JP2002314325A - Surface mount patch antenna for linear polarization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount patch antenna for linear polarization, which has a structure capable of being automatically mounted on a circuit board, etc., while improving antenna performance by providing a length of about 1/2 wavelength of a used frequency band and operating in a patch mode. SOLUTION: An antenna radiation electrode 2 having an electrical length of about 1/2 wavelength in the frequency band of a signal to be transmitted and received in the length in one direction is provided on one face of a dielectric board 1, a feeder line 3 is formed on one side face of the dielectric board 1 while the antenna radiation electrode 2 is displaced from a central part in the length in the one direction and connected with a side edge at a position where impedance matching is performed, and a feeder 4 is provided on the rear face of the dielectric board 2 by connecting to the feeder line 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type in which an antenna radiation electrode is formed with an electrical length of 1/2 wavelength in a frequency band of a signal to be transmitted and received on a dielectric substrate surface, and linearly polarized waves operate in a patch mode. The present invention relates to a patch antenna for linear polarization. More specifically, power supply to the antenna radiation electrode
A surface mount type linearly polarized patch antenna that enables surface mounting by being connected to an antenna radiation electrode and through a feed line provided on the side of the dielectric substrate by a feed unit formed on the back surface of the dielectric substrate. About.

[0002]

2. Description of the Related Art As shown in FIG. 3, an example of a patch antenna for a circularly polarized wave is an antenna radiation electrode 22 made of a conductive film on one surface of a dielectric substrate 21 and having a side λ / side.
2 (λ is the wavelength of the frequency band to be transmitted / received) and is formed in a substantially square shape (the ratio of length to width affects characteristics such as gain and bandwidth).
A feed point 22a is provided at a position displaced in the axial direction and in the y-axis direction, a feed pin 23 is connected to the feed point 22a, and the other end of the feed pin 23 is connected to a feed circuit. I have. In the patch antenna, the center of the antenna radiation electrode is the maximum point of the current, and the current is the minimum at the end, that is, the distribution is such that the voltage is the maximum. However, there is an impedance of about 50Ω which is the impedance on the power supply side, and the power supply point 23a is formed in that part. Then, on the back surface of the dielectric substrate 21, a conductive film serving as the ground electrode 25 is formed. The power supply pin 23 is separated from the ground electrode 25 and is led out to the lower side.

[0003] In the case of circularly polarized waves, the x-axis direction shown in FIG.
Since there is a current component in both the axial direction, the x-axis direction, y
Each of them is formed so as to have an electrical length of about 波長 wavelength in both axial directions. However, when used as linearly polarized light, about 方向 wavelength is used only in one direction (for example, the x direction in FIG. 3). The other width (for example, in the y-axis direction) is determined by the band characteristics of the antenna.

[0004]

As described above, the length of the patch antenna is approximately 1/1 of the used frequency band.
Although it has an electrical length of two wavelengths and has a drawback in terms of miniaturization, its antenna characteristics are far superior to inverted F antennas and the like, and have excellent antenna characteristics such as high gain and high bandwidth. For antennas requiring performance, it is also used for linear polarization. However, since this patch antenna has a structure in which power is supplied via a power supply pin that is led out while avoiding a ground electrode provided on the back surface of the dielectric substrate,
When an antenna is mounted, it cannot be directly connected to a circuit board or the like by soldering or the like. Therefore, there is a problem that handling is very troublesome and automatic mounting cannot be performed.

The present invention has been made in order to solve such a problem, and has a length of about 1/2 wavelength of a frequency band to be used, and operates in a patch mode.
It is an object of the present invention to provide a surface-mounted linearly polarized patch antenna having a structure that can be automatically mounted on a circuit board or the like while improving antenna performance.

[0006]

According to the present invention, a surface mount type linearly polarized patch antenna according to the present invention is provided on a dielectric substrate, and is provided on one surface of the dielectric substrate. An antenna radiation electrode having an electrical length of about 波長 wavelength, and a side edge portion at a position where the antenna radiation electrode is displaced from a central portion of the length in the one direction and impedance-matches with a power supply side, The power supply line includes a power supply line formed on a side surface of the dielectric substrate, and a power supply unit connected to the power supply line and formed on the back surface of the dielectric substrate. Here, the patch antenna refers to an antenna that has an antenna radiation electrode having an electrical length of about ほ ぼ wavelength in at least one direction and can operate in a patch mode in which a current is maximized at a central portion thereof. It is not necessary that the sides are formed to have a predetermined length and that circularly polarized waves can be transmitted and received.

With this structure, the antenna radiation electrode has an electrical length of approximately 波長 wavelength and operates in the patch mode. Therefore, an inverted-F antenna having an electrical length of １ ／ wavelength is used. Compared to an antenna with very high performance antenna characteristics, its feeder is formed on the back surface of the dielectric substrate via a feed line provided on the side of the dielectric substrate, so that it can be used as a circuit board. When the antenna is mounted on a circuit board, the antenna according to the present invention can be mounted on a circuit board and soldered by, for example, reflow. As a result, a high-performance patch mode antenna having antenna characteristics can be easily mounted on a circuit board or the like, and usability is greatly improved.

Since the power supply line is formed in a coplanar coaxial structure in which a ground conductor connected to a ground electrode is provided on both sides of the power supply line, a loss in the power supply line is reduced, and the antenna characteristics are further improved. improves.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A surface mount type linearly polarized patch antenna according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view and a bottom view of one embodiment of a surface mount type linearly polarized patch antenna according to the present invention. As shown in FIG. An antenna radiation electrode 2 having an electrical length of approximately ほ ぼ wavelength in a signal frequency band is provided, and the antenna radiation electrode 2 is displaced from a central portion of the length in the one direction in a position where impedance matching with a feed side is performed. A power supply line 3 is formed on one side surface of the dielectric substrate 1 connected to the edge, and a power supply unit 4 is provided on the back surface of the dielectric substrate 1 connected to the power supply line 3.

The dielectric substrate 1 is preferably made of a high dielectric constant ceramic such as barium titanate (having a relative dielectric constant of about 20). The use of a dielectric having a high dielectric constant as the dielectric substrate 1 is preferable because the antenna radiation electrode 2 can be reduced in size and the entire antenna can be reduced. Ceramics having a thickness of about 2 to 5 mm are used.

The size of the antenna radiation electrode 2 varies depending on the intended frequency band to be used.
Antennas (frequency band; 2.5 GHz band)
The length L is about 20 mm and the width W is about 4 mm.
By firing a printed material such as a silver paste on which a good conductor is printed, a conductive film having a thickness of about 10 to 20 μm is formed. A ground electrode 5 is formed on the back surface of the dielectric substrate 1 facing the antenna radiation electrode 2 by similarly providing a conductive film such as a silver paste by thick film printing or the like. That is, a patch antenna is formed by providing the antenna radiation electrode 2 and the ground electrode 5 with the dielectric substrate 1 interposed therebetween. The antenna radiation electrode 2 and the ground electrode 5 may be formed to have the same size as the dielectric substrate 1, and as shown in the antenna radiation electrode 2 of FIG. The structure which makes it do.

Since the radiation electrode 2 is used for linearly polarized light, it is sufficient that the length L has an electrical length of approximately 波長 wavelength, and the width W is not particularly limited. Since the characteristics are improved, according to the desired band characteristics,
For example, it is formed in the dimensions described above. With respect to linearly polarized waves, the antenna radiating electrode 2 has a current flowing in the length L direction and has a maximum current at the center thereof.
For this reason, the impedance is close to 0 at the center thereof, and the impedance increases as it shifts sideways. By feeding power to a place where the impedance on the feeding side becomes 50Ω, a loss occurs between the feeding side and the antenna radiation electrode. Both can be combined without the need.

With respect to linearly polarized waves, since there is a current component only in the length L direction, the impedance hardly changes in the width direction. Therefore, in the present invention, the power supply line 3 is connected to the position of the impedance of 50Ω, which is displaced laterally from the center O in the length L direction by a, and moved to the end in the width direction, A power supply line 3 is connected to a power supply unit 4 provided on the back surface of the dielectric substrate 1 via a side surface of the dielectric substrate 1.

According to the present invention, since the current direction of the patch antenna with respect to the linearly polarized wave is only in a fixed direction, the feeding point to the antenna radiating electrode is in the width direction perpendicular to the current direction. In the above, power is supplied from the end in the width direction by utilizing the property that the impedance hardly changes even when the impedance is not at the center in the width direction. Then, a structure is provided in which a side end of the antenna radiation electrode is connected to a power supply unit provided on the back surface of the dielectric substrate via a power supply line provided on a side surface of the dielectric substrate. As a result, since the power supply portion is formed on the back surface of the dielectric substrate to be connected to the power supply wiring such as a circuit board, for example, a solder paste is applied, and the antenna radiation electrode side is directed upward.
It can be mounted simply by placing the dielectric substrate on the circuit board and soldering.

In the above-described example, since the antenna radiation electrode 2 is not formed on the entire surface of the dielectric substrate 1 and the dielectric substrate 1 is exposed therearound, the feed line 3 is formed on the surface of the dielectric substrate 1. However, if the antenna radiation electrode 2 is formed on the entire surface of the dielectric substrate 1,
As a matter of course, the power supply line 3 is provided only on the side surface of the dielectric substrate 1. Note that the power supply unit 4 is formed to have a sufficient size such as soldering, and may be formed wider than the power supply line. The rear surface of the third dielectric substrate may be formed wider.

In the above-described example, the power supply line is formed directly on the side surface of the dielectric substrate 1. However, when the thickness of the dielectric substrate 1 is large, there is a risk that the impedance of the power supply line 3 shifts and the loss increases. There is. In such a case, as shown in FIG. 2, the feed line 3 may be a coplanar coaxial line.

That is, FIG. 2 is a view similar to the side view of FIG. 1, and the dielectric substrate 1, the antenna radiation electrode 2, and the ground electrode 5 are the same as the example shown in FIG. FIG.
Is characterized in that a ground conductor 5a is formed on both sides of the power supply line 3 so as to be continuous with the ground electrode 5. That is, since the power supply line 3 and the ground conductor 5a are formed on the same plane and the power supply line 3 is sandwiched between the ground conductors from both sides, a coplanar type coaxial structure is formed to prevent unnecessary radiation. The same impedance as the coaxial line is maintained. Ideally, the ground conductor 5a extends over both sides of the feed line 3 as much as possible, and preferably has an infinite lateral width.
When the ground conductor 5a comes close to this, the radiation characteristics of the radiation electrode 2 deteriorate, which is not preferable. For example, in the antenna having the dimensions shown in FIG. 1, the distance A between the ground conductor 5a and the feed line 3 is about 0.1 mm, and the height B from the bottom surface of the dielectric substrate 1 is about 1.5 to 2 mm (dielectric material). The thickness C of the substrate 1 is 2.5
mm), and the width D of the power supply line 3 is formed to be about 1 mm.

With this structure, the power supply line 3
Has a coplanar coaxial structure, so that its impedance can be maintained at about the same level as that of the coaxial line, the impedance can be matched with the power supply unit side on the circuit board side, and the efficiency of the entire antenna can be improved. .

[0019]

According to the present invention, the patch antenna is formed in a surface mount type while utilizing the high performance of the patch antenna.
Even when an antenna is mounted on a circuit board or the like, it can be mounted very easily without requiring connection by a power supply pin. As a result, the antenna can be automatically mounted on the circuit board and soldered, etc., which significantly reduces the assembly cost and greatly contributes to the cost reduction of electronic devices with the antenna, such as mobile phones. I do.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an antenna according to the present invention.

FIG. 2 is an explanatory side view showing another embodiment of the antenna according to the present invention.

FIG. 3 is an explanatory diagram of a conventional patch antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Antenna radiation electrode 3 Feeding line 4 Feeding part 5 Ground electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Yamaho 1112 Shinnohara, Tomioka-shi, Gunma Inside Yokoo Tomioka Plant Co., Ltd. (72) Inventor Hironori Okado 7-5-11 Takinogawa, Kita-ku, Tokyo Stock Company F-term in YOKOWO Company (reference) 5J045 AA01 AA02 CA01 DA10 EA07 HA05 5J046 AA04 AA07 AB13 PA07

Claims (2)

[Claims] 1. A dielectric substrate, an antenna radiating electrode provided on one surface of the dielectric substrate and having an electrical length of approximately 波長 wavelength in a frequency band of a signal transmitted and received in one direction, and the antenna A power supply line formed on a side surface of the dielectric substrate, which is connected to a side edge portion at a position displaced from a central portion of the length of the radiation electrode in the one-direction length and impedance-matched with a power supply side, and the power supply line, A surface mounting type linearly polarized patch antenna comprising: a power supply portion connected to a back surface of the dielectric substrate; 2. The patch antenna according to claim 1, wherein the feed line is formed in a coplanar coaxial structure.