JP2002141725A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna of a structure by which a frequency deviation caused when the antenna is mounted onto a printed circuit board or the like can simply be adjusted in matching the printed circuit board while the antenna of the same characteristics is manufactured and to provide an antenna system. SOLUTION: The antenna system consists of the antenna 10 where radiation elements 13 are provided on one side (front side), a ground conductor 11 is provided to the other side (rear side), and one-side ends of the radiation elements 13 are extended to the other side to form connection sections 13a and of the printed circuit board 20 on which the ground conductor 11 of the antenna 10 is mounted and onto which stubs 23 of a connection pattern 23, to which the connection sections 13a of the radiation elements 13 are connected, are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bluetooth or GPS (global positioning system).
The present invention relates to an antenna device in which a small antenna such as an inverted F antenna or a ceramic antenna is mounted on a circuit board such as a printed board. More specifically, the present invention relates to an antenna device that can easily adjust a deviation of a resonance frequency caused by being mounted on a circuit board or the like.

[0002]

2. Description of the Related Art In order to receive radio waves propagating in a space, antennas are usually arranged in a space so as to be able to receive radio waves from all sides. However, in some cases, such as for Bluetooth or GPS, the device may be directly mounted on a part of a circuit board or the like on which a signal processing circuit or the like is formed due to a demand for downsizing of the device. As such an antenna, an antenna having a structure in which a patch antenna element is provided on a surface thereof using a ceramic substrate in order to reduce the size of the antenna is known. That is, as shown in FIG. 5, a patch antenna element 22 is arranged on the front surface of the ceramic substrate 21, and a ground conductor 23 is provided on the back surface thereof. A power supply pin 24 is connected to a power supply portion 22a provided on the back side through a through hole provided in the ceramic substrate 21 and the ground conductor 23. Then, the ground conductor portion on the back surface is connected to a ground conductor on the back surface such as a circuit board, and the power supply portion is mounted by being bonded so as to be connected to a power supply portion formed on the circuit board.

[0003]

In an antenna in which a conductive film is formed on a dielectric substrate such as a ceramic as in the above-described patch antenna, the area of the patch antenna element, the thickness and the dielectric constant of the dielectric substrate are considered. Defines the resonance frequency, and is formed so as to correspond to the frequency of a desired reception signal. However, as described above, when mounted on a circuit board or the like, a shift in resonance frequency occurs due to the dielectric constant or thickness of the circuit board. In other words, when the antenna is mounted on a circuit board, the shape of the board or the surrounding conditions such as the thickness of the radome (case), the material, or the distance from the radiating element, etc., change from the state where the antenna is first tuned to the position where the antenna is mounted. And the resonance frequency changes.

Therefore, conventionally, a patch antenna itself is designed and manufactured so as to operate as a desired antenna in a state where the patch antenna is mounted on a circuit board, or a resonance frequency is adjusted by a variable capacitor after a variable capacitor is added and mounted. Is adopted. However, if the antenna itself is designed according to its mounting substrate, the type of substrate changes depending on the type of equipment, and if the material or thickness of the substrate changes, resonance will not occur at the desired frequency or the antenna will be manufactured each time. There is a problem that must be fixed. In addition, externally attaching a variable capacitor increases the number of parts and increases the cost, and requires more space, which goes against the recent trend toward smaller and lighter electronic devices. There is a problem that inconvenience occurs.

The present invention has been made in order to solve such a problem. As an antenna, a constant antenna is always manufactured, and a frequency deviation generated when the antenna is mounted on a circuit board or the like is removed. It is an object of the present invention to provide an antenna having a structure that can be easily adjusted while being mounted on a circuit board, and an antenna device integrated with a circuit board.

[0006]

An antenna according to the present invention comprises a dielectric substrate, a radiating element provided on a surface of the dielectric substrate, a power supply for supplying power to the radiating element, and a back surface of the dielectric substrate. The radiation element is extended to the back surface of the dielectric substrate to form a connection portion. When the back surface of the dielectric substrate is mounted on the circuit board, The radiating element is formed so that the connection portion can be electrically connected to a stub formed in the stub.

[0007] With this structure, even when the semiconductor device is directly mounted on a circuit board and the resonance frequency varies depending on the circuit board, the length of the stub provided on the circuit board side is adjusted to adjust the stub length. Can be resonated in a required frequency band in a state in which the above characteristics are added.

In the antenna device according to the present invention, a radiating element is provided on one surface side, a ground conductor is provided on the other surface side, and one end of the radiating element is extended to the other surface side to form a connection portion. And a circuit board on which the ground conductor portion of the antenna is mounted and a stub is formed in a connection pattern to which a connection portion of the radiating element is connected.

Here, one side means a side that radiates or receives radio waves, and the other side means an opposite side,
When formed on a dielectric substrate, they correspond to the front side and the back side, but even if there is no dielectric substrate and a radiating element and a ground conductor are provided through space, the side that radiates or receives radio waves is one side Means side.

With this configuration, even when the circuit board is slightly different depending on the device on which the antenna is mounted, and the resonance frequency is shifted, the stub formed on the circuit board is maintained as a constant antenna. By simply adjusting the length, it is possible to resonate very easily and reliably in a desired frequency band. In addition, since the resonance frequency can be adjusted while mounted on the circuit board, an antenna can be surely resonated in a desired frequency band even when its frequency characteristics change due to the thickness or material of the printed circuit board or the like. . On the other hand, once the specifications of the circuit board are determined and its thickness or permittivity becomes constant, if the circuit board is formed by printing with a pattern of the adjusted dimensions, then it is necessary to adjust the frequency one by one. Disappears.

Specifically, a connecting portion of the radiating element is connected to the ground conductor on the other surface, and a stub provided on the circuit board includes a connecting pattern connected to the connecting portion of the radiating element. The opposite end is formed by an open stub that is opened, or the connection part of the radiating element is not connected to the ground conductor on the other surface side, and the stub provided on the circuit board is a stub of the radiating element. An end opposite to the connection pattern connected to the connection portion is formed of a short stub connected to a ground plate provided on the circuit board.

For example, in the case of an open stub, the antenna is formed so as to resonate in a frequency band slightly lower than a desired frequency band, and the stub is cut and adjusted sequentially with the antenna mounted on a circuit board. By
The resonance frequency can be accurately adjusted in accordance with the characteristics of the antenna mounting board, and in the case of a short stub, the resonance frequency of the antenna alone is set to resonate in a frequency band slightly higher than the desired frequency band. The length of the stub is increased by shifting the short surface of the stub, so that resonance can be performed in a desired frequency band.

A plurality of radiating elements are provided, and by slightly detuning the resonance frequency of the plurality of radiating elements, it is possible to broaden the transmittable / receivable frequency band. Is also preferred because it is easier to adjust.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an antenna and an antenna device according to the present invention will be described with reference to the drawings.
The antenna device according to the present invention is provided with a radiating element 13 on one surface (front surface) side and the other surface (back surface), as shown in FIG. 1 showing an antenna of one embodiment and an antenna mounting portion of a circuit board. Antenna 10 in which a ground conductor 11 is provided on one side and one end of radiating element 13 extends to the other surface side to form connecting portion 13a;
No. 0 ground conductor 11 is mounted and connection pattern 23a to which connection portion 13a of radiating element 13 is connected.
And a circuit board 20 on which a stub 23 is formed. The example shown in FIG. 1 is an example of an open stub in which the tip of the stub 23 is opened.

An antenna according to the present invention is shown in FIGS. 1 (a) and 1 (b) as an explanatory view of one embodiment thereof.
The radiating element 13 and the excitation electrode 12 for feeding power to the radiating element 13 are provided on the surface of the dielectric substrate 16, and the ground conductor 11 and the feeding unit 14 are provided on the back surface of the dielectric substrate 16. One end of the radiating element 13 extends to the back surface of the dielectric substrate 16 to form a connection portion 13a. When the back surface of the dielectric substrate is mounted on the circuit board 20, Stub 23 formed on
The radiating element 13 is formed so that it can be electrically connected to the radiating element 13. In the example shown in FIG. 1, the connecting portion 13a extending to the back surface of the dielectric substrate 16 of the radiating element 13 is
1 are directly connected to each other to form a short surface.

In the example shown in FIG. 1, a radiating element 13 is provided on the surface of a dielectric substrate 16 made of, for example, ceramics, and the ground conductor 11 is provided on the back surface as shown in FIG. The radiating element 13 is provided on almost the entire surface except for the connection portion 13a which is one end thereof.
The excitation is performed via the excitation electrode 12. Reference numeral 15 denotes a power supply electrode that connects the power supply unit 14 and the excitation electrode 12.

As the dielectric substrate 16, a material having a dielectric constant as large as possible is preferable because the radiating element 13 can be made small. For example, BaO—TiO ₂ —SnO ₂ ,
It is preferable to use a ceramic such as MgO-CaO-TiO ₂ because the relative dielectric constant is about 30 or more. Also,
The ground conductor 11, the excitation electrode 12, and the radiating element 13
It is preferable to provide a conductive film such as a silver film provided on the dielectric substrate 16 by printing or vacuum deposition and patterning, which can be easily formed. However, the present invention is not limited to this example. Alternatively, a structure in which conductive plates are arranged on the dielectric substrate 16 may be used.

The excitation electrode 12 is an electrode for exciting a signal from the power supply unit 14 to the radiation element 13 or transmitting a signal received by the radiation element 13 to the power supply unit 14.
It is formed to have a length considerably smaller than / 4 wavelength, and is capacitively coupled to the radiating element 13 at the tip where the voltage is the maximum, and the other end is connected to the feeder 14. In the example shown in FIG. 1, the power supply electrode 15 is provided at the other end.
Feeder 14 provided on the back surface of dielectric substrate 16 through
Is connected to

The radiating element 13 is, in the example shown in FIG.
It consists of three arranged in parallel, each of which is, for example, 2417 MHz, 2450 MHz, 2483 MH
It has an electrical length that resonates at z. The width may be a width sufficiently shorter than the length, and each is formed to about 0.5 to 1 mm. Further, the distance between the radiating elements 13 is set to a value that does not cause mutual interference, for example, about 0.5 to 1 mm. That is, by using a plurality of radiating elements and slightly shifting the resonance frequency as in this example, resonance can be achieved in a wide band, and a wideband antenna can be realized. Then, as described above, one end of each radiating element 13 extends to the back surface of the dielectric substrate 16, and the circuit board 20
Connecting part 13 so that it can be connected to the connecting pattern 23a.
a is formed.

In the example shown in FIG. 1, each radiating element 13 has an end (the other end) on the surface side of the excitation electrode 1.
2 and a length thereof (the ground conductor 11 on the back surface of the dielectric substrate 16).
The length of the connection portion 13a is set to an electrical length of λ / 4, and the connection portion 13a at one end extends to the back surface via the side surface of the dielectric substrate 16 as described above, and It is connected. The physical length of the radiating element 13 also changes depending on the dielectric constant of the dielectric substrate 16, and when the relative dielectric constant of the dielectric substrate 16 is ε _r , the physical length is proportional to 1 / ε _r ^1/2. Target length can be shortened.

In the example shown in FIG. 1, the power supply section 14 is provided on the back surface of the dielectric substrate 16 on the same surface as the ground conductor 11, and is excited via the power supply electrode 15 provided on the side surface of the dielectric substrate 16. It is electrically connected to the electrode 12 for use, and has a structure in which it can be directly connected to the power supply line 24 of the circuit board by being mounted on the circuit board 20 or the like.

As the circuit board 20, a normal printed board made of, for example, glass epoxy resin is used, and printed wiring is provided on the surface side, and electronic components such as transistors are connected to form a signal processing circuit and the like. I have. As shown in FIG. 1C, a ground plate 21 made of a metal film is provided on a part of the surface, and a mounting portion of the antenna 10 is provided with a feeding portion 14 of the antenna. A power supply line 24 and a radiating element connection pattern 23a are formed so as to be connectable. The radiating element connecting pattern 23a is connected to the connecting portion 13 of the antenna 10.
It is longer than the length a and is formed so as to protrude from the antenna 10 portion, and is characterized in that a stub 23 is formed.

In the example shown in FIG. 1, the tip of the stub 23 is open and formed so as to face the ground plate 21, and as shown in the equivalent circuit diagram of FIG. And a capacitance C between the tip of the stub 23 and the ground plate 21 in a parallel circuit, and when the antenna 10 is mounted, this LC
The circuit has a structure hanging from the radiating element 13. In this case, even if the length of the stub 23 changes, the inductance L does not change much and the change of the capacitance C is large. Therefore, when the length of the stub 23 is changed, as shown in FIG.
It has the function of making the capacitance C variable. That is,
After the antenna 10 is mounted on the mounting portion, the tip of the stub 23 is cut while measuring the antenna characteristics, so that the capacitance C is reduced, the capacitive impedance is reduced, and the resonance frequency is increased. It can be adjusted.

In other words, the antenna 10 is manufactured in advance so that the resonance frequency thereof is slightly lower than the frequency band of the desired reception signal, and after mounting on the circuit board 20, the antenna characteristics of the stub 23 are measured while measuring the antenna characteristics. By cutting the tip, it is possible to resonate in a desired frequency band of a signal to be transmitted and received.

According to the antenna device of the present invention, a stub is formed on a radiating element connection pattern provided on a substrate on which an antenna such as a circuit board is mounted, and the length of the stub is adjusted with the antenna mounted. By doing so, it is formed so as to resonate in a desired frequency band, so that it is possible to always resonate in a desired frequency band irrespective of variations due to a change in circuit board model or lot. In addition, if it is constant for each model, by forming the circuit board with the length of the stub having such adjusted dimensions, an antenna device having desired resonance characteristics can be obtained without any subsequent adjustment. .

In the above-described example, the antenna has a structure in which the connecting portion 13a, which is one end of the radiating element 13 extending to the back surface of the dielectric substrate 16, is connected to the ground conductor 11, and FIG. 3 shows an example in which the tip of the stub 23 formed in the pattern 23a is open.
As shown in FIG. 1, which illustrates the same back surface of the antenna 10 as that of FIG. 1 and a portion where the antenna 10 of the circuit board 20 is mounted, the connection portion 13a of the radiating element 13 is When the circuit board 20
May be formed so as to be connected to the ground plate 21.

In this case, the tip of the stub 23 formed on the connection pattern 23a of the circuit board 20 is
The ground plane 21 of the short plane S, which is connected to the ground plane 21 of the short plane S, moves the short plane S farther from the antenna 10 and the radiating element 13 becomes substantially longer, The frequency can be adjusted to decrease. That is, contrary to the example shown in FIG. 1, the resonance frequency of the antenna whose resonance frequency has been set slightly higher in advance can be lowered and adjusted so as to resonate at a desired frequency. In this case, since the connection portion S of the circuit board 20 with the ground plate 21 becomes a short-circuit surface of the radiating element 13, the stub 23 formed on the circuit board 20 also constitutes a part of the length of the radiating element 13. And its length changes directly, making it very sensitive to frequency adjustments.

In each of the above examples, there are three radiating elements,
The antenna could be broadened by slightly shifting each resonance frequency, but it is not limited to this example.
As shown in FIG. 4, even in the case where one radiating element 13 is formed so as to operate in a single resonance frequency band, the connection pattern provided on the circuit board and the radiating element are connected in exactly the same manner. By adjusting the length of the stub formed in the connection pattern, the resonance frequency of the antenna can be adjusted to a desired frequency band. In addition, as shown in FIG.
3, or a structure provided over the entire width of the dielectric substrate 16.

In each of the above-described examples, the ceramic substrate is used as the substrate, and the ceramic antenna is excited through the excitation electrode. However, the present invention is not limited to the ceramic substrate, and an antenna such as a normal patch antenna may be used. , Reverse F
The same applies to an antenna having a structure in which a radiating element is formed on its surface, one end of which is extended to the back surface side, and which can be connected to a connection pattern of a circuit board on its back surface like an antenna. be able to.

[0030]

According to the present invention, an antenna mounted on a circuit board always transmits / receives a desired signal by a simple operation even if the thickness or material of the circuit board or the like changes and its electric constant changes. The antenna device can resonate in a frequency band and can have an extremely excellent antenna characteristic. As a result, even if the circuit board changes slightly due to a change in the model or lot, etc., without changing the design of the antenna one by one, simply adjusting the pattern of the circuit board to the adjusted pattern will always produce resonance characteristics. It can operate as an excellent antenna.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an embodiment of an antenna device according to the present invention.

FIG. 2 is an equivalent circuit diagram of the radiation element connection pattern of FIG.

FIG. 3 is a configuration explanatory view showing another embodiment of the antenna device according to the present invention.

FIG. 4 is a structural explanatory view showing still another embodiment of the antenna device according to the present invention.

FIG. 5 is a diagram showing an example of an antenna using a conventional ceramic substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna 13 Radiation element 13a Connection part 14 Feeding part 16 Dielectric substrate 20 Circuit board 23 Stub 23a Connection pattern

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hironori Okado 7-5-11 Takinogawa, Kita-ku, Tokyo Inside Yokoo Co., Ltd. (72) Inventor ▲ Kuzu ▼ Shunsho 7-5-1 Takinogawa, Kita-ku, Tokyo No. Yokowo F-term (reference) 5E338 AA01 BB75 CC01 CC06 CD13 CD25 EE11 EE32 5J045 AA01 AB06 EA07 HA03 NA01 5J046 AA01 AA07 AA09 AA19 AB13 PA07

Claims (5)

[Claims] 1. A dielectric substrate, a radiating element provided on a surface of the dielectric substrate, and a power supply unit for supplying power to the radiating element;
A ground conductor provided on the back surface of the dielectric substrate, wherein the radiating element extends to the back surface of the dielectric substrate to form a connection portion, and the back surface of the dielectric substrate is mounted on a circuit board. An antenna in which the radiating element is formed such that the connecting portion can be electrically connected to a stub formed on the circuit board when the radiating element is connected to the stub. 2. An antenna in which a radiating element is provided on one side and a ground conductor is provided on the other side, and one end of the radiating element extends to the other side to form a connection part; An antenna device comprising: a circuit board on which the ground conductor portion of the antenna is mounted and a stub is formed on a connection pattern to which a connection portion of the radiation element is connected. 3. A connecting portion of the radiating element is connected to the ground conductor on the other surface side, and a stub provided on the circuit board is provided on a side opposite to a connection pattern connected to the connecting portion of the radiating element. 3. The antenna device according to claim 2, wherein the antenna device is an open stub whose end is opened. 4. A connecting portion of the radiating element is not connected to the ground conductor on the other surface side, and a stub provided on the circuit board is opposite to a connection pattern connected to the connecting portion of the radiating element. 3. The antenna device according to claim 2, wherein the end on the side is a short stub connected to a ground plate provided on the circuit board. 5. A plurality of radiating elements are provided on one surface side of a dielectric substrate, and by slightly detuning the resonance frequencies of the plurality of radiating elements, a wider band of frequencies that can be transmitted and received is achieved. The antenna device according to claim 2, 3 or 4.