JP2005260382A - Dipole antenna - Google Patents

Abstract

When power is fed through an unbalanced line, it is not necessary to provide a balun for converting between balanced and unbalanced in the power feeding section, so that the characteristics of the antenna can be improved and the size can be reduced. Provide a dipole antenna.
In a dipole antenna 100, radiation conductors 10A and 10B are composed of linear radiation conductors 11 and 12 and helical structure conductors 13 and 14, respectively. Helical conductors 13 and 14 having different electrical lengths (or inductances) are provided so that the electrical length of the radiation conductor 10A connected to the signal line is longer than the radiation conductor 10B connected to the ground of the unbalanced line. In this case, the inductance of the helical structure conductor 13 is set to be larger than the inductance of the helical structure conductor 14, and the total electrical length of the radiation conductor 10A connected to the signal line and the radiation conductor 10B connected to the ground line is It becomes a half wavelength.
[Selection] Figure 1

Description

  The present invention relates to a dipole antenna fed through an unbalanced line. Specifically, the radiating conductor connected to the signal line or a part of both radiating conductors has a predetermined electric length so that the electric length of the radiating conductor connected to the signal line is longer than the radiating conductor connected to the ground line of the unbalanced line. By using a structure composed of conductors, when feeding power to the dipole antenna via an unbalanced line, it is not necessary to provide a balun that converts between balanced and unbalanced in the feeding section, improving the characteristics of the antenna In addition, the present invention relates to a dipole antenna that can be reduced in size.

  Conventionally, various antennas having various configurations have been proposed and used as small antennas used in mobile radio communication apparatuses and the like. A chip antenna is often used as such a small antenna.

  The chip antenna is a quarter-wave type small antenna having only one radiation conductor, but a large amount of current flows through the ground of the substrate on which the antenna is installed, and the chip antenna operates as one antenna including the ground. The antenna characteristics vary greatly depending on the position where the antenna is installed and the size of the substrate, making it difficult to layout the substrate. On the other hand, a dipole antenna having two radiating conductors having an electrical length of a quarter wavelength and having a half wavelength as a whole is easy to layout because no current flows to the ground. Therefore, dipole antennas are widely used.

  FIG. 6 is a diagram illustrating an example in which power is supplied to the dipole antenna via a balanced line. As shown in FIG. 6, this dipole antenna 1 is fed via a balanced line 4 to radiating conductors 2 and 3 having an electrical length of substantially a quarter wavelength. In this case, the dipole antenna 1 can be directly fed by the balanced line 4.

  FIG. 7 is a diagram illustrating an example in which power is supplied to the dipole antenna via an unbalanced line. As shown in FIG. 7, the dipole antenna 1 is connected to the radiation conductors 2 and 3 having an electrical length of substantially a quarter wavelength by an unbalanced line 6 through a balun 5 that performs balanced and unbalanced conversion. Power is supplied. In this case, since power cannot be directly supplied to the dipole antenna 1 by the unbalanced line 6, power is supplied through the balun 5 that performs conversion between balanced and unbalanced.

  In order to reduce the size, there has been proposed an antenna for portable radio equipment in which the effective antenna length is equivalently increased with respect to the actual size of the antenna (see, for example, Patent Document 1).

  In this case, by providing a loading coil on the feed terminal side of the dipole antenna, the antenna effective length is equivalent to the actual size of the antenna without reducing the efficiency and gain for the wavelength of the radio wave of the desired tuning frequency. Can be lengthened and the size can be reduced.

JP-A-9-36630 (pages 4, 5 and 5)

  However, since the dipole antenna is larger in size than the chip antenna, it is difficult to use the dipole antenna for a small portable wireless terminal or the like that cannot take up sufficient installation space for the antenna. In general, since a balanced line is used for feeding a dipole antenna, when feeding directly with an unbalanced line such as a coaxial cable, as shown in FIG. 8, there are resonance points at two frequencies near the fundamental frequency of the antenna. This is inconvenient for transmission / reception of a desired frequency. In this case, the antenna and the cable have to be connected with a balun that performs balanced and unbalanced conversion in the power feeding portion, which increases the number of components and increases the overall size.

  In addition, the dipole antenna has a drawback in that since the direction of current flow is in a straight line, the direction of polarization is constant, and polarized waves perpendicular to the direction cannot be transmitted and received.

  In Patent Document 1, the antenna can be reduced in size by providing a coil, but power cannot be directly supplied through an unbalanced line such as a coaxial cable.

  Therefore, the present invention eliminates the need to provide a balun that performs balanced and unbalanced conversion in the power feeding portion when power is fed through the unbalanced line, and can improve the antenna characteristics and reduce the size. An object of the present invention is to provide a dipole antenna that can be used.

  The dipole antenna according to the present invention is a dipole antenna in which two radiating conductors each having a predetermined electrical length corresponding to the resonance frequency are fed via an unbalanced line, and the resonance frequency in the vicinity of the fundamental frequency is united. Therefore, the radiating conductor connected to the signal line, or a part of both radiating conductors, has a predetermined electrical length so that the electric length of the radiating conductor connected to the signal line is longer than the radiating conductor connected to the ground line of the unbalanced line. It is composed of a structure conductor.

  For example, the helical structure conductor is arranged at a position closer to the feeding point than the center of the radiation conductor. The helical structure conductor is a chip coil.

  Further, for example, the chip coil is arranged so that the direction of the magnetic field induced by the chip coil is parallel to the metal surface in the vicinity thereof.

  Further, for example, the radiation conductor is provided with the capacitive load portion so that the conductor width of the portion closer to the tip portion than the center is wider than the conductor width of the portion closer to the feeding point.

  In the present invention, the radiation conductor connected to the signal line or a part of both radiation conductors has a predetermined electrical length so that the electrical length of the radiation conductor connected to the signal line is made longer than the radiation conductor connected to the ground line of the unbalanced line. It is composed of a conductor with a helical structure. Here, the helical conductor may be a three-dimensional helical line or a two-dimensional spiral.

  As a result, when power is supplied to the dipole antenna via an unbalanced line in which the voltage change of the signal line is larger than that of the ground line, the current is evenly distributed to the two radiation conductors connected to each line. It is not necessary to provide a balun for conversion between balanced and unbalanced in the part, and the characteristics of the antenna can be improved and the size can be reduced.

  In addition, by forming a part of the radiation conductor of the dipole antenna into a helical structure, a strong magnetic field and electric field concentrate in the vicinity, and the magnetic field and electric field leaking out around it become smaller, so the conventional dipole antenna without a helical structure Compared to, antenna characteristics change due to the surrounding environment is small. For example, the gain of a conventional dipole antenna is greatly deteriorated when the antenna is covered with a hand or installed near a metal plate, but the gain of a dipole antenna miniaturized using a helical structure is reduced even in such an environment. The degree is small.

  In addition, by using the chip coil, since the conductor of the chip coil is three-dimensionally formed in the base material, there is a current component that flows three-dimensionally. It becomes possible to have.

  Since the chip coil is used, the length of the radiation inside the chip coil can be changed, that is, the length of the radiation conductor can be changed simply by changing the inductance of the chip coil. It becomes possible to adjust. In addition, it is possible to suppress the influence on the antenna characteristics by the metal surface such as the RF connector in the vicinity of the chip coil.

  In addition, by providing a wide capacitive load at the tip of the radiating conductor, the amount of current flowing through the helical structure conductor is larger than when no capacitive load is provided, so the dipole antenna can be more effectively downsized. It becomes possible to do. That is, when making a dipole antenna having the same resonance frequency, the number of turns of the helical structure conductor can be reduced, and the physical length of the radiation conductor can be shortened. If the length of the conductor is short, the direct current resistance is small, so that the power lost as heat inside the dipole antenna is reduced and the radiation gain of the dipole antenna is increased.

  According to the present invention, in a dipole antenna fed through an unbalanced line, it is connected to the signal line so that the electrical length of the radiating conductor connected to the signal line is longer than the radiating conductor connected to the ground line of the unbalanced line. The radiating conductor, or a part of both radiating conductors, is composed of a conductor with a helical structure with a predetermined electrical length, and when feeding the dipole antenna via an unbalanced line, conversion between balanced and unbalanced in the feeding section Therefore, it is not necessary to provide a balun for performing the antenna, and the characteristics of the antenna can be improved and the size can be reduced.

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

  FIG. 1 is a diagram showing a configuration of a dipole antenna 100 according to the first embodiment of the present invention. As shown in FIG. 1, the dipole antenna 100 is composed of radiation conductors 10A and 10B. Here, the radiation conductors 10A and 10B are composed of linear radiation conductors 11 and 12 and helical conductors 13 and 14, respectively.

  The linear radiation conductors 11 and 12 are made of a metal wire having a predetermined electrical length, for example. In this example, the linear radiation conductor 11 is connected to a signal line of an unbalanced line via a conductor 13 having a helical structure. The linear radiating conductor 12 is connected to a ground line of an unbalanced line via a conductor 14 having a helical structure.

  The helical conductors 13 and 14 are formed in a spiral shape and are provided in the vicinity of the unbalanced line. The helical conductor 13 functions as a part of the radiation conductor 10A connected to the signal line. Further, the conductor 14 having a helical structure functions as a part of the radiation conductor 10B connected to the ground line. Therefore, the size of the dipole antenna 100 can be reduced.

  Further, in order to unite the resonance frequency near the fundamental frequency of the antenna, the conductor 13 having a helical structure is set so that the electrical length of the radiation conductor 10A connected to the signal line is longer than the radiation conductor 10B connected to the ground line. Is set to be larger than the inductance of the helical conductor 14. In this case, the total electrical length of the radiation conductor 10A connected to the signal line and the radiation conductor 10B connected to the ground line is a half wavelength.

  When the dipole antenna 100 shown in FIG. 1 is fed through an unbalanced line, the dipole antenna 100 can be effectively fed over a wide frequency band by the unbalanced line. As shown in FIG. 2, a resonance point can be formed at one frequency in the vicinity of the fundamental frequency of the dipole antenna 100.

  As described above, in the present embodiment, the dipole antenna 100 has the radiating conductors 10A and 10B such that the electrical length of the radiating conductor 10A connected to the signal line is longer than the radiating conductor 10B connected to the ground line of the unbalanced line. A part is composed of conductors 13 and 14 having a helical structure. In this case, the inductance of the helical structure conductor 13 is set to be larger than the inductance of the helical structure conductor 14, and the total electrical length of the radiation conductor 10A connected to the signal line and the radiation conductor 10B connected to the ground line is It becomes a half wavelength.

  Accordingly, when supplying power to the dipole antenna 100 through an unbalanced line, it is not necessary to provide a balun for performing conversion between balanced and unbalanced between the radiation conductor and the unbalanced line, and the characteristics of the antenna can be improved. In addition, the size can be reduced.

  In addition, since the helical conductors 13 and 14 are three-dimensionally configured by using the helical helical conductors 13 and 14, current components that flow three-dimensionally exist. It can have a certain sensitivity for polarization.

  In addition, by making a part of the radiation conductor of the antenna into a helical structure, a strong magnetic field and electric field concentrate in the vicinity, and the magnetic field and electric field leaking out around it become smaller, so compared to conventional antennas without a helical structure The change in antenna characteristics due to the surrounding environment is small. For example, the gain of a conventional dipole antenna is greatly deteriorated when the antenna is covered with a hand or placed near a metal plate, but the gain of a dipole antenna miniaturized using a helical structure is lowered even in such an environment. The degree is small.

  FIG. 3 is a diagram showing a configuration of a dipole antenna 200 according to the second embodiment of the present invention. FIG. 3A is a side view of the dipole antenna 200, and FIG. 3B is a plan view of the dipole antenna 200. The dipole antenna 200 is an example in which a spiral helical structure is used as a part of a radiation conductor.

  As shown in FIG. 3, the dipole antenna 200 includes radiation conductors 20A and 20B and an RF connector 25 as a power feeding unit. Here, the radiation conductors 20A and 20B are composed of pattern-shaped radiation conductors 21 and 22 and helical-structure conductors 23 and 24, respectively.

  The patterned radiation conductors 21 and 22 are patterns having a predetermined electrical length formed on the printed circuit board. The patterned radiation conductors 21 and 22 are electrically connected to the conductors 23 and 24 having a helical structure formed on the opposite side of the printed board by through holes. In this example, the patterned radiation conductor 21 is connected to a signal line of an unbalanced line via a conductor 23 having a helical structure. The patterned radiation conductor 22 is connected to a ground line of an unbalanced line via a conductor 24 having a helical structure.

  The helical conductors 23 and 24 are spiral helical patterns formed on the printed circuit board, and are provided in the vicinity of the RF connector 25 serving as a power feeding unit. The helical structure conductor 23 functions as a part of the radiation conductor 20A connected to the signal line. The helical structure conductor 24 functions as a part of the radiation conductor 20B connected to the ground line. Therefore, the size of the dipole antenna 200 can be reduced.

  Further, in order to unite the resonance frequency in the vicinity of the fundamental frequency of the antenna, the helical conductor 23 is set so that the electrical length of the radiation conductor 20A connected to the signal line is longer than the radiation conductor 20B connected to the ground line. Is set to be larger than the inductance of the conductor 24 having a helical structure. In this case, the total electrical length of the radiation conductor connected to the ground line and the radiation conductor connected to the signal line is a half wavelength.

  The RF connector 25 has a signal terminal and a ground terminal, and is a connector for connecting an antenna and a transmission / reception circuit with a coaxial cable.

  When the dipole antenna 200 shown in FIG. 3 is fed via an unbalanced line, a resonance point can be formed at one frequency near the fundamental frequency (see FIG. 2).

  Thus, in the present embodiment, the dipole antenna 200 is a part of the radiation conductors 20A and 20B so that the electrical length of the radiation conductor 20A connected to the signal line is longer than the radiation conductor 20B connected to the ground of the unbalanced line. Is composed of conductors 23 and 24 having a helical structure. In this case, the inductance of the helical structure conductor 23 is set to be larger than the inductance of the helical structure conductor 24, and the total electrical length of the radiation conductor 20A connected to the signal line and the radiation conductor 20B connected to the ground line is It becomes a half wavelength.

  As a result, when feeding power to the dipole antenna 200 through an unbalanced line, it is not necessary to provide a balun for performing balanced and unbalanced conversion in the feeding section, and the antenna characteristics can be improved and the size can be reduced. Can be planned.

  Further, by using the spiral helical conductors 23 and 24 formed on the printed circuit board, the antenna can be easily manufactured and the cost can be reduced.

  FIG. 4 is a diagram showing a configuration of a dipole antenna 300 according to the third embodiment of the present invention. The dipole antenna 300 is an example in which a chip coil is used as a helical structure conductor.

  As shown in FIG. 4, the dipole antenna 300 includes radiation conductors 30A and 30B and an RF connector 35 as a power feeding unit. Here, the radiation conductors 30 </ b> A and 30 </ b> B are composed of pattern-shaped radiation conductors 31 and 32 and chip coils 33 and 34.

  The patterned radiation conductors 31 and 32 are patterns having a predetermined electrical length formed on the printed circuit board. In the case of this example, the patterned radiation conductor 31 is formed in two parts at a predetermined interval in the vicinity of the RF connector 35, and the two parts are electrically connected by the chip coil 33. The pattern radiation conductor 31 is connected to a signal line of an unbalanced line. The patterned radiation conductor 32 is formed in two parts with a predetermined interval in the vicinity of the RF connector 35, and the two parts are electrically connected by a chip coil 34. The patterned radiation conductor 31 is connected to the ground line of the unbalanced line.

  The patterned radiation conductors 31 and 32 play a role of fixing the chip coils 33 and 34 to the substrate in addition to the function of radiating radio waves. Thereby, the strong dipole antenna 300 can be made without using another reinforcing jig.

  The chip coils 33 and 34 have helical conductors spirally wound on the surface or inside of a substrate such as ceramic. The chip coils 33 and 34 include, for example, a winding type, a laminated type, and a film type.

  The chip coils 33 and 34 are provided in the vicinity of the RF connector 35 as a power feeding unit. The chip coil 33 functions as a part of the radiation conductor 30A connected to the signal line. The chip coil 34 functions as a part of the radiation conductor 30B connected to the ground line. Therefore, the size of the dipole antenna 300 can be reduced.

  Further, in order to make the resonance frequency near the fundamental frequency of the antenna one, the inductance of the chip coil 33 is set so that the electrical length of the radiation conductor connected to the signal line is longer than the radiation conductor connected to the ground line. The inductance is made larger than the inductance of the chip coil 34. In this case, the total electrical length of the radiation conductor 30B connected to the ground line and the radiation conductor 30A connected to the signal line is a half wavelength.

  The RF connector 35 has a signal terminal and a ground terminal, and is a connector for connecting the antenna and the transmission / reception circuit with a coaxial cable.

  When the dipole antenna 300 shown in FIG. 4 is fed via an unbalanced line, a resonance point can be formed at one frequency in the vicinity of the fundamental frequency (see FIG. 2).

  As described above, in this embodiment, the dipole antenna 300 is a part of the radiation conductors 30A and 30B so that the electrical length of the radiation conductor 30A connected to the signal line is longer than the radiation conductor 30B connected to the ground of the unbalanced line. Chip coils (helical structure conductors) 33 and 34 are provided. In this case, the inductance of the chip coil 33 is made larger than the inductance of the chip coil 34, and the total electrical length of the radiation conductor 30A connected to the signal line and the radiation conductor 30B connected to the ground line is half. It becomes a wavelength.

  As a result, when feeding power to the dipole antenna 300 via an unbalanced line, it is not necessary to provide a balun for performing balanced and unbalanced conversion in the feeding portion, and the antenna characteristics can be improved and the size can be reduced. Can be planned.

  Further, since the current components flowing three-dimensionally exist by using the chip coils 33 and 34 in which the conductor is three-dimensionally formed in the base material, there is a certain degree of sensitivity with respect to the polarization in all directions. be able to.

  Further, since the chip coils 33 and 34 are used, the length of the radiation conductor can be changed simply by changing the length of the conductor inside the chip coils 33 and 34, that is, by changing the inductance of the chip coils 33 and 34. The resonance frequency of the dipole antenna 300 can be easily adjusted.

  FIG. 5 is a diagram showing a configuration of a dipole antenna 400 according to the fourth embodiment of the present invention. The dipole antenna 400 is an example in which a chip coil is used as a helical structure conductor and a capacitive load portion is provided at the tip of the radiation conductor.

  As shown in FIG. 5, the dipole antenna 400 includes radiation conductors 40A and 40B and an RF connector 45 as a power feeding unit. Here, the radiation conductors 40A and 40B are composed of pattern radiation conductors 41 and 42 and chip coils 43 and 44, respectively.

  The patterned radiation conductors 41 and 42 are patterns having a predetermined electrical length formed on the printed circuit board. In the case of this example, the pattern radiation conductors 41 and 42 have a meander structure portion near the RF connector 45 and a wide capacitive load portion at the tip portion. Further, the meander structure portion is provided with an intermittent portion, and chip coils 43 and 44 are provided at the intermittent portion and are electrically connected.

  The patterned radiation conductors 41 and 42 play a role of fixing the chip coils 43 and 44 to the substrate in addition to the function of radiating radio waves. Thereby, the strong dipole antenna 400 can be made without using another reinforcing jig.

  The chip coils 43 and 44 have helical conductors spirally wound on the surface or inside of a substrate such as ceramic. The chip coils 43 and 44 include, for example, a winding type, a laminated type, and a film type.

  The chip coils 43 and 44 are in the vicinity of the RF connector 45 serving as a power feeding unit, and the chip coils 43 and 44 are parallel to the metal surface of the RF connector 45 in which the direction of the magnetic field induced by the chip coils 43 and 44 is in the vicinity. Are arranged as follows. The chip coil 43 functions as a part of the radiation conductor 40A connected to the signal line. The chip coil 44 functions as a part of the radiation conductor 40B connected to the ground line. Therefore, the size of the dipole antenna 400 can be reduced.

  The radiation conductor 40A is connected to a signal line of an unbalanced line. The radiation conductor 40B is connected to the ground line of the unbalanced line.

  Further, in order to unite the resonance frequency near the fundamental frequency of the antenna, the inductance of the chip coil 43 is set so that the electrical length of the radiation conductor 40A connected to the signal line is longer than the radiation conductor 40B connected to the ground line. Is made larger than the inductance of the chip coil 44. In this case, the total electrical length of the radiation conductor 40A connected to the signal line and the radiation conductor 40B connected to the ground line is a half wavelength.

  The RF connector 45 has a signal terminal and a ground terminal, and is a connector for connecting the antenna and the transmission / reception circuit with a coaxial cable.

  When the dipole antenna 400 shown in FIG. 5 is fed via an unbalanced line, a resonance point can be formed at one frequency near the fundamental frequency (see FIG. 2).

  As described above, in this embodiment, the dipole antenna 400 includes a part of the radiation conductors 40A and 40B so that the electrical length of the radiation conductor 40A connected to the signal line is longer than the radiation conductor 40B connected to the ground of the unbalanced line. Chip coils (helical structure conductors) 43 and 44 are provided. In this case, the inductance of the chip coil 43 is made larger than the inductance of the chip coil 44, and the total electrical length of the radiation conductor 40A connected to the signal line and the radiation conductor 40B connected to the ground line is 1/2. It becomes a wavelength.

  As a result, when power is supplied to the dipole antenna 400 via an unbalanced line, it is not necessary to provide a balun that performs conversion between balanced and unbalanced in the power supply unit, and the characteristics of the antenna can be improved and miniaturization can be achieved. Can be planned.

  Further, since the chip coils 43 and 44 are used, the length of the radiation conductor can be changed only by changing the length of the conductor inside the chip coils 43 and 44, that is, by changing the inductance of the chip coils 43 and 44. The resonance frequency of the dipole antenna 400 can be easily adjusted.

  In addition, since the wide capacitive load portion is provided at the ends of the radiation conductors 40A and 40B, the amount of current flowing through the helical structure conductor is larger than when no capacitive load portion is provided. It can be downsized. That is, when making antennas having the same resonance frequency, the number of turns of the conductor having a helical structure can be reduced, and the physical length of the radiation conductor can be shortened. Since the direct current resistance is small when the length of the conductor is short, the power lost as heat inside the antenna is reduced, and the radiation gain of the antenna is increased.

  In addition, the influence of the metal surface such as the RF connector 45 in the vicinity of the chip coils 43 and 44 on the antenna characteristics can be suppressed.

  Although the dipole antenna has been described in the above embodiment, the present invention is not limited to this. The present invention can also be applied to a case where power is fed via an unbalanced line to an antenna that is fed via another balanced line.

  In the above-described embodiment, in the dipole antenna, the two radiating conductors are provided with helical conductors so that the electrical length of the radiating conductor connected to the signal line is longer than the radiating conductor connected to the ground of the unbalanced line. Although the thing was demonstrated, it is not limited to this. For example, a helical conductor may be provided only on the radiation conductor connected to the signal line.

  As described above, the dipole antenna according to the present invention is a transmission / reception device including an antenna system fed via an unbalanced line, particularly a communication device such as a wireless terminal that is required to be small, light, and high performance. Applicable to.

It is a figure which shows the structural example of the dipole antenna of 1st Embodiment. It is a figure which shows the resonance characteristic of a dipole antenna in the case of supplying electric power via an unbalanced line. It is a figure which shows the structural example of the dipole antenna of 2nd Embodiment. It is a figure which shows the structural example of the dipole antenna of 3rd Embodiment. It is a figure which shows the structural example of the dipole antenna of 4th Embodiment. It is a figure which shows the example electrically fed to a dipole antenna via the conventional balanced line. It is a figure which shows the example electrically fed to a dipole antenna via the conventional unbalanced line. It is a figure which shows the resonance characteristic of the dipole antenna in the case of supplying electric power directly through the conventional unbalanced line.

Explanation of symbols

10A, 10B, 20A, 20B, 30A, 30B, 40A, 40B ... Radiation conductor, 11, 12 ... Linear radiation conductor, 13, 14, 23, 24 ... Helical structure conductors, 25, 35 45, RF connector, 21, 22, 31, 32, 41, 42 ... Patterned radiation conductor, 33, 34, 43, 44 ... Chip coil, 100, 200, 300, 400 ... Dipole antenna

Claims (5)

In a dipole antenna that is fed via an unbalanced line to two radiating conductors each having a predetermined electrical length corresponding to the resonance frequency,
In order to unite the resonance frequency in the vicinity of the fundamental frequency, the signal line is set so that the electrical length of the radiation conductor connected to the signal line is longer than the radiation conductor connected to the ground line of the unbalanced line. A dipole antenna, characterized in that a part of both of the radiating conductors connected to the radiating conductor is formed of a helical structure conductor having a predetermined electrical length. The dipole antenna according to claim 1, wherein the conductor having the helical structure is disposed at a position closer to a feeding point than a center of the radiation conductor. The dipole antenna according to claim 2, wherein the conductor having the helical structure is a chip coil. The dipole antenna according to claim 3, wherein the chip coil is disposed so that a direction of a magnetic field induced by the chip coil is parallel to a metal surface in the vicinity thereof. 2. The capacitive load portion according to claim 1, wherein the radiating conductor is provided with a capacitive load portion so that a conductor width in a portion closer to a tip portion than a center is wider than a conductor width in a portion closer to a feeding point. Dipole antenna.

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