JPH0738325A - Wide band dipole antenna - Google Patents

Abstract

PURPOSE:To provide the wide band dipole antenna whose wide band characteristic is satisfactory. CONSTITUTION:This wide band dipole antenna is provided with dipole elements 11a, 11b, and a parasitic element 13 which is formed by bending rectangularly a conductor of long size having length of 1/2 wavelength or above of radiation wavelength so as to surround the periphery of the elements 11a, 11b in a plane being parallel to electric field axes of these elements 11a, 11b, further, has a notch 13a in a center part of a side in one electric field axis direction thereof. It is also allowable that the dipole elements 11a, 11b and the parasitic element 13 are constituted of a metallic thin layer stuck to the surface of a dielectric substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dipole antenna for a base station in mobile communication, and more particularly to a wide band dipole antenna.

[0002]

2. Description of the Related Art FIG. 9 is a front view showing an essential part of an example of a conventional dipole antenna, and FIG. 10 is a side view of FIG.

In the figure, 1a and 1b are dipole elements, and 2 is a feeding circuit composed of parallel lines. An equivalent circuit of this dipole antenna is shown in FIG. T and T'in the figure are high frequency power supply connection terminals. L, C, and R are an effective inductance, an effective capacitance, and an effective resistance that form an equivalent constant of the dipole elements 1a and 1b, and these form a series resonance circuit.

FIG. 12 is a graph showing an example of the voltage standing wave ratio (hereinafter referred to as "VSWR") of the dipole antenna having the above-mentioned configuration. The horizontal axis shows frequency and the vertical axis shows VSWR. As can be seen from this graph, the relative bandwidth at which VSWR is 1.5 or less is narrow, about 8%.

[0005]

By the way, the following methods are generally known as methods for widening the band of the conventional dipole antenna. If the dipole element is made of a cylindrical or rod-shaped conductor, increase its diameter, and if the dipole element is made of a slender plate-shaped conductor, widen it to reduce the change in reactance with changes in the operating frequency. Widening the band by making it smaller.

However, in the case of such a method, there is a possibility that cross-polarized components may be generated, so that the diameter or width of the dipole element cannot be increased to a certain extent or more, and the wide band is limited. was there.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wideband dipole antenna having good wideband characteristics.

[0008]

In order to solve the above-mentioned problems, a first invention is to radiate a dipole element and to surround the dipole element in a plane parallel to the electric field axis of the dipole element. A long conductor having a length of ½ wavelength or more is formed by bending it into a rectangular shape,
A parasitic element having a notch at the center of one of the sides in the electric field axis direction is provided.

According to a second aspect of the present invention, a dipole element made of a thin metal layer is attached to the surface of a dielectric substrate, and the dipole element is formed on the surface of the dielectric substrate in a plane parallel to the electric field axis of the dipole element. A parasitic element in which a metal thin film having a length equal to or more than 1/2 wavelength of a radiation wavelength is formed in a rectangular shape so as to surround the periphery, and a slit is formed in a central portion of one side of the electric field axis direction. Is affixed.

According to a third aspect of the present invention, a dipole element made of a thin metal layer is attached to the front surface of a dielectric substrate that is sufficiently thin as compared with the radiation wavelength, and the back surface of the dielectric substrate is parallel to the electric field axis of the dipole element. A metal film layer having a length of ½ wavelength or more of the emission wavelength is formed in a rectangular shape so as to surround the periphery of the dipole element in a plane, and one of the central portions of the side in the electric field axis direction is formed. It is characterized in that a parasitic element having a notch formed therein is attached.

[0011]

Since the parasitic element is arranged so as to surround the dipole element, good broadband characteristics can be realized.

The dipole element and the parasitic element are
The use of thin metal layers attached to the front and back surfaces of the dielectric substrate improves productivity and facilitates mass production.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a front view showing the wideband dipole antenna of this embodiment, FIG. 2 is a plan view of the wideband dipole antenna of FIG. 1, and FIG. 3 is a side view of the wideband dipole antenna of FIG.

Reference numerals 11a and 11b in the figure denote dipole elements. The dipole elements 11a and 11b are formed of round rod-shaped conductors. The length of the dipole elements 11a and 11b in the longitudinal direction, that is, the length in the electric field axis direction (hereinafter referred to as "long side") is formed to be 1/2 or approximately 1/2 of the wavelength with respect to the center frequency of the operating frequency band. Reference numeral 12 is a feeding circuit composed of parallel lines.

Reference numeral 13 is a parasitic element formed so as to surround the dipole elements 11a and 11b. The parasitic element 13 is formed of a round bar-shaped conductor like the dipole elements 11a and 11b. Parasitic element 13 is 1
It is formed by bending a rod-shaped conductor of a book. Notch 1 which is a part where both ends of this rod-shaped conductor are butted at regular intervals
3a is a dipole element 11a, 11b on the long side.
Is located at the central portion (the abutting portion of the two elements 11a and 11b). The parasitic element 13 is in a plane parallel to the electric field axes of the dipole elements 11a and 11b, and is located in the long side direction of the parasitic element 13 and the dipole element 11b.
It is arranged so that the long side directions of a and 11b are parallel to each other. The length of the parasitic element 13 is not less than 1/2 wavelength of the radiation wavelength of the antenna, and is formed by bending a linear conductor having about 1 wavelength. In addition, in the parasitic element 13, a conductor having the same cross-sectional shape as the long side portion is used also in the direction orthogonal to the long side direction, that is, in the portion orthogonal to the electric field axis (hereinafter referred to as “short side”).

Although the dipole elements 11a and 11b are formed of round rod-shaped conductors, they may be formed of rod-shaped conductors having a rectangular cross-section, tubular conductors having a circular or square cross-section, conductors having other shapes such as elongated plate-like conductors or linear conductors. You may form. Further, the parasitic element 13 can also be formed of conductors of various shapes in the same manner. In this case, the dipole elements 11a and 11b and the parasitic element 13 are formed of conductors having the same cross-sectional shape, or one of them is formed of a conductor having a round bar shape and the other is formed of a conductor having a square bar shape. They may be appropriately selected from the inside and combined. Further, in the parasitic element 13, other than using the conductors having the same cross-sectional shape on the long side and the short side, it may be configured by appropriately selecting and combining from conductors having various cross-sectional shapes.

The dipole element 11 on the long side is also provided.
The distance between a and 11b and the parasitic element 13 and the parasitic element 1
When 3 is formed of a round bar conductor, a circular annular conductor, or a linear conductor, its outer diameter, its width when the parasitic element 13 is formed of a rod-shaped conductor having a rectangular cross section, the interval between the cuts 13a, The total length of the parasitic element 13 before being bent (hereinafter referred to as “total axial length”) and the like are appropriately selected according to the difference in wide band characteristics. In this case, the length of the parasitic element 13 on the long side is such that the parasitic element 13 has the dipole element 11a,
Because of the structure surrounding 11b, the dipole elements 11a, 11
It is appropriately set within a range longer than the length of the long side of b.

The following are means for supporting and fixing the parasitic element 13 at a predetermined position. That is, the parasitic element 13 is mounted on the dipole elements 11a and 11b by using an elongated rod-shaped or plate-shaped support body formed of an insulator having a low dielectric constant.
And a means for integrally molding the dipole elements 11a and 11b and the parasitic element 13 by a molding method using the insulator.

FIG. 4 is a circuit diagram showing an equivalent circuit of the dipole antenna having the above structure. T and T'in the figure are high frequency power supply connection terminals. L, C, and R are an effective inductance, an effective capacitance, and an effective resistance that form an equivalent constant of the dipole elements 11a and 11b, and these form a series resonance circuit. Furthermore, L, C and R
Is an effective inductance, an effective capacitance, and an effective resistance that form an equivalent constant of the parasitic element 13, and these form a series resonance circuit. Cc and Cc 'are coupling capacitances, and the resonance circuit of the dipole elements 11a and 11b and the resonance circuit of the parasitic element 13 are coupled to each other by this coupling capacitance and operate as a double tuning circuit.

In this case, the dipole elements 11a, 11
b, the degree of coupling between the resonance circuits of the parasitic element 13 is changed, the resonance frequency of one or both of the resonance circuits is appropriately adjusted, or the degree of coupling between the resonance circuits is changed and both resonance circuits are changed. By adjusting the resonance frequency of either or both of them, a wide band characteristic can be provided.

In order to adjust the degree of coupling between the two resonance circuits, the distance between the dipole elements 11a, 11b and the parasitic element 13 on the long side is changed or each element 11a, 11b, 1 is changed.
The thickness of one or both of the conductors forming 3 is changed, or the dipole element 11a on the long side is
This is performed by changing the distance between 11b and the parasitic element 13 and changing the thickness of one or both of the conductors forming each element 11a, 11b, 13.

The resonance frequency of each resonance circuit is adjusted by any of the following means.

(1) The lengths of the dipole elements 11a and 11b in the long side direction are changed.

(2) Either or both of the interval between the cuts 13a of the parasitic element 13 and the total axial length of the parasitic element 13 are changed.

(3) The thickness of one or both of the conductors forming the dipole elements 11a and 11b and the parasitic element 13 is changed.

(4) The above three cases are appropriately combined and adjusted.

FIG. 5 is a graph showing an example of the VSWR of the wide band dipole antenna having the wide band characteristic by the above adjustment. Similar to the graph of FIG. 12 described above, the horizontal axis represents frequency and the vertical axis represents VSWR. As can be seen from this graph, the specific bandwidth for VSWR of 1.5 or less is about 20%, which is a wider band than the conventional dipole.

(First Modification) FIG. 6 is a front view showing a first modification of this embodiment, and FIG. 7 is a plan view of FIG.

21a and 21b in the figure are dipole elements,
Reference numeral 23 is a parasitic element. These are constituted by a thin metal layer provided on the surface of the dielectric substrate 24 in a plane.
Specifically, it is provided on the surface of the dielectric substrate 24, for example, by the same method as the printed wiring by the photoetching method. Reference numeral 22 is a feeding circuit composed of parallel lines.

The lengths of the long sides of the dipole elements 21a and 21b, and the dipole elements 21a and 21 on the long side are longer.
b between the parasitic element 23 and the dipole element 21a,
The widths of 21b and the parasitic element 23, the intervals of the notches 23a, the total axial length of the parasitic element 23, etc. are set in the same manner as in the above-described embodiment.

Further, although the dipole elements 21a and 21b and the parasitic element 23 are formed in an angular shape, it goes without saying that they may be formed in a smooth curved shape. Further, when the dielectric substrate 24 is sufficiently thin with respect to the radiation wavelength, the dipole elements 21a and 21b are provided on the surface of the dielectric substrate 24, and the parasitic element 23 is provided as the dielectric substrate 24.
It may be provided on the back surface of.

With the above structure, the wide band characteristic similar to that of the above embodiment can be realized.

Further, the productivity is improved by the printed wiring method, and a wide band dipole antenna having uniform characteristics can be mass-produced. As a result, cost reduction can be achieved.

(Second Modification) FIG. 8 is a perspective view showing a second modification of the present embodiment.

In the figure, 31a and 31b are dipole elements,
Reference numeral 32 is a feeding circuit, 33 is a parasitic element, and 35 is a flat reflector.

The dipole elements 31a and 31b, the feeding circuit 32, and the parasitic element 33 are formed of plate conductors. An insertion hole 35a is provided in the central portion of the flat reflector 35. Each of the two power supply circuits 32 is formed in a T shape and is inserted into the insertion hole 35a. Dipole element 3
1a and 31b are continuously formed at both ends of each feeding circuit 32. The parasitic element 33 is a dipole element 31a,
It is bent and arranged so as to surround 31b.

With the above structure, the wide band characteristic similar to that of the above embodiment can be realized.

Although the reflector 35 is a flat conductor, other shapes such as a corner reflector may be used.

[0040]

As described above in detail, according to the wideband dipole antenna of the present invention, since the parasitic element is arranged so as to surround the dipole element, a good wideband characteristic can be realized.

In addition, the dipole element and the parasitic element are
The use of thin metal layers attached to the front and back surfaces of the dielectric substrate improves productivity and facilitates mass production.

[Brief description of drawings]

FIG. 1 is a front view showing a wideband dipole antenna according to the present invention.

FIG. 2 is a plan view of the wideband dipole antenna of FIG.

FIG. 3 is a side view of the wideband dipole antenna of FIG.

4 is a circuit configuration diagram showing an equivalent circuit of the dipole antenna of FIG.

5 is a frequency and V in the dipole antenna of FIG.
The graph which shows the relationship with SWR.

FIG. 6 is a front view showing a first modified example.

FIG. 7 is a plan view of FIG.

FIG. 8 is a perspective view showing a second modified example.

FIG. 9 is a front view showing a main part of a conventional dipole antenna.

10 is a side view of the dipole antenna of FIG.

11 is an equivalent circuit of the dipole antenna of FIG.

12 is a graph showing a relationship between frequency and VSWR in the dipole antenna of FIG.

[Explanation of symbols]

 11a, 11b Dipole element 12 Feed circuit 13 Parasitic element 13a Cut T, T'High frequency power supply connection terminal L, L Effective inductance C, C Effective capacitance R, R Effective resistance

Claims (3)

[Claims] 1. A dipole element and a long conductor having a length of ½ wavelength or more of a radiation wavelength so as to surround the circumference of the dipole element in a plane parallel to an electric field axis of the dipole element. A wide-band dipole antenna, which is formed by bending into a rectangular shape, and is provided with a parasitic element having a notch in a central portion of one side in the electric field axis direction. 2. A dipole element made of a thin metal layer is attached to the surface of a dielectric substrate, and the surface of the dielectric substrate surrounds the periphery of the dipole element in a plane parallel to the electric field axis of the dipole element. As described above, while forming a metal thin film having a length of ½ wavelength or more of the emission wavelength into a rectangular shape,
A broadband dipole antenna, wherein a parasitic element having a cut is attached to the center of one of the sides in the electric field axis direction. 3. A dipole element made of a thin metal layer is attached to the surface of a dielectric substrate that is sufficiently thinner than the emission wavelength, and the dipole element is attached to the back surface of the dielectric substrate in a plane parallel to the electric field axis of the dipole element. A metal film layer having a length of ½ wavelength or more of the emission wavelength is formed in a rectangular shape so as to surround the dipole element, and a notch is formed at the center of one of the sides in the electric field axis direction. Broadband dipole antenna characterized in that the parasitic element is attached.