JP4095072B2 - Antenna for portable communication equipment - Google Patents

Description

The present invention relates to an antenna of a portable communication device, and more particularly to an antenna used for a mobile phone.

  In recent years, mobile phones have been used around the world. However, since the frequency band used for the mobile phone is different in each country, in order to use the mobile phone all over the world, it is necessary to have a mobile phone having an antenna adapted to the frequency band of each country. On the other hand, as a mobile phone manufacturer, it is more desirable in terms of production cost to produce a mobile phone having an antenna having a common specification than to produce a mobile phone having an antenna having a different specification for each country.

  An example of the frequency band for each country for reference is as follows.

Europe, Asia: GSM 880-960MHz
Europe: DCS 1710-1880MHz
North America: PCS 1850-1990MHz
World: UMTS (IMT2000) 1920-2170MHz
In addition, there are communication frequencies other than calls such as GPS (Global Positioning System), non-contact IC (Integrated Circuit), Bluetooth (R), and W-LAN.

  Thus, while it is desired that the cellular phone antenna has a wider bandwidth, the antenna itself is also desired to be miniaturized because of the desire to reduce the size of the cellular phone. In order to reduce the size of the antenna, it is conceivable to employ a loop antenna, an inverted F-type antenna, or the like, but it is difficult to realize a wide band of these antennas.

On the other hand, as a technique for increasing the bandwidth of a mobile phone, a technique using a folded loop antenna is disclosed (see Patent Documents 1 and 2).
JP 2004-228917 A JP 2004-228918 A

  However, in the above-described technology using a folded loop antenna in a mobile phone, the folded loop antenna is near the tip of a finite conductor plate corresponding to a shield plate (ground plate) of a mobile phone having the same width as the antenna length. Provided on the top surface. In the folded loop antenna, a loop is formed in a direction perpendicular to the ground plate.

  Accordingly, the occupied area becomes large when viewed three-dimensionally, and there has been a problem that the demand for miniaturization of the antenna cannot be met even if the bandwidth is wide.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an antenna of a portable communication device that has a wide band and can be downsized.

According to the antenna of the portable communication device according to the first aspect of the present invention, the first element extending from the power supply terminal and the first element are formed in a direction orthogonal to the extending direction of the first element. A first antenna element having a second element having a first line width larger than a line width of the first element, and one end connected to the second element of the first antenna element; The second end is disposed so as to surround a part of the periphery of the element, and the other end is connected to a ground terminal of a portable communication device provided in the vicinity of the power supply terminal, and is narrower than the first line width. A second antenna element having a line width of: a line width ratio between the second element of the first antenna element and the second antenna element and a distance between the feeding terminal and the ground terminal. At least one is formed from the first antenna element and the second antenna element. Characterized in that it is configured to match the desired impedance of that antenna.

Moreover, according to the antenna of the portable communication device according to the second aspect of the present invention, the first element extended from the power supply terminal and the direction orthogonal to the extending direction of the first element are formed. A first antenna element having a second element having a first line width greater than a line width of the first element, and one end connected to the second element of the first antenna element; The second element is disposed so as to surround a part of the periphery of the second element, and the other end is connected to a ground terminal of a portable communication device provided in the vicinity of the power supply terminal, and is narrower than the first line width. A second antenna element having a second line width; and a monopole antenna having one end extending from the second element of the first antenna element or the second antenna element. To do.

According to the present invention, it is possible to provide an antenna for a portable communication device that has a wide band and can be downsized.

Hereinafter, an antenna of a mobile phone according to an embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a diagram showing an appearance of a mobile phone 10 which the antenna according to the embodiment is an antenna chip 20 disposed of the invention is incorporated.

  As shown in the figure, the mobile phone 10 includes a housing 11. A ground plate (ground plate) 12 and an antenna chip 20 are accommodated in the housing 11, and a liquid crystal display unit 13 and keys 14 are provided on the surface of the housing 11.

The antenna chip 20 is made of a non-conductive material, and the antenna according to the embodiment of the present invention is formed. Although FIG. 1 shows an example in which the antenna chip 20 is provided inside and below the housing 11, the position of the antenna chip 20 is not limited to this. For example, in a folding-type mobile phone, an antenna chip 20 is provided in the lower part of the housing 11 and a hinge part for connecting a main body part provided with keys and a liquid crystal display part. May be provided inside the main body portion.

Figure 2 is a diagram showing an antenna chip external structure of the antenna is formed according to an embodiment of the present invention, FIG. 3 is a rear view of the antenna chip from the A direction in FIG. 2, FIG. 4 It is the side view which looked at the antenna chip from the B direction of FIG. Here, the shape of the antenna chip 20 is shown as a rectangle, but the shape of the antenna chip 20 is determined by the design restrictions of the housing 11 of the mobile phone 10 and is not limited to a rectangle. Needless to say.

  As shown in the figure, a power supply terminal 31 is provided on the front surface of the antenna chip 20 for power supply from the power supply unit of the mobile phone 10. Then, one end of a bent dipole antenna 32 according to the embodiment of the present invention is connected to the power supply terminal 31.

  A ground terminal 36 for connecting to the ground plate (ground plate) 12 of the mobile phone 10 is formed on the front surface of the antenna chip 20, and the other end of the bent dipole antenna 32 is connected to the ground terminal 36. The Note that the power supply terminal 31 and the ground terminal 36 are preferably arranged on the end side of the ground plate in terms of terminal circuit design.

The bent dipole antenna 32 is connected to the power supply terminal 31 and has a first conductive portion 33 formed so as to extend in a vertical direction from the front surface of the antenna chip 20 toward the upper surface, and the first conductive portion 33. A second conductive portion 34 formed on the upper surface of the antenna chip 20 and having a line width d ₁ and having one end connected to the first conductive portion 33. The second conductive portion 34 has a third conductive portion 35 having one end connected to the other end and the other end connected to the ground terminal 36.

The third conductive portion 35 has a line width d ₂ that is narrower than the line width d _{1 of} the second conductive portion 34, and is mainly formed on the surface of the antenna chip 20. In addition, one end of the third conductive portion 35 is bent after a predetermined length is formed from the other end of the second conductive portion 34 in a direction orthogonal to the longitudinal direction of the second conductive portion 34, 2 is a longitudinal direction of the second conductive portion 34 and is bent after a predetermined length is formed in the direction of the second conductive portion 34, and is further orthogonal to the longitudinal direction of the second conductive portion 34. The antenna chip 20 is formed from the top surface to the front surface in the direction toward the second conductive portion 34 and is connected to the ground terminal 36.

That is, the third conductive portion 35 is disposed so as to surround a part of the periphery of the second conductive portion 34. Further, the distance d ₃ between the feeding terminal 31 and the ground terminal 36 of the bent dipole antenna 32 is set so as to match a desired impedance (50Ω in the present embodiment) in the bent dipole antenna 32. Further, the impedance adjustment of the bent dipole antenna 32 is determined by the ratio between the line width d ₁ of the second conductive portion 34 and the line width d _{2 of} the third conductive portion 35 in the direction parallel to the second conductive portion 34. . Incidentally, by adjusting the distance d ₃ of the can also be impedance matching between the feeding terminal 31 and the ground terminal 36. In the experiment, it was confirmed that under a predetermined condition, a VSWR (Voltage Standing Wave Ratio) was reduced by 0.5 to 1.0 to achieve a wide band.

Furthermore, the antenna according to the embodiment of the present invention has one end connected to the third conductive portion 35, extends from the front surface to the back surface of the antenna chip 20, and then is bent in a direction perpendicular to the extending direction. The monopole antenna 41 is formed to extend from the back surface of the antenna chip 20 to the left side surface. The monopole antenna 41 has a resonance frequency designed according to its length. This length adjustment is performed by bending the monopole antenna 41, making the length itself, a meander shape, or the like. Note that the monopole antenna 41 may be connected to the second conductive portion 34.

FIG. 5 is a diagram showing a modification of the antenna according to the embodiment of the present invention. The same parts as those in FIG.

A significant difference from the antenna shown in FIG. 2 is that the monopole antenna 41 connected to the bent dipole antenna 32 is formed in a meander shape on the antenna chip 20 and then formed from the back surface to the side surface of the antenna chip 20. It is in. The reason why the monopole antenna 41 is formed in a meander shape is to secure the impedance necessary for the resonance frequency by securing the length of the monopole antenna.

6, an antenna according to the embodiment of the present invention, showing the relationship between the grounding plate 51 which is stored in the housing of the mobile phone, FIG. 7, the scale of the antenna pattern of the antenna shown in FIG. 6 FIG. 8 is a diagram for explaining the positional relationship between the ground plate and the antenna element, and FIG. 9 is a diagram showing frequency characteristics of the antenna shown in FIGS.

  FIG. 10A is a diagram showing the relationship between the plate-like inverted F antenna 61 and the ground plate 51 to be compared for explaining the effect of the present invention, and FIG. 10B is formed on the ground plate 51. FIG. 11 is a diagram showing the frequency characteristics of the plate-like inverted F antenna 61.

  FIG. 12A is a diagram showing the relationship between the inverted L antenna 71 and the ground plate 51 to be compared for explaining the effect of the present invention, and FIG. 12B is an inverted L antenna formed on the ground plate 51. 71 is a top view, and FIG. 13 is a diagram showing the frequency characteristics of the inverted L antenna.

As shown in FIGS. 6 and 8, the antenna formed in the antenna chip 20 according to the embodiment of the present invention does not need to be provided on the ground plate 51. Therefore, the plate-like inverted F antenna 61 shown in FIG. Compared to the above, the three-dimensional occupied area is small, and as a result, the mobile phone can be made thinner.

In FIG. 9 showing the frequency characteristics of the antenna according to the embodiment of the present invention shown in FIGS. 5 to 7, it is the frequency characteristics of the monopole antenna that has a peak in the vicinity of 900 MHz, and has a peak in the vicinity of 1900 MHz. Is a frequency characteristic of a bent dipole antenna.

  In general, in view of the fact that the frequency band that can be used in a mobile phone needs to have a VSWR of 3.0 or less, the usable frequency band of a folded dipole antenna is as wide as about 1700 MHz to 2200 MHz. DCS, PCS and UMTS bands can be covered. The usable frequency band of the monopole antenna is about 880 MHz to 960 MHz, and can cover the above-mentioned GSM band.

  On the other hand, as shown in FIG. 11, the frequency characteristics of the plate-shaped inverted F antenna are narrow bands of about 1700 MHz to 1950 MHz, and the purpose of achieving a wide band cannot be achieved. Further, as shown in FIG. 13, the frequency characteristic of the inverted L antenna is a wide band of about 1750 MHz to 2000 MHz. However, impedance matching is difficult due to the characteristic, and the GSM band cannot be covered as described above.

<Other embodiments>
When the used frequency band is a high frequency, the antenna itself can be downsized in relation to the wavelength. In such a case, the antenna shown in FIG. 14 can also be used. The same parts as those in FIG. 2 will be described with the same reference numerals. Figure 14 is a antenna chip external view antenna is formed according to an embodiment other of the present invention, FIG. 15 is a rear view of the antenna chip from A 'direction in FIG. 14, FIG. 16 is an antenna It is the side view which looked at the chip | tip from the B 'direction of FIG.

As shown in the figure, this antenna is formed by a combination of a bent dipole antenna 81 and a monopole antenna 82. One end of the bent dipole antenna 81 is connected to a power supply terminal 31 that supplies power to the mobile phone 10, and the other end is connected to a ground terminal 36 for connection to a ground plate (ground plate) of the mobile phone 10.

The bent dipole antenna 81 is formed in a rectangular shape on the upper surface of the antenna chip 20, and the long side line width d ₁ ′ near the power supply terminal 31 and the ground terminal 36 among the long sides is the other long side. It is wider than the line width d ₂ ′. Impedance adjustment for matching the resonance frequency of the bent dipole antenna 81 is determined by the ratio between the line width d ₁ ′ and the line width d ₂ ′. Further, the distance d ₃ ′ between the power feeding terminal 31 and the ground terminal 36 is set so as to match the resonance frequency of the bent dipole antenna 81.

Furthermore, the antenna according to the embodiment of the present invention is connected to the bent dipole antenna 81 at one end, extends from the front surface to the back surface of the antenna chip 20, and then bent in a direction orthogonal to the extending direction. The monopole antenna 82 is formed so as to extend from the back surface of the chip 20 to the left side surface. The monopole antenna 82 is formed so as to match a target resonance frequency. That is, the impedance adjustment of the monopole antenna 82 is designed according to its length. The adjustment of the length is performed by bending the monopole antenna 82, making the length itself, a meander shape, or the like.

Therefore, according to the antenna according to the embodiment of the present invention, since it is not necessary to form the antenna element on the ground plate, it may take the height in comparison such as folded loop antenna formed of the antenna Therefore, the mobile phone can be thinned.

  Further, by forming a dipole antenna mainly on the surface of the antenna chip and forming a monopole antenna on the side surface, it is possible to deal with other frequencies with one antenna chip.

  Furthermore, since only a folded dipole antenna can handle multiple frequencies (for example, DCS, PCS, and UMTS bands) and can be formed on one surface of the antenna chip surface, an element for other frequencies is provided on the other surface. It becomes possible to arrange.

  Furthermore, since the folded dipole antenna has a self-balancing action, current leakage to the housing side can be suppressed without the need for a balun (balance / unbalance conversion unit), and humans use mobile phones. There is little influence on the antenna when

  Further, the folded dipole antenna (FIG. 14) described in the other embodiments described above has less leakage of current to the ground plate side than the folded dipole antenna (FIG. 2) in the embodiment. There is an effect that the self-equilibrium action is high.

  Furthermore, in the above description, a dipole antenna is obtained by capturing the ground plate as an antenna element. However, if the ground plate is viewed as the ground, it can be captured as a monopole antenna.

  In the above-described embodiment, a mobile phone has been described as an example. However, the present invention is not limited to this and can be applied to a mobile terminal such as a PDA (Personal Digital Assistant).

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

Antenna chip antenna according to an embodiment of the present invention is provided is a diagram showing an appearance of a mobile phone incorporated. Is a diagram illustrating an antenna chip external structure of the antenna is formed according to an embodiment of the present invention. It is the rear view which looked at the antenna chip from the A direction of FIG. It is the side view which looked at the antenna chip from the B direction of FIG. It is a figure which shows the modification of the antenna which concerns on embodiment of this invention. It is a figure which shows the relationship between the antenna which concerns on embodiment of this invention, and the earth board stored in the housing | casing of a mobile telephone. It is a diagram for explaining the scale of the antenna pattern of the antenna shown in FIG. It is a figure explaining the arrangement | positioning relationship between a ground plate and an antenna . It is a figure which shows the frequency characteristic of the antenna shown in FIG. 5 thru | or FIG. (A) is a figure which shows the relationship between the plate-shaped inverted F antenna and ground plate compared in order to demonstrate the effect of this invention, (b) is a top view of the plate-shaped inverted F antenna formed on the ground plate. It is. It is a figure which shows the frequency characteristic of a plate-shaped inverted F antenna. (A) is a figure which shows the relationship between the reverse L antenna and ground plate compared in order to demonstrate the effect of this invention, (b) is a top view of the reverse L antenna formed on the ground plate. It is a figure which shows the frequency characteristic of a reverse L antenna. Is an external view of the antenna chip antenna is formed according to another embodiment of the present invention. It is the rear view which looked at the antenna chip from the A 'direction of FIG. It is the side view which looked at the antenna chip from the B 'direction of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Mobile phone ground plate, 20 ... Antenna chip, 31 ... Feeding terminal, 32 ... Bending dipole antenna, 41 ... Monopole antenna, 51 ... Mobile phone ground plate

Claims (5)

A first element extending from the power supply terminal and a second element formed in a direction orthogonal to the extending direction of the first element and having a first line width larger than the line width of the first element A first antenna element having an element;
A portable type in which one end is connected to the second element of the first antenna element, is disposed so as to surround a part of the periphery of the second element, and the other end is provided in the vicinity of the feeding terminal. A second antenna element connected to a ground terminal of a communication device and having a second line width narrower than the first line width ;
At least one of the line width ratio between the second element of the first antenna element and the second antenna element and the distance between the feeding terminal and the ground terminal is determined by the first antenna element and the second antenna element. An antenna for a portable communication device, wherein the antenna is set so as to match a desired impedance of an antenna formed by the antenna element.   A first element extending from the power supply terminal and a second element formed in a direction orthogonal to the extending direction of the first element and having a first line width larger than the line width of the first element A first antenna element having an element;
  A portable type in which one end is connected to the second element of the first antenna element, is disposed so as to surround a part of the periphery of the second element, and the other end is provided in the vicinity of the feeding terminal. A second antenna element connected to a ground terminal of a communication device and having a second line width narrower than the first line width;
A monopole antenna having one end extending from the second element of the first antenna element or from the second antenna element;
An antenna for a portable communication device, comprising: The first antenna element and the second antenna element are formed on a surface of an antenna chip, and the monopole antenna is formed on at least one of a surface and a side surface of the antenna chip. The antenna of the portable communication device according to claim 2. 4. The antenna according to claim 1, wherein a region having the first line width is formed in a part of the second antenna element. 5. The antenna according to any one of claims 1 to 3, wherein the first antenna element and the second antenna element form a bent dipole antenna.

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