JPH10341107A - Surface mount antenna and antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount antenna and an antenna system with a high antenna gain and a wide specific band width. SOLUTION: Two through holes 8 are made from one end face of a rectangular prism base 1 toward an opposite end face, a ground electrode 2 is formed onto one major side of the base 1, and a radiation electrode 3 whose one end connects to the ground electrode and whose other end acts like an open end is formed to the other major side to one end face. Moreover, a feeding electrode 4 is formed from one major side of the base 1 to the other major side via one end face, and a ground electrode 5 is formed to the other end face opposed to the end face on which the feeding electrode 4 is formed. The feeding electrode 4 and the open end of the radiation electrode 3 are placed close to each other via a gap 6, and part of the radiation electrode 3 and the ground electrode 5 are placed close to each other via a gap 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount antenna used for mobile communication equipment and the like, and an antenna device.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional surface mount antenna. In FIG. 4, a surface-mounted antenna 50 has a rectangular parallelepiped base body 51 made of a dielectric, a ground electrode 52 formed on one main surface, a radiation electrode 53 formed on the other main surface, and one A power supply electrode 54 is formed from the end face to the other main face. One end of the radiation electrode 53 is formed as a planar capacitor portion 53a having a large width, and the other end is formed as a meander-shaped inductor portion 53b having a narrow width. The other end on which the inductor portion 53b is formed is disposed close to the electrode 54 with a gap 55 therebetween.
Is connected to the ground electrode 52 via one end face of

FIG. 5 shows an example of a conventional antenna device. In FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 5, the antenna device 60
The surface mount antenna 50 shown in FIG. 4 is mounted on the end of the mounting board 61, and the power supply electrode 54 of the surface mounting antenna 50 is connected to a signal processing circuit (not shown) arranged on the mounting board 61. Connected to transmit and receive signals. In addition, a ground electrode 62 is formed on a portion of the mounting substrate 61 on which the surface mount antenna 50 is mounted and around the portion except for a portion of a wiring connected to the power supply electrode 54.

In the antenna device 60 configured as described above, when a high-frequency signal is input to the feed electrode 54 of the surface mount antenna 50, an electrostatic force formed between the radiation electrode 53 and the feed electrode 54 in the gap 55. A high-frequency signal is transmitted to the radiation electrode 53 via the capacitor. The radiation electrode 53 resonates as a microstrip line resonator having one end open and the other end short-circuited with a length of about λ / 4. At this time, the radiation electrode 53 and the ground electrode 52, the feeding electrode 54, and the ground electrode of the mounting board 61. A part of the energy of the electric field formed between the antenna and the antenna 62 is radiated to the space and functions as an antenna.

[0005]

FIG. 6 shows an AA cross section of the antenna device 60 shown in FIG. FIG. 7 is a cross-sectional view similar to FIG. 6 in a case where the surface-mount antenna 50 is mounted at the center of the mounting board 61 as a comparison target for clarifying the problems of the conventional example. 6 and 7
, A radiation electrode 53 of the surface mount antenna 50,
The electric fields formed between the ground electrode 52 of the surface mount antenna 50 and the ground electrode 62 of the mounting board 61 are indicated by arrows 64 and 65.

First, in order to clarify the basic problem, FIG. 7 will be described first. As shown in FIG. 7, when the surface mount antenna 50 is mounted at the center of the mounting board 61, the mounting board 61
Is formed, the electric field is concentrated between the radiation electrode 53 of the surface mount antenna 50 and the ground electrode 52 and the ground electrode 62 of the mounting substrate 61, and as a result, the antenna gain is reduced. Concentration of the electric field means that the radiation electrode 53 (particularly, the inductor portion 53b) formed on the other main surface of the base 51 and the base 5
1 means that the capacitance between the ground electrode 52 formed on one main surface and the ground electrode 62 formed on the mounting substrate 61 is increased, thereby increasing the relative bandwidth of the surface mount antenna and the antenna device. There is also a problem that the width becomes narrow.

On the other hand, as shown in FIG. 6, when the surface mount antenna 50 is mounted on the end of the mounting board 61, the ground electrode 62 of the mounting board 61 is connected to the surface mounting antenna 5
0, there is almost no presence on at least one end surface side, so the radiation surface 53 of the surface mount antenna 50, the ground electrode 52 of the surface mount antenna 50, and the mounting substrate on the end surface side (end side of the mounting substrate 61). The concentration of the electric field between the ground electrode 61 and the ground electrode 62 is reduced. As a result, the antenna gains of the surface mount antenna 50 and the antenna device 60 are improved, and the specific bandwidth can be increased.

However, in the mounting state shown in FIG. 6, the electric field between the radiation electrode 53 of the surface-mount antenna 50 and the ground electrode 52 of the surface-mount antenna 50 and the ground electrode 62 of the mounting board 61 is increased. Substrate 61
There is a limit to the improvement of the antenna gain because it further concentrates in the inward direction by an amount reduced on the end side of the antenna. Also, a radiation electrode 53 of the surface mount antenna 50,
Since the capacitance between the ground electrode 52 of the surface mount antenna 50 and the ground electrode 62 of the mounting board 61 is also relatively large, it is difficult to further increase the specific bandwidth of the surface mount antenna 50 and the antenna device 60. There is also a problem.

Therefore, the present invention provides a high antenna gain,
An object of the present invention is to provide a surface-mounted antenna and an antenna device having a wide relative bandwidth.

[0010]

In order to solve the above problems, a surface mounting type antenna according to the present invention has a first ground electrode formed on one main surface of a substantially rectangular parallelepiped base made of a dielectric or magnetic material. Forming a strip-shaped radiation electrode on at least the other main surface of the base, forming one end of the radiation electrode as an open end, and forming a feed electrode on the open end via a first gap; The same number of second ground electrodes are formed close to each other via one or more second gaps, and the second ground electrodes are connected to the first ground electrodes. .

Further, in the surface mount antenna according to the present invention, the other end of the radiation electrode is connected to the first ground electrode.

Further, the surface mount antenna according to the present invention is characterized in that the base has one or more through holes provided from one end face to the other end face.

Further, according to the antenna device of the present invention, the above-mentioned surface mount antenna is mounted on an end of a mounting board, and
Or the end face close to the second gap is mounted toward the end of the mounting substrate.

With such a configuration, according to the surface mount antenna and the antenna device of the present invention, the antenna gain can be increased and the fractional bandwidth can be widened.

[0015]

FIG. 1 shows an embodiment of a surface mount antenna according to the present invention. In FIG. 1, a surface-mounted antenna 10 includes a rectangular parallelepiped base 1 made of a dielectric material such as ceramics and resin, a first ground electrode 2 formed on one main surface thereof, and a first ground electrode 2 formed on the other main surface of the base 1. A radiation electrode 3 formed over one end face, a feed electrode 4 formed from one main face of the base 1 through one end face to the other main face,
It is constituted by a second ground electrode 5 formed on another end face opposite to the end face on which the power supply electrode 4 is formed. Also,
Two through holes 8 are provided from the end face of the base 1 on which the power supply electrode 4 is formed to the other end face opposite thereto.

Here, the radiation electrode 3 is formed at one end as a wide and planar capacitor portion 3a, and at the other end as a narrow and meandering inductor portion 3b.
a is formed near the power supply electrode 4 via the first gap 6, and the other end on which the inductor portion 3 b is formed is connected to the first ground electrode 2 via one end face of the base 1. It is connected to the. In addition, a part of the radiation electrode 3 is disposed at the other end face of the base 1 in close proximity to the second ground electrode 5 via the second gap 7, and the second ground electrode 7 is connected to the first ground electrode 5. It is connected to the ground electrode 2.

When the surface-mounted antenna 10 is compared with the conventional surface-mounted antenna 50, the ground electrode 2 is connected to the ground electrode 52, the radiation electrode 3 is connected to the radiation electrode 53, the capacitance 3a is connected to the capacitance 53a, and The portion 3b corresponds to the inductor portion 53b, the power supply electrode 4 corresponds to the power supply electrode 54, and the first gap 6 corresponds to the gap 55, and functions similarly. Further, in the surface-mounted antenna 10, since a part of the radiation electrode 3 is further disposed close to the second ground electrode 5 via the gap 7, the capacitance formed here is added. This is different from the conventional example in that the through hole 8 of the base 1 is provided.

FIG. 2 shows an embodiment of the antenna device of the present invention. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 2, the antenna device 20 includes a surface-mounted antenna 1
0 is mounted. At this time, the end surface of the surface-mounted antenna 10 where the second gap 7 is formed is arranged so as to face the end of the mounting substrate 21. Also,
The power supply electrode 4 of the surface mount antenna 10 is connected to a signal processing circuit (not shown) disposed on the mounting board 21 to transmit and receive signals. A ground electrode 22 is formed on a portion of the mounting substrate 21 on which the surface-mounted antenna 10 is mounted and around the portion, except for a portion of a wiring connected to the power supply electrode 4.

In the antenna device 20 configured as described above, when a high-frequency signal is input to the power supply electrode 4 of the surface mount antenna 10 as in the conventional example, the radiation electrode 3 and the power supply electrode 4 are connected in the first gap 6. A high-frequency signal is transmitted to the radiation electrode 3 via the capacitance formed therebetween. The radiation electrode 3 resonates as a microstrip line resonator having one end open and the other short-circuited with a length of λ / 4. At that time, the radiation electrode 3 and the first ground electrode 2, the second ground electrode 5, and the mounting A part of the energy of the electric field formed between the substrate 21 and the ground electrode 22 is radiated to the space and functions as an antenna. At this time, the surface mount antenna 10
In the portion of the second gap 7 formed between the radiation electrode 3 and the second ground electrode 5, that is, the portion near the end of the mounting board 21, most of the radiation electrode 3 and the ground electrode Since a relatively large capacitance is locally formed as compared with the capacitance formed between the two, a relatively strong electric field is formed between them. Conversely, in the portion of the surface-mounted antenna 10 that is closer to the inside of the mounting board 21, the concentration of the electric field is reduced as compared with the conventional example.

Here, FIG. 3 shows a BB cross section of the antenna device 20. In FIG. 3, an electric field formed between the radiation electrode 3 of the surface-mounted antenna 10, the ground electrode 2 of the surface-mounted antenna 10, and the ground electrode 22 of the mounting board is indicated by an arrow 24.

As shown in FIG. 3, when the surface-mounted antenna 10 is mounted on the end of the mounting board 21, the ground electrode 22 of the mounting board 21 hardly exists on at least one end face of the surface-mounted antenna 10. Therefore, the concentration of the electric field is reduced on the end face side (end side of the mounting board 21) except for the portion of the second gap 7. As a result, the antenna gain is improved and the fractional bandwidth can be increased.

In addition, due to the capacitance locally formed in the second gap 7, the distance between the radiation electrode 3 and the ground electrode 2 of the surface mount antenna 10 at a portion near the inside of the mounting board 21. Since the concentration of the electric field is reduced, the antenna gain in this portion is improved. As a result, the surface mount antenna 10 and the antenna device 2
At 0, the antenna gain can be improved compared to the conventional example shown in FIG.

Further, the through hole 8 formed in the base 1 allows the surface of the radiating electrode 3 formed on the other main surface of the base 1 of the surface-mount type antenna 10, particularly the inductor portion 3 b, to be connected to one main surface of the base 1. The capacitance between the formed ground electrode 2 can be reduced. Accordingly, the inductance of the inductor portion 3b of the radiation electrode 3 increases, and the same value of inductance can be realized in a small size, so that the surface mount antenna 10 can be downsized. Further, the radiation electrode 3 of the surface mount antenna 10 and the first
The specific bandwidth can also be widened due to the decrease in the capacitance between the first and second ground electrodes 2.

In each of the above embodiments, one second gap is used. However, a plurality of second gaps may be provided at one end face of the base 1 or at a position close to that on the other main face. Absent. Further, the λ / 4 type antenna has one end of the radiation electrode of the surface-mounted antenna as an open end and the other end as a short-circuited end.
It functions similarly as a type 2 antenna. In addition, although a case where a dielectric is used as the base of the surface mount antenna has been described, the antenna may be formed using a magnetic material. Further, the shape of the radiation electrode is not limited to the shape in which the planar capacitor portion and the meandering inductor portion are connected, and the entire shape may be a meandering shape, a planar shape, or a linear shape. However, another shape may be used.

[0025]

According to the surface mount antenna and the antenna device of the present invention, the second ground electrode is provided on a part of the radiation electrode via the second gap, and the end face of the base provided with the second gap is provided. Is mounted toward the edge of the mounting board, the concentration of the electric field between the radiation electrode and the ground electrode of the surface mount antenna is reduced, and the antenna gain of the surface mount antenna and the antenna device can be improved. it can.

Further, by providing a through hole from one end face of the base of the surface mount antenna toward the other end face, the capacitance between the radiation electrode and the ground electrode is reduced, and the same value is obtained. Can be realized in a small area, so that the size of the surface-mount antenna can be reduced, and the specific bandwidth of the surface-mount antenna and the antenna device can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a surface mount antenna according to the present invention.

FIG. 2 is a perspective view of an embodiment of the antenna device of the present invention.

FIG. 3 is a diagram illustrating a distribution of an electric field in a cross section BB of the antenna device of FIG. 2;

FIG. 4 is a perspective view showing a conventional surface mount antenna.

FIG. 5 is a perspective view showing a conventional antenna device.

6 is a diagram illustrating a distribution of an electric field in an AA section of the antenna device of FIG. 5;

FIG. 7 is a diagram illustrating a distribution of an electric field in an AA cross section when the surface mount antenna is mounted on a center portion of a mounting board in the antenna device of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base | substrate 2 ... 1st ground electrode 3 ... Radiation electrode 3a ... Capacitance part 3b ... Inductor part 4 ... Feeding electrode 5 ... 2nd ground electrode 6 ... 1st gap 7 ... 2nd gap 8 ... Through-hole 10 … Surface mount antenna

Claims (4)

[Claims] A first ground electrode formed on one main surface of a substantially rectangular parallelepiped base made of a dielectric or a magnetic material; a strip-shaped radiation electrode formed on at least the other main surface of the base; One end of the electrode is an open end, a feed electrode is formed at the open end through a first gap, and the same number of second grounds are located close to the radiation electrode through one or more second gaps. An electrode is formed, and the second ground electrode is connected to the first ground electrode. 2. The surface mount antenna according to claim 1, wherein the other end of the radiation electrode is connected to the first ground electrode. 3. The surface mount antenna according to claim 1, wherein the base has one or more through holes provided from one end face to the other end face. 4. An antenna device comprising the surface-mounted antenna according to claim 1 mounted on an end of a mounting board, wherein the second gap is formed or the second gap is formed. An antenna device, wherein an end face close to the mounting substrate is mounted toward an end of the mounting substrate.