JP5872008B1 - Multi-frequency antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a multi-frequency antenna while avoiding an increase in antenna size in an antenna incorporated in an information terminal device such as a personal computer or a PDA. An adjusting element is extended from a ground part, and the adjusting element is brought close to the radiating element part, thereby adjusting a frequency of a third harmonic generated in the radiating element part to a desired frequency band, and the radiating element part. The antenna is made to correspond to multiple frequencies in combination with the frequency band that is originally supported. [Selection] Figure 1

Description

  The present invention relates to a three-dimensional antenna incorporated in an information terminal device such as a personal computer, a PDA (portable information device), a mobile phone, or a VICS (registered trademark).

In recent wireless data communication systems such as wireless LAN, wireless WAN, WiMAX (registered trademark), and LTE, there is an increasing demand for multi-frequency antennas.
Recently, with the spread of LTE, there is a demand for antennas corresponding to the 1.8 GHz band (1.71 to 1.88 GHz) and 2.5 GHz band (2.5 to 2.69 GHz) used for LTE. There is a plan to use the 3.5 GHz band (3.4 to 3.6 GHz) for LTE in the future.
Especially for personal computer antennas, in addition to conventional wireless WAN bands (824 to 960 MHz), antennas that can handle a few frequency bands such as LTE 1.8 GHz band and 2.5 GHz band are standard. It has become a required specification.

In addition, with the recent progress in downsizing of information terminal equipment, the space for mounting antennas in equipment has also been reduced, and there is a demand for further downsizing of antennas while maintaining performance equal to or higher than that of conventional antennas. .

As small antennas that can handle multiple frequencies with a single antenna, the antennas described in Patent Documents 1 and 2 are known.
In the antenna described in Patent Literature 1, a shaft portion common to a low frequency band and a high frequency band connected to a single power feeding portion, a low frequency band feeding element branched from the shaft portion, and a high frequency band feeding element By providing the antenna, multi-frequency antenna is realized.
However, since it is necessary to provide two feeding elements having lengths corresponding to two frequency bands, there is a limit to downsizing the antenna.

In the antenna described in Patent Document 2, the radiating element has a meander shape, and the length of a part extending in a direction intersecting with the direction approaching / separating from the ground conductor in a part of the radiating element is set to approach / separate. By making the length longer than the length of the portion extending in the direction of the antenna, multi-frequency antenna is realized.
However, since the meander-shaped radiating element also needs to have a certain length and size in order to cope with a plurality of frequencies, the size of the antenna in the height direction tends to increase. However, there is a limit to the miniaturization of the antenna.

JP 2012-178741 A JP 2008-199204 A

An object of the present invention is to provide a multi-frequency antenna corresponding to at least two frequency bands while minimizing the size of the antenna.

  The present inventors pay attention to the fact that when a high frequency current is fed to the antenna, in addition to the fed frequency current, a current having a frequency three times that frequency, so-called third harmonic, is generated. By adjusting the harmonics to a desired frequency band, a multi-frequency antenna corresponding to at least two frequency bands of a low frequency band and a high frequency band was realized without increasing the size of the antenna.

With the antenna of the present invention, the following effects can be expected.

(1) The antenna can handle two frequencies while suppressing the increase in size of the antenna.

(2) When adding a radiating element in order to make the antenna correspond to three or more frequencies,
Since the original antenna size is small, the increase in size can be minimized.

It is a basic composition of the antenna of the present invention. It is another example of the basic composition of the antenna of the present invention. It is an example of the relationship between the corresponding | compatible frequency of an antenna, and a 3rd harmonic. It is another example of the relationship between the corresponding frequency of the antenna and the third harmonic. It is a modification of the antenna element used for this invention. It is another modification of the antenna element used for this invention. It is a plane expanded view of the antenna element used for the 1st example of the present invention. It is a VSWR characteristic of the 1st example of the present invention. It is an antenna element used for the 2nd Example of this invention. It is a plane expanded view of the antenna element used for the 2nd Example of this invention. It is a VSWR characteristic of the 2nd example of the present invention. It is a plane expanded view of the antenna element used for the 3rd Example of the present invention. It is a VSWR characteristic of the 3rd example of the present invention. It is a plane expanded view of the antenna element used for the 4th example of the present invention. It is a VSWR characteristic of the 4th example of the present invention.

Hereinafter, the present invention will be described with reference to FIGS. 1 and 2.

1 and 2, 1 is an antenna element, 2 is a ground portion, 3 is a short circuit portion, 4 (4a, 4b) is a radiating element portion, 5 is a feeding point, 6 is an adjustment element, 7 is a coaxial cable for feeding, 8 is an earth point, and 9 is a frequency adjusting unit.

What is characteristic of the present invention is that in the antenna element 1, the adjustment element 6 is extended from the ground portion 2 and the adjustment element 6 is brought close to the radiating element portion 4.
The position where the adjustment element 6 extends from the ground portion 2 may be appropriately adjusted according to the shape of the radiating element portion 4 as shown in FIGS.

In the present invention, “adjusting the adjusting element 6 to the radiating element part 4” means that one surface of the adjusting element 6 and the radiating element part are obtained as shown in FIG. 4, or one side of the adjustment element 6 and one side of the radiating element unit 4 are arranged in parallel as shown in FIG.
The actual proximity method is not limited to this, and other proximity methods may be used or the adjustment element 6 and the radiating element unit 4 may be separated as long as the third harmonic fluctuation effect is obtained.

By bringing one side of the adjusting element 6 close to the radiating element unit 4, the radiating element unit 4 corresponding to only one desired frequency band originally corresponds to the two desired frequency bands, and the multi-frequency of the antenna Can be realized. The principle of multi-frequency will be described below.

By feeding a high frequency current having a corresponding frequency f to the radiating element unit 4 corresponding to a specific frequency band, the radiating element unit 4 transmits and receives a signal of the frequency f.
At this time, in addition to the high-frequency current having the frequency f, a current having a frequency 3f that is three times the frequency, that is, a so-called third harmonic is generated in the radiating element unit 4. The present invention utilizes this third harmonic.

The third harmonic will be specifically described with reference to FIGS.

FIG. 3 shows a VSWR of a conventional antenna designed to support an 860 MHz signal belonging to the wireless WAN band. A peak (decrease) in VSWR seen in the vicinity of 860 Hz is a peak corresponding to the design frequency.
A specific antenna shape is the antenna shown in FIG. 1 in which the adjustment element 6 is not provided. The peak of VSWR seen in the vicinity of 860 MHz is a peak corresponding to the design frequency.

FIG. 4 shows the structure and VSWR of an antenna designed to support a 960 MHz signal belonging to the wireless WAN band.
A specific antenna shape is the antenna shown in FIG. 2 in which the adjustment element 6 is not provided. The peak of VSWR seen in the vicinity of 960 MHz is a peak corresponding to the design frequency.

In general, an antenna has sufficient communication characteristics with respect to a frequency band in which a VSWR is 2.5 or less, centering on a peak appearing in the wireless WAN band of FIGS.

In addition to the peaks corresponding to these design frequencies, a VSWR peak is also seen in the vicinity of 2.9 GHz in FIG. 3 and in the vicinity of 3.6 GHz in FIG. This is because a third harmonic having a frequency near 2.9 GHz in FIG. 3 and a frequency near 3.6 GHz in FIG. 4 is generated, and in addition to the communication in the wireless WAN band, This suggests the possibility of communication.
The frequency of the third harmonic derived from the high-frequency current of 860 MHz is about 2.6 GHz, and the frequency of the third harmonic derived from the high-frequency current of 960 MHz is about 2.9 GHz. Waves are rarely exactly three times the frequency due to the shape of the antenna and the like, and are often on the higher frequency side than three times the design frequency as shown in FIGS.

A phenomenon in which the frequency of the third harmonic generated in the radiating element unit 4 fluctuates by bringing the adjusting element 6 close to the radiating element unit 4 and capacitively coupling both of them.
This is because the impedance of the radiating element unit 4 is reduced due to the occurrence of capacitive coupling, and a third harmonic having a frequency matched to the impedance after the reduction is generated. Since the influence of the increase / decrease in impedance is greatly affected by a current having a higher frequency, the third harmonic generated in the radiating element unit 4 is greatly affected by the capacitive coupling, and the frequency fluctuates. Little affected by capacitive coupling.
By using this phenomenon and adjusting the frequency of the third harmonic to a frequency band corresponding to desired communication, the antenna corresponds to two frequency bands.

That is, the antenna of the present invention corresponds to the low frequency band desired by the radiating element unit 4 and corresponds to the high frequency band desired by the third harmonic whose frequency is changed by the adjusting element 6.

The adjustment element 6 needs to be changed in size and shape in accordance with a desired frequency band, and the shape includes a rectangular shape in addition to the substantially L shape shown in FIGS.
Although the suitable size and shape of the adjusting element 6 cannot be specified at all, the function of the adjusting element 6 is the third harmonic frequency fluctuation, and the adjusting element 6 itself is not directly involved in signal transmission / reception.
For this reason, the total length of the adjustment element 6 is shorter than the total length of the radiating element portion, specifically, a length that is less than or equal to one-fourth of the signal wavelength of the highest frequency band supported by the antenna.

The total length of the adjustment element 6 is shorter than the length of the element originally required for the high frequency band supported by the antenna, so that the antenna can be multi-frequency while minimizing the size of the antenna. it can.

In the present invention, the antenna element 1 may be obtained by stamping and integrally molding a single metal plate such as white (brass), copper, iron, brass or the like. The thickness of the single metal plate is preferably about 0.1 to 1 mm.

  The ground part 2 takes a bent shape according to the mounting space of the electrical equipment on which the antenna is mounted, or is provided with a cut-off or cut-out part to avoid interference with other parts existing in the mounting space. You may deform | transform suitably.

In the present invention, the feeding coaxial cable 7 may be a well-known high-frequency coaxial cable such as a fluororesin coating. In order to connect the inner conductor or the outer conductor of the feeding coaxial cable 7 to a predetermined place of the antenna element 1, fixing by soldering or fixing by caulking may be used.

In the present invention, the feeding point 5 is provided at an arbitrary location of the radiating element unit 4. The specific position of the feeding point 5 is determined by appropriately adjusting so that the antenna operates with the intended characteristics.
The location where the feed point 5 is provided is not necessarily on the radiating element portion 4. If the location of the feed point 5 on the short-circuit portion 3 is preferable according to the antenna characteristics depending on the shape of the antenna element 1, etc. The invention does not prevent the feeding point 5 from being provided on the short-circuit portion 3.

The position of the adjusting element 6 is from the ground point 8 where the outer conductor of the feeding coaxial cable 7 is connected to the ground portion 2, the radio wave in the highest frequency band corresponding to the antenna, that is, the third harmonic whose frequency is changed by the adjusting element 6. The location is preferably within a quarter wavelength of the wave.
By setting this position, the fluctuation effect of the third harmonic by the adjustment element 6 becomes more stable, and communication in a high frequency band is stabilized.
This is because the capacitive coupling generated between the radiating element unit 4 and the adjusting element 6 becomes more stable when the proximal end of the adjusting element 6 and the ground point 8 are close to each other. In particular, this effect is prominent when the distance between the base end of the adjustment element 6 and the earth point 8 is within a quarter wavelength of the radio wave in the high frequency band supported by the antenna.

The preferred shape of the short-circuit part 3 in the antenna of the present invention is such that the second part extends parallel to the edge of the ground part 2 after extending from the ground part 2 in the first direction as shown in FIGS. It is the shape bent in the direction of the so-called L-shape.
In the case of this shape, since the edge of the ground portion 2 and the short-circuit portion 3 are arranged close to each other in parallel, capacitive coupling occurs between the ground portion 2 and the short-circuit portion 3, and as a result, the radiation element portion 4. The third harmonic generated in is stabilized.

The preferred shape of the radiating element portion 4 in the antenna of the present invention is such that the first radiating element portion 4a that is directly connected to the short-circuit portion 3 and extends in the first direction as shown in FIGS. And a second radiating element part 4b extending from the first radiating element part 4a in a second direction parallel to the edge of the ground part 2 or in a third direction opposite to the second direction. Shape.
By adopting this shape, the electrical length of the radiating element portion 4 necessary for dealing with the low frequency band can be obtained in a space-saving manner, and the adjusting element 6 extending from the ground portion 2 is short to the second radiating element portion 4b. It can be close in length and contributes to the miniaturization of the antenna.

When it is desired to increase the frequency band that can be handled by the antenna, as shown in FIGS. 5 and 6, the desired frequency from the first radiating element portion 4 a toward the opposite side of the extending direction of the second radiating element portion 4 b. It is preferable to extend the third radiating element portion 4c corresponding to the band.

Since the antenna corresponding to the two frequency bands is small, even if the third radiating element portion 4c is added to support three frequencies, the final antenna size falls into the small category, particularly as shown in FIG. When the second radiating element portion 4b extends in the second direction, the third radiating element portion 4c can be provided in the space above the short-circuit portion 3, so that the maximum vertical width and lateral width of the antenna are increased. Is minimized.

Further, when the third radiating element portion 4c is added to the aspect in which the second radiating element portion 4b extends in the second direction, the L-shaped short-circuit portion 3 described in the paragraph [0031] is employed. It is preferable to do this.
By using the short-circuit portion 3 having this shape, impedance matching in the frequency band corresponding to the third radiating element portion 4c can be easily achieved, and the third radiating element portion 4c is separated from the ground portion 2 to thereby generate the third radiating element. The gain of the element part 4c can be increased.

Furthermore, the radiating element unit 4 may be provided with a frequency adjusting unit 9 as necessary in order to perform fine adjustment to make the antenna correspond to a desired frequency band.
As the shape of the frequency adjusting unit 9, the shape of the radiating element unit 4 as shown in FIG. 5 or the shape of the radiating element unit 4 as shown in FIG. What is necessary is just to select and provide the shape etc. which folded the front-end | tip in the U shape.

In the antenna of the present invention, the shape of the short-circuit portion 3 and the radiating element portion 4 and the corresponding frequency band are not limited to those described above, and the radiating element portion 4 and the adjusting element 6 are brought close to each other. Thus, the shape and the corresponding frequency band can be variously changed within the scope of the technical idea of changing the frequency of the third harmonic to a desired high frequency band.

In the present invention, there are a mode in which the adjustment element 6 is provided on a different plane from the short-circuit portion 3 and a mode in which the adjustment element 6 is provided on the same plane. Each aspect will be described below.

1 and 5 show an embodiment in which the adjustment element 6 is provided on a different plane from the short-circuit portion 3.
When this mode is adopted, a part of the ground portion 2 is bent so that when the antenna element 1 is viewed from the side, the adjustment element 6, the ground portion 2, and the short-circuit portion 3 are substantially connected with the ground portion 2 as the bottom. The antenna is formed so as to have the shape of
1 and 5, the dielectric element (not shown) is sandwiched between the adjustment element 6, the short-circuit part 3 and the radiating element part 4, and the length of the radiating element part 4 utilizing the wavelength shortening effect is adjusted. This is a preferred mode when shortening.

1 and 5, it is preferable that the radiating element portion 4 is bent so that the end side of the radiating element portion 4 is close to the adjusting element 6.

As the dielectric, a known dielectric material such as ABS resin, PPE resin, or LCP (liquid crystal polymer) mixed with ceramic may be appropriately selected and used.

2 and 6 are embodiments in which the adjustment element 6 is provided on the same plane as the short-circuit portion 3.
This aspect is a particularly preferable aspect when there is no room in the space in the depth direction in the installation space of the antenna in the electronic device.

Even in an aspect in which the adjustment element 6 is formed on the same plane as the short-circuit portion 3, a dielectric may be provided or the radiating element portion 4 may be bent as necessary.

As a first embodiment, an antenna corresponding to a wireless WAN band and one LTE band, in which the adjustment element 6 shown in FIG. 1 is provided on a different plane from the short-circuit unit 3, will be described.

1. Creating the antenna element in Figure 1:
An antenna element 1 having a shape shown in FIG. 1 was produced by punching out a single white plate having a thickness of 0.2 mm.
The antenna element 1 is intended to correspond to the radiating element provided with the frequency adjusting unit corresponding to the 860 MHz band of the wireless WAN band and the third harmonic changed by the adjusting element to the 2.5 GHz band of the LTE band. Each dimension was determined by simulation.

FIG. 7 is a developed plan view of the antenna element 1 used in the first embodiment. One square corresponds to 1 mm square, and the three-dimensional antenna element 1 shown in FIG. 1 is obtained by performing mountain folds with broken lines and valley folds with one-dot broken lines.

The dimensions and shape of each member of the antenna element 1 developed in a plane are as follows.
The dimensions not described are as shown in FIG.

・ Ground plate 2: A shape in which a space having a width of 7 mm and a height of 12 mm for providing the adjusting element 6 is provided in a rectangular shape having a height of 15 mm and a width of 84 mm.

・ Short-circuit portion 3: a shape extending from the ground plate 2 in the Y direction with a width of 10 mm and a height of 2 mm and then extending in the −X direction with a width of 1 mm and a length of 20 mm so as to be parallel to the edge of the ground plate 2 .

First radiation element portion 4a: a shape extending from the end of the short-circuit portion in the Y direction with a width of 3 mm and a height of 7 mm.

Second radiation element portion 4b: a shape extending from the first radiation element portion 4a in the X direction with a width of 1 mm and a length of 56 mm.

Adjustment element 6: An L-shape that extends 3 mm in width and 10 mm in length in the −Y direction on the space provided in the ground plate 2 and then extends 2 mm in width and 2 mm in length in the X direction.

Feed point 5: a position 3 mm in the X direction from the lowest part of the left end side of the first radiating element portion 4a.

Earth point 8: A position of 24 mm in the X direction from the left end side of the ground plate 2 along the upper end side.

2. Regarding members other than the antenna element 1, the dimensions, materials, and other characteristics of the members other than the antenna element 1 are as follows.

・ Feeding coaxial cable 8: inner conductor diameter 0.15 mm, fluororesin (PFA) insulator diameter 0.4 mm, outer conductor diameter 0.65 mm, PFA jacket diameter 0.8 mm

3. A feeding coaxial cable 7 provided with a known coaxial cable connector corresponding to an electronic device to be connected is prepared on the opposite side of the antenna assembly tip, and the inner conductor serves as the feeding point 5 and the outer conductor serves as the outer conductor. Each antenna was soldered to the ground point 8 to complete the antenna.
The feeding coaxial cable 7 is connected to the surface side in FIG.

The size of the antenna excluding the feeding coaxial cable 7 is as small as 20 mm in height, 84 mm in width, and 4 mm in thickness.

When the VSWR of the obtained antenna was measured, as shown in FIG. 8, the peak of VSWR is present in the LTE 2.5 GHz band in addition to the vicinity of 860 MHz of the wireless WAN band, and the target band is sufficient. A small dual-frequency antenna having communication characteristics was obtained.
Compared with FIG. 3, which corresponds to VSWR when the adjustment element 6 is omitted from the first embodiment, the peak due to the third harmonic moves to the lower frequency side by about 0.4 GHz, and the fluctuation of the third harmonic due to the adjustment element 6 It can be confirmed that the effect is obtained.

As a second embodiment, an antenna that has the structure shown in FIG. 9 by adding a third radiating element to the antenna of FIG. 1 and that corresponds to the wireless WAN band and two LTE bands will be described.

In principle, the shape, dimensions, assembly method, and the like of the antenna of the second embodiment are the same as those of the antenna described in the first embodiment.
The difference is that a third radiating element 4c is added on the opposite side of the extending direction of the second radiating element 4b in order to increase the corresponding frequency band.

The third radiating element 4c is intended to correspond to the 1.8 GHz band among a plurality of LTE bands.

FIG. 10 is a plan development view of the antenna element 1 used in the second embodiment. One square corresponds to 1 mm square, and a three-dimensional antenna element 1 shown in FIG. 9 is obtained by performing mountain folds with broken lines and valley folds with one-dot broken lines.

The dimension and shape of the added third radiating element portion 4c are as follows.

Third radiation element portion 4c: a shape extending from the first radiation element portion 4a in the -X direction with a width of 1 mm and a height of 25 mm.

When the VSWR of the obtained antenna was measured, as shown in FIG. 11, VSWR peaks were also present in the vicinity of 1.8 GHz and 2.6 GHz in addition to 860 MHz in the wireless WAN band.

The peak appearing in the vicinity of 1.8 GHz is due to the third radiating element 4c, and sufficient communication characteristics were confirmed even in the 1.8 GHz band of LTE.

The peak that appears in the vicinity of 2.6 GHz is due to the fluctuating third harmonic, and sufficient communication characteristics were confirmed even in the 2.5 GHz band of LTE.

As described above, as the antenna of the second embodiment, the wireless WAN band and the two LTE bands 3
A small antenna corresponding to the frequency was obtained.

As a third embodiment, an antenna corresponding to the wireless WAN band and one LTE band, in which the adjustment element 6 shown in FIG. 2 is provided on the same plane as the short-circuit unit 3, will be described.

The antenna of the third embodiment is basically the same as the antenna described in the first embodiment except for the shape, dimensions, and the corresponding frequency band.

FIG. 12 is a plan development view of the antenna element 1 used in the third embodiment. One square corresponds to 1 mm square, and a three-dimensional antenna element 1 shown in FIG. 12 is obtained by performing mountain folds with broken lines and valley folds with one-dot broken lines.
In this antenna element 1, the radiating element section 4 provided with the frequency adjusting section 9 is 960 MHz of the wireless WAN band, and the third harmonic fluctuated by the adjusting element is 3.4 to 3.5 out of the 3.5 GHz band of the LTE band. It was intended to support 3.5 GHz, and each dimension was determined by simulation.

The dimensions and shape of each member of the antenna element 1 developed in a plane are as follows.
The dimensions not described are as shown in FIG.

Ground plate 2: a shape in which a narrow portion having a width of 1 mm and a length of 11 mm extends in a −X direction from a rectangular portion having a height of 15 mm and a width of 28 mm.

Short-circuit portion 3: a shape extending from the ground plate 2 in the Y direction with a width of 4 mm and a height of 2 mm and then extending in the −X direction with a width of 1 mm and a length of 18 mm so as to be parallel to the edge of the ground plate 2.

Radiating element part 4: After the first radiating element part 4a extends in the Y direction with a width of 8 mm and a height of 10 mm from the end of the short circuit part 3, the second radiating element part 4b with a width of 2 mm and a length of 52 mm in the -X direction. The shape that is extended.

Frequency adjusting unit 9: A rectangular part having a width of 11 mm and a height of 4 mm is provided at the tip of the second radiating element part 4b.

Adjusting element 6: After extending from the vicinity of the tip of the narrow part of the ground plate 2 with a width of 1 mm and a height of 7 mm in the Y direction, it extends to the −X direction with a width of 3 mm and a length of 9 mm, and the vicinity of the tip becomes 4 mm in width. Has an approximately L shape.

Feeding point 5: a position 5 mm in the X direction from the lowest part of the left end side of the first radiating element portion 4a7.

Earth point 8: Near the upper left corner of the rectangular top of the ground plate 2. A position 3 mm in the X direction from the left edge to the upper edge.

The feeding coaxial cable 7 is connected to the back side in FIG.

The size of the antenna excluding the feeding coaxial cable 7 is as small as 20 mm in height, 84 mm in width, and 4 mm in thickness.

When the VSWR of the obtained antenna was measured, as shown in FIG. 13, the peak of VSWR was present not only in the vicinity of 960 MHz in the wireless WAN band but also in 3.4 GHz belonging to the LTE 3.5 GHz band. Thus, a small dual-frequency antenna having sufficient communication characteristics in the band to be obtained was obtained.
Compared with FIG. 4 corresponding to VSWR when the adjustment element 6 is omitted from the third embodiment, the peak due to the third harmonic moves to the low frequency side by about 0.2 GHz, and the fluctuation of the third harmonic due to the adjustment element 6 It can be confirmed that the effect is obtained.

As a fourth embodiment, an antenna corresponding to the wireless WAN band and two LTE bands will be described by adding a third radiating element portion 4c to the antenna of FIG.

In principle, the shape, dimensions, assembly method, and the like of the antenna of the fourth embodiment are the same as those of the antenna described in the third embodiment.
The difference is that a third radiating element 4c having a frequency adjusting unit 9 is added to the opposite side of the extending direction of the second radiating element 4b in order to increase the corresponding frequency band.

The third radiating element 4c is intended to correspond to the 1.8 GHz band among a plurality of LTE bands.
Further, due to the change in the antenna shape accompanying the addition of the third radiating element 4c, the harmonics around 3.4 GHz generated in the antenna described in the third embodiment are further changed to the low frequency side, and one of the LTE bands is changed. It is also intended to correspond to the 2.5 GHz band.

FIG. 14 is a developed plan view of the antenna element 1 used in the fourth embodiment. One square corresponds to 1 mm square, and a three-dimensional antenna element 1 shown in FIG. 6 is obtained by performing mountain folds with broken lines and valley folds with one-dot broken lines.

The dimensions and shape of the third radiating element unit 4c having the added frequency adjusting unit 9 are as follows.

Third radiation element portion 4c: a shape extending from the first radiation element portion 4a in the X direction with a width of 2 mm and a height of 24 mm.

-Frequency adjustment part 9: It is provided in the front-end | tip of the 3rd radiation | emission element part 4c in the shape by which the notch of width 2mm * length 2mm was provided in the front-end | tip by width 14mm x height 3mm.

In the antenna of the fourth embodiment, since the third radiating element 4c is provided in the space above the short-circuit portion 3 in the antenna of the third embodiment, the size of the antenna excluding the feeding coaxial cable 7 is increased. Is the same as in the third embodiment, and further multi-frequency can be realized without increasing the size of the antenna.

When the VSWR of the obtained antenna was measured, as shown in FIG. 15, VSWR peaks were also present in the vicinity of 2 GHz and 2.9 GHz in addition to the vicinity of 960 MHz in the wireless WAN band.

The peak that appears in the vicinity of 2 GHz is due to the third radiating element 4c. The peak position is out of the LTE 1.8 GHz band (1.71 to 1.88 GHz), but in the frequency range belonging to the 1.8 GHz band, the VSWR is 2.5 or less, and in the LTE 1.8 GHz band. Sufficient communication characteristics were confirmed.

The peak that appears near 2.9 GHz is due to the fluctuating third harmonic. The peak position is out of the 2.5 GHz band (2.5 to 2.69 GHz) of LTE, but this peak affects the VSWR belonging to the 2.5 GHz band of LTE to 2.5 or less and a high frequency. Since it tends to decrease as it goes to the side, sufficient communication characteristics in the 2.5 GHz band of LTE have been confirmed.

As described above, a small antenna corresponding to the three frequencies of the wireless WAN band and the two LTE bands was obtained as the antenna of the fourth embodiment.

  The antenna corresponding to the wireless WAN band and the LTE band has been described above. However, this is only an example of the present invention, and can be applied to antennas corresponding to other bands as long as it is within the scope of the present invention. Needless to say.

The antenna of the present invention can be used not only for personal computers but also for various information terminal devices such as mobile phones, PDAs, VICSs, etc., as well as for information home appliances having communication functions, and also for automobile-related devices.

DESCRIPTION OF SYMBOLS 1 Antenna element 2 Ground part 3 Short circuit part 4 Radiation element part 4a 1st radiation element part 4b 2nd radiation element part 4c 3rd radiation element part 5 Feeding point 6 Adjustment element 7 Coaxial cable 8 for feeding 8 Grounding point 9 Frequency adjustment part

Claims (7)

A ground plate, a radiating element portion electrically connected to the ground plate through a short-circuit portion, and an inner conductor, a dielectric, an outer conductor, and a jacket from the inside are configured in this order, and the inner conductor is the radiating element. An antenna constituted by a feeding coaxial cable connected to a feeding point provided in a section, and the outer conductor connected to an earth point provided on the ground plate,
The adjustment element extends from the ground plate, the adjustment element is close to the radiating element portion, and the short-circuit portion and the adjustment element are formed on different planes,
The radiating element section is provided with a frequency adjusting section,
A multi-frequency antenna, wherein the antenna corresponds to at least two frequency bands. The multi-frequency antenna according to claim 1, wherein the shape of the frequency adjusting unit is a shape in which a tip and / or an intermediate part of the radiating element unit are partially thickened. 3. The multi-frequency antenna according to claim 1, wherein the shape of the frequency adjusting unit is a shape in which a tip of the radiating element unit is folded back in a U-shape. The distance between the ground point and the base end of the adjusting element is a length of one quarter or less of the wavelength of the highest frequency band to which the multi-frequency antenna according to claim 1 corresponds. The multi-frequency antenna according to any one of claims 1 to 3, wherein the multi-frequency antenna is characterized. After the short-circuit portion extending in a first direction from said ground plate, characterized in that extending in the second direction so as to parallel to the edge of the ground plate, any claim 1-4 multi-frequency antenna according to any. The radiation element portion, first, and having a second radiating element, the multi-frequency antenna according to any one of claims 1 to 5 shown below (a), (b).
(A) A first radiating element portion that is directly connected to the short-circuit portion and extends in the first direction.
(B) A second radiating element portion extending from the first radiating element portion in the second direction or a third direction opposite to the second direction. The multi-frequency antenna according to claim 6 , wherein a third radiating element portion also extends from the first radiating element portion toward an opposite side of the extending direction of the second radiating element portion. .

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