JP3095267B2 - choke coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil for cutting off high-frequency signal components and passing low-frequency power components.

[0002]

2. Description of the Related Art Conventionally, a relay device such as an amplifier is inserted into a transmission line in a CATV system or a coaxial cable transmission system, and a cable superposition for feeding power through the transmission line to one of the power supply systems for the relay device. There is a method. This cable superposition method is a method in which a high-frequency signal and DC or low-frequency AC power are superimposed on a coaxial cable and transmitted, and power is separated from the coaxial cable in each relay device and supplied to an active circuit.

[0003] In this cable superposition method, a circuit that superimposes a high-frequency signal on the transmission path and a circuit that separates only the power from the transmission path on which the high-frequency signal and the power are superimposed are used. These circuits use a choke coil formed by winding a conducting wire 2 around a ferrite core 1 as shown in FIG. 6, which passes only a power component and blocks a high-frequency signal component.

[0004]

However, as the CATV system becomes larger in scale, the power transmitted by being superimposed on the transmission line also tends to increase, and the choke coil is becoming larger.

[0005] In addition, there is also a tendency to use higher bands.
For this reason, the transmission path is affected by the resonance characteristics of the choke coil due to the addition of the choke coil, and there is a problem in that the transmission frequency characteristic of the transmission path generates a large trap in the used band.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the characteristics of a choke coil and improve the transmission frequency characteristics of a transmission line to which a choke coil is added. Is to improve.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a choke coil comprising a ferrite core and a coil formed by winding a conductive wire around the ferrite core. And a plurality of circuits which are arranged at a plurality of substantially antinodes of the voltage standing wave distributed in and are insulated in a DC manner with a conducting wire but are coupled in a high frequency and form a closed circuit in a high frequency. And a plurality of circuits, wherein a resistor is provided for connecting the circuits in which the phases of the voltage standing waves are different by approximately 180 degrees.

[0008]

By providing the circuit having the above configuration and the resistor for connecting the circuits, a high-frequency current flows through the resistor due to the high-frequency coupling between the coil and the circuit, thereby reducing the resonance impedance of the choke coil. The transmission frequency characteristics of the transmission line using the choke coil are improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. First Embodiment FIG. 1 is a front view showing a configuration of a choke coil according to a first embodiment. A main wire C is formed by winding a conductor 2 having a thickness of about 1.4 mm in the direction of arrow A 16 times around a cylindrical ferrite core 1 having a diameter of about 8 mm and a length of about 3 cm. Then, as shown in FIG. 1, a voltage standing wave is formed in the axial direction X of the main winding C. As shown in FIG. 1, the end portions of the voltage standing wave are not connected to the plurality of antinode positions X1 and X2 of the voltage standing wave as shown in FIG. E2 (closed by electrostatic coupling in terms of high frequency) is provided.

The circuits E1 and E2 are connected to the conductor 2 of the main winding C.
And is disposed in a substantially ring shape in a state of being insulated from the conducting wire 2 in a DC manner. As a result, the circuits E1, E2
Is electrostatically coupled to the main winding C in terms of high frequency.

As shown in FIG. 1, the circuits E1 and E2 are arranged at antinodes where the phases of the voltage standing waves differ by 180 degrees. And a circuit E1 whose phase is different by 180 degrees,
The resistor 4 is connected so as to bridge E2 in the direction of the axis X.

FIG. 3 shows the measurement results of the transmission frequency characteristics of the transmission line to which the choke coil shown in FIG. 1 is connected. For comparison, FIG. 5 shows the transmission frequency characteristics when the choke coil shown in FIG. 6 without the circuits E1 and E2 is connected to the transmission line.

As is apparent from these figures, the resistor 4
When a choke coil without the circuits E1 and E2 is used, about 0.2 dB at 200 MHz and about 0.8 dB at 375 MHz
There is dB attenuation. However, when the choke coil of the embodiment is used, the trap generated around 200 MHz can be eliminated, the trap around 375 MHz can be reduced to 0.3 dB, and the transmission amount in the used band can be reduced. The frequency characteristics could be improved.

According to the inventor's guess, the reason why the trap can be eliminated by the above configuration is as follows. Since the circuits E1 and E2 are arranged at the antinodes of the voltage standing waves distributed in the axial direction of the main winding C, the circuits E1 and E2
2, a voltage is induced by the electrostatic coupling with the main winding C. Since the voltages induced in the circuit E1 and the circuit E2 are different in antinode phase of the voltage standing wave by 180 degrees, when the voltage distribution shows a peak, the potential difference between the two circuits E1 and E2 becomes maximum. . That is, the effective value of the potential difference between the two circuits E1 and E2 provided at the antinode of the voltage standing wave is the difference between the two circuits provided at any position other than the antinode of the voltage standing wave. Becomes larger than the effective value of the potential difference generated at the time. Therefore, the current loss flowing through the resistor 4 bridging the two circuits E1 and E2 can be increased, and as a result, the trapping can be reduced by reducing the resonance impedance of the choke coil.

Second Embodiment A choke coil according to a second embodiment is, as shown in FIG.
In addition to the circuits E1 and E2 shown in FIG. 1 and the resistor 4 bridging the circuits, auxiliary windings D are formed at both ends of a main winding C wound in the direction of arrow A. The auxiliary winding D is composed of a conducting wire 3 having a thickness of about 1 mm.
Are electrically connected to one end 2a of the conductor 2 of the main winding C by soldering. The conductor 3 is wound once in the direction indicated by the arrow B opposite to the direction in which the main winding C is wound, along the rightmost end valley 2b of the adjacent conductor 2 while keeping the conductor 2 insulated from the conductor 2. Then, the conductor 2 engages with the conductor 2 while maintaining an insulated state at the end 2 c near the one end 2 a, and then separates the right end 1 a of the ferrite core 1 from the right end of the main winding C in the direction of arrow B. The wire 2 is wound once and locked again with the wire 2 while maintaining the insulating state at the end 2c of the wire 2, and the end of the wire 3 is open.

FIG. 4 shows the measurement results of the transmission frequency characteristics of the transmission line in which the ferrite core is inserted. As can be seen from this measurement result, the trap of about 0.3 dB generated around 375 MHz can be eliminated compared to the configuration shown in FIG. The frequency characteristics could be improved.

In the above embodiment, the circuits E1 and E2 are:
It is composed of an open circuit with a partially cut direct current. However, the open ends may be coupled by capacitance. Further, it may be a completely closed circuit (DC). Further, the open ends may be connected with a high resistance (approximately several tens kΩ to several hundred kΩ or more) of which transmission loss on the high frequency transmission line can be ignored. Further, the number of circuits (E1, E2, etc.) arranged at the antinode of the voltage standing wave is arbitrary. The resistor (4
), The antinode phase of the voltage standing wave is 18
If they differ by 0 degrees, they may be connected between any circuits.

[0018]

The present invention relates to a choke coil comprising a ferrite core and a coil formed by winding a conductive wire around the ferrite core, wherein a plurality of substantially antinode positions of a voltage standing wave distributed in the axial direction of the coil are provided. And a plurality of circuits that are insulated in a DC manner but are coupled in a high frequency manner to form a closed circuit in a high frequency range, and that the phases of the voltage standing waves in the plurality of circuits are substantially the same. As a result of providing a resistor that connects between circuits that differ by 180 degrees, a current generated by the coil and the high-frequency coupling flows through the resistor, so that the resonance impedance can be reduced, and the transmission frequency of the transmission line in which the choke coil is inserted The characteristics could be improved.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a choke coil according to a first embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a choke coil according to a second embodiment.

FIG. 3 is a measurement diagram of a transmission amount frequency characteristic of a transmission line in which the choke coil according to the first embodiment is inserted.

FIG. 4 is a measurement diagram of a transmission frequency characteristic of a transmission line in which a choke coil according to a second embodiment is inserted.

FIG. 5 is a measurement diagram of transmission frequency characteristics of a transmission line in which a conventional choke coil is inserted.

FIG. 6 is a front view showing the configuration of a conventional choke coil.

[Explanation of symbols]

1: Ferrite core 2, 3: Conductor wire 4: Resistor C:
Main winding D ... Auxiliary winding E ... Closed circuit

Claims (2)

(57) [Claims] 1. A choke coil comprising a ferrite core and a coil formed by winding a conductive wire around the ferrite core, wherein the choke coil is disposed at a plurality of substantially antinode positions of a voltage standing wave distributed in an axial direction of the coil. And a plurality of circuits that are insulated in a direct current and the high frequency but are coupled in a high frequency to form a closed circuit in a high frequency, and in the plurality of circuits, a phase of the voltage standing wave is About 1
A choke coil comprising a resistor for connecting between circuits different by 80 degrees. 2. An auxiliary winding, one end of which is electrically connected to at least one end of the coil and the other end of which is opened, and which is wound in a direction opposite to a winding direction of the coil, is connected to at least a transmission path of the coil. The coil is wound around the outer periphery of the coil in the vicinity of one end on the side connected to the coil.
The choke coil described in the above.