JPS6032361B2 - How to use current passing type high frequency signal attenuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of using an attenuator to attenuate high frequency voltages.

Conventionally, for example, television signals (4K MHZ to 100M
H2) A current-passing type fixed attenuator used in a circuit (also called a transmission line for high-frequency signals) has the ability to attenuate only the low-frequency component of direct current, in addition to the circuit that attenuates the high-frequency voltage. Not only does the attenuator become large because a choke coil is required to pass the choke coil, but the mounting position of the choke coil must be adjusted in order to avoid high-frequency coupling between the attenuation circuit element and the choke coil. It had the disadvantage of being limited.

Another problem is that as the operating frequency increases, the actual amount of attenuation deviates from the design value of the attenuation circuit due to stray capacitance between the choke coil windings. The present invention aims to provide a method of using an attenuator that can help solve the above-mentioned problems.

The configuration of the embodiment of the present application will be described below with reference to example diagrams.

In FIG. 1, 1 is the entire high frequency resistor, 2 is a hollow cylindrical ferromagnetic material, and 4 is a conductive wire inserted through the through hole 3 thereof.
Next, in the attenuator shown in FIG. 2, Z is the above-mentioned high frequency resistor, R, , R2 are ordinary resistance elements, and these constitute an attenuation circuit. Note that C is a capacitor for DC and low frequency cutoff, a. a' is an input terminal, b and b' are output terminals.
Next, the operation of the above configuration will be explained.

First of all, when only direct current or low frequency waves enter the input terminals a and a', the presence of the ferromagnetic material 2 of the high frequency resistor Z has no effect on the circuit between the input and output terminals, and the equivalent circuit is Third
It will look like the figure. Next, when a high frequency wave is superimposed and input to the input terminals a and a', electromagnetic coupling occurs between the conducting wire 4 and the ferromagnetic material 2, and impedance is generated when viewed from both ends of the high frequency resistor Z. According to experiments, this impedance is a resistance with extremely small inductance, and is effectively considered to be pure resistance at high frequencies. Therefore, the equivalent circuit of the attenuator for high frequency components is as shown in FIG. 4, which is equivalent to an attenuator without a choke coil. Here, the occurrence of the above impedance can be understood from the following theoretical formula.

First, in Fig. 5, when a current 1 is passed through the center conductor, the magnetic field at a point at an arbitrary distance r from the center conductor inside the ferromagnetic body is H; therefore, the magnetic flux density B at this point is Magnetic permeability, mountain s is the relative magnetic permeability of this ferromagnetic material, B
=''OASH=Mutonous Youth 1 Then, the inner radius r,, the outer radius r2, the length, and the total number of magnetic flux passing through the ferromagnetic body ■=' 〒28 and dr = Hakubanken student Ldr -A female 1ri Therefore, the impedance Z between the terminals T and T2 is the angular frequency, and if we set the relative magnetic permeability r3 as the mountain S, the mountain S1, the JArS, we get Z4, which is the pure resistance. If we separate a certain mito and the imaginary part, which is inductance, and substitute Muo=4m×10-7, we get Z=R+FL
The late R: and.

-World〃S rebuke sheep 2 middle: ku4 middle fsorrS and n harm) X・〇-7...{21 Here, f represents the frequency, and w has a relationship of f: step.

As the ferromagnetic material, a material with a large loss, that is, a material with a large n6 (indicating loss) is used.

〇n6 is fence=volume〉>1 and 1s″>>rs′, and the imaginary part of the equation (①) can be ignored.

Therefore, formula [1} is pure resistance at high frequencies, and when a conductor is passed through a magnetic body with the structure shown in Figure 5, the impedance between T and T2 is given by the real part 1, which indicates the high frequency pure resistance value. . Figure 6 shows the characteristic curves of 1s' and 1s''.The usable area of the ferromagnetic material as a pure resistance is the area between the diagonal lines.The high-frequency resistance value of the ferromagnetic material 2 It can be changed by the length of the through hole 3, the diameter of the through hole 3, the thickness of the conducting wire 4, and the number of times the conducting wire is passed through the through hole 3.Next, the relative permeability of the ferromagnetic material of the high frequency resistor s can be changed. The loss term ``s'' (relative magnetic permeability ``s'' is expressed in multiple forms by the lossless term ``As'' and the loss term ``s'', as is well known and as shown earlier) and the high-frequency signal to be passed. An example of the product of the angular frequency of is shown in FIG. 7, and the value is almost constant in the region from 4 Sengawa z to 1000 MHz.

This is OL made by Nippon Ferrite as an example of ferromagnetic material.
-3 ferromagnetic material (dimensions r, = 0.5 wind, r2 =
This is the value obtained by actually measuring 1.7 candles, evening 7 side). Furthermore, actual measured values of the attenuation characteristics of an attenuator using the high frequency resistor 1 as the first resistance element Z of the attenuation circuit shown in FIG. 2 are shown by solid lines in FIG. As is clear from the figure, each frequency exhibits a substantially constant attenuation value in a wide frequency band from 4 MHz to 100 MHz. As described above, in this invention, the input terminals a, a' and the output terminals b,
b' are connected through the first to third resistive elements Z, R, , R2, the high frequency signal that is about to pass through the line in one direction will be routed from the input terminals a, a'. When connected to an attenuator, the high frequency signal has the advantage of passing through the attenuator and being sent out to the line from the output terminals b, b'.

Moreover, in this case, since an attenuation circuit is formed between the input terminal and the output terminal by the first to third resistance elements Z, R, and R2, the line passes through the line in one direction. It is possible to attenuate a high frequency signal by a predetermined amount at the location where this attenuator is installed in the line,
This has the effect that the high frequency signal can be sent to the next stage at a predetermined level.

Furthermore, in order to attenuate a signal passing through the line in one direction between the input terminal and the output terminal of the attenuator, in the present invention, a through hole is formed in the ferromagnetic material. A high frequency resistor 1 constructed by inserting a conductive wire through the through hole is used as the first resistance element Z connected between the input and output terminals, and an attenuator using such a high frequency resistor is used as the high frequency resistor. Since it is used in the high frequency frequency region where the product of the loss value s'' of the relative magnetic permeability s in the ferromagnetic material of the container and the angular frequency of the high frequency signal to be passed is always constant, in the above-mentioned FIG. As shown in Figure 8, each frequency can be attenuated with a constant amount in the high frequency range. As shown by the broken line in , there is a peak in the attenuation characteristic at some frequency ranges, which has the disadvantage that high-frequency signals at those frequencies are abnormally weakened, but in the case of the present invention, In the above region, the high frequency signal in the high frequency range, the high frequency signal in the medium frequency range, and the high frequency signal in the low frequency range can all be output with uniformity.Furthermore, in the present invention, the above configuration A high-frequency resistor is used by connecting one end (for example, terminal T,) of the conductor 4 to input terminal a, and the other end (for example, terminal T2) to output terminal b. When direct current or low frequency signals are superimposed on top of such high frequency signals and sent along a line, the high frequency signal is passed in one direction of the line as described above, and in the process of passing, the high frequency signal is Even if the DC or low frequency waves sent in the same direction (or opposite direction) are attenuated, it can be passed through with almost no attenuation. It has the effect of being able to transmit these voltages without any adverse effect on the voltage used in the device.

[Brief explanation of drawings]

The drawings show an embodiment of the present application. Fig. 1 is a perspective view of a high frequency resistor, Fig. 2 is an electrical wiring diagram of an attenuator, and Fig. 3 is a diagram of the attenuator shown in Fig. 2 for low frequency and DC components. Equivalent circuit, Figure 4 is a diagram similar to Figure 3 for high frequencies, Figure 5 is a perspective view of a high frequency resistor, Figure 6 is a diagram showing the relationship between relative magnetic permeability and frequency, and Figure 7 is a diagram showing the loss term. FIG. 8 is a graph showing an example of the product of angular frequency and angular frequency, and FIG. 8 is a graph showing an example of attenuation characteristics. 2...Ferromagnetic material, 3...Through hole, 4...
... Conductor, 1, Z ... High frequency resistor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A high-frequency resistor constructed by drilling a through hole in a ferromagnetic material and inserting a conductive wire into the through hole is used as the first resistance element described later in a current passing type high frequency signal attenuator, and the above-mentioned current passing The type high frequency signal attenuator has a pair of input terminals and a pair of output terminals, and further has an attenuation between one terminal of the pair of input terminals and one terminal of the pair of output terminals. A first resistance element for a circuit configuration is connected, and a series circuit of a second resistance element and a third resistance element for an attenuation circuit configuration is further connected between these terminals, respectively. The other terminal of the pair of input terminals and the other terminal of the pair of output terminals are directly connected to each other, and the connection point thereof is connected to the second and third resistance elements. A DC and low frequency blocking capacitor is connected between the high frequency resistor and the high frequency resistor. The current passing type high frequency signal attenuator is used by connecting its ends to the one terminal of the pair of output terminals, and the current passing type high frequency signal attenuator is connected to a line through which direct current or low frequency and high frequency signals are superimposed. The current passing type high-frequency signal attenuator is used as an intervening device, and the current passing type high-frequency signal attenuator has a loss term μ_5″ of the relative magnetic permeability μ_3 of the ferromagnetic material of the high-frequency resistor and the angular frequency ω of the high-frequency signal to be passed. A method of using a current passing type high frequency signal attenuator, characterized in that it is used in a high frequency frequency region where the product is always constant.