JP4050206B2 - Dipole antenna - Google Patents

Description

  The present invention relates to a half-wave dipole antenna fed to a central portion, and more particularly, to a dipole antenna whose longitudinal dimension is shortened by forming a radiating element in a meander shape.

  As a technique for shortening the longitudinal dimension of a dipole antenna, there is conventionally known a technique of forming a radiating element in a meander shape (meandering shape) and loading an inductive load (see, for example, Patent Document 1). That is, when an inductive load is loaded, the electrical length of the antenna is extended, so that the apparent longitudinal dimension can be shortened.

  FIG. 2 is a plan view showing a conventional dipole antenna whose longitudinal dimension is shortened in this manner. In the figure, a dipole antenna 1 feeds and excites opposite ends of a pair of substantially identical radiating elements 2 and 3, and feed points 2a and 3a are connected to a feed circuit (not shown). It is connected. In the dipole antenna 1, the radiating elements 2 and 3 are patterned on the insulating substrate 4 made of a dielectric or the like, but each radiating element may be made of a sheet metal such as a copper plate.

In such a conventional dipole antenna 1, since the radiating elements 2 and 3 are both provided with meander-shaped portions, the electrical length is extended by loading an equivalent inductive loading coil. Therefore, when the wavelength of the tuning radio wave is λ, the longitudinal dimension L of the dipole antenna 1 can be shorter than λ / 2, and downsizing is realized.
JP-A-9-36630 (page 4-5, FIG. 5)

  As described above, in the conventional dipole antenna 1, the longitudinal dimension is shortened by providing the radiating elements 2 and 3 with the meander-shaped portion, but the radiating elements 2 and 3 are closer to the feeding points 2a and 3a. Since the current is large and the voltage is small, the input impedance is undesirably increased if the meander-shaped portions of the radiating elements 2 and 3 are arranged in the vicinity of the feeding points 2a and 3a. Therefore, in the conventional dipole antenna 1, as shown in FIG. 2, the meander-shaped portions of the radiating elements 2 and 3 have to be arranged at some distance from the feeding points 2a and 3a. That is, in this type of dipole antenna 1, in order to obtain impedance matching, a wide space D must be secured between the meandering portions of the radiating elements 2 and 3, so that the longitudinal dimension L is λ / 2. In contrast, it has been difficult to achieve a significant downsizing that is significantly shortened.

  The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a dipole antenna that can realize a remarkable miniaturization by bringing a pair of meander-shaped radiating elements close to each other. .

  In order to achieve the above-described object, according to the present invention, in a half-wavelength dipole antenna that feeds and excites the opposite ends of a pair of meander-shaped radiating elements, the vicinity of the feeding point of one of the radiating elements and the other A short bar for short-circuiting the vicinity of the feeding point of the radiation element is provided.

  In the dipole antenna configured as described above, the vicinity of the feeding point of the pair of radiating elements is short-circuited by a short bar, so that the input impedance is not required even if the meandering portion of each radiating element is not separated from the feeding point. The input impedance is not increased as desired, and the input impedance can be appropriately changed by adjusting the length and connection position of the short bar. Therefore, in this dipole antenna, even if the interval between the meandering portions of the pair of radiating elements is narrowed, impedance matching is not hindered, and a remarkable downsizing with a greatly shortened longitudinal dimension can be realized.

  A dipole antenna having such a configuration, for example, preferably includes a pair of radiating elements and a short bar made of a conductor pattern, whereby each radiating element having a meander-shaped portion and a short bar can be collectively formed, and can be manufactured at low cost. .

  However, the pair of radiating elements and the short bar may be a dipole antenna made of conductive sheet metal. In this case as well, each radiating element and the short bar can be collectively formed by pressing the sheet metal, etc. it can.

  In the dipole antenna of the present invention, the input impedance is lowered by providing a short bar that short-circuits the vicinity of the feeding point of a pair of radiating elements having meander-shaped portions, and the interval between the meander-shaped portions of each radiating element is reduced. However, since impedance matching can be performed without any problem, it is possible to realize a remarkable downsizing with a greatly shortened longitudinal dimension.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a dipole antenna according to an embodiment of the present invention.

  The dipole antenna 11 shown in the figure includes a pair of radiating elements 12 and 13 formed in a substantially meander shape, and a short bar 14 that short-circuits both the radiating elements 12 and 13 near the feeding point. It has become. The dipole antenna 11 feeds and excites the opposite ends of the radiating elements 12 and 13 and feed points 12a and 13a are connected to a feed circuit (not shown). One end of the short bar 14 is connected to the vicinity of the feeding point 12 a of the radiating element 12, and the other end of the short bar 14 is connected to the vicinity of the feeding point 13 a of the radiating element 13. These radiating elements 12 and 13 and the short bar 14 are made of a conductor pattern formed on an insulating substrate 10 made of a dielectric or the like.

  In the dipole antenna 11 configured as described above, since the radiating elements 12 and 13 are formed in a meander shape, the electrical length is extended by loading an equivalent inductive loading coil. Therefore, when the wavelength of the tuning radio wave is λ, the longitudinal dimension L of the dipole antenna 11 can be shorter than λ / 2. Further, in this dipole antenna 11, the radiating elements 12 and 13 are extended as meander-shaped conductor patterns immediately from the feeding points 12a and 13a, respectively, but each of the radiating elements 12 and 13 is located near the feeding point 12a and the feeding point. Since the vicinity of 13a is short-circuited by the short bar 14, the input impedance does not increase so much. Moreover, since the input impedance can be changed as appropriate by adjusting the length and connection position of the short bar 14, the dipole antenna 11 eventually sets the distance d between the meander-shaped portions of the pair of radiating elements 12 and 13 to each other. Even if it is set to be quite narrow, there is no worry of impeding impedance matching. Therefore, the longitudinal dimension L of the dipole antenna 11 can be significantly shortened than λ / 2, and a remarkable downsizing can be realized as compared with the conventional half-wavelength dipole antenna in which the radiating element has a meander-shaped portion. .

  In the dipole antenna 11 according to this embodiment, the pair of radiating elements 12 and 13 and the short bar 14 are formed of a conductor pattern, so that these can be formed collectively. Therefore, even if it is the structure which attached the short bar 14, a cost increase can be avoided. However, the radiating elements 12 and 13 and the short bar 14 may be a dipole antenna made of a conductive sheet metal such as a copper plate, and in this case, the sheet metal can be manufactured at a low cost by pressing the sheet metal.

It is a top view of the dipole antenna concerning the example of an embodiment of the present invention. It is a top view of the dipole antenna which concerns on a prior art example.

Explanation of symbols

10 Insulating substrate 11 Dipole antenna 12, 13 Radiating element 12a, 13a Feed point 14 Short bar

Claims (3)

A half-wave dipole antenna that feeds and excites opposite ends of a pair of radiating elements in a meander shape, and includes a vicinity of a feeding point of one of the radiating elements and a vicinity of a feeding point of the other radiating element. A dipole antenna, characterized in that a shorting bar is provided as a continuous line from the pair of radiating elements .   2. The dipole antenna according to claim 1, wherein the pair of radiating elements and the short bar are made of a conductor pattern.   2. The dipole antenna according to claim 1, wherein the pair of the radiating elements and the short bar are made of conductive sheet metal.

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