JP5005466B2 - Multi-frequency antenna - Google Patents

Description

  The present invention relates to a multi-frequency antenna suitable as an antenna for a portable radio device such as a mobile phone operating in a plurality of frequency bands, and more particularly to a multi-frequency common mobile phone monopole antenna using a meander structure. The target frequency band of the multifrequency antenna of the present invention is, for example, GSM (920 MHz) / GPS (1575.42 MHz) / DCS (1795 MHz) / PCS (1920 MHz) / UMTS (2045 MHz).

Conventionally, various types of antennas for portable wireless devices such as cellular phones have been proposed. For example, Non-Patent Documents 1 and 2 disclose planar inverted F antennas. Patent Document 1 discloses a helical antenna. Non-Patent Documents 3 to 6 disclose monopole antennas.
K. Taga, “Analysis of planar inverted-F antennas and antenna design for portable radio equipment,” Analysis, Design, and Measurement of Small and Low Profile Antennas, K. Hirasawa and M. Haneishi, Eds. Boston, MA: Artech, 1992, eh. 5. H.-J. Lee, S.-H. Cho, J.-K. Park Y.-H. Cho, J.-M. Kim, K.-H. Lee, I.-Y. Lee, and J .-S. Kim, “The compact quad-band planar iternal antenna for mobile handsets,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp. 2045-2048. JP 2003-37426 A K.-L. Wong, “Very-low-profile monopoles for internal mobile phone antennas,” Planar antenna for wireless communications, Hoboken, New Jersey: John Wiley & Sons, 2003, ch. 3 H.-C. Tung, T.-F. Chen, C.-Y. Chang, C.-Y. Lin, and T.-F. Huang, “Shorted monopole antenna for curved shape phone housing in clamshell phone,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp. 1060-1063. Y.-W. Chi and K.-L. Wong, “Printed dual-band loop antenna for mobile phone application,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp. 3576-3579 . H. Deng and Z. Feng, “A triple-band compact monopole antenna for mobile handsets,” in Proc. IEEE Antennas Propag. Int. Symp., Hawai, USA, 2007, pp. 2069-2072.

  The frequency band used by the mobile telephone system is generally a plurality of frequency bands. For example, the PDC system (Personal Digital Cellular telecommunication system) in Japan uses the 800 MHz band (810-956 MHz) and the 1.4 GHz band (1429-1501 MHz), and the digital cellular system in the United States uses AMPS (Advanced Mobile Phone). At least 900 MHz band (824-894 MHz) is used as a service (Service) system and 1.8 GHz band (1850-1990 MHz) is used as a PCS (Personal Communication Service) system. In Europe, the 900 HMz band (880-960 MHz) is used as a GSM (Global System for Mobile communications) system, and the 1.8 GHz band (1710-1880 MHz) is used as a DCS (Digital Cellular System) system. In addition, a 2.0 GHz band (1920-2170 MHz) is used as a UMTS (Universal Mobile Telecommunications System) system, and a 2.4 GHz band (2400-2500 MHz) is used as a Bluetooth system. The reason why a plurality of frequency bands are used in this way is that the frequency used is insufficient in one frequency band due to an increase in subscribers.

  Thus, it is necessary to mount an antenna that operates in a plurality of frequency bands in a portable radio device such as a mobile phone that receives or transmits a plurality of frequency bands. Therefore, conventionally, as an antenna that operates at a plurality of frequencies, in addition to the main antenna, a flat antenna or a small-volume chip antenna is built in the radio housing. However, in such a structure, there is a problem that the antenna takes away the volume inside the wireless device casing and is not suitable for miniaturization of the portable wireless device. Furthermore, when the user grips the portable wireless device, the ratio of the built-in antenna covered by the hand is large, and there is a problem that the antenna characteristics when using the portable wireless device are deteriorated.

  To realize an antenna that satisfies such requirements, a quarter-wave antenna is promising. However, when using PIFA (Planar Inverted-F antenna) as disclosed in Non-Patent Documents 1 and 2, the weight and size of the substrate for supporting the antenna and the increase in price are widespread. It becomes a problem toward.

  Further, when using the helical antenna disclosed in Patent Document 1, the impact on the user is reduced to some extent, but the size is large and it is difficult to incorporate the portable antenna into the portable wireless device.

  The monopole antennas disclosed in Non-Patent Documents 3 to 6 are thin and have an attractive structure as an antenna to be mounted on a portable wireless device, but are large in size and difficult to be incorporated in a portable wireless device. It is. In addition, as disclosed in Non-Patent Documents 3 to 5, an antenna capable of covering two bands has been proposed. However, in this case, the available frequency is insufficient in the frequency band.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small multi-frequency antenna that operates well in a plurality of frequency bands.

In order to achieve the object, the present invention has a ground plane, a matching plate connected to the ground plane via a feeding point, and a first arm and a second arm extending from the matching plate,
A part of at least one of the first arm and the second arm is formed in a meander shape,
The first arm is composed of four parts, a first arm first part, a first arm second part, a first arm third part, and a first arm fourth part, which are sequentially provided from the matching plate toward the tip side. And
The second arm includes the first arm first portion as a shared portion, and includes the second arm first portion, the second arm second portion, and the second arm third provided in this order toward the distal end side. It consists of a total of four parts,
The first arm is divided between the first arm second part and the first arm third part and between the first arm third part and the first arm fourth part by folding the folding line, respectively. The first arm second portion and the first arm fourth portion are opposed to each other by the bending , and the second arm is between the second arm first portion and the second arm second portion, and The two-arm second part and the second arm third part are divided by folding of the folding lines, respectively, and the second arm first part and the second arm third part are arranged to face each other by these foldings. And
And the first arm and the second arm are provided in the same direction,
First arm second portion and second arm first portion, first arm third portion and second arm second portion, and first arm fourth portion and second with first arm first portion as a base end The arm third part is arranged in parallel with each other ,
The first arm is used to control the fundamental mode and the higher order mode on the low frequency side,
The second arm is used to adjust the fundamental mode on the high frequency side.
The bend line that divides each part of the first arm and the second arm is set at a position where the distance between the fundamental mode and the higher order mode can be adjusted and the resonance frequency can be controlled.
The dimensions of each part of the first arm and the second arm are set so that the higher frequency mode and the fundamental mode on the high frequency side can be added and the band on the high frequency side can be expanded. to provide a multi-frequency antenna, characterized in that it is.

  In the multi-frequency antenna of the present invention, it is preferable that the radiating element of the antenna has a size of 24.3 mm × 20 mm × 4 mm.

In the multi-frequency antenna of the present invention, the GSM frequency is f _GSM , the GPS frequency is f _GPS , the DCS frequency is f _DCS , the PCS frequency is f _PCS , and the UMTS frequency is f _UMTS, and 880 MHz ≦ f _GSM ≦ 960 MHz 1570 MHz ≦ f _GPS ≦ 1580 MHz, 1710 MHz ≦ f _DCS ≦ 1785 MHz, 1850 MHz ≦ f _PCS ≦ 1910 MHz and 1920 MHz ≦ f _UMTS ≦ 2170 MHz, it is preferable that the voltage standing wave ratio VSWR ≦ 3.5 or less.

  The multi-frequency antenna of the present invention is a monopole pair antenna, wherein the ground plane length is gL, the ground plane width is gw, the first arm first portion length is fedL, and the first arm first portion width is fedw. In this case, it is preferable that the dimensions of these parts satisfy the relationships of 40 mm ≦ gL ≦ 150 mm, 30 mm ≦ gw ≦ 60 mm, 5 mm ≦ feedL ≦ 40 mm, and 0.1 mm ≦ feedw ≦ 5 mm.

In the multi-frequency antenna of the present invention, a monopole pair antenna,
The first arm second part length GSM1L is 15 mm ≦ GSM1L ≦ 30 mm,
The first arm second partial width GSM1w is 0.5 mm ≦ GSM1w ≦ 5 mm,
The first arm third part length GSM2L is 1 mm ≦ GSM2L ≦ 10 mm,
The first arm third partial width GSM2w is 0.5 mm GSM2w ≦ 5 mm,
The first arm fourth portion length GSM3L is 15 mm ≦ GSM3L ≦ 30 mm,
The first arm fourth partial width GSM3w is 1 mm ≦ GSM3w ≦ 10 mm,
The second arm first part length DCS1L is 10 mm ≦ DCS1L ≦ 20 mm,
The second arm first partial width DCS1w is 0.5 mm ≦ DCS1w ≦ 5 mm,
The second arm second part length DCS2L is 1 mm ≦ DCS2L ≦ 10 mm,
The second arm second partial width DCS2w is 0.5 mm ≦ DCS2w ≦ 5 mm,
The second arm third part length DCS3L is 10 mm ≦ DCS3L ≦ 20 mm,
The second arm third partial width DCS3w is 1 mm ≦ DCS3w ≦ 10 mm,
It is preferable to satisfy the relationship.

In the multi-frequency antenna of the present invention, a monopole pair antenna,
It is preferable that the fourth portion of the first arm is formed in a meander shape, and the line width slitGSM of the meander conductor satisfies 0 ≦ slitGSM ≦ 1 mm and the meander conductor spacing spaceGSM satisfies 0 ≦ spaceGSM ≦ 1 mm.

  The multi-frequency antenna of the present invention includes a ground plane, a matching plate connected to the ground plane via a feeding point, and a first arm and a second arm extending from the matching plate. A part of at least one of the two arms is formed in a meander shape, and the first arm is composed of four parts, a first part to a fourth part, which are sequentially provided from the matching plate toward the tip side. Is composed of a total of four parts, including a first part, a first part, and a first part as a common part, and a first part to a third part provided in order from the first part toward the tip side. The first arm and the fourth arm are opposed to each other, the second arm first portion and the second arm third portion are opposed to each other, and the first arm and the second arm are provided in the same direction. Can be downsized, and many It is possible to have a sufficient radiation characteristics in the wave band.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are diagrams showing an embodiment of a multi-frequency antenna according to the present invention. FIG. 1A is a plan view of the multi-frequency antenna 1, and FIG. 1B is a perspective view. In this figure, reference numeral 1 is a multi-frequency antenna, 2 is a ground plane, 3 is a matching plate, 4 is a feeding point, 5 is a first arm, 5a is a first arm first part, 5b is a first arm second part, and 5c. Is a first arm third part, 5d is a first arm fourth part formed in a meander shape, 6 is a second arm, 6a is a second arm first part, 6b is a second arm second part, and 6c is a first arm part. 2 arms third part.

  The multi-frequency antenna 1 of the present embodiment includes a ground plane 2, a matching plate 3 connected to the ground plane 2 via a feeding point 4, and a first arm 5 and a second arm 6 extending from the matching plate 3. And at least a part of the first arm 5 and the second arm 6 (in this example, the first arm fourth portion 5d) is formed in a meander shape. The first arm 5 is composed of four parts of a first part to a fourth part 5a to 5d provided in order from the matching plate 3 toward the tip side, and the second arm 6 is a first arm first part 5a. Is composed of a total of four parts including the first part to the third part 6a to 6c, which are provided in order toward the tip side. Among the arm portions, the first arm second portion 5b and the first arm fourth portion 5d are opposed to each other, and the second arm first portion 6a and the second arm third portion 6c are opposed to each other. In addition, the first arm 5 and the second arm 6 are provided in the same direction. The multifrequency antenna 1 is configured using a perfect conductor.

  In the multi-frequency antenna 1 of the present embodiment, the first arm 5 is used for controlling the low-frequency basic mode and the higher-order mode, and the second arm 6 is used for adjusting the high-frequency basic mode. It has become. The bend line 7 that divides each part of the first arm 5 and the second arm 6 is set at a position where the distance between the fundamental mode and the higher-order mode can be adjusted and the distance between the resonance frequencies can be controlled. In addition, the size of each part of the first arm 5 and the second arm 6 can add the low-frequency side higher-order mode and the high-frequency side fundamental mode, and can widen the band on the high-frequency side. Is set to

In the multi-frequency antenna 1 of the present embodiment, the GSM frequency is f _GSM , the GPS frequency is f _GPS , the DCS frequency is f _DCS , the PCS frequency is f _PCS , the UMTS frequency is f _UMTS, and 880 MHz ≦ f _GSM ≦ 960 MHz, 1570 MHz ≦ f _GPS ≦ 1580 MHz, 1710 MHz ≦ f _DCS ≦ 1785 MHz, 1850 MHz ≦ f _PCS ≦ 1910 MHz and 1920 MHz ≦ f _UMTS ≦ 2170 MHz, it is preferable that the voltage standing wave ratio VSWR ≦ 3.5 or less.

  The multi-frequency antenna 1 of the present embodiment is a monopole pair antenna, and the ground plane length is gL, the ground plane width is gw, the first arm first part length is fedL, and the first arm first part width is In the case of feedw, it is preferable that the dimensions of these parts satisfy the relationships of 40 mm ≦ gL ≦ 150 mm, 30 mm ≦ gw ≦ 60 mm, 5 mm ≦ feedL ≦ 40 mm, and 0.1 mm ≦ feedw ≦ 5 mm.

In the multi-frequency antenna 1 of the present embodiment,
The first arm second part length GSM1L is 15 mm ≦ GSM1L ≦ 30 mm,
The first arm second partial width GSM1w is 0.5 mm ≦ GSM1w ≦ 5 mm,
The first arm third part length GSM2L is 1 mm ≦ GSM2L ≦ 10 mm,
The first arm third partial width GSM2w is 0.5 mm GSM2w ≦ 5 mm,
The first arm fourth portion length GSM3L is 15 mm ≦ GSM3L ≦ 30 mm,
The first arm fourth partial width GSM3w is 1 mm ≦ GSM3w ≦ 10 mm,
The second arm first part length DCS1L is 10 mm ≦ DCS1L ≦ 20 mm,
The second arm first partial width DCS1w is 0.5 mm ≦ DCS1w ≦ 5 mm,
The second arm second part length DCS2L is 1 mm ≦ DCS2L ≦ 10 mm,
The second arm second partial width DCS2w is 0.5 mm ≦ DCS2w ≦ 5 mm,
The second arm third part length DCS3L is 10 mm ≦ DCS3L ≦ 20 mm,
The second arm third partial width DCS3w is 1 mm ≦ DCS3w ≦ 10 mm,
It is preferable to satisfy the relationship.

  In the multi-frequency antenna 1 of the present embodiment, the first arm fourth portion 5d is formed in a meander shape, the meandering line width slitGSM is 0 ≦ slitGSM ≦ 1 mm, and the meander conductor spacing spaceGSM is 0 ≦ spaceGSM ≦ It is preferable to satisfy the relationship of 1 mm.

  The multi-frequency antenna 1 of the present embodiment can generate two resonances by using the two arms 5 and 6, and can widen the band on the high frequency side by using the matching plate 3. Is possible.

  The multi-frequency antenna 1 of the present embodiment uses the first arm 5 to control the low-frequency side fundamental mode and the higher-order mode, and uses the second arm 6 to adjust the high-frequency side fundamental mode. Is possible. Further, the interval between the fundamental mode and the higher order mode can be adjusted at the position of the fold line 7 of the first arm 5 and the second arm 6, and the interval between the resonance frequencies can be controlled. By using these two arms 5 and 6, it is possible to add a higher-order mode on the low frequency side and a fundamental mode on the high frequency side, and the band on the high frequency side can be expanded. Note that the positions of the first arm 5 and the second arm 6 may be changed.

  Further, since the wavelength of ¼ of the arm length generally used in a small antenna is too large, in the multi-frequency antenna 1 of the present embodiment, the meander structure is used for the first antenna fourth portion 5d. Thus, the antenna is downsized.

  A multi-frequency antenna (hereinafter abbreviated as an antenna) shown in FIG. 2 was produced. 2A is a perspective view of the antenna, FIG. 2B is an enlarged view of a main part showing each part of the arm, and FIG. 2C is a plan view of a state in which each arm is developed. The antenna manufactured in this example has the same structure as the antenna 1 shown in FIG. 1 described above, and the same reference numerals are given to the same components.

  The overall size of the antenna of this example is 24.3 mm × 20 mm × 4 mm. Note that the size of the ground plane 2 used was gL = 70 mm × gw = 40 mm, which is a typical value for a mobile phone. Detailed dimensions are summarized in Table 1.

Using the above parameters, the characteristics of the fabricated antenna were examined.
FIG. 3 shows the S parameter. From this figure, it can be seen that two resonances are performed in the GSM900 and 3G bands (DCS, PCS, UMTS) in the target frequency band represented by the broken line. Assuming a standard of VSWR <3.5, the bandwidths of the 900 MHz band (centered at 920 MHz) and the 3G band (here centered on 1920 MHz) are 87.3 MHz and 856.2 MHz, respectively. Detailed results are summarized in Table 2.

FIG. 4 shows the matching state of the antenna. From this figure, it can be seen that the resistance and reactance of 925 MHz and 1995 MHz are R in _{925 MHz} = 40.29 Ω, R in _{1995 MHz} = 66.64 Ω, X in _{925 MHz} = 2.16 Ω, and X in _{1995 MHz} = 1.52 Ω, respectively.

5A to 5E show the radiation characteristics (in the vertical plane) of the antenna in the yz plane of this antenna, and FIGS. 6A to 6E show the antenna characteristics in the xy plane of the antenna. Indicates the radiation characteristics (in the horizontal plane). The radiation characteristic of the antenna is indicated by the frequency at which the S parameter is the lowest value.
Also, the peak gain values in each band obtained from the results of FIG.

5 and 6 and Table 3, this antenna can be used in each band of GSM (920 MHz) / GPS (1575.42 MHz) / DCS (1795 MHz) / PCS (1920 MHz) / UMTS (2045 MHz). I understand that.
In addition, it can be seen from FIG. 6 that the antenna of this example has a characteristic close to that of a monopole.

Embodiment of the multi-frequency antenna of this invention is shown, (a) is a top view of a multi-frequency antenna, (b) is a perspective view. The multi-frequency antenna produced in the Example which concerns on this invention is shown, (a) is a perspective view of an antenna, (b) is a principal part enlarged view showing each part of an arm, (c) is a top view of the state which expand | deployed each arm It is. It is a graph which shows the S parameter of the antenna of an Example. It is a graph showing the matching state of the antenna of an Example. It is a graph which shows the radiation characteristic (in a perpendicular plane) of an antenna in yz plane of this antenna. It is a graph which shows the radiation characteristic (in a horizontal surface) of an antenna in xy plane of an antenna.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multi-frequency antenna, 2 ... Ground plane, 3 ... Matching board, 4 ... Feeding point, 5 ... 1st arm, 5a ... 1st arm 1st part, 5b ... 1st arm 2nd part, 5c ... 1st arm 1st 3 part, 5d ... 1st arm 4th part, 6 ... 2nd arm, 6a ... 2nd arm 1st part, 6b ... 2nd arm 2nd part, 6c ... 2nd arm 3rd part, 7 ... fold line.

Claims (6)

A ground plate, a matching plate connected to the ground plate via a feeding point, and a first arm and a second arm extending from the matching plate,
A part of at least one of the first arm and the second arm is formed in a meander shape,
The first arm is composed of four parts, a first arm first part, a first arm second part, a first arm third part, and a first arm fourth part, which are sequentially provided from the matching plate toward the tip side. And
The second arm includes the first arm first portion as a shared portion, and includes the second arm first portion, the second arm second portion, and the second arm third provided in this order toward the distal end side. It consists of a total of four parts,
The first arm is divided between the first arm second part and the first arm third part and between the first arm third part and the first arm fourth part by folding the folding line, respectively. The first arm second portion and the first arm fourth portion are opposed to each other by the bending , and the second arm is between the second arm first portion and the second arm second portion, and The two-arm second part and the second arm third part are divided by folding of the folding lines, respectively, and the second arm first part and the second arm third part are arranged to face each other by these foldings. And
And the first arm and the second arm are provided in the same direction,
First arm second portion and second arm first portion, first arm third portion and second arm second portion, and first arm fourth portion and second with first arm first portion as a base end The arm third part is arranged in parallel with each other ,
The first arm is used to control the fundamental mode and the higher order mode on the low frequency side,
The second arm is used to adjust the fundamental mode on the high frequency side.
The bend line that divides each part of the first arm and the second arm is set at a position where the distance between the fundamental mode and the higher order mode can be adjusted and the resonance frequency can be controlled.
The dimensions of each part of the first arm and the second arm are set so that the higher frequency mode and the fundamental mode on the high frequency side can be added and the band on the high frequency side can be expanded. Multi-frequency antenna characterized by being . The multi-frequency antenna according to claim 1 , wherein the radiating element of the antenna has a size of 24.3 mm x 20 mm x 4 mm. GSM frequency is f _GSM , GPS frequency is f _GPS , DCS frequency is f _DCS , PCS frequency is f _PCS , UMTS frequency is f _UMTS , 880 MHz ≦ f _GSM ≦ 960 MHz, 1570 MHz ≦ f _GPS ≦ 1580 MHz, 1710MHz ≦ _{f DCS} ≦ 1785MHz, in 1850MHz ≦ _{f PCS} ≦ 1910MHz and 1920MHz ≦ _{f UMTS} ≦ 2170MHz, multifrequency according to claim 1 or 2, characterized in that less voltage standing wave ratio VSWR ≦ 3.5 antenna. When it is a monopole pair antenna, the length of the ground plane is gL, the width of the ground plane is gw, the length of the first part of the first arm is fedL, and the width of the first part of the first arm is fedw, the dimensions of these parts are 40mm ≦ gL ≦ 150mm, 30mm ≦ gw ≦ 60mm, 5mm ≦ feedL ≦ 40mm, multi-frequency antenna according to any one of claims 1 to 3, characterized in that satisfies the relationship of 0.1mm ≦ feedw ≦ 5mm. Monopole vs. antenna,
The first arm second part length GSM1L is 15 mm ≦ GSM1L ≦ 30 mm,
The first arm second partial width GSM1w is 0.5 mm ≦ GSM1w ≦ 5 mm,
The first arm third part length GSM2L is 1 mm ≦ GSM2L ≦ 10 mm,
The first arm third partial width GSM2w is 0.5 mm GSM2w ≦ 5 mm,
The first arm fourth portion length GSM3L is 15 mm ≦ GSM3L ≦ 30 mm,
The first arm fourth partial width GSM3w is 1 mm ≦ GSM3w ≦ 10 mm,
The second arm first part length DCS1L is 10 mm ≦ DCS1L ≦ 20 mm,
The second arm first partial width DCS1w is 0.5 mm ≦ DCS1w ≦ 5 mm,
The second arm second part length DCS2L is 1 mm ≦ DCS2L ≦ 10 mm,
The second arm second partial width DCS2w is 0.5 mm ≦ DCS2w ≦ 5 mm,
The second arm third part length DCS3L is 10 mm ≦ DCS3L ≦ 20 mm,
The second arm third partial width DCS3w is 1 mm ≦ DCS3w ≦ 10 mm,
Multi-frequency antenna according to claim 1-4 characterized by satisfying the relationship. Monopole vs. antenna,
The fourth portion of the first arm is formed in a meander shape, and the line width slitGSM of the meander conductor satisfies 0 ≦ slitGSM ≦ 1 mm, and the distance between the meander conductors spaceGSM satisfies 0 ≦ spaceGSM ≦ 1 mm. Item 6. The multi-frequency antenna according to any one of Items 1 to 5 .

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