JPH09275305A - Nonreciprocal circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a low loss of the nonreciprocal circuit element by adopting a ferrite core disk and rounding each edge. SOLUTION: The nonreciprocal circuit element has at least one ferrite core, a center conductor for signal transmission and a permanent magnet used to apply a magnetic field to the ferrite core. The ferrite core is formed to be a disk and a round whose radius is 0.05mm or over is formed to the edge. Furthermore, it is desirable that a ratio r/t of a radius (r) of the round to a thickness of the ferrite core is selected to be r/t>=0.1. When the radius of the round is smaller than 0.05mm, the effect of forming the round is less and the radius of the round is selected preferably to be 0.1mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reciprocal circuit device used as a mobile communication device or the like and functioning as a circulator / isolator.

[0002]

2. Description of the Related Art As a conventional non-reciprocal circuit device used in a microwave band such as a VHF or UHF band, there is a lumped constant isolator as shown in FIG. An exploded perspective view of this lumped constant isolator is shown in FIG. In this isolator, a ground plate 34 is soldered onto a magnetic metal case 33, and a dielectric substrate 35 is arranged thereon. An electrode for grounding is formed on the back surface of the dielectric substrate 35, and the electrode and the ground plate 34 are soldered and fixed. A through hole 36 is formed in the central portion of the dielectric substrate 35, and the central conductor portion 41 is inserted therein. As shown in FIG. 5, the center conductor portion 41 is made by processing a copper plate, and a ferrite core 38 is arranged on a circular portion 37 at the center of the center conductor portion 41. The three center conductors 60 are insulated from each other via the insulating sheet 39, and are bent and arranged so as to intersect at every 120 degrees. This central conductor portion 41
Are arranged in the through holes 36 of the dielectric substrate 35, and the circular portion 3
It is soldered to the ground plate 34 on the back surface of 7. Then, the respective center conductors 60 are connected to the capacitor electrode films 45, 46, 47 formed on the dielectric substrate 35, respectively. A resistance film 48 is connected to one electrode film 47, and the resistance film 48 is connected to a ground electrode 49. The ground electrode 49 is connected to the ground electrode on the back surface through the through hole 59. On top of this, the permanent magnet 43
A lumped-constant type isolator is configured by combining the metal cases 40 bonded to each other. In the above conventional example,
Capacitor electrodes are formed on the dielectric substrate to obtain the required capacitance, but chip capacitors may be connected to the respective center conductors. In addition, there may be two ferrite cores.

[0003]

This non-reciprocal circuit device is strongly required to be compact, thin, low loss and low price with the spread of mobile phones and the like. In particular, mobile phones are required to have low loss in order to prolong the life of the battery. In this non-reciprocal circuit device, conventionally, the size of the permanent magnet, the shape of the yoke (the metal case of the magnetic material), and the size of the ferrite core were examined, and it was designed to apply a uniform external magnetic field to the ferrite core. . However, even if the external magnetic field is made uniform, the non-uniformity of the internal magnetic field due to the shape anisotropy still remains due to the disk shape of the ferrite core, which has been a cause of loss. The present invention particularly focuses on the shape of the ferrite core, and an object thereof is to provide a non-reciprocal circuit device using a ferrite core that can achieve low loss.

[0004]

SUMMARY OF THE INVENTION The present invention provides at least one
In a nonreciprocal circuit device having a single ferrite core, a central conductor for transmitting a signal, and a permanent magnet for applying a magnetic field to the ferrite core, the ferrite core is disk-shaped, and its edge portion has an radius of 0.05 mm or more. Is a non-reciprocal circuit element in which is formed. Further, the present invention provides a nonreciprocal circuit device having at least one ferrite core, a central conductor for transmitting a signal, and a permanent magnet for applying a magnetic field to the ferrite core, wherein the ferrite core is disk-shaped, and an edge portion thereof is provided. The radius r of the radius and the thickness t of the ferrite core have a relation r /
It is a non-reciprocal circuit device with t ≧ 0.1. Also, the present invention
In a nonreciprocal circuit device having at least one ferrite core, a central conductor that transmits a signal, and a permanent magnet that applies a magnetic field to the ferrite core, the ferrite core is a spheroidal nonreciprocal circuit device.

The present invention is intended to make the internal magnetic field of the ferrite core uniform in order to reduce the loss of the non-reciprocal circuit device. That is, the shape of the ferrite core is a spheroid that theoretically provides a uniform internal magnetic field. Further, since it is not easy to form the spheroidal ferrite core, the rounded shape is formed at the edge portion of the disk-shaped ferrite core in order to obtain a shape close to that. If the radius is smaller than 0.05 mm, the effect of forming the radius is small, and the radius is set to 0.05 mm or more. Further, preferably, the radius is 0.1 mm or more. The radius of the radius is r (mm) and the thickness of the ferrite core is t (mm).
When r / t <0.1, the effect of forming roundness is small, and r / t ≧ 0.1. Further preferably, r / t ≧ 0.2. By forming the radius at the edge of the ferrite core, the internal magnetic field in the ferrite core is made uniform, which helps reduce the loss of the nonreciprocal circuit device. Further, the presence of this radius also has the effect of facilitating bending and enhancing adhesion when the central conductor is bent and laminated on the ferrite core. Also, when bending this center conductor, if there are corners as in the past, it is quite difficult to bend the center conductor at a right angle and follow the ferrite core due to springback, etc. The present invention also solves the problem of scratches. Although a method of forming a cut on the edge portion may be considered, the same effect as that of the present invention cannot be obtained by simply forming the cut.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The ferrite core of the present invention is generally obtained by filling a ferrite raw material powder in a mold, compression molding, and firing the molded body. Therefore,
It is possible to form the radius when molding the mold. Also,
For example, in the case where the surface is polished after firing, it is possible to form it by post-firing processing without forming the rounds at the time of molding. A barrel is one of the processing methods. An example of this barrel is shown below. Outer diameter 3.35 mm, thickness t = 0.55
A disc-shaped ferrite core sintered body of mm was barrel-polished. The barrel condition is that the carrier is HS1 manufactured by Chipton Co.
0,750g, 500cc of water, barrel polishing time 1
Time was 2 hours. As a result, 1 hour barrel polishing
= 0.13 mm, r = 1.19 mm after barrel polishing for 2 hours
Could be obtained. In addition, r before barrel polishing is 0.0
It was about 1 mm. A side view of Sample 3 is shown in FIG.

[0007]

[Table 1]

A nonreciprocal circuit device was constructed using this ferrite core. The structure of the non-reciprocal circuit device of this example is the same as the structure shown in FIG. 4, except for the ferrite core. In this example, the magnet has an outer diameter of 5.
A ferrite magnet having a thickness of 5 mm and a thickness of 1.6 mm was used, the center conductor was a 0.1 mm thick copper plate plated with Ag, and the load capacitance was a dielectric substrate. The insertion loss of this example is shown in Table 2 and FIG. This non-reciprocal circuit device has the characteristics at room temperature of an isolator having a center frequency of 836 MHz. The external shape of this isolator is 7mm x 7m.
m, height 4 mm.

[0009]

[Table 2]

As shown in Table 2 and FIG. 2, it is understood that the insertion loss can be reduced by forming the rounded edges of the ferrite core as shown in the present invention. If this insertion loss is reduced, in the case of a mobile phone, the life of the battery is extended, the portability is improved, and the effect is great.

Table 1 shows the surface roughness Ra of each sample at the same time. In this example, barrel polishing reduces the surface roughness of the ferrite core. The smaller the surface roughness, the lower the loss. From this, the surface roughness Ra of the ferrite core is 0.4 with respect to the loss reduction.
It can be seen that the thickness is preferably 5 μm or less. Needless to say, since the ferrite core of this embodiment has rounded edges, it is easy to bend the center conductor,
The adhesion of the central conductor on the ferrite core was also good. Further, the center conductor was not damaged at the edge of the ferrite core.

[0012]

According to the present invention, the loss of the non-reciprocal circuit device can be reduced, and the workability and reliability thereof can be improved, which is extremely excellent.
In addition, the function of applied products such as mobile phones can be improved.

[Brief description of drawings]

FIG. 1 is a front view of a ferrite core according to an embodiment of the present invention.

FIG. 2 is a graph of insertion loss of an example according to the present invention.

FIG. 3 is a perspective view of a conventional example.

FIG. 4 is an exploded perspective view of a conventional example.

FIG. 5 is an exploded perspective view of a central conductor portion of a conventional example.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shigeru Takeda 33-12 Minamieicho, Tottori City, Tottori Prefecture Hitachi Metals Co., Ltd. Magnetic Materials Research Laboratory Tottori Branch Office

Claims (3)

[Claims] 1. A nonreciprocal circuit device having at least one ferrite core, a central conductor for transmitting a signal, and a permanent magnet for applying a magnetic field to the ferrite core, wherein the ferrite core is disk-shaped, and an edge portion thereof is provided. At 0.0
A non-reciprocal circuit device having a radius of 5 mm or more. 2. In a nonreciprocal circuit device having at least one ferrite core, a central conductor for transmitting a signal, and a permanent magnet for applying a magnetic field to the ferrite core, the ferrite core is disk-shaped, and an edge portion thereof is provided. A non-reciprocal circuit device, characterized in that a radius is formed in the radius r and a relation between a radius r of the radius and a thickness t of the ferrite core is r / t ≧ 0.1. 3. A nonreciprocal circuit device having at least one ferrite core, a central conductor for transmitting a signal, and a permanent magnet for applying a magnetic field to the ferrite core, wherein the ferrite core is a spheroid. Non-reciprocal circuit device.