JP2000332529A - Plane antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a plane antenna small-sized and broadband by connecting a feeder to a feed point of a dielectric substrate, interposed between a ground conductor and a radiation element so that the whole shape is plane, through a capacitive lumped-constant circuit. SOLUTION: The dielectric substrate 102 is interposed between the ground conductor 101 and radiation element 103 so that the whole shape is plane and the feeder 106 is connected to the feed point of the dielectric substrate 102 through the capacitive lumped-constant circuit 104. With the lumped constant of the lumped-constant circuit 104, the reactance component of the plane antenna is canceled, so even the radiation element 103 which is shorter than length corresponding to a transmission/reception frequency is able to eliminate the reactance component of impedance, and consequently the plane antenna can be made small-sized. A strip line which connects the lumped-constant circuit 104 and feeder 106 can be formed on the earth conductor 101.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric substrate interposed between a ground conductor and a radiating element so as to form a planar shape as a whole, and power is supplied to the dielectric substrate via a feed line. The present invention relates to a planar antenna, and more particularly to a planar antenna suitable for use in mobile stations such as mobile phones, information terminals, and navigation terminals in mobile communication systems.

[0002]

2. Description of the Related Art A planar antenna can be made compact due to its characteristics. However, in recent years, communication devices such as portable telephones have become increasingly popular, and further miniaturization has been demanded. There is a demand for further downsizing of the planar antenna.

Conventionally, a flat antenna has been disclosed in
There is one described in Japanese Patent No. 55820. This planar antenna is configured using a strip antenna having a ring-shaped radiating element.

[0004]

However, in the conventional device, the size of the ordinary circular or square patch radiating element, which is a component of the planar antenna, is determined according to the transmission / reception frequency. As described above, there is a problem that the size cannot be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a planar antenna capable of easily realizing a small size and a wide band by using a circular or square patch radiating element. I do.

[0006]

According to the present invention, a dielectric substrate is interposed between a ground conductor and a radiating element so as to form a planar shape as a whole, and a capacitive condenser is provided at a feeding point of the dielectric substrate. The power supply line is connected via a constant circuit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is directed to a ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and power feeding of the dielectric substrate. And a power supply line connected to the point via a lumped capacitive circuit.

According to this configuration, even if the radiating element is shorter than the length corresponding to the transmission / reception frequency, the reactance component of the impedance can be made zero by the lumped constant of the lumped constant circuit, thereby reducing the size of the planar antenna. Can be.

According to a second aspect of the present invention, in the first aspect, a strip line for matching the radiating element and the feed line via the lumped constant circuit is provided between the lumped constant circuit and the feed line. The configuration to interpose is adopted.

[0010] According to this configuration, the operating point is not limited according to the resistance component of the impedance, and the operating point can be further shifted to the position on the power supply side. Can be further shortened than in the embodiment.

According to a third aspect of the present invention, there is provided a ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and a capacitive element provided at a feeding point of the dielectric substrate. And a power supply line connected via a distributed constant circuit.

According to this configuration, even with a radiating element shorter than the length corresponding to the transmission / reception frequency, the reactance component of the impedance can be made zero by the distributed constant of the distributed constant circuit, thereby reducing the size of the planar antenna. Can be.

According to a fourth aspect of the present invention, in the third aspect, a strip line for matching the radiating element and the feed line via the distributed constant circuit is provided between the distributed constant circuit and the feed line. The configuration to interpose is adopted.

According to this configuration, the operating point is not limited in accordance with the resistance component of the impedance, and the operating point can be further shifted to the position on the power supply side, thereby making the length of the radiating element the third. Can be further shortened than in the embodiment.

According to a fifth aspect of the present invention, there is provided a ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and a variable capacitor provided at a feeding point of the dielectric substrate. And a power supply line connected via an element.

According to this configuration, the operating point can be tuned by changing the reactance component of the variable capacitance element to tune to an arbitrary transmission / reception frequency, thereby realizing a wider band of the planar antenna. it can.

According to a sixth aspect of the present invention, in the fifth aspect, a strip line for matching the radiating element and the feed line via the variable capacitance element is provided between the variable capacitance element and the feed line. The configuration to interpose is adopted.

According to this configuration, the operating point is not limited in accordance with the resistance component of the impedance, and the operating point can be further shifted to the position on the power supply side. Broadbanding of the planar antenna can be realized.

A seventh aspect of the present invention employs a configuration in which the mobile station apparatus includes the planar antenna according to any one of the first to sixth aspects.

According to this configuration, in the base station apparatus,
The same operation and effect as any of the first to sixth aspects can be obtained.

An eighth aspect of the present invention employs a configuration in which the mobile communication system includes the mobile station apparatus according to the seventh aspect.

According to this configuration, in the mobile communication system, the same operation and effect as any one of the first to sixth aspects can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram of a planar antenna according to Embodiment 1 of the present invention.

The planar antenna 100 shown in FIG. 1 has a rectangular patch shape, and includes a ground conductor 101, a dielectric substrate 102 formed on the ground conductor 101, and a And a lumped capacitive circuit 104 formed on the ground conductor 101.
And the lumped constant circuit 1 at the feeding point 105 of the dielectric substrate 102
And a power supply line 106 connected via the power supply line 04. However, a capacitor or the like is used for the lumped constant circuit 104.

The operation principle of the planar antenna 100 having such a configuration will be described with reference to FIG. FIG. 2 is a relationship diagram between the impedance Z of the planar antenna and the length a of the radiating element.

In FIG. 2, a curve 201 shows a resistance component R of the impedance Z (Z = R + jX), a curve 202 shows a reactance component X of the impedance Z, and a curve 203 shows a case where the lumped constant circuit 104 is used. 3 shows a reactance component X1 of FIG.

In the conventional planar antenna, the lumped constant circuit 1
04 is not used, the operating point is a position where the resistance component R of the length a of the radiating element according to the transmission / reception frequency takes the maximum value R1 and the reactance component X becomes 0, as indicated by reference numeral 204. , A feed point is set at this position.
This limits the length a of the radiating element that can be tuned.

In planar antenna 100 of the first embodiment, lumped constant circuit 104 of reactance component X3 for canceling reactance component X2 when resistance component R takes an arbitrary value R2 is interposed in feeder line 106. .

That is, by interposing the lumped constant circuit 104, the operating point can be shifted to the position on the power supply side indicated by reference numeral 205.

This is because the reactance component X2 is canceled by the reactance component X3 of the lumped constant circuit 104, so that the reactance component becomes zero, thereby shortening the length a of the radiation element 103.

As described above, according to the planar antenna 100 of the first embodiment, the ground conductor 1 is formed so as to form a planar shape as a whole.
01 and the radiating element 103, and a feed line 106 is connected to a feed point of the dielectric substrate 102 via a lumped capacitive circuit 104. Radiating element 10 shorter than the length corresponding to
Also in 3, the lumped constant of the lumped constant circuit 104 can reduce the reactance component of the impedance to 0, thereby reducing the size of the planar antenna.

(Embodiment 2) FIG. 3 is a configuration diagram of a planar antenna according to Embodiment 2 of the present invention. However, in the second embodiment shown in FIG. 3, portions corresponding to the respective portions of the first embodiment in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The planar antenna 300 according to the second embodiment shown in FIG. 3 is different from the planar antenna 100 according to the first embodiment in that a strip connecting a lumped constant circuit 104 and a feeder line 106 on a ground conductor 101. The point is that the line 301 is formed.

As shown in FIG. 4, the strip line 301 has first to third lines 401, 402, and 403 whose widths W1, W2, and W3 spread stepwise from the lumped constant circuit 104 toward the power supply line 106. Is formed.

Assuming that the impedance of each line 401, 402, 403 is Z1, Z2, Z3, the second line 40
If the strip line 301 is formed such that the impedance of the second line Z2 = √ (Z1 × Z3) and the length of the second line 402 = λ / 4, the first line 401 and the third line
Matching with the line 403 is achieved, and accordingly, matching between the radiating element 103 and the feed line 106 via the lumped constant circuit 104 is achieved. That is, the impedance Z of the planar antenna 300 can be matched by the strip line 301. Here, λ is the wavelength of the transmission / reception frequency.

As described above, according to the planar antenna 300 of the second embodiment, in addition to the configuration of the first embodiment, the lumped constant circuit 10 is provided between the lumped constant circuit 104 and the feeder line 106.
4, the strip line 301 for matching the radiating element 103 and the feed line 106 is provided, so that the operating point is not limited according to the resistance component of the impedance Z as in the first embodiment. , The operating point can be further shifted to the position on the power supply side, so that the radiating element 103
Can be made shorter than in the first embodiment.

(Embodiment 3) FIG. 5 is a configuration diagram of a planar antenna according to Embodiment 3 of the present invention. However, in the third embodiment shown in FIG. 5, portions corresponding to the respective portions of the first embodiment in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The planar antenna 500 of the third embodiment shown in FIG. 5 is different from the planar antenna 100 of the first embodiment in that a capacitive distributed constant circuit 501 is provided instead of the lumped constant circuit 104. On the point.

As shown in FIG. 6, the distributed constant circuit 501 is formed by separating substrates 601 and 602 such as two copper plates in parallel and separated by a predetermined distance.
The distance between 602 is d, the area of the substrates 601 and 602 is S,
Assuming that the dielectric constant is ε, the capacitance C is represented by C = ε × S / d.

In such a planar antenna 500, the distributed constant circuit 501 is provided to
As shown in (2), the operating point can be shifted to the position indicated by reference numeral 205, that is, the position on the power supply side where the resistance component R takes an arbitrary value R2 and the reactance component becomes X2.

This is because the reactance component X2 is canceled by the reactance component X3 of the distributed constant circuit 501, so that the reactance component becomes zero, thereby shortening the length a of the radiation element 103.

As described above, according to the planar antenna 500 of the third embodiment, the ground conductor 1 is formed so as to form a planar shape as a whole.
01 and the radiating element 103, and a feed line 106 is connected to a feed point of the dielectric substrate 102 via a capacitive distributed constant circuit 501. Radiating element 10 shorter than the length corresponding to
Even in the case of 3, the reactance component of the impedance can be set to 0 by the distributed constant of the distributed constant circuit 501, whereby the size of the planar antenna can be reduced.

(Embodiment 4) FIG. 7 is a configuration diagram of a planar antenna according to Embodiment 4 of the present invention. However, in the fourth embodiment shown in FIG. 7, portions corresponding to the respective portions of the third embodiment in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

The planar antenna 700 according to the fourth embodiment shown in FIG. 7 is different from the planar antenna 500 according to the third embodiment in that a strip connecting the distributed constant circuit 501 and the feeder line 106 on the ground conductor 101. The point is that the line 301 is formed.

However, as described above with reference to FIG. 4, the strip lines 301 have their widths W1, W2, W
The first to third lines 401, 402, and 403 spread stepwise from the lumped constant circuit 104 toward the power supply line 106.
Is formed from.

Assuming that the impedance of each line 401, 402, 403 is Z1, Z2, Z3, the second line 40
If the strip line 301 is formed such that the impedance of the second line Z2 = √ (Z1 × Z3) and the length of the second line 402 = λ / 4, the first line 401 and the third line
The matching with the line 403 is obtained, and accordingly, the matching between the radiating element 103 and the feeder line 106 via the distributed constant circuit 501 is obtained.

That is, the impedance Z of the planar antenna 300 can be matched by the strip line 301.

As described above, according to the planar antenna 700 of the fourth embodiment, in addition to the configuration of the third embodiment, the distributed constant circuit 50 is provided between the distributed constant circuit 501 and the feeder line 106.
Since the strip line 301 that matches the radiating element 103 and the feed line 106 via the first line 1 is provided, the operating point is not limited according to the resistance component of the impedance Z as in the third embodiment. , The operating point can be further shifted to the position on the power supply side, so that the radiating element 103
Can be further reduced than in the third embodiment.

(Embodiment 5) FIG. 8 is a configuration diagram of a planar antenna according to Embodiment 5 of the present invention. However, in the fifth embodiment shown in FIG. 8, portions corresponding to the respective portions of the first embodiment in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The flat antenna 800 of the fifth embodiment shown in FIG. 8 is different from the flat antenna 100 of the first embodiment in that
1 is provided.

The operation principle of the planar antenna 800 having such a configuration will be described with reference to FIG. FIG. 9 is a diagram showing the relationship between the impedance Z of the planar antenna and the frequency f.

In FIG. 9, a curve 901 shows a resistance component R of the impedance Z (Z = R + jX), a curve 902 shows a reactance component X of the impedance Z, and a curve 903 shows a case where the variable capacitance element 801 is used. 3 shows the reactance component Xn.

In the conventional planar antenna, the variable capacitance element 8
01, the operating point is located at a position where the resistance component R of the length a of the radiating element according to the transmission / reception frequency takes the maximum value R1 and the reactance component X becomes 0, as indicated by reference numeral 904. , A feed point is set at this position.
As a result, the transmission and reception frequencies at which tuning can be performed are limited.

In the planar antenna 800 of the fifth embodiment, by setting the variable capacitance element 801 to the reactance component X6 that cancels out the reactance component X5 when the resistance component R takes an arbitrary value R3, the operating point can be represented by a code. The position 905 can be shifted to the position on the power supply side. This is because the reactance component X5 is canceled by the reactance component X6 of the variable capacitance element 801 and thus the reactance component becomes zero.

As described above, by changing the reactance component Xn of the variable capacitance element 801 and moving the operating point, it is possible to tune to an arbitrary transmission / reception frequency.

As described above, according to the planar antenna 800 of the fifth embodiment, the ground conductor 1 is formed so that the whole forms a planar shape.
01 and the radiating element 103, a variable capacitance element 80 is provided at a feeding point of the dielectric substrate 102.
1 is connected to the feeder line 106, the operating point can be moved by changing the reactance component Xn of the variable capacitance element 801 to tune to an arbitrary transmission / reception frequency. 800
Bandwidth can be realized.

(Embodiment 6) FIG. 10 is a configuration diagram of a planar antenna according to Embodiment 6 of the present invention. However, in the sixth embodiment shown in FIG. 10, portions corresponding to the respective portions of the fifth embodiment in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.

The planar antenna 1000 according to the sixth embodiment shown in FIG. 10 is different from the planar antenna 800 according to the fifth embodiment in that a strip connecting the variable capacitance element 801 and the feed line 106 on the ground conductor 101. The point is that the line 301 is formed.

However, as described above with reference to FIG. 4, the strip line 301 has its width W1, W2, W
Reference numeral 3 denotes first to third lines 401, 402, and 403 extending stepwise from the variable capacitance element 801 toward the power supply line 106.
Is formed from.

Assuming that the impedance of each line 401, 402, 403 is Z1, Z2, Z3, the second line 40
If the strip line 301 is formed such that the impedance of the second line Z2 = √ (Z1 × Z3) and the length of the second line 402 = λ / 4, the first line 401 and the third line
Matching with the line 403 is obtained, and the radiating element 1
03 and the feeder 106 can be matched.

That is, the impedance Z of the planar antenna 1000 can be matched by the strip line 301.

As described above, according to the planar antenna 1000 of the sixth embodiment, in addition to the configuration of the fifth embodiment, the radiating element 103 is provided between the variable capacitance element 801 and the feed line 106.
Strip line 301 that matches the power supply line 106
As in the fifth embodiment, the operating point is not limited according to the resistance component of the impedance Z, and the operating point can be further shifted to a position on the power supply side.
Thereby, the planar antenna 1 is further improved than in the fifth embodiment.
000 bandwidth can be realized.

In the above description, a planar antenna having a rectangular patch shape has been described as an example, but the present invention is not limited to this.
Applicable to radiating elements of all shapes. Further, such a planar antenna can be applied to a mobile station device such as a mobile phone, an information terminal, and a navigation terminal in a mobile communication system.

[0065]

As described above, according to the present invention,
Using a radiating element in the shape of a circular or square patch can easily realize miniaturization and broadening of the band.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a planar antenna according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the impedance of the planar antenna according to the first embodiment and the length of a radiating element;

FIG. 3 is a configuration diagram of a planar antenna according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a strip line of the planar antenna according to the second embodiment.

FIG. 5 is a configuration diagram of a planar antenna according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a distributed constant circuit of the planar antenna according to the third embodiment.

FIG. 7 is a configuration diagram of a planar antenna according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of a planar antenna according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing the relationship between impedance and frequency of the planar antenna according to the fifth embodiment.

FIG. 10 is a configuration diagram of a planar antenna according to a sixth embodiment of the present invention.

[Explanation of symbols]

100, 300, 500, 700, 800, 1000
Planar antenna 101 Ground conductor 102 Dielectric substrate 103 Radiating element 104 Capacitive lumped circuit 105 Feed point 106 Feed line 301 Stripline 501 Capacitive distributed constant circuit 801 Variable capacitive element

Claims (8)

[Claims] 1. A ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and a capacitive lumped circuit connected to a feed point of the dielectric substrate. And a connected power supply line. 2. The strip line according to claim 1, wherein a strip line for matching the radiating element and the feed line via the lumped constant circuit is interposed between the lumped constant circuit and the feed line. Planar antenna. 3. A ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and a feed point of the dielectric substrate via a capacitive distributed constant circuit. And a connected power supply line. 4. The device according to claim 3, wherein a strip line for matching the radiating element and the feed line via the distributed constant circuit is provided between the distributed constant circuit and the feed line. Planar antenna. 5. A ground conductor, a radiating element, a dielectric substrate interposed between the ground conductor and the radiating element, and connected to a feeding point of the dielectric substrate via a variable capacitance element. And a feed line. 6. The variable capacitance element and a feed line, wherein a strip line for matching the radiation element and the feed line via the variable capacitance element is interposed. Planar antenna. 7. A mobile station device comprising the planar antenna according to claim 1. Description: 8. A mobile communication system comprising the mobile station device according to claim 7.