JP3869354B2 - antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna, and more particularly to an antenna that is optimal as a basic radiating element of a mobile telephone base station antenna that has a planar shape and is commonly used for transmission and reception.
[0002]
[Prior art]
Microstrip antennas are used as planar antennas for mobile telephone base stations because of their simple structure and low profile.
FIG. 14 is a diagram showing a schematic configuration showing an example of a conventional microstrip antenna used as a basic radiating element of a mobile phone base station antenna. FIG. 14 (a) is a perspective view, and FIG. 14 (b) It is sectional drawing for demonstrating a connector part.
In this figure, 21 is a square microstrip element, 22 is a dielectric substrate that is thinner than the radiation wavelength, 23 is a ground conductor, 24 is a connector to which a feed line (for example, a coaxial cable) is connected, and 25 is a connector. Reference numeral 24 denotes an inner conductor, 26 denotes an outer conductor of the connector 24, and 27 denotes a ribbon-like conductor. The internal conductor 25 of the connector 24 and the microstrip element 21 are connected by solder 29 or the like.
Further, in the antenna shown in FIG. 14, by supplying power from two straight lines passing through the center of the microstrip element 21, the modes are orthogonal and almost independent from each other, so that it is possible to share polarization. .
As described above, the conventional microstrip antenna has advantages such as being able to share polarization by adopting a circular or square shape, and being small and light and thin.
[0003]
[Problems to be solved by the invention]
As shown in FIG. 14, in the conventional microstrip antenna, the outer conductor 26 of the connector 24 is fixed to the ground conductor 23 with solder or the like. In this case, copper is generally used as the material for the inner conductor 25 and the outer conductor 26 of the connector 24.
In addition, although copper is used as the material of the microstrip element 21, when the ground conductor 23 is shared and an array antenna is formed by arranging a plurality of microstrip elements 21, the ground conductor 23 is reduced for weight reduction. For example, aluminum may be used as the material.
Therefore, in such a case, the outer conductor 26 of the connector 24 made of copper is fixed on the ground conductor made of aluminum.
However, when bonding dissimilar metals as described above, intermodulation noise, etc. is generated in the received wave received by the microstrip antenna due to the non-linear characteristics that occur when the dissimilar metals are bonded to each other. When it is planned to do so, the reception performance may be deteriorated by the transmission wave of the local station.
[0004]
The present invention has been made to solve the problems of the prior art, and an object of the present invention is to enable power supply to a radiating element without bringing a ground conductor and a connector into contact with each other. An object of the present invention is to provide an antenna that can reduce the occurrence of noise.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.
[0005]
[Means for Solving the Problems]
FIG. 1 is a schematic diagram for explaining a method of supplying power to a microstrip antenna.
In the microstrip antenna shown in FIG. 14, as shown in FIG. 1A, the power source side terminal (terminal to which + is given in FIG. 1) of the excitation power source 30 is connected to the microstrip element (radiating element) 21. The ground side terminal of the excitation power source 30 (the terminal to which − is given in FIG. 1) is connected to the ground conductor 23.
However, as shown in FIG. 1B, the power supply side terminal of the excitation power source 30 (the terminal to which + is added in FIG. 1) is connected to the ground conductor 23, and the ground side terminal of the excitation power source 30 (FIG. 1). May be connected to the microstrip element 21.
In the present invention, focusing on the fact that the microstrip element and the connector are made of the same kind of metal, applying the above-mentioned principle, the outer conductor of the connector is fixed to the microstrip element, and the inner conductor of the connector is It extends to the periphery of the microstrip element and is electromagnetically connected to the ground conductor at the periphery of the microstrip element.
According to the present invention, it is not necessary to fix the connector on the ground conductor, and contact between dissimilar metals is eliminated, so that generation of noise can be reduced.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
[Embodiment 1]
2A and 2B are diagrams showing a schematic configuration of the microstrip antenna according to the first embodiment of the present invention. FIG. 2A is a perspective view, and FIG. 2B is an AA shown in FIG. 'A cross-sectional view taken along a cutting line.
In the figure, 1 is a square microstrip element (radiation element of the present invention), 2 is a dielectric substrate that is thinner than the radiation wavelength, 3 is a ground conductor, and 4 is connected to a feed line (for example, a coaxial cable). Connection means (hereinafter referred to as “connector”) 5 is an internal conductor of the connector 4, and 6 is an external conductor of the connector 4.
In the present embodiment, the first hole 31 is formed at the center of the microstrip element 1, and the first hole 31 is exposed in the dielectric substrate 2 and the ground conductor 3. A second hole 32 having a larger diameter than that is formed.
Then, the outer conductor 6 of the connector 4 is fixed to the microstrip element 1 by the second hole 32.
In this case, since the microstrip element 1 and the external conductor 6 of the connector are made of the same kind of metal (for example, copper), in the present embodiment, when different kinds of metals are fixed together as described above. Due to the generated non-linear characteristics, intermodulation noise does not occur in the received wave received by the microstrip antenna.
In the present embodiment, it goes without saying that the microstrip element 1 has sufficient strength even if the outer conductor 6 of the connector is fixed.
[0007]
A third hole 33 is formed at the peripheral portion of the microstrip element 1 in the dielectric substrate 2 and the ground conductor 3, and the ground conductor 3 is further extended to extend the third hole 33. A cylindrical conductor 7 is formed.
As shown in FIG. 2, the internal conductor 5 of the connector 4 extends through the first hole 31, extends in parallel with the microstrip element 1, to the periphery of the microstrip element 1, and The open end of the cylindrical conductor 7 is terminated through the hole 33.
For example, when the virtual input impedance between the end of the microstrip antenna 1 and the ground conductor 3 is a pure resistance, the ground of the cylindrical conductor 7 is grounded from the surface in contact with the dielectric substrate 2 of the ground conductor 3. The length L to the open end opposite to the side fixed to the conductor 3 is λg / 4 (L = λg / 4).
Here, lambda] g is the electrical length calculated by λg = λo / √ε _r, λo is the free space wavelength of the used frequency of the antenna, is epsilon _r is the dielectric constant of the cylindrical conductive body of the dielectric.
Since the (λg / 4) line having an open end is equivalent to a state where the line is short-circuited to the ground potential, the internal conductor 5 of the connector 4 is electromagnetically connected to the ground conductor 3.
As described above, in this embodiment, the power feeding method shown in FIG. 1B can be realized without mechanically connecting to the ground conductor 3.
The central portion of the microstrip element 1 is a portion where the electric field is minimized due to the internal electromagnetic field distribution of the microstrip element 1, so that even if the outer conductor 6 of the connector 4 is fixed to this portion, the microstrip antenna It does not affect the characteristics of
Further, the length L from the surface of the ground conductor 3 in contact with the dielectric substrate 2 to the open end of the cylindrical conductor 7 opposite to the side fixed to the ground conductor 3 is the input impedance of the microstrip antenna 1. Λo / 4 does not necessarily have to be satisfied, and if (0.8 × λg) / 4 ≦ L ≦ (1.2 × λg) / 4 is satisfied, the above-described effect can be obtained. It is possible to obtain
[0008]
3 to 5 are perspective views showing a schematic configuration of a modified example of the microstrip antenna according to the first embodiment of the present invention.
The microstrip antenna shown in FIG. 3 is configured to feed power from two straight lines that pass through the center of the microstrip element 1 and is similar to the microstrip antenna shown in FIG. Makes it possible to share polarization.
The microstrip antenna shown in FIG. 4 uses a circular microstrip element as the microstrip element 1.
Further, the microstrip antenna shown in FIG. 5 uses a circular microstrip element as the microstrip element 1 and feeds power from two perpendicular lines that pass through the center of the microstrip element 1.
Even in these microstrip antennas, the feeding method is the same as that of the microstrip antenna shown in FIG.
However, in the present embodiment or the following embodiments, the microstrip element 1 is not limited to a quadrangular microstrip element, and a polygonal microstrip element may be used.
[0009]
[Embodiment 2]
6A and 6B are diagrams showing a schematic configuration of the microstrip antenna according to the second embodiment of the present invention. FIG. 6A is a perspective view, and FIG. 6B is an AA shown in FIG. 'A cross-sectional view taken along a cutting line.
Hereinafter, the microstrip antenna of the present embodiment will be described focusing on the differences from the microstrip antenna of the first embodiment.
In the present embodiment, the insulating layer 10 is provided on the microstrip element, and the first connection conductor 11 is provided on the insulating layer. Further, the first hole 31 and the third hole 33 are formed so as to also penetrate the insulating layer 10.
As shown in FIG. 6, the internal conductor 5 of the connector 4 is connected to one end of the first connection conductor 11 by the solder 13 after passing through the first hole 31. Further, the end portion of the first connection conductor 11 is connected to the second connection conductor 12 by the solder 13.
The second connection conductor 12 is openly terminated at the open end of the cylindrical conductor 7 through the third hole 33.
That is, this embodiment is obtained by replacing the portion of the inner conductor 5 of the connector 4 parallel to the microstrip element 1 with the first connecting conductor 11 in the first embodiment.
Also in the present embodiment, the length L from the surface of the ground conductor 3 in contact with the dielectric substrate 2 to the open end of the cylindrical conductor 7 opposite to the side fixed to the ground conductor 3 is (0 .8 × λg) / 4 ≦ L ≦ (1.2 × λg) / 4, which makes it possible to obtain the same operation and effect as in the first embodiment also in the present embodiment. Become.
[0010]
7 to 10 are perspective views showing a schematic configuration of a modification of the microstrip antenna according to the second embodiment of the present invention.
The microstrip antenna shown in FIG. 7 is configured to feed power from two straight lines that pass through the center of the microstrip element 1 and are orthogonal to each other, similarly to the microstrip antenna shown in FIG.
The microstrip antenna shown in FIG. 8 uses a circular microstrip element as the microstrip element 1.
Further, the microstrip antenna shown in FIG. 9 uses a circular microstrip element as the microstrip element 1 and feeds power from two straight lines passing through the center of the microstrip element 1.
Even in these microstrip antennas, the feeding method is the same as that of the microstrip antenna shown in FIG.
Further, in the microstrip antenna shown in FIG. 10, the width of the first connection conductor 11 is partially different in order to match the feeder line connected to the connector 4.
As shown in FIG. 10, by changing the width of the first connection conductor 11 partially and changing the width of the first connection conductor 11 to be partially changed, the input of the microstrip element 1 is changed. The impedance can be adjusted to an arbitrary value.
[0011]
[Embodiment 3]
11A and 11B are diagrams showing a schematic configuration of the microstrip antenna according to the third embodiment of the present invention. FIG. 11A is a perspective view, and FIG. 11B is an AA shown in FIG. 'A cross-sectional view taken along a cutting line.
Hereinafter, the microstrip antenna of the present embodiment will be described focusing on the differences from the microstrip antenna of the first embodiment.
In the present embodiment, when viewed from the microstrip element side, the area of the dielectric substrate 2 is smaller than the area of the ground conductor 3 so that the ground conductor 3 protrudes from the dielectric substrate 2, that is, The dielectric substrate 2 is formed slightly larger than the microstrip element 1.
In the present embodiment, the third hole 33 and the cylindrical conductor 7 of the first embodiment are deleted.
Instead, in the present embodiment, as shown in FIG. 11, the inner conductor 5 of the connector 4 passes through the first hole 31 and extends in parallel to the microstrip element 1 to the periphery of the microstrip element 1. After the extension, the open end of the coaxial line 9 arranged along the ground conductor 3 is terminated.
Here, the central conductor of the coaxial line 9 is connected to the inner conductor 5 of the connector 4, and the outer conductor of the coaxial line 9 is electrically connected to the ground conductor 3.
In this case, the length L of the coaxial line 9 is λg / 4 (L = λg / 4). Here, lambda] g is the electrical length calculated by λg = λo / √ε _r, λo is the free space wavelength of the use frequency of the microstrip antenna, epsilon _r is the dielectric constant of the dielectric in the coaxial line.
Since the (λg / 4) line having an open end is equivalent to a state where the line is short-circuited to the ground potential, the internal conductor 5 of the connector 4 is electromagnetically connected to the ground conductor 3.
Thus, also in the present embodiment, it is possible to obtain the same operations and effects as those of the first embodiment.
The length L of the coaxial line 9 is not necessarily λg / 4, and the length L of the coaxial line 9 is (0.8 × λg) / 4 ≦ L ≦ (1.2 × λg) / If 4 is satisfied, the above-described effects can be obtained.
[0012]
Further, instead of extending the inner conductor 5 of the connector 4 to the peripheral portion of the microstrip element 1 in parallel with the microstrip element 1, as shown by a dotted line in FIG. In order to align with the electric wire, the inner conductor 5 of the connector 4 may be inclined with respect to the microstrip element 1 and extended to the periphery of the microstrip element 1.
As shown by a dotted line in FIG. 11B, the inner conductor 5 of the connector 4 is inclined with respect to the microstrip element 1 and extended to the peripheral portion of the microstrip element 1 to thereby increase the length of the inner conductor 5. Can be adjusted to an arbitrary length, whereby the input impedance of the microstrip element 1 can be adjusted to an arbitrary value. This is the same as in the first embodiment.
FIG. 12 is a perspective view showing a schematic configuration of a modified example of the microstrip antenna according to the third embodiment of the present invention.
The microstrip antenna shown in FIG. 12 is configured such that the inner conductor 5 of the connector 4 is covered with an insulating sleeve 8 so that the inner conductor 5 of the connector 4 does not contact the microstrip element 1.
[0013]
[Embodiment 4]
13A and 13B are diagrams showing a schematic configuration of a microstrip antenna according to a fourth embodiment of the present invention. FIG. 13A is a plan view, and FIG. 13B is an AA shown in FIG. 'A cross-sectional view taken along a cutting line.
Hereinafter, the microstrip antenna of the present embodiment will be described focusing on the differences from the microstrip antenna of the third embodiment described above.
In the present embodiment, the insulating layer 10 is provided on the microstrip element, and the first connection conductor 11 is provided on the insulating layer. Further, the first hole 31 is formed so as to also penetrate the insulating layer 10.
As shown in FIG. 13, the internal conductor 5 of the connector 4 is connected to one end of the first connection conductor 11 by the solder 13 after passing through the first hole 31. The other end of the first connection conductor 11 is extended over the dielectric substrate beyond the insulating layer 10 and terminated open.
In this case, the length L of the first connecting conductor 11 on the dielectric substrate is λg / 4 (L = λg / 4). Here, lambda] g is the electrical length calculated by λg = λo / √ε _r, λo is the free space wavelength of the use frequency of the microstrip antenna, epsilon _r is the dielectric constant of the dielectric substrate 2.
Thereby, also in the present embodiment, it is possible to obtain the same operation and effect as in the first embodiment.
[0014]
Note that the length L of the first connection conductor 11 on the dielectric substrate is not necessarily λg / 4, and the length L of the first connection conductor 11 on the dielectric substrate is (0.8). The above-described effects can be obtained if xλg) / 4 ≦ L ≦ (1.2 × λg) / 4 is satisfied.
Further, as indicated by a dotted line in FIG. 13, the first connection conductor 11 may be bypassed in order to match the feeder line connected to the connector 4.
As shown by a dotted line in FIG. 13, the length of the first connection conductor 11 can be adjusted to an arbitrary length by detouring the first connection conductor 11. The input impedance can be adjusted to an arbitrary value. This is the same as in the second embodiment.
Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.
[0015]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the antenna of the present invention, it is possible to supply power to the radiating element without bringing different metals into contact with each other, and it is possible to reduce the generation of noise.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a method of supplying power to a microstrip antenna.
FIG. 2 is a diagram showing a schematic configuration of the microstrip antenna according to the first embodiment of the present invention.
FIG. 3 is a perspective view showing a schematic configuration of a modified example of the microstrip antenna according to the first embodiment of the present invention.
FIG. 4 is a perspective view showing a schematic configuration of a modified example of the microstrip antenna according to the first embodiment of the present invention.
FIG. 5 is a perspective view showing a schematic configuration of a modified example of the microstrip antenna according to the first embodiment of the present invention.
FIG. 6 is a diagram showing a schematic configuration of a microstrip antenna according to a second embodiment of the present invention.
FIG. 7 is a perspective view showing a schematic configuration of a modification of the microstrip antenna according to the second embodiment of the present invention.
FIG. 8 is a perspective view showing a schematic configuration of a modification of the microstrip antenna according to the second embodiment of the present invention.
FIG. 9 is a perspective view showing a schematic configuration of a modification of the microstrip antenna according to the second embodiment of the present invention.
FIG. 10 is a perspective view showing a schematic configuration of a modification of the microstrip antenna according to the second embodiment of the present invention.
FIG. 11 is a diagram showing a schematic configuration of a microstrip antenna according to a third embodiment of the present invention.
FIG. 12 is a perspective view showing a schematic configuration of a modified example of the microstrip antenna according to the third embodiment of the present invention.
FIG. 13 is a diagram showing a schematic configuration of a microstrip antenna according to a fourth embodiment of the present invention.
FIG. 14 is a diagram showing a schematic configuration showing an example of a conventional microstrip antenna.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,21 ... Microstrip element, 2,22 ... Dielectric board | substrate, 3,23 ... Grounding conductor, 4,24 ... Connector, 5,25 ... Internal conductor, 6,26 ... External conductor, 7 ... Cylindrical conductor , 8 ... Insulating sleeve, 9 ... Coaxial line, 10 ... Insulating layer, 11, 12 ... Connection conductor, 13, 29 ... Solder, 27 ... Ribbon conductor, 30 ... Excitation power source, 31, 32, 33 ... Hole.

Claims (9)

A dielectric substrate that is thinner than the radiation wavelength;
A radiating element having a circular or polygonal shape provided on the first surface of the dielectric substrate;
A ground conductor provided on a second surface opposite to the first surface of the dielectric substrate;
An antenna comprising a connector having an inner conductor and an outer conductor,
A first hole provided in the center of the circular or polygonal shape of the radiating element;
A second hole having a diameter larger than that of the first hole provided in the dielectric substrate and the ground conductor so that the first hole is exposed;
The outer conductor of the connector is made of the same type of metal as the radiating element, and is fixed to the radiating element in the second hole,
The inner conductor of the connector extends through the first hole to a peripheral portion of the radiating element, and is electromagnetically connected to the ground conductor in the peripheral portion of the radiating element. antenna. A third hole provided in the dielectric substrate and the ground conductor at the periphery of the radiating element;
A cylindrical conductor fixed to the ground conductor so as to extend the third hole,
The inner conductor extends through the third hole to an open end on the opposite side of the cylindrical conductor that is fixed to the ground conductor,
The length L from the surface of the ground conductor in contact with the dielectric substrate to the open end of the cylindrical conductor opposite to the side fixed to the ground conductor is λo as a free space of the antenna operating frequency. wavelength, the dielectric permittivity of the epsilon _r conductive body of the cylindrical, when the electrical length is calculated the lambda] g at _{λg = λo / √ε r, (} 0.8 × λg) / 4 ≦ L ≦ ( The antenna according to claim 1, wherein 1.2 × λg) / 4 is satisfied. The ground conductor, the dielectric substrate, and the dielectric substrate so that the ground conductor protrudes around the dielectric substrate when the area of the dielectric substrate is smaller than the ground conductor and viewed from the radiation element side. Is placed
Having a coaxial line arranged along the ground conductor at the periphery of the radiating element;
The coaxial line has a center conductor connected to the inner conductor extended to the periphery of the radiating element, and an outer conductor electrically connected to the ground conductor around the dielectric substrate,
The length L of the coaxial line, the free space wavelength of the used frequency of the antenna to .lamda.o, dielectric permittivity in the epsilon _r coaxial line with an electric length which is calculated the lambda] g at λg = λo / √ε _r The antenna according to claim 1, wherein (0.8 × λg) / 4 ≦ L ≦ (1.2 × λg) / 4 is satisfied. The length of the internal conductor extended to the peripheral part of the radiating element is set to a predetermined length according to the input impedance of the antenna. The described antenna. A dielectric substrate that is thinner than the radiation wavelength;
A radiating element having a circular or polygonal shape provided on the first surface of the dielectric substrate;
A ground conductor provided on a second surface opposite to the first surface of the dielectric substrate;
An insulating layer provided on the radiating element and the dielectric substrate;
A first connection conductor provided on the insulating layer so as to extend from a circular or polygonal center of the radiating element to a peripheral part of the radiating element;
An antenna comprising a connector having an inner conductor and an outer conductor,
A first hole provided in the center of the radiating element and the insulating layer in a circular or polygonal shape of the radiating element;
A second hole having a diameter larger than that of the first hole provided in the dielectric substrate and the ground conductor so that the first hole is exposed;
The outer conductor of the connector is made of the same type of metal as the radiating element, and is fixed to the radiating element in the second hole,
The inner conductor of the connector is connected to one end of the first connection conductor through the first hole,
The antenna is characterized in that the other end of the first connection conductor is electromagnetically connected to the ground conductor in the periphery of the radiating element. A third hole provided in the dielectric substrate, the ground conductor, and the insulating layer at a peripheral portion of the radiating element;
A cylindrical conductor fixed to the ground conductor so as to extend the third hole;
One end is connected to the other end of the connection conductor, and the other end is extended through the third hole to an open end opposite to the side fixed to the ground conductor of the cylindrical conductor. A second connecting conductor;
The length L from the surface of the ground conductor in contact with the dielectric substrate to the open end of the cylindrical conductor opposite to the side fixed to the ground conductor is λo as a free space of the antenna operating frequency. wavelength, the dielectric permittivity of the epsilon _r conductive body of the cylindrical, when the electrical length is calculated the lambda] g at _{λg = λo / √ε r, (} 0.8 × λg) / 4 ≦ L ≦ ( The antenna according to claim 5, wherein 1.2 × λg) / 4 is satisfied. The area of the insulating layer is smaller than that of the dielectric substrate and the ground conductor, and the dielectric substrate and the ground conductor protrude around the insulating layer when viewed from the radiating element side. The insulating layer, the ground conductor, and the dielectric substrate are arranged,
The first connection conductor extends to the dielectric substrate around the insulating layer;
The length L of the dielectric substrate of the first connecting conductor, the free space wavelength of the used frequency of the antenna to .lamda.o, epsilon dielectric constant of the circular dielectric substrate _r, lambda] g to λg = λo / √ε _r The antenna according to claim 5, wherein (0.8 × λg) / 4 ≦ L ≦ (1.2 × λg) / 4 is satisfied when the electrical length calculated by the following equation is satisfied. The antenna according to any one of claims 5 to 7, wherein the length of the first connection conductor is set to a predetermined length according to an input impedance of the antenna. The antenna according to any one of claims 5 to 7, wherein a width of the first connection conductor is partially different depending on an input impedance of the antenna.

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