JPH104310A - Ferrite antenna - Google Patents

Abstract

(57) [Problem] To provide a ferrite antenna having excellent productivity, high sensitivity and stable antenna characteristics. SOLUTION: A ferrite square rod 11 is made of metal plates 12,13.
To the circuit board 14. The entire metal plate 12 and a part of the metal plate 13 are wound around a ferrite square bar 11 to form a ferrite antenna. On the other hand, the ferrite square bar 11
Is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite antenna for a communication device, and more particularly to a structure for connecting and fixing a metal plate wound around a ferrite member.

[0002]

2. Description of the Related Art A conventional ferrite antenna has a structure as shown in Japanese Utility Model Laid-Open No. 62-32613, Japanese Utility Model Laid-Open No. 62-32614 and FIG. That is, in FIG.
1 is a ferrite square bar and 10 is a metal plate. The ferrite antenna is composed of a ferrite square bar 1 and a metal plate 10, and the metal plate 10 is integrated and continuously wound several times.
Was composed. Also, connection and fixation of the ferrite antenna to the circuit board have been performed by soldering both ends of the metal plate 10 to the surface of the circuit board.

[0003]

However, in the above-mentioned prior art, the winding process of the metal plate is complicated, so that the productivity is inferior and the winding dimensions vary, so that the characteristics of the antenna are not stable. There is a problem that the board and the circuit board are separated due to dropping, impact, or the like. The present invention is intended to solve such a problem, and an object of the present invention is to provide a ferrite antenna having excellent productivity, high sensitivity, and stable antenna characteristics.

[0004]

A ferrite antenna according to the present invention comprises at least a first antenna portion composed of a ferrite member, a metal plate wound around the ferrite member, and a first antenna portion. A second antenna unit connected to form an air core loop not including a ferrite member, wherein the first antenna unit and the second antenna unit are fixed to a substrate having a conductive pattern. And

In this case, it is desirable that a part of the air-core loop is constituted by a metal plate formed by extending from a part wound around the ferrite member. The metal plate formed as described above is desirably configured in a direction orthogonal to the longitudinal direction of the ferrite member.

[0006] The second antenna section may be a conductive pattern formed along the periphery of the substrate.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

A first embodiment will be described with reference to FIGS. FIG. 1 is an external view of a ferrite antenna according to one embodiment, and FIG. 2 is an external view of a circuit board in FIG. FIG. 3 is an external view of the metal plate 2 wound on the ferrite square bar of FIG.

[0009] The metal plate 2 is bent by a machine and is in a form that can be easily manufactured. This metal plate 2
Can be mounted on the circuit board 3 to fix the ferrite square bar 1 (hereinafter, referred to as a ferrite square bar) as a ferrite member. However, the metal plate 2 has 3/4 turns, and a pattern 4 which is a part of a coil is provided on the circuit board 3 to make one turn, and two metal plates 2 are mounted together.
A two-turn ferrite antenna can be made. Also, by arranging a large number of metal plates 2, a multi-turn ferrite antenna can be manufactured. By machining, a ferrite antenna having the same characteristics as a conventional ferrite antenna (shown in FIG. 16) which is spirally wound by hand can be easily manufactured. In addition, since the interval between the coils, which is an important condition of the metal plate 2, can be set accurately, variations in antenna characteristics during manufacture can be suppressed, and stable manufacture can be achieved as compared with a manually wound ferrite antenna. Further, even when a thin ferrite is used for a large metal plate, it can be easily manufactured by holding the ferrite square bar 1 with an adhesive or a case to be stored.

A second embodiment will be described with reference to FIGS. FIG. 4 is an external view of a ferrite antenna according to a second embodiment. FIG. 5 is an external view of the circuit board 5 of FIG. FIG.
FIG. 5 is an external view of a metal plate 7 wound around the ferrite square bar 1 of FIG.

The metal plate 7 shown in FIG. 6 is bent by a machine and can be easily manufactured. This metal plate 7
Are mounted and fixed in the through holes 6a to 6d of the circuit board. The terminal portion 7a of the metal plate 7 has a through hole 6
a, and the terminal portion 7b is connected to the through hole 6b by soldering or the like. When a two-turn coil is used, the terminals 7a and 7b may be connected to the through holes 6c and 6d using the same metal plate 7 as described above. Through hole 6
b and 6c are electrically connected by the connection pattern 8 on the front and back surfaces of the substrate. Thereby, the through holes 6b and 6c,
The pattern 8 on the front and back forms a part of the metal plate coil 7. Also, the terminal portions 7b and 7a can be connected by forming the through holes 6b and 6c into one large through hole. Also in this method, as in the first embodiment, a ferrite antenna can be easily manufactured, and a ferrite antenna in which the impedance characteristics of the antenna are stable without variation can be manufactured.

The connection / fixing structure of the metal plates 2 and 7 makes it possible to easily support a heavy and easily broken ferrite antenna, and to fix a multi-turn metal plate coil to a circuit board at two or more locations. Damage such as peeling of the substrate pattern can be dispersed, and the product can be made hard to break.

In the circuit board 5 of FIG. 5, the connection patterns 9a and 9b for the antenna tuning circuit are provided on different front and back surfaces of the circuit board 5, so that the terminals 7a of the metal plate 7 are provided.
And 7b are connection patterns 9a and 9b directly from the front and back.
, The space of the circuit board 5 can be used effectively. Further, the connection patterns 9a and 9b may be upside down in FIG.

A third embodiment will be described with reference to FIGS. FIG. 7 is an external view of a ferrite antenna device according to a third embodiment. FIG. 8 is an external view of the ferrite antenna device when FIG. 7 is viewed from the back. FIG. 9 is an external view of contact pins 16a and 16b connected to the circuit board 14 of FIG. FIG.
Is an external view of the metal plates 12 and 13.

The ferrite square bar 11 and the circuit board 14 are fixed and mounted with an adhesive or the like. The metal plates 12, 13 and the contact pins 16a, 16b are bent by a machine,
It can be easily manufactured. Contact pins 16a, 16b
Is an input terminal for connecting the antenna to the antenna tuning circuit by spring contact.

The metal plates 12 and 13 are inserted into through holes 14a to 14d of the circuit board 14 and mounted and fixed. The metal plate 12 is formed so as to cover the ferrite square bar 11 in close proximity after assembly. On the other hand, the distance between the metal plate 13 and the ferrite square bar is wider in the direction perpendicular to the longitudinal direction of the ferrite square bar than the metal plate 12.

The contact pins 16a and 16b are
And is mounted and fixed in the through holes 14f to 14e. The chip capacitor 17 on the circuit board 14 is connected to the circuit pattern by soldering or the like, and has an effect of adjusting the inductance of the entire antenna. The circuit patterns 15a to 15d form part of a metal plate. The ferrite antenna device shown in FIG. 8 is connected to the antenna tuning circuit board from the contact pins 16a and 16b to form a wireless device.

The ferrite antenna device shown in the third embodiment of FIG. 7 forms a ferrite antenna and an air-core loop antenna in the same direction as the ferrite antenna.

In FIG. 9, a circuit pattern 15a, a through hole 14b, a metal plate 12, and a metal pattern 12 are formed from the through hole 14e.
Through hole 14c → circuit pattern 15b → chip capacitor 17 → circuit pattern 15c → through hole 14a
→ The ferrite antenna is constituted up to the metal plate 13 (only the portion close to the ferrite square bar).

Further, through the metal plate 13 to the through hole 14d
An air-core loop antenna is constituted by → the circuit pattern 15d → the through hole 14f → the contact pin 16b → the antenna tuning circuit board → the contact pin 16a → the through hole 14e. This air core loop is a feature, and is formed by widening the distance between the metal plate and the ferrite square bar in a direction perpendicular to the longitudinal direction of the ferrite square bar.

In general, the characteristics of the ferrite antenna are determined by the characteristics of the ferrite square bar and the size of the ferrite square bar. Further, the characteristics of the ferrite square bar are almost determined by the operating frequency. Therefore, when the operating frequency is determined, the factor that determines the sensitivity of the ferrite antenna is only the size of the ferrite, and the sensitivity obtained by the size of the ferrite antenna is limited. Therefore, the present invention improves the sensitivity of the ferrite antenna by changing the size and shape of the metal plate and adding an air-core loop antenna to improve the sensitivity beyond the limit sensitivity of the ferrite antenna. There are the following effects in comparison.

・ Improvement of sensitivity by adding air core loop antenna ・ When the ferrite antenna body and the antenna terminal on the circuit side are separated, the antenna sensitivity is improved by using the distance and space to form an air core loop. The directivity is sharper because the ferrite antenna and the air-core loop antenna are in the same direction. The sharpness of the directivity has little effect on the noise radiated from the radio itself.

FIG. 14 is a sensitivity comparison diagram of the antenna shown in the embodiment of FIG. 7 and the ferrite antenna using the same size ferrite, which shows the above effects. 14, the sensitivity of the ferrite antenna device is improved by 0.5 to 2.0 dB as compared with the conventional ferrite antenna. this is,
There is an improvement in sensitivity due to the addition of an air core loop antenna, and the effect on noise radiated from the radio itself is small (2.8 MHz from the receiving circuit used for this measurement).
Harmonic noise is generated, and the effect is f0, f0
Appears at −5.4 MHz, f0 + 5.4 MHz. If the antenna is affected by high frequency noise, sensitivity degradation will occur at the frequency. ).

A fourth embodiment will be described with reference to FIGS. FIG. 11 is an external view of a ferrite antenna according to the eighth embodiment. FIG. 12 is an external view of the ferrite antenna when FIG. 11 is viewed from the back. FIG. 13 is an external view of the metal plate 18 wound around the ferrite square bar 11 of FIG.

The ferrite square bar 11 is fixed and mounted on a circuit board 19 with an adhesive or the like. The metal plate 18a is inserted into the through holes 19a to 19b on the circuit board 19 and mounted.
Fixed. The metal plate 18b is inserted into the through holes 19c to 19d on the circuit board 19, and is mounted and fixed. The circuit patterns 20a to 20c form part of a metal plate. The chip capacitor 17 on the circuit board 19 is
It is connected on the circuit pattern by soldering or the like. The chip capacitor 17 has a tuning effect of the ferrite antenna device. Although not shown in FIGS. 11 and 12, a receiving circuit 21 is formed on the circuit board 19, and the ferrite antenna device is connected to the receiving circuit 21 to constitute a wireless device.

The ferrite antenna shown in the fourth embodiment of FIG. 11 forms an air core loop antenna perpendicular to the ferrite antenna and the loop of the ferrite antenna. In FIG. 12, from the circuit pattern 20a to the through hole 19a → the metal plate 18b → the through hole 19b
→ circuit pattern 20b → through hole 19c → metal plate 1
8a → through hole 19d → circuit pattern 20c → chip capacitor 17 constitute a ferrite antenna.

An air-core loop antenna is formed from the chip capacitor 17 to the circuit pattern 20d → the receiving circuit unit 21 on the circuit board 19 → the chip capacitor 22. Ferrite antennas have sensitivity only to a single polarization component. The present invention improves the directivity of a ferrite antenna and realizes relatively non-directional characteristics having sensitivity with respect to a polarization component by changing the size and shape of a metal plate.

The antenna shown in the embodiment of FIG. 11 is an antenna in which a vertical air-core loop antenna and a ferrite antenna are formed by the patterns of the metal plates 18a, 18b and the circuit board 19, so that the conventional ferrite antenna is not used. There are the following effects in comparison.

・ Improvement of sensitivity by adding air-core loop antenna ・ Since ferrite antenna and air-core loop antenna are orthogonal to each other, it has sensitivity with multiple polarization components and realizes relatively non-directional characteristics. It can be applied to a wide range of general portable wireless devices as well as wireless devices mounted on a human body.

FIG. 15 shows a comparison of sensitivity in eight directions between the antenna shown in the embodiment of FIG. 11 and the ferrite antenna using the same size ferrite, which shows the above-mentioned effects. FIG. 15 shows that the antenna shown in the embodiment of FIG. 12 has a substantially constant sensitivity in all directions.

[0031]

According to the ferrite antenna of the present invention, since the second antenna portion which forms an air core loop which does not include a ferrite member is provided, a component of the air core loop antenna is added. This has the effect of improving sensitivity over sensitivity.

The metal plate of the ferrite antenna of the present invention comprises:
The part extended from the part wound around the ferrite member,
Since it is configured in a direction orthogonal to the longitudinal direction of the ferrite member, the component of the air-core loop antenna in the same direction as the ferrite antenna is added. . In addition, since the second antenna portion is formed of a conductive pattern formed along the periphery of the substrate, a component of an air-core loop antenna in a direction orthogonal to the ferrite antenna is added, so that sensitivity is improved by a double polarization component. It has the effect of being able to realize relatively non-directional characteristics, and can be widely applied not only to a wireless device mounted on a human body but also to a general mobile wireless device.

[Brief description of the drawings]

FIG. 1 is an external view showing a first embodiment of a ferrite antenna according to the present invention.

FIG. 2 is an external view of the circuit board shown in FIG.

FIG. 3 is an external view of the metal plate shown in FIG.

FIG. 4 is an external view showing a second embodiment of the ferrite antenna of the present invention.

5 is an external view of the circuit board shown in FIG.

FIG. 6 is an external view of the metal plate shown in FIG.

FIG. 7 is an external view showing a third embodiment of the ferrite antenna according to the present invention.

8 is an external view of the ferrite antenna shown in FIG. 7 viewed from another direction.

FIG. 9 is an external view of a contact pin shown in FIG. 7;

FIG. 10 is an external view of the metal plate shown in FIG.

FIG. 11 is an external view showing a fourth embodiment of the ferrite antenna according to the present invention.

12 is an external view of the ferrite antenna device shown in FIG. 11 viewed from another direction.

FIG. 13 is an external view of the metal plate shown in FIG.

14 is a frequency sensitivity comparison diagram of the ferrite antenna device shown in the embodiment of FIG. 7 and a ferrite antenna using the same ferrite.

FIG. 15 is a comparison diagram of the eight directions of the ferrite antenna device shown in the embodiment of FIG. 11 and a ferrite antenna using the same ferrite.

FIG. 16 is an external view showing an example of a conventional ferrite antenna.

[Explanation of Signs] 1,11 Ferrite square bar 2,7,12,13,18a, 18b Metal plate 3,5,14,19 Circuit board 4,15a, 15b, 15c, 15d, 20a, 20
b, 20c, 20d Circuit pattern 6a, 6b, 6c, 6d, 14a, 14b, 14c, 1
4d, 14e, 14f 19a, 19b, 19c, 19
d Through-hole 7a, 7b Terminal part of metal plate 8, 9a, 9b Connection pattern 10 Metal foil coil spirally wound by hand 16a, b Contact pin 17 Chip capacitor 21 Receiving circuit part

Claims (4)

[Claims] 1. A first antenna unit including at least a ferrite member and a metal plate wound around the ferrite member; and a vacant space connected to the first antenna unit and not including the ferrite member. A ferrite antenna, comprising: a second antenna unit that forms a core loop; wherein the first antenna unit and the second antenna unit are fixed to a substrate having a conductive pattern. 2. The ferrite antenna according to claim 1, wherein a part of the air-core loop is formed by a metal plate formed by extending from a part wound around the ferrite member. 3. The ferrite according to claim 2, wherein the metal plate formed by extending from a portion wound around the ferrite member is formed in a direction orthogonal to a longitudinal direction of the ferrite member. antenna. 4. The ferrite antenna according to claim 1, wherein the second antenna portion is a conductive pattern formed along a periphery of the substrate.