JP2011035676A - Multi-frequency antenna - Google Patents

Abstract

A multi-frequency antenna suitable for mounting on a small wireless device is realized.
An antenna includes a ground plane and a radiating element connected to the ground plane via a feeding point, and a slot is opened in the ground plane. As a result, it is possible to realize multi-frequency without increasing the weight, making the structure three-dimensional, or applying deformation that increases the size to the ground plane 11 or the radiating element 12.
[Selection] Figure 1

Description

  The present invention relates to an antenna, and more particularly to a multi-frequency antenna having a plurality of operating bands.

  Multiple wireless communication standards using different bands coexist. For example, wireless LAN (IEEE802.11b / g) and Bluetooth (registered trademark) using 2.4 GHz band (2400 MHz to 2483.5 MHz), and high-speed wireless using 5.0 GHz band (5150 MHz to 5875 MHz) An example is LAN (IEEE802.11a).

  Also, in recent years, expectations for WiMAX (Worldwide Interoperability for Microwave Access) are increasing as a wireless communication standard for wireless communication of so-called last one mile, which is not reached by networks such as optical access networks and metallic access networks. WiMAX uses a 2.5 GHz band (2500 MHz to 2700 MHz), a 3.5 GHz band (3300 MHz to 3800 MHz), and a 5.8 GHz band (5250 MHz to 5850 MHz).

  In order to cope with such a situation, an antenna mounted on a wireless device is required to have multiple frequencies (multiple operation bands). Examples of the multi-frequency antenna include a semicircular slot antenna described in Non-Patent Document 1, a PIFA (plate-shaped inverted F antenna) described in Non-Patent Documents 2 and 3, and a dipole antenna described in Non-Patent Document 4. And a monopole antenna described in Patent Document 1.

Taiwan Patent No. 262625 Specification

HM Hsiao, JW. Wu, JH. Lu, and YD. Wang, “A novel dual-broadband semi-circle slot antenna for wireless communication,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp.385-388. H.S. Yoon and S. O. Park, “A dual-band internal antenna of PIFA type for Bluetooth / WLAN in mobile handsets,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp.665-668. Y.S. Shin and S. O. Park, “A novel PIFA for 2.4 and 5 GHz WLAN application,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp.645-648. SH Yeh, WC. Yang, and WK. Su, “2.4 / 5.2 GHz WLAN unequal-arms dipole antenna woth a meandered strip for omni-directional radiation patterns,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA , 2007, pp.649-652.

  However, the conventional multi-frequency antenna has a problem that it is not suitable for mounting on a small wireless device such as a personal computer or a PDA (Personal Digital Assistant).

  For example, the semicircular slot antenna described in Non-Patent Document 1 requires a semicircular radiating element to be formed on a substrate having a dielectric layer, and thus has a large weight and is not suitable for mounting on a small wireless device. . In addition, the PIFAs described in Non-Patent Documents 2 to 3 require a three-dimensional structure (three-dimensional structure), and thus are not suitable for mounting on a small wireless device. Although the dipole antenna described in Non-Patent Document 4 has the merit that a ground plane is not required, since it is a λ / 2 antenna, a low frequency side band such as a 2.4 GHz band or a 2.5 GHz band is used as an operating band. Further, the total length of the radiating element becomes very long, and it is not suitable for mounting on a small wireless device.

  In addition, the monopole antenna described in Patent Document 1 includes a ground plane, and a T-type radiating element in which a straight portion perpendicular to the end of the ground plane and a straight portion parallel to the end of the ground plane are combined in a T shape. This is a monopole antenna that realizes three frequencies by adding a branch parallel to the edge of the ground plane to a straight portion perpendicular to the edge of the ground plane. For this reason, when the low frequency side band such as the 2.4 GHz band or the 2.5 GHz band is used as the operating band, the total length of the straight portion parallel to the ground plane becomes long, which is also not suitable for mounting on a small wireless device. . There is also a problem that a huge ground plane (using the display as a ground plane) is necessary.

  The present invention has been made in view of the above problems, and an object thereof is to realize a multi-frequency antenna suitable for mounting on a small wireless device.

  In order to solve the above problems, an antenna according to the present invention is an antenna including a ground plane and a radiating element connected to the ground plane via a feeding point, and the ground plane is provided with an opening. It is characterized by.

  According to said structure, in addition to the resonant frequency of the said radiation element, the said antenna can be resonated in the resonant frequency of the said opening. For this reason, in addition to the band in the vicinity of the resonance frequency of the radiating element, a multi-frequency antenna having the band in the vicinity of the resonance frequency of the opening as the operation band can be realized.

  Moreover, in order to realize multi-frequency, it is not necessary to increase the weight, make the structure three-dimensional, or apply a deformation that increases the size to the radiating element. For this reason, there exists an effect that the multifrequency antenna suitable for mounting to a small radio | wireless apparatus is realizable.

  In the antenna according to the present invention, it is preferable that the shape of the opening is a band shape.

  According to said structure, the 1st resonance frequency of the said opening is decided according to the length (dimension of the longitudinal direction of an opening) of the said opening. For this reason, it has the further effect that the said opening which has a 1st resonance frequency in the target zone | band can be designed easily.

  The antenna which concerns on this invention WHEREIN: It is preferable that the said ground plane has the protrusion part extended to the said feed point.

  According to said structure, the capacity | capacitance produced between the said ground plane and the said radiation | emission element can be changed by changing at least any one of the size and shape of the said protrusion part. Thereby, the input impedance of the antenna can be changed. That is, by changing at least one of the size and shape of the protruding portion, there is a further effect that impedance matching can be easily achieved without increasing the size of the ground plane.

  The antenna which concerns on this invention WHEREIN: It is preferable that the said opening is provided so that the base of the said protrusion part may be followed.

  In the ground plane, a stronger current flows in the vicinity of the base of the projecting portion (connection portion with the main body of the ground plane) than in other areas. Therefore, according to the above configuration, at least a part of the opening can be arranged in a region where a current that is stronger than other regions flows, and resonance at the resonance frequency of the opening can be more effectively generated. There is a further effect of being able to.

  In the antenna according to the present invention, the ground plane has a rectangular portion adjacent to the protruding portion, and the opening includes a first side of the rectangular portion including a base portion of the protruding portion, and the first. It is preferable to be provided along the second side and the third side adjacent to the side.

  According to said structure, a part (1st edge | side) of the said opening is along the base part (connection part with the rectangular part which is a main body of a ground plate) of the said protrusion part where a strong electric current flows compared with another area | region. It is formed. For this reason, resonance at the resonance frequency of the opening can be more effectively generated. Moreover, when the shape of the said opening is strip | belt shape, the length (dimension of the longitudinal direction of an opening) of the said opening can be made longer than the length of the said 1st side of the said rectangular part. For this reason, it is possible to reduce the operating band without incurring an increase in the size of the ground plane, or to reduce the size of the ground plane without incurring an increase in the operating band. The effect which becomes.

  In the antenna according to the present invention, the ground plane has a rectangular portion connected to the protruding portion, and the opening includes a first side of the rectangular portion including a boundary with the protruding portion, the first side. It is preferable that the second side and the third side that are adjacent to the side and the fourth side that faces the first side are provided.

  According to said structure, a part (1st edge | side) of the said opening is along the base part (connection part with the rectangular part which is a main body of a ground plate) of the said protrusion part where a strong electric current flows compared with another area | region. It is formed. For this reason, resonance at the resonance frequency of the opening can be more effectively generated. In the case where the shape of the opening is a band shape, the length of the opening (the dimension in the longitudinal direction of the opening) is set such that the length of the first side of the rectangular portion, the length of the second side, It can be made longer than the sum of the length of the third side. For this reason, it is possible to reduce the operating band without incurring an increase in the size of the ground plane, or to reduce the size of the ground plane without incurring an increase in the operating band. The effect which becomes.

  In the antenna according to the present invention, it is preferable that the radiating element is bent.

  According to said structure, the 2nd resonance frequency of the said radiation element can be shifted by changing the bending method of the said radiation element. Thereby, the further effect that the space | interval of the operation band containing the 1st resonance frequency of the said radiating element and the operation band containing the 2nd resonance frequency of the said radiating element can be adjusted is produced. Further, the space required for the arrangement of the radiating elements can be reduced without increasing the space required for the arrangement of the radiating elements, or by reducing the frequency of the operating band, or without increasing the frequency of the operating band. It has the further effect of being able to be made into an image.

  In the antenna according to the present invention, the radiating element is connected to the feeding point and extends in a first direction, and is connected to the first linear portion and perpendicular to the first direction. A second linear portion extending in a second direction, connected to the second linear portion, a third linear portion extending in the first direction, connected to the third linear portion, and the second linear portion. It is preferable that it has the 4th linear part extended in the direction opposite to this direction.

  According to the above configuration, the second resonance frequency of the radiating element is determined according to the sum of the length of the first straight line portion and the length of the second straight line portion. For this reason, the further effect that the said radiation | emission element which has a 2nd resonance frequency in the target zone | band can be designed easily is produced.

  In the antenna according to the present invention, the radiating element is connected to the feeding point and extends in a first direction. The radiating element is connected to the first linear portion and is connected to the first linear portion and is perpendicular to the first direction. A second straight portion extending in the direction of 2, a third straight portion connected to the second straight portion and extending in the first direction, and a second straight portion connected to the third straight portion and the second direction. It is preferable to have a meander part that extends in the opposite direction and is at least partially meandered.

  According to the above configuration, the second resonance frequency of the radiating element is determined according to the sum of the length of the first straight line portion and the length of the second straight line portion. For this reason, the further effect that the said radiation | emission element which has a 2nd resonance frequency in the target zone | band can be designed easily is produced. In addition, as part of the radiating element is made into a meander, it is possible to lower the operating band or increase the operating band without increasing the space required for arranging the radiating element. Without this, there is a further effect that the space required for the arrangement of the radiating elements can be reduced.

  The antenna according to the present invention preferably further includes a short-circuit portion that short-circuits the ground plane and the radiating element.

  According to the said structure, there exists the further effect that an impedance matching can be taken easily by changing the shape of a short circuit part.

  In the antenna according to the present invention, the frequency is increased by providing an opening in the ground plane without increasing the weight, making the structure three-dimensional, or applying deformation that increases the size to the radiating element. Therefore, a multi-frequency antenna suitable for mounting on a small wireless device can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a first embodiment of the present invention and is a plan view illustrating a configuration of an antenna. FIG. 2 is a plan view illustrating a first specific configuration example of the antenna illustrated in FIG. 1. 3 is a graph showing VSWR (voltage standing wave ratio) characteristics of the antenna shown in FIG. 2. 3 is a graph showing radiation directivity at 2442 MHz (2.4 GHz band) of the antenna shown in FIG. 2, and (a), (b), and (c) are radiation directivities in the xy plane, radiation directivities in the yz plane, The radiation directivity in the zx plane is shown. 3 is a graph showing radiation directivity at 2600 MHz (2.5 GHz band) of the antenna shown in FIG. 2, and (a), (b), and (c) are radiation directivities on the xy plane and yz plane, The radiation directivity in the zx plane is shown. 3 is a graph showing the radiation directivity at 5470 MHz (5.0 GHz band) of the antenna shown in FIG. 2, wherein (a), (b), and (c) are the radiation directivity on the xy plane, the radiation directivity on the yz plane, The radiation directivity in the zx plane is shown. FIG. 3 is a graph showing frequency characteristics of average gain in the xy plane of the antenna shown in FIG. Show. FIG. 6 is a plan view showing a second specific configuration example of the antenna shown in FIG. 1. It is a graph which shows the VSWR (voltage standing wave ratio) characteristic of the antenna shown in FIG. It is a graph which shows the radiation directivity in 2442MHz (2.4GHz band) of the antenna shown in FIG. 8, (a), (b), and (c), respectively, the radiation directivity in xy plane, the radiation directivity in yz plane, The radiation directivity in the zx plane is shown. It is a graph which shows the radiation directivity in 2600 MHz (2.5 GHz band) of the antenna shown in FIG. 8, (a), (b), and (c), respectively, the radiation directivity in xy plane, the radiation directivity in yz plane, The radiation directivity in the zx plane is shown. It is a graph which shows the radiation directivity in 5470 MHz (5.0 GHz band) of the antenna shown in FIG. 8, (a), (b), and (c) are the radiation directivity in xy plane, the radiation directivity in yz plane, The radiation directivity in the zx plane is shown. It is a graph which shows the frequency characteristic of the average gain in xy plane of the antenna shown in FIG. 8, (a) is the frequency dependence regarding the operating band on the low frequency side, (b) is the frequency dependence regarding the operating band on the high frequency side. Show. The 2nd Embodiment of this invention is shown and it is a top view which shows the structure of an antenna. FIG. 15 is a plan view illustrating a specific configuration example of the antenna illustrated in FIG. 14. It is a graph which shows the VSWR (voltage standing wave ratio) characteristic of the antenna shown in FIG. 16 is a graph showing the radiation directivity at 824 MHz of the antenna shown in FIG. 15, wherein (a), (b), and (c) are radiation directivity on the xy plane, radiation directivity on the yz plane, and radiation directivity on the zx plane, respectively. Indicates. 16 is a graph showing radiation directivity at 960 MHz of the antenna shown in FIG. 15, and (a), (b), and (c) are radiation directivity on the xy plane, radiation directivity on the yz plane, and radiation directivity on the zx plane, respectively. Indicates. 16 is a graph showing the radiation directivity at 1710 MHz of the antenna shown in FIG. 15, and (a), (b), and (c) are radiation directivities in the xy plane, radiation directivities in the yz plane, and radiation directivities in the zx plane, respectively. Indicates. 16 is a graph showing radiation directivity at 2170 MHz of the antenna shown in FIG. 15, and (a), (b), and (c) are radiation directivity on the xy plane, radiation directivity on the yz plane, and radiation directivity on the zx plane, respectively. Indicates. FIG. 16 is a graph showing frequency characteristics of average gain in the xy plane of the antenna shown in FIG. 15, where (a) shows frequency dependence regarding the operating band on the low frequency side, and (b) shows frequency dependence concerning the operating band on the high frequency side. Show.

[Embodiment 1]
The following describes the first embodiment of the present invention with reference to FIGS.

(Antenna configuration)
First, the configuration of the antenna 10 according to the present embodiment will be described with reference to FIG. FIG. 1 is a plan view showing a configuration of an antenna 10 according to the present embodiment.

  As shown in FIG. 1, the antenna 10 includes an earth plate 11, a radiating element 12 connected to the earth plate 11 via a feeding point 14, and a short-circuit portion 13 that short-circuits the earth plate 11 and the radiating element 12. It is. The ground plane 11 and the radiating element 12 are separated in the vicinity of the feeding point 14, and one of the two conducting wires constituting the feeding line (for example, a coaxial cable) is connected near the feeding point 14 of the ground plane 11. The other conducting wire is connected in the vicinity of the feeding point 14 of the radiating element 12.

The main feature of the antenna 10 is that the base plate 11 is provided with an opening 11c. Thereby, in addition to the resonance frequency {f _e 1, f _e 2, ...} of the radiating element 12 (resonance frequency determined according to the shape of the radiating element 12), the resonance frequency {f _s 1, f _s 2 of the opening 11c. ,... (Resonance frequency determined according to the size and shape of the opening 11c), the antenna 10 can resonate. As a result, the antenna 10 operates within a band that satisfies a predetermined operating condition among bands including these resonance frequencies {f _e 1, f _e 2,...} {F _s 1, f _s 2,. It functions as a multi-frequency antenna.

For example, when predetermined operating conditions are satisfied in the band including the first resonance frequency f _e 1 of the radiating element 12 and the band including the first resonance frequency f _s 1 of the opening 11c, these two bands are operated. It functions as a dual frequency antenna for the band. Further, when a predetermined operating condition is satisfied in a band including the second resonance frequency _fe 2 of the radiating element 12, the radiating element 12 functions as a three-frequency antenna having these three bands as operating bands.

In the present embodiment, as shown in FIG. 1, a band-like opening called a slot is adopted as the opening 11 c provided in the base plate 11. When the shape of the opening 11c provided in the base plate 11 is a belt-like shape, the first resonance frequency f _s 1≈c / (4Ls) (c is the speed of light) is determined according to the total length Ls regardless of whether or not it is bent. For this reason, it is possible to easily design the opening 11c having the first resonance frequency f _s 1 within the target band. However, the present invention is not limited to this. That is, the shape of the opening 11c does not need to be a band shape as long as it has a resonance frequency within the target band.

In the present embodiment, a strip-shaped conductor is employed as the radiating element 12. When a strip-like or rod-like conductor (conductor film or conductor wire) is adopted as the radiating element 12, the first resonance frequency _fe 1 ≈c / (4Le) is obtained according to the total length Le regardless of whether it is bent or not. Determined. Therefore, it is possible to easily design the radiating element 12 having the first resonance frequency _fe 1 in the target band. However, the present invention is not limited to this. That is, the radiating element 12 does not need to be in the shape of a band or a rod as long as it has a resonance frequency within the target band.

  Next, configuration examples of the ground plane 11, the radiating element 12, and the short-circuit portion 13 will be described with reference to FIG. In addition, although the ground plane 11, the radiation element 12, and the short circuit part 13 are demonstrated as separate members, in the antenna 10 according to the present embodiment, these members are integrally formed by a single conductor. The boundary between the members (dotted line in FIG. 1) is merely determined for convenience of explanation.

  First, a configuration example of the main plate 11 will be described.

  As shown in FIG. 1, the ground plane 11 is a plate-like conductor having a rectangular portion 11a having a long side parallel to the z-axis and a rectangular protruding portion 11b having a long side parallel to the y-axis. The protruding portion 11b is arranged at the end of the short side 11a1 on the z-axis positive direction side of the rectangular portion 11a on the y-axis positive direction side, and is connected to the rectangular portion 11a via the short side 11a1. One of the two conductors constituting the feeder line is connected to the protruding portion 11b in the vicinity of the feeder point 14.

  By connecting the power supply line to the protruding portion 11b extending to the power supply point 14 as described above, impedance matching can be easily achieved as compared with the case where the power supply line is directly connected to the rectangular portion 11a. This is because the capacitance generated between the ground plane 11 and the radiating element 12 is changed without changing the size and shape of the rectangular portion 11 a by changing the size and shape of the protruding portion 11 b, that is, the antenna 10. This is because the input impedance can be changed.

  In particular, when the radiating element 12 is bent, the radiation resistance is reduced as compared with the case where the radiating element 12 is not bent, and the reactance component in the input impedance of the antenna 10 is increased. However, if the size and shape of the protruding portion 11b are changed so as to cancel these, even if the radiating element 12 is bent, impedance matching can be achieved without changing the size and shape of the rectangular portion 11a. Can do. As will be described later, when the radiating element 12 is bent along the projecting portion 11b, the capacitance generated between the ground plane 11 and the radiating element 12 can be increased, so that impedance matching can be performed more effectively. Can take.

  As described above, the opening 11 c is provided in the rectangular portion 11 a of the base plate 11. As shown in FIG. 1, the opening 11c includes a straight portion 11c1 along the short side 11a1 (first side) on the z-axis positive direction side of the rectangular portion 11a, and a long side 11a2 on the y-axis negative direction side of the rectangular portion 11a. This is a folded band-shaped opening having a straight line portion 11c2 along the (second side) and a straight line portion 11c3 along the long side 11a3 (third side) on the y-axis positive direction side of the rectangular portion 11a. Each of the straight portions 11c1 to 11c3 is a rectangular opening, and these are integrated to form a continuous band-shaped opening 11c. Hereinafter, the opening 11c is defined as “slot 11c”, the width of the straight portions 11c1 to 11c3 (the dimension in the short side direction) is defined as “the width of the slot 11c”, and the length of the straight portions 11c1 through 11c3 (the dimension in the long side direction). The sum is referred to as “the total length Ls of the slot 11c”.

Thus, by making the shape of the slot 11c into a bent shape, the space required for the arrangement of the slot 11c can be reduced while maintaining the total length Ls of the slot 11c. That is, the space required for arranging the slot 11c can be reduced without shifting the first resonance frequency f _s 1≈c / (4Ls) of the slot 11c to the high frequency side. For this reason, size reduction of the ground plane 11 can be achieved without inviting high frequency operation band. Alternatively, the total length Ls of the slot 11c can be increased without increasing the space required for the arrangement of the slot 11c. In this case, the operation band can be lowered without incurring an increase in the size of the ground plane 11.

In addition, it is preferable that the slot 11c is arrange | positioned so that the short side 11a1 of the rectangular part 11a including the base part of the protrusion part 11b may be followed. Because, since the strong current flows than other regions in the base of the projecting portion 11b, the resonant frequency of the slot _{11c {f s 1, f s} 2, ...} in, to resonate more effectively the antenna 10 Because it can. However, it is sufficient that at least a part of the slot 11c (specifically, the straight part 11c1) is along the short side 11a1 of the rectangular part 11a, and the other part of the slot 11c (specifically, the straight part 11c2 and the straight part). 11c3) does not need to be along the short side 11a1 of the rectangular part 11a.

  Next, a configuration example of the radiating element 12 will be described.

  As shown in FIG. 1, the radiating element 12 is connected to the feeding point 14, and extends in the z-axis positive direction (first direction), and the linear portion 12 a (first straight portion), and the z-axis positive of the linear portion 12 a. A straight line portion 12b (second straight line portion) that is connected to the straight line portion 12a via the end portion on the direction side and extends in the y-axis positive direction (second direction), and an end of the straight line portion 12b on the y-axis positive direction side A straight portion 12c (third straight portion) that is connected to the straight portion 12b through the portion and extends in the z-axis positive direction (first direction), and an end portion on the z-axis positive direction side of the straight portion 12c. A bent strip-shaped conductor that is connected to the straight portion 12c and has a straight portion 12d (fourth straight portion) extending in the negative y-axis direction (the direction opposite to the second direction). Further, the end portion of the straight portion 12a on the negative side of the z-axis is connected to a short-circuit portion 13 described later. One of the two conductors constituting the feeder line is connected to the end of the linear portion 12a on the negative z-axis direction side (short-circuit portion 13 side) (not shown).

  Each of the straight portions 12a to 12d is a rectangular conductor, which constitutes a band-shaped radiating element 12 that is bent together. Therefore, the end on the z-axis positive direction side of the straight portion 12a refers to the end of the straight portion 12a that appears when the straight portion 12a and the straight portion 12b are divided. The same applies to the end portions of the straight portions 12b to 12c. In the following, the width (dimension in the short side direction) of each straight line portion 12a to 12d is defined as “the width of the radiation element 12”, and the sum of the lengths (dimensions in the long side direction) of each straight line portion 12a to 12d is denoted as “radiation element 12”. The total length Le ”.

By bending the radiating element 12 in this way, it is possible to reduce the space required for disposing the radiating element 12 while maintaining the full length Le of the radiating element 12. That is, the space required for disposing the radiating element 12 can be reduced without shifting the first resonance frequency f _e 1≈c / (4Le) of the radiating element 12 to the high frequency side. For this reason, the space required for disposing the radiating element 12 can be reduced without increasing the frequency of the operating band. Alternatively, the entire length Le of the radiating element 12 can be increased and the operating band can be lowered without increasing the space required for disposing the radiating element 12.

Further, by bending the radiating element 12 in this way, the second resonance frequency _fe 2 can be shifted to the low frequency side. More specifically, the second resonance frequency fe2 is a frequency c / {4 (La + Lb)} in which the sum of the length La of the straight portion 12a and the length Lb of the straight portion 12b corresponds to a quarter of the wavelength. Can be shifted. Therefore, it is possible to easily design the radiating element 12 having the second resonance frequency _fe 2 within the target band.

  Next, a configuration example of the short-circuit unit 13 will be described.

  The short-circuit portion 13 includes a straight portion 13a extending in the z-axis positive direction, and a straight portion 13b connected to the straight portion 13a via the end of the straight portion 13a on the z-axis positive direction side and extending in the y-axis positive direction. A bent strip-shaped conductor. The end of the straight portion 13a on the negative side of the z-axis is connected to the outer edge of the base plate 11, more specifically, the short side 11a1 of the rectangular portion 11a on the positive side of the z-axis, and the y-axis of the straight portion 13b. The end portion on the positive direction side is connected to the end portion on the z-axis negative direction side of the linear portion 12 a included in the radiating element 12. Each of the straight portions 13a to 13b is a rectangular conductor, which constitutes a belt-like short-circuit portion 13 that is bent together.

  By providing such a short-circuit portion 13, impedance matching can be easily achieved. This is because the input impedance of the antenna 10 can be changed without changing the size and shape of the ground plane 11 and the radiating element 12 by changing the length of the straight line portion 13a.

(Antenna characteristics)
Next, antenna characteristics of the antenna 10 according to the present embodiment will be described with reference to FIGS.

<Specific example 1>
FIG. 2 is a plan view showing a first specific example of the antenna 10. The antenna 10 according to this specific example is mounted in a flexible printed circuit board, and the ground plane 11, the radiating element 12, and the short-circuit portion 13 made of a copper foil having a thickness of 12 μm are made of polyimide films from the front and back sides. It was obtained by sandwiching. In this specific example, a coaxial cable having a diameter of 1.13 mm and a length of 500 mm was used as the feeder line.

  The size of each part of the antenna 10 according to this example is 2.4 GHz band (2400 MHz to 2483.5 MHz) used in a wireless LAN (IEEE802.11b / g), and 2.5 GHz band used in WiMAX. (2500 MHz to 2700 MHz) and 5.0 GHz band (5150 MHz to 5875 MHz) used in high-speed wireless LAN (IEEE802.11a) is defined as shown in FIG. It has been. The width of the radiating element 12 is 0.75 mm (uniform), and the width of the slot 11c is 1 mm (uniform).

  The design points in this example are as follows.

Setting (1): The wavelength λ _2.4 GHz of the electromagnetic wave of _{2.4 GHz} is 125 mm, and λ _{2.4 GHz} / 4 is 31.25 mm. Therefore, in this specific example, the 2.4 GHz band is covered using the first resonance frequency _fe 1 of the radiating element 12 by setting the total length Le of the radiating element 12 to 31.25 mm. In this specific example, the distal end 2.25 mm (straight line portion 12 e) of the radiating element 12 is bent so that the total length Le of the radiating element 12 is 31.25 mm without increasing the width of the entire antenna 10. .

Setting (2): The wavelength λ _2.5 GHz of the electromagnetic wave of _{2.5 GHz} is 120 mm, and λ _{2.5 GHz} / 4 is 30.00 mm. Therefore, in this specific example, by setting the total length Ls of the slot 11c to 29.00 mm, the 2.5 GHz band is covered using the first resonance frequency f _s 1 of the slot 11c.

Setting (3): The wavelength λ _5.0 GHz of the electromagnetic wave of _{5.0 GHz} is 60 mm, and λ _{5.0 GHz} / 4 is 15.00 mm. In this specific example, by setting the sum La + Lb of the length La of the straight portion 12a and the length Lb of the straight portion 12b to 12.00 mm, the second resonance frequency _fe 2 of the radiating element 12 is used. Covers the 5.0 GHz band.

  FIG. 3 to FIG. 7 show that the antenna 10 designed in this way can have the target bands (2.4 GHz band, 2.5 GHz band, and 5.0 GHz band) as the operating band.

FIG. 3 is a graph showing the VSWR (voltage standing wave ratio) characteristics of the antenna 10 shown in FIG. Referring to FIG. 3, a decrease in the VSWR value is recognized in the 2.4 GHz band, the 2.5 GHz band, and the 5.0 GHz band, and the multi-frequency in which the antenna 10 according to this example has a target band as an operation band. It can be seen that it is operating as an antenna. Assuming that VSWR is 2.0 or less as an operating condition, the operating band on the low frequency side is 320 MHz and the operating band on the high frequency side is 845 MHz. In this specific example, since the difference between the first resonance frequency f _e 1 of the radiating element 12 and the first resonance frequency f _s 1 of the slot 11c is small, there are two discontinuous operating bands including these separately. Instead of being formed, one continuous operating band including them together is formed, and a dual frequency antenna is realized in which the operating band on the low frequency side is widened.

  FIGS. 4A to 4C are graphs showing radiation directivities at 2442 MHz (2.4 GHz band) of the antenna 10 shown in FIG. FIG. 4A is a graph showing the radiation directivity in the xy plane, FIG. 4B is a graph showing the radiation directivity in the yz plane, and FIG. 4C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 1.1 dBi, −9.3 dBi, and −3.4 dBi, respectively.

  FIG. 5A to FIG. 5C are graphs showing the radiation directivity at 2600 MHz (2.5 GHz band) of the antenna 10 shown in FIG. 5A is a graph showing the radiation directivity in the xy plane, FIG. 5B is a graph showing the radiation directivity in the yz plane, and FIG. 5C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 0 dBi, −13.4 dBi, and −3.7 dBi, respectively.

  6A to 6C are graphs showing radiation directivities at 5470 MHz (5.0 GHz band) of the antenna 10 shown in FIG. FIG. 6A is a graph showing the radiation directivity in the xy plane, FIG. 6B is a graph showing the radiation directivity in the yz plane, and FIG. 6C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 2.5 dBi, -21.2 dBi, and -3.9 dBi, respectively.

  As described above, according to FIGS. 4A to 6C, it is recognized that the antenna 10 according to this example has a radiation directivity close to that of the monopole antenna.

FIG. 7A to FIG. 7B are graphs showing frequency characteristics of average gain in the xy plane of the antenna 10 shown in FIG. FIG. 7A is a graph showing the frequency dependence of the average gain on the xy plane with respect to the operating band on the low frequency side, and FIG. 7B is the frequency dependence of the average gain on the xy plane with respect to the operating band on the high frequency side. It is the graph which showed. In any of the drawings, the measured value of the average gain in the xy plane for each frequency is indicated by a black triangle.
An example of the average gain and the minimum gain required when mounted on a mobile terminal is also shown.

  Referring to FIG. 7A, it can be seen that an average gain of −4.0 dBi or more can be secured in the operating band on the low frequency side. Also, referring to FIG. 7B, it can be seen that an average gain of −6.0 dBi or more can be secured in the high frequency side operation band.

<Specific example 2>
FIG. 8 is a plan view showing a second specific example of the antenna 10. The antenna 10 according to this specific example is also mounted in a flexible printed circuit board, and the base plate 11, the radiating element 12, and the short-circuit portion 13 made of a copper foil having a thickness of 12 μm are made of polyimide films from the front and back sides. It was obtained by sandwiching. In this specific example, a coaxial cable having a diameter of 1.13 mm and a length of 500 mm was used as the feeder line.

  Similarly to the first specific example, the size of each part of the antenna 10 according to this specific example is 2.4 GHz band (2400 MHz to 2483.5 MHz) used in a wireless LAN (IEEE802.11b / g), WiMAX. For the purpose of setting the operating band to the 2.5 GHz band (2500 MHz or more and 2700 MHz or less) used in the operation and the 5.0 GHz band (5150 MHz or more and 5875 MHz or less) used in the high-speed wireless LAN (IEEE802.11a), It is determined as shown in FIG. The width of the slot 11c is 1 mm (uniform).

  The design points in this example are as follows.

Setting (1): The wavelength λ _2.4 GHz of the electromagnetic wave of _{2.4 GHz} is 125 mm, and λ _{2.4 GHz} / 4 is 31.25 mm. Therefore, in this example, by setting the total length Le of the radiating element 12 in 33.00Mm (ignoring the length of the straight portion 12c), by using the first resonance frequency f _e 1 of the radiating element 12 2. Covers the 4 GHz band. In this specific example, in order to increase the total length of the radiating element 12 without increasing the width of the entire antenna 10, the tip of the radiating element 12 is bent at 2.5 mm (straight portion 12 e).

Setting (2): The wavelength λ _2.5 GHz of the electromagnetic wave of _{2.5 GHz} is 120 mm, and λ _{2.5 GHz} / 4 is 30.00 mm. Therefore, in this specific example, by setting the total length Ls of the slot 11c to 29.00 mm, the 2.5 GHz band is covered using the first resonance frequency f _s 1 of the slot 11c.

Setting (3): The wavelength λ _5.0 GHz of the electromagnetic wave of _{5.0 GHz} is 60 mm, and λ _{5.0 GHz} / 4 is 15.00 mm. In this specific example, by setting the sum La + Lb of the length La of the straight portion 12a and the length Lb of the straight portion 12b to 13.75 mm, the second resonance frequency _fe 2 of the radiating element 12 is used. Covers the 5.0 GHz band.

  In the antenna 10 designed as described above, the target bands (2.4 GHz band, 2.5 GHz band, and 5.0 GHz band) can be set as the operation bands, and further, from the first specific example. 9 to 13 show that excellent characteristics can be obtained.

  FIG. 9 is a graph showing the VSWR (voltage standing wave ratio) characteristics of the antenna 10 shown in FIG. Referring to FIG. 9, a decrease in the VSWR value is recognized in the 2.4 GHz band, the 2.5 GHz band, and the 5.0 GHz band, and the multi-frequency having the target band as the operating band of the antenna 10 according to this specific example. It can be seen that it is operating as an antenna. Assuming that VSWR is 2.0 or less as an operating condition, the operating band on the low frequency side is 415 MHz, and the operating band on the high frequency side is 840 MHz. That is, the bandwidth of the operation band on the low frequency side is expanded as compared with the first specific example.

  FIG. 10A to FIG. 10C are graphs showing radiation directivities at 2442 MHz (2.4 GHz band) of the antenna 10 shown in FIG. 10A is a graph showing the radiation directivity in the xy plane, FIG. 10B is a graph showing the radiation directivity in the yz plane, and FIG. 10C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 3.4 dBi, −10.5 dBi, and −4.1 dBi, respectively.

  11A to 11C are graphs showing the radiation directivity at 2600 MHz (2.5 GHz band) of the antenna 10 shown in FIG. FIG. 11A is a graph showing the radiation directivity in the xy plane, FIG. 11B is a graph showing the radiation directivity in the yz plane, and FIG. 11C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 3.4 dBi, −12.3 dBi, and −1.8 dBi, respectively.

  FIGS. 12A to 12C are graphs showing the radiation directivity at 5470 MHz (5.0 GHz band) of the antenna 10 shown in FIG. FIG. 12A is a graph showing the radiation directivity in the xy plane, FIG. 12B is a graph showing the radiation directivity in the yz plane, and FIG. 12C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, minimum gain, and average gain in the xy plane were 2.0 dBi, −14.6 dBi, and −3.5 dBi, respectively.

  As described above, according to FIGS. 10A to 12C, it is recognized that the antenna 10 according to this specific example has a radiation directivity close to that of the monopole antenna.

  FIG. 13A to FIG. 13B are graphs showing frequency characteristics of average gain in the xy plane of the antenna 10 shown in FIG. FIG. 13A is a graph showing the frequency dependence of the average gain on the xy plane with respect to the operating band on the low frequency side, and FIG. 13B is the frequency dependence of the average gain on the xy plane with respect to the operating band on the high frequency side. It is the graph which showed. In any of the drawings, the measured value of the average gain in the xy plane for each frequency is indicated by a black triangle. An example of the average gain and the minimum gain required when mounted on a mobile terminal is also shown.

  Referring to FIG. 13A, it can be seen that an average gain of −3.0 dBi or more can be secured in the low frequency side operation band. Further, referring to FIG. 13B, it can be seen that an average gain of −5.0 dBi or more can be secured in the high frequency side operation band. That is, it can be seen that a higher average gain than that of the first specific example can be ensured both in the low frequency side operation band and in the high frequency side operation band.

[Embodiment 2]
The following describes the second embodiment of the present invention with reference to FIGS.

(Antenna configuration)
First, the configuration of the antenna 20 according to the present embodiment will be described with reference to FIG. FIG. 14 is a plan view showing the configuration of the antenna 20 according to the present embodiment.

  As shown in FIG. 14, the antenna 20 is an antenna including a ground plane 21, a radiating element 22 that faces the ground plane 21 via a feeding point 24, and a short-circuit portion 23 that short-circuits the ground plane 21 and the radiating element 22. is there. The ground plane 21 and the radiating element 22 are separated in the vicinity of the feeding point 24, and one of the two conducting wires constituting the feeding line (for example, a coaxial cable) is connected near the feeding point 24 of the ground plane 21. The other conducting wire is connected in the vicinity of the feeding point 24 of the radiating element 22.

The main feature of the antenna 20 is that an opening 21c is provided in the ground plane 21 as in the antenna 10 (FIG. 1) according to the first embodiment. Thus, in addition to the resonance frequency {f _e 1, f _e 2, ...} of the radiating element 22 (resonance frequency determined according to the size and shape of the radiating element 22), the resonance frequency {f _s 1, f of the opening 21c. _s 2,...} (resonance frequency determined according to the size and shape of the opening 21c), the antenna 20 can resonate, and these resonance frequencies {f _e 1, f _e 2, ...} ∪ {f _s 1, Among the bands including f _s 2,..., the band that satisfies a predetermined operating condition can be set as the operating band.

  Next, configuration examples of the ground plane 21, the radiating element 22, and the short-circuit portion 23 will be described with reference to FIG.

  First, a configuration example of the main plate 21 will be described.

  As shown in FIG. 14, the ground plane 21 is a plate-like conductor having a rectangular portion 21a having a short side parallel to the z-axis and a rectangular protruding portion 21b having a long side parallel to the y-axis. The protruding portion 21b is disposed at the approximate center of the long side 21a1 on the z-axis positive direction side of the rectangular portion 21a, and is connected to the rectangular portion 21a via the long side 21a1. One of the two conductors constituting the feeder line is connected to the protruding portion 21 b in the vicinity of the feeder point 24.

  By connecting the power supply line to the projecting portion 21b extending to the power supply point 24 in this way, for the same reason as in the first embodiment, compared to the case where the power supply line is directly connected to the rectangular portion 21a. Impedance matching can be easily taken.

  An opening 21 c is provided in the rectangular portion 21 a of the base plate 21. As shown in FIG. 14, the opening 21c includes a straight line portion 21c1 along the long side 21a1 (first side) on the z-axis positive direction side of the rectangular portion 21a, and a short side 21a2 on the y-axis negative direction side of the rectangular portion 21a. The straight line portion 21c2 along the (second side), the straight line portion 21c3 along the short side 21a3 (third side) on the y-axis positive direction side of the rectangular portion 21a, and the length of the rectangular portion 21a on the negative z-axis direction side. A straight line portion 21c4 located on the y-axis negative direction side along the side 21a4 (fourth side) and a straight line portion located on the y-axis positive direction side along the long side 21a4 on the negative z-axis direction side of the rectangular portion 21a. A bent band-like opening having 21c5. The straight portions 21c1 to 21c5 are rectangular openings, which are integrated to form a continuous band-shaped opening 21c. Also in this embodiment, the opening 21c is “slot 21c”, the widths of the straight portions 21c1 to 21c5 (dimensions in the short side direction) are “width of the slot 21c”, and the lengths of the straight portions 21c1 to 21c5 (dimensions in the long side direction). ) Is referred to as "the total length Ls of the slot 21c".

By making the shape of the slot 21c bent in this way, the space required for the placement of the slot 21c can be divided into the straight portion 21c4 and the straight portion 21c5 as compared with the first embodiment while maintaining the overall length Ls of the slot 21c. Can only be further reduced. That is, the space required for the arrangement of the slot 21c can be further reduced as compared with the first embodiment without shifting the first resonance frequency f _s 1≈c / (4Ls) of the slot 21c to the high frequency side. For this reason, further downsizing of the ground plane 21 can be achieved without inviting a higher frequency in the operation band. Alternatively, the entire length Ls of the slot 21c can be made longer by the straight portion 21c4 and the straight portion 21c5 than in the first embodiment without increasing the space required for the arrangement of the slot 21. For this reason, it is possible to further reduce the operating band without incurring an increase in the size of the main plate 21.

  Next, a configuration example of the radiating element 22 will be described.

  As shown in FIG. 14, the radiating element 22 is connected to the feeding point 24, and extends in the positive z-axis direction (first direction) 22a (first straight part), and the positive z-axis of the straight part 22a. A straight portion 22b (second straight portion) that is connected to the straight portion 22a through the end portion on the direction side and extends in the y-axis positive direction (second direction); and an end on the y-axis positive direction side of the straight portion 22b A straight portion 22c (third straight portion) that is connected to the straight portion 22b through the portion and extends in the z-axis positive direction (first direction), and an end portion on the z-axis positive direction side of the straight portion 22c. A bent strip-shaped conductor that has a meander portion 22d that is connected to the straight portion 22c and extends in the negative y-axis direction (the direction opposite to the first direction) at least partially. Further, the end of the linear portion 22a on the negative side of the z-axis is connected to a short-circuit portion 23 described later. One of the two conductors constituting the power supply line is connected to the end of the straight line portion 22a on the negative z-axis direction side (short-circuit portion 23 side) (not shown).

  Note that each of the straight portions 22a to 22c is a rectangular conductor, and the meander portion 22d is a meander portion of at least a portion of the rectangular conductor, which is a band-shaped radiating element bent integrally. 22 is constituted. Hereinafter, the width (dimension in the short side direction) of the straight portions 22a to 22c and the width (dimension in the short side direction) of each straight portion constituting the meander portion 22d are referred to as “width of the radiation element 12”, and the straight portion 22a. The sum of the lengths ˜22c (dimensions in the long side direction) and the lengths (dimensions in the long side direction) of the straight portions constituting the meander part 22d is referred to as “the total length Le of the radiation element 12”.

  The “direction in which the meander part 22d extends” can be defined as follows. That is, if the meander part 22d is traced from the side closer to the feeding point 24, a traveling direction sequence such as {y-axis negative direction, z-axis positive direction, y-axis negative direction, z-axis negative direction,. Can be configured. In this progression direction column, a progression direction whose direction is reversed (in this case, z-axis positive direction / z-axis negative direction) and a progression direction whose direction is not reversed (in this case, the y-axis negative direction) alternately appear. Of the traveling directions appearing in the traveling direction row, the traveling direction whose direction is not reversed may be the “direction in which the meander portion 22d extends”.

By bending the radiating element 22 in this way, it is possible to reduce the space required for disposing the radiating element 22 while maintaining the full length Le of the radiating element 22. That is, the space required for the arrangement of the radiating element 22 can be reduced without shifting the first resonance frequency _fe 1 ≈c / (4Le) of the radiating element 22 to the high frequency side. For this reason, the space required for disposing the radiating element 22 can be reduced without increasing the frequency of the operating band. Alternatively, the entire length Le of the radiating element 22 can be increased and the operating band can be lowered without enlarging the space required for disposing the radiating element 22. In the present embodiment, since a part of the radiating element 22 is meandered, an even greater effect can be obtained.

Further, by bending the radiating element 22 in this way, the second resonance frequency _fe 2 can be shifted to the low frequency side. More specifically, the second resonance frequency fe2 is a frequency c / {4 (La + Lb)} in which the sum of the length La of the straight portion 22a and the length Lb of the straight portion 22b corresponds to a quarter of the wavelength. Can be shifted.

  Next, a configuration example of the short-circuit portion 23 will be described.

  The short-circuit portion 23 includes a straight portion 23a extending in the z-axis positive direction, and a straight portion 23b connected to the straight portion 23a via the end of the straight portion 23a on the z-axis positive direction side and extending in the y-axis positive direction. A bent strip-shaped conductor. The end of the straight line portion 23a on the negative side in the z-axis direction is connected to the outer edge of the base plate 21, more specifically, the long side 21a1 on the positive side of the z-axis direction of the rectangular portion 21a, and the y-axis of the straight line portion 23b. The end portion on the positive direction side is connected to the end portion on the z-axis negative direction side of the linear portion 22 a included in the radiating element 22.

  By providing such a short-circuit portion 23, impedance matching can be easily achieved as in the first embodiment.

(Antenna characteristics)
Next, the characteristics of the antenna 20 according to the present embodiment will be described with reference to FIGS.

  FIG. 15 is a plan view showing a specific example of the antenna 20. The antenna 20 according to this specific example is mounted in a flexible printed circuit board, and the base plate 21, the radiating element 22, and the short-circuit portion 23 made of a copper foil having a thickness of 12 μm are made of polyimide films from the front and back sides. It was obtained by sandwiching. In the present embodiment, a coaxial cable having a diameter of 1.13 mm and a length of 500 mm was used as the feeder line.

  The size of each part of the antenna 20 according to this specific example is intended to set the operating band to a band of 824 MHz to 960 MHz and a band of 1710 MHz to 2170 MHz used in a wireless WAN (Wide Area Network). It is determined as shown in FIG. The slot 21c has a width of 1 mm (uniform), and the meander depth of the meander portion 22d is 3.5 mm at the deeper side and 2 mm at the shallower side.

  FIG. 16 to FIG. 21 show that the antenna 20 designed in this way can use the band used in the wireless WAN (Wide Area Network) as the operation band.

FIG. 16 is a graph showing the VSWR (voltage standing wave ratio) characteristics of the antenna 20 shown in FIG. Referring to FIG. 16, a decrease in the VSWR value is recognized in both the low frequency band and the high frequency band used in the wireless WAN, and the target band of the antenna 20 according to this specific example is defined as the operation band. It can be seen that it is operating as a multi-frequency antenna. Assuming that the operating condition is that VSWR is 3.0 or less, the operating band on the low frequency side is 415 MHz, and the operating band on the high frequency side is 445 MHz. Also in this specific example, since the difference between the first resonance frequency f _e 1 of the radiating element 22 and the first resonance frequency f _s 1 of the slot 21c is small, there are two discontinuous operating bands including these separately. Instead of being formed, one continuous operating band including them together is formed, and a dual frequency antenna is realized in which the operating band on the low frequency side is widened.

  FIGS. 17A to 17C are graphs showing the radiation directivity at 824 MHz of the antenna 20 shown in FIG. FIG. 17A is a graph showing the radiation directivity in the xy plane, FIG. 17B is a graph showing the radiation directivity in the yz plane, and FIG. 17C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were −1.8 dBi, −16.3 dBi, and −5.1 dBi, respectively.

  FIGS. 18A to 18C are graphs showing the radiation directivity at 960 MHz of the antenna 20 shown in FIG. FIG. 18A is a graph showing the radiation directivity in the xy plane, FIG. 18B is a graph showing the radiation directivity in the yz plane, and FIG. 18C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were 0.7 dBi, -10. 6 dBi, and -4.3 dBi, respectively.

  FIG. 19A to FIG. 19C are graphs showing the radiation directivity at 1710 MHz of the antenna 20 shown in FIG. 19A is a graph showing the radiation directivity in the xy plane, FIG. 19B is a graph showing the radiation directivity in the yz plane, and FIG. 19C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were −0.1 dBi, −13.5 dBi, and −4.7 dBi, respectively.

  20A to 20C are graphs showing the radiation directivity at 2170 MHz of the antenna 20 shown in FIG. 20A is a graph showing the radiation directivity in the xy plane, FIG. 20B is a graph showing the radiation directivity in the yz plane, and FIG. 20C is the radiation directivity in the zx plane. It is a graph which shows sex. The maximum gain, the minimum gain, and the average gain in the xy plane were −1.3 dBi, −12.6 dBi, and −5.9 dBi, respectively.

  FIG. 21A to FIG. 21B are graphs showing frequency characteristics of average gain in the xy plane of the antenna 20 shown in FIG. FIG. 21A is a graph showing the frequency dependence of the average gain on the xy plane with respect to the operating band on the low frequency side, and FIG. 21B is the frequency dependence of the average gain on the xy plane with respect to the operating band on the high frequency side. It is the graph which showed. In any of the drawings, the measured value of the average gain in the xy plane for each frequency is indicated by a black triangle. An example of the average gain and the minimum gain required when mounted on a mobile terminal is also shown.

  Referring to FIG. 21 (a), it can be seen that an average gain of −5.1 dBi or more can be secured in the operating band on the low frequency side. In addition, referring to FIG. 21B, it can be seen that an average gain of −6.2 dBi or more can be secured in the high frequency side operation band.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be suitably used for a multi-frequency antenna to be mounted on a small wireless device. As an example, it can be suitably used for a multi-frequency antenna having an operation band of 2.4 GHz band, 2.5 GHz band, and 5.0 GHz band.

10 antenna 11 ground plane 11a rectangular portion 11a1 short side (first side, base of protruding portion 11b)
11a2 long side (second side)
11a3 long side (third side)
11b Protruding part 11c Slot (opening)
12 Radiation Element 12a Straight Line (First Straight Line)
12b Straight part (second straight part)
12c Straight part (third straight part)
12d Straight part (fourth straight part)
13 Short-circuit part 14 Feeding point 20 Antenna 21 Ground plane 21a Rectangular part 21a1 Long side (1st side, base part of the protrusion part 21b)
21a2 short side (second side)
21a3 short side (third side)
21a4 long side (fourth side)
21b Protruding part 21c Slot (opening)
22 Radiation element 22a Straight part (first straight part)
22b Straight part (second straight part)
22c Straight part (third straight part)
22d meander part 23 short circuit part 24 feeding point

Claims (10)

An antenna comprising a ground plane and a radiating element connected to the ground plane via a feeding point,
An antenna, wherein an opening is provided in the ground plane. The shape of the opening is a band shape,
The antenna according to claim 1. The ground plane has a protrusion extending to the feeding point.
The antenna according to claim 1 or 2. The opening is provided along the base of the protrusion,
The antenna according to claim 3. The ground plane has a rectangular portion adjacent to the protruding portion,
The opening is provided along the first side of the rectangular portion including the base of the protruding portion, and the second side and the third side adjacent to the first side.
The antenna according to claim 4. The ground plane has a rectangular portion connected to the protruding portion,
The opening includes a first side of the rectangular part including a boundary with the projecting part, a second side and a third side adjacent to the first side, and a first side facing the first side. Provided along the side of 4,
The antenna according to claim 4. The radiating element is bent,
The antenna according to any one of claims 1 to 6, characterized in that: The radiating element is connected to the feeding point, and is connected to the first straight line portion extending in a first direction and the first straight line portion, and is extended in a second direction perpendicular to the first direction. Connected to the second straight portion, the third straight portion that extends in the first direction, and the third straight portion that extends in the direction opposite to the second direction. Having a fourth straight part,
The antenna according to claim 7. The radiating element is connected to the feeding point and extends in a first direction, and a second straight line that extends in a first direction and connects to the first straight part and extends in a second direction perpendicular to the first direction. A straight line portion, a third straight portion connected to the second straight portion and extending in the first direction, and at least one connected to the third straight portion and extending in a direction opposite to the second direction. The part has a meander part that is converted to a meander,
The antenna according to claim 7. It further includes a short-circuit portion that short-circuits the ground plane and the radiating element.
The antenna according to any one of claims 1 to 9, wherein

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