JP2003298335A - Electromagnetic coupling type four-point feeding loop antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily match impedance. <P>SOLUTION: The electromagnetic coupling type four-point feeding loop antenna (10) has a cylinder (11) where an insulating film member (20) is formed around a center shaft (0), and a loop section (12). Four power-feeding lines (13) are provided on the peripheral surface of the cylinder to feed power to the loop section at four points. Power is fed to the loop section by electromagnetic coupling. The diameter of the cylinder is 20 mm, the width dimensions (W<SB>1</SB>, W<SB>2</SB>, and W<SB>3</SB>) of the loop section, the power-feeding line, and an electromagnetic coupling line are the same when a power-feeding impedance is set to 25 to 100 Ω, and a gap ranges within 0.2 to 0.8 mm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention receives radio waves from artificial satellites (hereinafter also referred to as "satellite waves") or radio waves on the ground (hereinafter also referred to as "terrestrial waves") to listen to digital radio broadcasting. And a loop antenna used in the digital radio receiver.

[0002]

2. Description of the Related Art Recently, a digital radio receiver capable of listening to a radio wave (satellite wave) or a ground wave from an artificial satellite to listen to a digital radio broadcast has been developed and is about to be put to practical use in the United States. This digital radio receiver is installed in a mobile station such as an automobile and has a frequency of about 2.33.
It is possible to receive radio waves of 8 GHz and listen to radio broadcasts. That is, the digital radio receiver is a radio receiver capable of listening to mobile broadcasting.
The terrestrial wave is obtained by once receiving the satellite wave at the earth station and then slightly shifting the frequency.

In order to receive the radio wave having the frequency of about 2.338 GHz, it is necessary to install an antenna outside the vehicle. As such an antenna, various structures are conceivable, but it is common to use a stick type instead of a flat type (flat type).

A loop antenna is known as one of stick type antennas. The loop antenna has a structure in which one conductor wire is wound in a loop around a cylindrical or cylindrical (hereinafter referred to as “cylinder”) member. It is known that if the entire circumference of the loop is selected to be near one wavelength, the current distribution will be sinusoidal, and the antenna will have directivity in the axial direction.

In such a loop antenna, it is necessary to feed it, but it is common to feed it at four points. Such a loop antenna that feeds power at four points is called a four-point feeding loop antenna. Conventional 4
In the point-fed loop antenna, power is directly fed to the loop part.

More specifically, the conventional four-point feeding loop antenna has a tubular body formed by rolling a flexible insulating film member in a tubular shape around a central axis, and the tubular body along its peripheral surface. A loop portion made of a conductor formed in a loop around the central axis and four power supply lines formed on the peripheral surface of the cylindrical body for feeding power to the loop portion at four points. However, the loop portion and each of the four power supply lines are directly connected.

In the four-point feeding loop antenna, the radio waves received by the loop portion are phase-shifted by the phase shifter via the four feeding lines to match (adjust) the phases. After being synthesized, a low noise amplifier (LN
It is amplified by A) and sent to the receiver body. Here, the combination of the 4-point feeding loop antenna, the phase shifter and the LNA is called an antenna device.

[0008]

As described above, in the conventional four-point feeding loop antenna, since the power is directly fed to the loop portion, there is a problem that the feeding impedance becomes too high. Therefore, the conventional four-point feeding loop antenna has a problem that it is difficult to perform impedance matching.

Therefore, an object of the present invention is to provide a four-point feeding loop antenna which can easily achieve impedance matching.

[0010]

According to the present invention, flexibility
The insulating film member (20) of the cylinder around the central axis (O)
A cylindrical body (11) formed into a round shape,
A conductor formed in a loop around the central axis along a surface.
A loop part (12) composed of a body and a shape formed on the peripheral surface of the cylindrical body.
And four power supply lines for supplying power to the formed loop portion,
Each of the four feeding lines has a loop
From the loop with a gap (δ) left
It extends toward the lower side along the four power supply lines.
Four electromagnetic coupling wires (17) are connected,
Power supply impedance of 25 Ω to 100
When set to Ω, the width of the loop part (20)
(W ₁), The width dimension of the power supply line (13) (W_Two) And before
The width of the electromagnetic coupling wire (17) (W_Three) Have the same width
And the gap (δ) is in the range of 0.2 to 0.8 mm.
The electromagnetically coupled four-point feeding loop loop
The antenna (10) is obtained.

In the electromagnetic coupling type four-point feeding loop antenna, in order to feed power to the loop portion at four points,
Four feed lines (1
3) and the insulating film member (20) has an upper side (20 _U ), a lower side (20 _L ), a first side (20 _S1 ) and a second side (20 _S2 ). It has a substantially rectangular shape, and the tubular body (11) is formed by connecting the first side and the second side to each other, and the loop portion (12) is The four feeders (1) are formed on one surface of the insulating film member near the upper side.
Each of 3) may extend from the lower side of the insulating film member to the vicinity of the loop portion.

Further, the electromagnetic coupling type four-point feeding loop amplifier
In the tenor, set the feeding impedance to 25Ω
The width of the loop portion (20) (W₁),
The width dimension (W of the power supply line (13)_Two) And the electromagnetic coupling
Width of line (17) (W_Three) Is 1 mm,
The cap (δ) is 0.4 mm, and the upper side (2
0 _U) Side of the loop portion (20) to the lower side (2
0_L) Width dimension (W_Four) Is 20 mm, and below
Tip of the electromagnetic coupling wire (17) extending toward the side
From the lower side (20_L) Width dimension (W₅) Is 9 mm
And the power supply line extending toward the upper side
The tip of (13) faces the tip of the power supply line (13).
The width dimension (W to the side of the loop portion (20)₆) Is 1
It may be 5 mm.

Further, the electromagnetic coupling type four-point feeding loop amplifier
In the tenor, set the power supply impedance to 50Ω
The width of the loop portion (20) (W₁),
The width dimension (W of the power supply line (13)_Two) And the electromagnetic coupling
Width of line (17) (W_Three) Is 1 mm,
The cap (δ) is 0.4 mm, and the upper side (2
0 _U) Side of the loop portion (20) to the lower side (2
0_L) Width dimension (W_Four) Is 20 mm, and below
Tip of the electromagnetic coupling wire (17) extending toward the side
From the lower side (20_L) Width dimension (W₅) Is 5 mm
And the power supply line extending toward the upper side
The tip of (13) faces the tip of the power supply line (13).
The width dimension (W to the side of the loop portion (20)₆) Is 1
It may be 2 mm.

In the above electromagnetically coupled four-point feeding loop antenna, when the feeding impedance is set to 100Ω, the width dimension (W ₁ ) of the loop portion (20) and the width dimension of the feeding line (13). (W ₂ ) and the width (W ₃ ) of the electromagnetic coupling wire (17) are 1 mm, the gap (δ) is 0.4 mm, and the loop portion (20 _U ) side of the loop portion ( The width dimension (W ₄ ) from the side of 20) to the lower side (20 _L ) is 20 mm,
The electromagnetic coupling wire (17) extending toward the lower side
Has a width dimension (W ₅ ) from the tip of the bottom to the lower side (20 _L ) of 3 mm, and extends from the tip of the feeder line (13) extending toward the top side to the tip of the feeder line (13). Width dimension (W ₆ ) to the side of the loop portion (20) facing to
May be 8 mm.

The reference numerals in the parentheses are given to facilitate the understanding of the present invention, and are of course only examples and are not limited to these.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of an electromagnetically coupled four-point feeding loop antenna according to the present invention will be described in detail below with reference to the drawings.

Referring to FIGS. 1 to 3, an electromagnetically coupled four-point feeding loop antenna 10 has a flexible insulating film member rolled into a cylindrical shape around a central axis O, as will be described later. In order to supply power to the formed tubular body 11, a loop portion 12 made of a conductor formed in a loop shape around the central axis O along the peripheral surface of the tubular body 11, and to the loop portion 12 at four points. In addition, the four feeders 1 formed on the peripheral surface of the cylindrical body 11
3 and 3. As the conductor forming the loop portion 12,
For example, copper foil is used. Further, as the flexible insulating film member forming the cylindrical body 11, for example, plastic such as polyimide is used. The diameter of the cylinder 11 is 2
It is 0 mm.

Here, in the present invention, as shown in FIG. 2, a gap (gap) δ is provided between the loop portion 12 and each of the four power supply lines 13, and the loop 12 is connected to the loop 12 by electromagnetic coupling. Power supply. In the illustrated example, the gap δ is 0.4 mm, but is 0.2 to 0.8 m.
It is preferably in the range of m.

As shown in FIG. 1, one end of the cylinder 11 in the cylinder axis direction is fixed to the circuit board 14.
A phase shifter 15 is formed on the main surface 14a of the circuit board 14, and a ground conductor pattern (not shown) is formed on the back surface 14b of the circuit board 14. The power supply terminals 13 a of the four power supply lines 13 are electrically and mechanically connected to the input terminals of the phase shifter 15 by the solder 16.

Referring to FIG. 3, the insulating film member 20 for forming the cylindrical body 11 has an upper side 20 _U and a lower side 20 _L.
And has a substantially rectangular shape with a first side 20 _S1 and a second side 20 _S2 . And the first side 20
_{By connecting S1} and the second side 20 _S2 to each other,
A tubular body 11 as shown in FIG. 1 is formed. The connection between the first side 20 _S1 and the second side 20 _S2 is made, for example, with a double-sided adhesive tape or an adhesive.

The loop portion 12 is formed on one surface of the insulating film member 20 near the upper side 20 _U. When the insulating film member 20 is rolled to form the tubular body 11, both ends of the loop portion 12 are electrically connected by solder.

In the embodiment, each of the four feeders 13 is connected to the loop portion 1 from the lower side 20 _L of the insulating film member 20.
It extends parallel to the central axis O up to the vicinity of 2. And
The loop portion 12 extends from the loop portion 12 along the four power supply lines 13 toward the lower side 20 _L in a state in which the four power supply lines 13 are close to each other with a gap δ between them. A book electromagnetic coupling wire 17 is connected. By changing the coupling length between the feeding line 13 and the electromagnetic coupling line 17 which are adjacent to each other, the frequency characteristic of the electromagnetic coupling type four-point feeding loop antenna 10 can be changed.

The loop portion 12, the four power supply lines 13, and the four electromagnetic coupling lines 17 formed on one surface of the insulating film member 20 may be made of the same conductive material (for example, copper foil).

Generally, in a four-point feeding loop antenna, the feeding impedance needs to be 50Ω. In the electromagnetic coupling type four-point feeding loop antenna 10 according to the present embodiment, the impedance at each feeding terminal 13a can be lowered to 25Ω. Thereby, the impedance at the output terminal 15a of the phase shifter 15 can be set to 50Ω to 100Ω. That is, impedance matching can be easily achieved by supplying power to the loop portion 12 by electromagnetic coupling. The impedance at each power supply terminal 13a can be changed by changing the size of the gap δ.

On the other hand, in the conventional four-point feeding loop antenna having a structure in which each feeding line 13 is directly connected to the loop portion 12, the impedance at each feeding terminal 13a is too high as 250 to 300Ω. . Therefore, it is difficult to obtain impedance matching at the output terminal 15a of the phase shifter 15.

Below, the loop portion 12 and the four feeders 1
The positional relationship among the three, the gap δ, and the four electromagnetic coupling wires 17 will be described with specific dimensions.

[0027] With reference to FIG. 3, the four-point feeding loop antenna, as the diameter of the cylindrical body 11 is 20 mm, the width _{W 1} of the loop portion 20, the width of the feed line 13 _{W 2} and the electromagnetic coupling lines 1
The width dimension W _{3 of} 7 is the same width dimension. At this time, the phase shifter 1
When the feeding impedance for feeding power by electromagnetic coupling at the output terminal 15a of No. 5 is set in the range of 25Ω to 100Ω, the gap δ is set in the range of 0.2 to 0.8 mm.

Furthermore, specifically by the in electromagnetic coupling type four-point feeding loop antenna, when setting the power supply impedance 25Ω, the width W ₂ and the electromagnetic width dimension W _1, the feed line 13 of the loop portion 20 The width W ₃ of the connecting line 17 is 1 mm, and the gap δ is 0.4 mm. The width W ₄ from the side of the loop portion 20 on the upper side 20 _U side to the lower side 20 _L is 20 mm. The width W ₅ from the tip of the electromagnetic coupling wire 17 extending toward the lower side to the lower side 20 _L is 9 mm. The width dimension W ₆ from the tip of the power feeding line 13 extending toward the upper side 20 _U to the side of the loop portion 20 facing the tip of the power feeding line 13 is set to 15 mm.

In the above electromagnetically coupled 4-point feeding loop antenna, when the feeding impedance is set to 50Ω, the width dimension W ₁ of the loop portion 20 and the feeding line 13 are set.
The width dimension W _{2 of the} and the width dimension W ₃ of the electromagnetic coupling wire 17 are 1 mm
And the gap δ is 0.4 mm. Upper side (20 _U )
Width W ₄ from the side of the side loop part 20 to the lower side 20 _L
Is 20 mm, and the width dimension W from the tip of the electromagnetic coupling wire 17 extending toward the lower side 20 _L to the lower side 20 _L
5 is 5 mm, and the width W ₆ from the tip of the power feeding line 13 extending toward the upper side 20 _U to the side of the loop portion 20 facing the tip of the power feeding line 13 is 12 mm.

Further, in the electromagnetic coupling type four-point feeding loop antenna, when the feeding impedance is set to 100Ω, the width dimension of the width W _1, the width W ₂ and the electromagnetic coupling line 17 of the feed line 13 of the loop portion 20 W ₃ is 1 mm and the gap δ is 0.4 mm. The width W ₄ from the side of the loop portion 20 on the upper side 20 _U side to the lower side 20 _L is 20
and mm, the width _{W 5} from the tip of the electromagnetic coupling line 17 to the lower side 20 _L extending toward the lower bottom edge 20 _L 3m
As m, the power supply line 13 extending toward the upper side 20 _U
The width W ₆ from the tip of the above to the side of the loop portion 20 facing the tip of the power supply line 13 is set to 8 mm.

FIGS. 4A and 4B show an electromagnetic coupling type four-point feeding loop antenna 10 according to the second embodiment. In the following description, the configuration is the same as that of the first embodiment except for the pole antenna,
The same reference numerals as those of the first embodiment are given, and the description other than the pole antenna is omitted.

Referring to FIGS. 4A and 4B, the electromagnetic coupling type four-point feeding loop antenna 10 has a pole antenna 30. That is, the electromagnetically coupled four-point feeding loop antenna 10 is an antenna device that integrally includes a loop antenna / monopole antenna, and the electromagnetically coupled four-point feeding loop antenna 10 can receive satellite waves. The pole antenna 30 can receive ground waves.

The pole antenna 30 is provided on the central axis O of the tubular body 11 formed by rolling an insulating film member around the central axis O in a tubular shape. In this embodiment, the protrusion length dimension above the pole antenna 30 is 1.
It is set to 8 mm.

Although the present invention has been described with reference to the preferred embodiments, it goes without saying that the present invention is not limited to the above-mentioned embodiments. For example, in the above embodiment, the power supply line 13 (main power supply line portion 131) and the electromagnetic coupling line 1 are provided.
7 extends in a direction substantially perpendicular to the lower side 20L of the insulating film member 20, but it goes without saying that it may extend in a substantially oblique direction.

[0035]

As is apparent from the above description, in the present invention, a gap is provided between the loop portion and each of the four power supply lines, and power is supplied to the loop portion by electromagnetic coupling. The effect that impedance matching can be taken easily is exhibited.

[Brief description of drawings]

FIG. 1 shows a configuration of an electromagnetically coupled four-point feeding loop antenna according to a first embodiment of the present invention, (a) is a plan view and (b) is a front view.

FIG. 2 is a perspective view showing an arrangement relationship between a loop portion and four feeders, which configure the electromagnetically coupled four-point feeding loop antenna shown in FIG.

FIG. 3 is a development view of the electromagnetically coupled four-point feeding loop antenna of FIG.

FIG. 4 shows a configuration of an electromagnetically coupled four-point feeding loop antenna according to a second embodiment of the present invention, (a) is a plan view and (b) is a front view.

[Explanation of symbols]

10 Electromagnetically coupled 4-point feeding loop antenna 11 cylinder 12 loop section 13 power lines 14 circuit board 15 Phase shifter 16 Solder 17 Electromagnetic coupling wire 20 Insulating film member 30 pole antenna

Continued front page    (72) Inventor Toshihiko Inaba             2 Mitsu, 8-8, Kokuryo-cho, Chofu-shi, Tokyo             Mi Electric Co., Ltd. F term (reference) 5J046 AA03 AA07 AB11 MA00 PA07                       PA09

Claims (5)

[Claims] 1. A tubular body formed by rolling a flexible insulating film member around a central axis into a tubular shape, and a tubular body formed along the circumferential surface of the tubular body around the central axis in a loop shape. A loop portion formed of a conductor and four power feeding lines that feed power to the loop portion formed on the peripheral surface of the tubular body. And four electromagnetic coupling lines that extend along the four power supply lines from the loop portion are connected to each other in a state where a gap is formed, and a power supply impedance that supplies power by electromagnetic coupling is 2
When set to 5Ω to 100Ω, the width of the loop portion, the width of the feeder line and the width of the electromagnetic coupling line are the same, and the gap is 0.2 to 0.8m.
An electromagnetically coupled four-point feed loop antenna characterized by being in the range of m. 2. The insulating film member has a substantially rectangular shape having an upper side, a lower side, a first side and a second side, and the first side and the second side. The tubular body is formed by connecting the side edges of the insulating film member to each other, and the loop portion is formed on one surface of the insulating film member in the vicinity of the upper side. The electromagnetically coupled four-point feeding loop antenna according to claim 1, wherein the insulating film member extends from the lower side to the vicinity of the loop portion. 3. When the feeding impedance is set to 25Ω, the width of the loop portion, the width of the feeding wire and the width of the electromagnetic coupling wire are 1 mm, and the gap is 0.4 mm. And the width dimension from the side of the loop portion on the upper side to the lower side is 20 mm, and the width dimension from the tip of the electromagnetic coupling wire extending toward the lower side to the lower side is 9 mm. The width dimension from the tip of the feed line extending toward the upper side to the side of the loop portion facing the tip of the feed line is 15 mm. The electromagnetically coupled 4-point feeding loop antenna described. 4. When the feeding impedance is set to 50Ω, the width of the loop portion, the width of the feeding wire and the width of the electromagnetic coupling wire are 1 mm, and the gap is 0.4 mm. The width dimension from the side of the loop portion on the upper side to the lower side is 20 mm, and the width dimension from the tip of the electromagnetic coupling wire extending toward the lower side to the lower side is 5 mm. The width dimension from the tip of the power supply line extending toward the upper side to the side of the loop portion that faces the tip of the power supply line is 12 mm. The electromagnetically coupled 4-point feeding loop antenna described. 5. When the feeding impedance is set to 100Ω, the width of the loop portion, the width of the feeding wire and the width of the electromagnetic coupling wire are 1 mm, and the gap is 0.4 mm. And the width dimension from the side of the loop portion on the upper side to the lower side is 20 mm,
The width dimension from the tip of the electromagnetic coupling wire extending toward the lower side to the lower side is 3 mm, and from the tip of the power feeding line extending toward the upper side to the tip of the power feeding line. The electromagnetic coupling type four-point feeding loop antenna according to claim 1 or 2, wherein a width dimension to the sides of the facing loop portions is 8 mm.