Patent Application
20220224008
The present disclosure relates to an antenna device and a radio communication device including the same.
For example, Patent Document 1 discloses what is called a dual-band dipole antenna capable of communication at a frequency in a predetermined low-frequency band and at a frequency in a predetermined high-frequency band. To support the dual-band communication, the dipole antenna includes, as a band elimination filter, an LC parallel circuit on the antenna conductor. The LC parallel circuit passes frequencies in the low-frequency band but attenuates frequencies in the high-frequency band.
Patent Document 1: U.S. Patent Application Publication No. 2005/0280579 Specification
A folded antenna such as a folded dipole antenna is known as a downsized antenna. A dual-band antenna can also be downsized likewise. However, the folding has caused the deterioration of antenna efficiency in a high-frequency band on occasions.
Hence, the present disclosure addresses reducing the deterioration of antenna efficiency in a high-frequency band in a dual-band antenna device including a folded antenna conductor.
To solve the technical problem described above, according to an aspect of the present disclosure, the present disclosure provides an antenna device that is a dual-band antenna device allowed to perform communication at a first frequency in a predetermined frequency band and at a second frequency in a frequency band higher than the predetermined frequency band. The antenna device includes a ground conductor; a folded antenna conductor including a first linear part and a second linear part that are caused to face each other at a distance by folding; an LC resonant circuit that is included in the folded antenna conductor, that passes the first frequency, and that attenuates the second frequency; and a feeding point between the ground conductor and the folded antenna conductor. A narrow gap part is provided between the first linear part and the second linear part of the folded antenna conductor, the narrow gap part measuring a distance shorter than a distance measured in a different portion between the first linear part and the second linear part.
According to another aspect of the present disclosure, the present disclosure provides an antenna device that is a dual-band antenna device allowed to perform communication at a first frequency in a predetermined frequency band and at a second frequency in a frequency band higher than the predetermined frequency band. The antenna device includes: a ground conductor; a folded antenna conductor including a first linear part and a second linear part that are caused to face each other at a distance by folding; an LC resonant circuit that is included in the folded antenna conductor, that attenuates the first frequency, and that passes the second frequency; and a feeding point between the ground conductor and the folded antenna conductor. A narrow gap part is provided between the first linear part and the second linear part of the folded antenna conductor, the narrow gap part measuring a distance shorter than a distance measured in a different portion between the first linear part and the second linear part. The LC resonant circuit is included in the narrow gap part.
Further, according to another aspect of the present disclosure, the present disclosure provides a radio communication device including: the antenna device; and a feeder circuit that supplies power to the feeding point of the antenna device.
According to the present disclosure, the deterioration of antenna efficiency in a high-frequency band can be reduced in the dual-band antenna device including the folded antenna conductor.
An antenna device according to an aspect of the present disclosure is a dual-band antenna device allowed to perform communication at a first frequency in a predetermined frequency band and at a second frequency in a frequency band higher than the predetermined frequency band. The antenna device includes a ground conductor; a folded antenna conductor including a first linear part and a second linear part that are caused to face each other at a distance by folding; an LC resonant circuit that is included in the folded antenna conductor, that passes the first frequency, and that attenuates the second frequency; and a feeding point between the ground conductor and the folded antenna conductor. A narrow gap part is provided between the first linear part and the second linear part of the folded antenna conductor, the narrow gap part measuring a distance shorter than a distance measured in a different portion between the first linear part and the second linear part.
According to the aspect as above, the deterioration of antenna efficiency in a high-frequency band can be reduced in the dual-band antenna device including the folded antenna conductor.
For example, in a case where the first linear part and the second linear part extend parallel to each other, the antenna device may include a branch part that forms a narrow gap part such that one of the first linear part and the second linear part extends toward a different one of the first linear part and the second linear part.
For example, the distance between the first linear part and the second linear part can be longer than each of respective line widths of the first linear part and the second linear part.
For example, the folded antenna conductor may include a floating-island-like part between the first linear part and the second linear part. The narrow gap part may include a first narrow gap part between the floating-island-like part and the first linear part and a second narrow gap part between the floating-island-like part and the second linear part.
For example, the antenna device may further include a capacitor chip included in the narrow gap part and connecting the first linear part and the second linear part.
For example, the LC resonant circuit may include the capacitor chip and an inductor chip that are disposed in parallel.
For example, the folded antenna conductor may be a folded dipole antenna.
For example, the first frequency may be a frequency in a 2.4 GHz band, and the second frequency may be a frequency in a 5 GHz band.
An antenna device according to another aspect of the present disclosure is a dual-band antenna device allowed to perform communication at a first frequency in a predetermined frequency band and at a second frequency in a frequency band higher than the predetermined frequency band. The antenna device includes: a ground conductor; a folded antenna conductor including a first linear part and a second linear part that are caused to face each other at a distance by folding; an LC resonant circuit that is included in the folded antenna conductor, that attenuates the first frequency, and that passes the second frequency; and a feeding point between the ground conductor and the folded antenna conductor. A narrow gap part is provided between the first linear part and the second linear part of the folded antenna conductor, the narrow gap part measuring a distance shorter than a distance measured in a different portion between the first linear part and the second linear part. The LC resonant circuit is included in the narrow gap part.
According to the aspects as above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device including the folded antenna conductor.
A radio communication device according to another aspect of the present disclosure includes the antenna device and a feeding point of the antenna device that supplies power to a feeder circuit.
According to the aspect as above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band radio communication device including the folded antenna conductor.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
As illustrated in
As illustrated in
In the case of Embodiment 1, the ground conductor 12 of the antenna device 10 is a conductor pattern formed on the base substrate 52 and formed from an insulating material such as copper.
In the case of Embodiment 1, the folded antenna conductor 14 of the antenna device 10 is what is called a folded dipole antenna and is a conductor pattern formed from, for example, copper on the base substrate 52.
Specifically, the folded antenna conductor 14 includes a first element part 20 and a second element part 22 in a symmetrical structure (with respect to the Y axis). The folded antenna conductor 14 also includes a parasitic line part 24 and a feeding line part 26 that respectively connect the first element part 20 and the second element part 22 to the ground conductor 12.
The first element part 20 in the folded antenna conductor 14 is connected to an edge 12a of the ground conductor 12 (one end in the Y axis) with the parasitic line part 24 interposed therebetween. The first element part 20 also includes a first linear part 20a and a second linear part 20b that are caused to face each other at a distance by the folding.
Specifically, the first element part 20 in the folded antenna conductor 14 extends from the parasitic line part 24 toward an outer side portion (in a negative direction along the X axis) and then extends toward an inner side portion (in a positive direction along the X axis) in such a manner as to change the direction by 180 degrees, that is, being folded. As the result, the first element part 20 includes the first linear part 20a and the second linear part 20b that face each other at a distance.
Note that in the case of Embodiment 1, in the first element part 20, the first linear part 20a and the second linear part 20b are parallel to each other, are a distance D1 spaced, and extend parallel to the edge 12a of the ground conductor 12. The distance D1 can be longer than each of widths W1 and W2 of the respective first and second linear parts 20a and 20b. Unlike this, if the distance D1 is shorter than each of the widths W1 and W2, a magnetic field generated by current flowing through the first linear part 20a hinders the flow of current flowing in an opposite direction through the second linear part 20b.
The second linear part 20b of the first element part 20 also includes an open end 20c. The electrical length of the first element part 20 from the parasitic line part 24 to the open end 20c is substantially ¼ the length of the wavelength of the first frequency.
The second element part 22 in the folded antenna conductor 14 is connected to the edge 12a of the ground conductor 12 with the feeding line part 26 interposed therebetween. The second element part 22 includes a first linear part 22a and a second linear part 22b that are caused to face each other at a distance by the folding.
Specifically, the second element part 22 in the folded antenna conductor 14 extends from the feeding line part 26 toward an outer side portion (in the positive direction along the X axis), then extends toward an inner side portion (in the negative direction along the X axis) in such a manner as to change the direction by 180 degrees, that is, being folded, and terminates. As the result, the second element part 22 includes the first linear part 22a and the second linear part 22b that face each other at a distance.
Note that in the case of Embodiment 1, in the second element part 22, the first linear part 22a and the second linear part 22b are parallel to each other, are the distance D1 spaced, and extend parallel to the edge 12a of the ground conductor 12. The distance D1 can be longer than each of the widths W1 and W2 of the respective first and second linear parts 22a and 22b.
The second linear part 22b of the second element part 22 includes an open end 22c. The electrical length of the second element part 22 from the feeding line part 26 to the open end 22c is ¼ the length of the wavelength of the first frequency.
Further, the first linear part 20a of the first element part 20 and the first linear part 22a of the second element part 22 are located on one straight line, and the second linear part 20b of the first element part 20 and the second linear part 22b of the second element part 22 are located on one straight line.
Note that in the case of Embodiment 1, the feeding point 18 is provided between the ground conductor 12 and the folded antenna conductor 14. In the case of Embodiment 1, the feeding point 18 is provided in the connecting part between the ground conductor 12 and the feeding line part 26.
The LC resonant circuits 16 are respectively provided in the first element part 20 and the second element part 22 of the folded antenna conductor 14. In the case of Embodiment 1, the LC resonant circuits 16 respectively include capacitor chips 28 having predetermined capacitance and inductor chips 30 disposed parallel to the respective capacitor chips 28 and having predetermined inductance.
Each LC resonant circuit 16 is an LC parallel circuit that passes the first frequency in the predetermined lower frequency band but attenuates the second frequency in the frequency band higher than the predetermined frequency band, that is, that resonates at the first frequency. The LC resonant circuit 16 is provided in a corresponding one of the first and second element parts 20 and 22 at a position away by ¼ of the wavelength of the second frequency from a corresponding one of the parasitic line part 24 and the feeding line part 26.
According to the antenna device 10 as described above, the first and second element parts 20 and 22 of the folded antenna conductor 14 function as the dipole antenna. In addition, since the first and second element parts 20 and 22 are folded, the antenna device 10 (that is, the radio communication device 50) is downsized compared with a case where the first and second element parts 20 and 22 extend on the straight line without necessarily being folded.
Further, when communication is performed at the first frequency in the predetermined lower frequency band, current flows through the entire first and second element parts 20 and 22. In contrast, when communication is performed at the second frequency in the frequency band higher than the predetermined frequency band, current flows through each of portions of the respective first and second element parts 20 and 22 between a corresponding one of the parasitic line part 24 and the feeding line part 26 and the corresponding LC resonant circuit 16. That is, each LC resonant circuit 16 functions as a band elimination filter for the second frequency. The antenna device 10 functions as the dual-band antenna allowed to perform communication at the first and second frequencies.
However, the inventor has found that there is a possibility of deterioration of antenna efficiency at the second frequency in the higher frequency band in the antenna device 10 as described above. The inventor has also identified the cause thereof and found out the following configurations to cope therewith.
As illustrated in
In the case of Embodiment 1, the first linear part 20a of the first element part 20 includes a branch part 20e extending toward the second linear part 20b and forming the narrow gap part 20d between the first linear part 20a and the second linear part 20b. Likewise, the first linear part 22a of the second element part 22 includes a branch part 22e extending toward the second linear part 22b and forming the narrow gap part 22d between the first linear part 22a and the second linear part 22b.
As illustrated in
Advantageous effects exerted by providing the narrow gap parts 20d and 22d as described above will be described.
In
As illustrated in
Note that the shifting degree of the harmonic wave at the first frequency can be controlled by changing the width W3 and the location of the branch parts 20e and 22e.
As illustrated in Examples 1 to 3 in
Thus, as illustrated in
According to Embodiment 1 as described above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device 10 including the folded antenna conductor 14.
Note that in the case of Embodiment 1, as illustrated in
Embodiment 2 is an embodiment improved from Embodiment 1 described above. Embodiment 2 will thus be described with a focus on a point different from Embodiment 1 above. Note that substantially the same components in Embodiment 2 as the components in Embodiment 1 above are denoted by the same reference numerals.
As illustrated in
Narrow gap parts 120d are provided between the first linear part 120a and the second linear part 120b of the first element part 120, the narrow gap parts 120d each measuring a distance shorter than a distance measured in the other portions therebetween. Likewise, narrow gap parts 122d are provided between a first linear part 122a and a second linear part 122b of the second element part 122, the narrow gap parts 122d each measuring a distance shorter than a distance measured in the other portions therebetween.
Unlike Embodiment 1 above, in the case of Embodiment 2, branch parts do not extend from the first linear parts 120a and 122a and thus do not form the narrow gap parts 120d and 122d.
Instead, the first and second element parts 120 and 122 of the folded antenna conductor 114 respectively include floating-island-like parts 120e and 122e each provided between a corresponding one of the first linear parts 120a and 122a and a corresponding one of the second linear parts 120b and 122b.
The floating-island-like parts 120e and 122e are not respectively continuous with the first linear parts 120a and 122a and the second linear parts 120b and 122b and each have one end forming a corresponding one of the narrow gap parts 120d and 122d (first narrow gap parts) between the one end and a corresponding one of the first linear parts 120a and 122a and the other end forming a corresponding one of the narrow gap parts 120d and 122d (second narrow gap parts) between the other end and a corresponding one of the second linear parts 120b and 122b.
Also in Embodiment 2 as described above, like Embodiment 1 above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device 110 including the folded antenna conductor 114.
Embodiment 3 is an embodiment improved from Embodiment 1 described above. Embodiment 3 will thus be described with a focus on a point different from Embodiment 1 above. Note that substantially the same components in Embodiment 3 as the components in Embodiment 1 above are denoted by the same reference numerals.
As illustrated in
A narrow gap part 220d is provided between the first linear part 220a and the second linear part 220b of the first element part 220, the narrow gap part 220d measuring a distance shorter than a distance measured in the other portions therebetween. Likewise, a narrow gap part 222d is provided between a first linear part 222a and a second linear part 222b of the second element part 222, the narrow gap part 222d measuring a distance shorter than a distance measured in the other portions therebetween.
Unlike Embodiment 1 above, in the case of Embodiment 3, branch parts do not extend from the first linear parts 220a and 222a and thus do not form the narrow gap parts 220d and 222d. In addition, unlike Embodiment 2 above, any of floating-island-like parts is not formed between a corresponding one of the first linear parts 220a and 222a and a corresponding one of the second linear parts 220b and 222b and thus does not form a corresponding one of the narrow gap parts 220d and 222d.
Instead, the second linear parts 220b and 222b extend obliquely with respect to a direction in which the first linear parts 220a and 222a extend (X-axis direction), in such a manner that portions, of the second linear parts 220b and 222b, closer to open ends 220c and 222c become closer to the first linear parts 220a and 222a. As the result, the narrow gap parts 220d and 222d are each formed between a corresponding one of the open ends 220c and 222c and a corresponding one of the first linear parts 220a and 222a.
Also in Embodiment 3 as described above, like Embodiment 1 above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device 210 including the folded antenna conductor 214.
Embodiment 4 is an embodiment improved from Embodiment 1 described above. Embodiment 4 will thus be described with a focus on a point different from Embodiment 1 above. Note that substantially the same components in Embodiment 4 as the components in Embodiment 1 above are denoted by the same reference numerals.
As illustrated in
Appropriately selecting capacity value of the capacitor chips 332 enables the capacitance Cl in the narrow gap parts 20d and 22d to be controlled desirably and easily (for example, compared with the case of changing the shape of the folded antenna conductor 14). The shifting degree of the harmonic wave at the first frequency can thereby be controlled desirably. As the result, the interference of the harmonic wave at the first frequency with the fundamental at the second frequency can be reduced more.
Also in Embodiment 4 as described above, like Embodiment 1 above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device 310 including the folded antenna conductor 14.
In the case of Embodiment 1, to function as the dual-band antenna device, the antenna device 10 includes the LC resonant circuits 16. Each LC resonant circuit 16 is the LC parallel circuit that passes the first frequency in the lower frequency band but attenuates the second frequency in the higher frequency band, that is, that resonates at the first frequency. In contrast, LC resonant circuits of the antenna device in Embodiment 5 perform different operations. Embodiment 5 will thus be described with a focus on a point different from Embodiment 1 above. Note that substantially the same components in Embodiment 5 as the components in Embodiment 1 above are denoted by the same reference numerals.
As illustrated in
The first element part 420 of the folded antenna conductor 414 includes a first linear part 420a and a second linear part 420b that are caused to face each other at a distance by the folding. Likewise, the second element part 422 also includes a first linear part 422a and a second linear part 422b that are caused to face each other at a distance by the folding.
In addition, a narrow gap part 420d is provided between the first linear part 420a and the second linear part 420b of the first element part 420, the narrow gap part 420d measuring a distance shorter than a distance measured in the other portions therebetween. In the case of Embodiment 5, the first linear part 420a includes a branch part 420e extending toward the second linear part 420b and forming the narrow gap part 420d between the branch part 420e and the second linear part 420b.
Likewise, a narrow gap part 422d is also provided between the first linear part 422a and the second linear part 422b of the second element part 422, the narrow gap part 422d measuring a distance shorter than a distance measured in the other portions therebetween. In the case of Embodiment 5, the first linear part 422a includes a branch part 422e extending toward the second linear part 422b and forming the narrow gap part 422d between the branch part 422e and the second linear part 422b.
In the case of Embodiment 5, LC resonant circuits 434 are respectively provided in the narrow gap parts 420d and 422d of the respective first and second element parts 420 and 422 and each connect a corresponding one of the first linear parts 420a and 422a and a corresponding one of the second linear parts 420b and 422b.
In addition, in the case of Embodiment 5, LC resonant circuits 434 respectively include capacitor chips 436 having predetermined capacitance and inductor chips 438 disposed parallel to the respective capacitor chips 436 and having predetermined inductance.
Further, unlike the LC resonant circuits 16 in Embodiment 1 above, the LC resonant circuits 434 in Embodiment 5 let the second frequency in the higher frequency band pass but let the first frequency in the lower frequency band attenuate, that is, resonate at the first frequency. The capacitance of each capacitor chip 436 of the corresponding LC resonant circuit 434 is 2.1 pF, and the inductance of each inductor chip 438 is 2.0 nH.
The antenna device 410 according to Embodiment 5 as described above also provides the same advantageous effects as those in Embodiment 1 above.
As illustrated in
Also in Embodiment 5 as described above, like Embodiment 1 above, the deterioration of the antenna efficiency in the high-frequency band can be reduced in the dual-band antenna device 410 including the folded antenna conductor 414.
The present disclosure has heretofore been described by citing embodiments, but the embodiments of the present disclosure are not limited to these embodiments.
For example, in the cases of Embodiment 1 and Embodiment 5 above, the LC resonant circuits 16 and 434 each includes the capacitor chip and the inductor chip that are disposed in parallel. The antenna devices are thereby downsized. However, the configuration of the LC resonant circuits is not limited to this configuration. For example, a capacitor element composed of a pair of parallel conductor patterns and an inductor element as a meandering conductor pattern may form an LC resonant circuit on the base substrate.
In addition, for example, in the cases of Embodiments 1 to 5 above, each folded antenna conductor is the folded dipole antenna. However, the antenna conductor according to each embodiment of the present disclosure is not limited to this. The folded antenna conductor may be another folded wire antenna such as a folded monopole antenna or a folded inverted-F antenna.
The present disclosure has heretofore been described by citing embodiments, it is obvious for those skilled in the art that an embodiment may be combined as a whole or partially with at least one different embodiment to obtain a further embodiment according to the present disclosure.
The present disclosure is applicable to a dual-band antenna device including a linear antenna conductor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-182742 | Oct 2019 | JP | national |
This is a continuation of International Application No. PCT/JP2020/033117 filed on Sep. 1, 2020 which claims priority from Japanese Patent Application No. 2019-182742 filed on Oct. 3, 2019. The contents of these applications are incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/033117 | Sep 2020 | US |
| Child | 17657174 | US |
