, the other does not perform communication in the present embodiment. Therefore, the present embodiment can prevent the degradation of the antenna characteristics of the chip antenna element21and the loop antenna31during the communication.

In addition, the position of the chip antenna element21is not limited to the above-described position and can be changed as appropriate provided that the antenna characteristics required by the radio equipment100are satisfied.

The above description is made with reference to the exemplary case where the antenna pattern constituting the loop antenna31has two turns, but the present invention is not limited to such. In order to improve the communication characteristics of the RFID tag, the number of the turns of the loop antenna31may be increased to three or four using a multilayer substrate so that the inductance L value is raised. In this case, the antenna patterns in the respective layers are also formed to overlap each other.

Note that the shape of the loop antenna31is not limited to the shape shown inFIG. 6and the like. The loop antenna31may be shaped like a square, polygon, circle, ellipsoid or the like.

The program to implement some or all of the functions of the radio equipment100relating to the present invention except for the functions of the antenna module1may be stored in a computer readable storage medium, and the program stored in the storage medium may be read and executed by a computer system so that the computer system can perform some or all of the operations performed by the radio equipment100(except for the antenna module1). Here, the “computer system” may include OS and hardware such as peripheral devices. The term “computer system” may also include a WWW system provided with a website providing environment (or displaying environment). The term “computer readable storage medium” means a storage device including a portable medium such as a flexible disk, a magnetooptical disk, ROM or CDROM, and a hard disk embedded in the computer system. In addition, the term “computer readable storage medium” also includes a medium configured to retain the program for a certain period of time, such as volatile memory (RAM) incorporated into the computer system, which serves as a server or client when the program is transmitted over a network such as the Internet and a communication link such as a phone link.

The above-mentioned program may be transmitted from a computer system that stores the program into a storage device or the like to a different computer system via a transmission medium or a transmission wave in the transmission medium. Here, the term “transmission medium” via which the program is transmitted denotes a medium that is capable of transmitting information, for example, a network (communication network) such as the Internet or a communication link (communication line) such as a phone link. The above-mentioned program may be designed to implement some of the above-mentioned functions. The above-mentioned program may be designed to be capable of implementing the above-mentioned functions in combination with the program that has already been stored in the computer system, that is to say, a differential file (differential program).

EXPLANATION OF REFERENCES