JPS61232702A - Terminal resistor for microwave coaxial type line - Google Patents

Abstract

PURPOSE:To execute the corresponding even when the manufacture is easy, the shape is simple and the wide band characteristic is needed in the high frequency by setting the internal of a resistor connected to the inner electric conductor terminal and the outer electric conductor to cover the outside narrower than the interval of the inner electric conductor and the outer electric conductor. CONSTITUTION:A resistor 3 is extended and connected at the terminal of an inner electric conductor, the outside of the resistor 3 is covered by providing an extending part 2a at outer electric conductor 2 and the terminal of the resistor 3 is connected to a shorting part 7 provided at the terminal surface of the extending part 2a of the outer electric conductor 2. The extending part 2a is formed to thickness from the outer electric conductor 2, and an interval (d) of the resistor outer circumferential surface 3a is made narrower than an interval D of the inner electric conductor 1 and the outer electric conductor 2. Thus, the reflecting loss can be decreased up to the area of the high frequency with the simple means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminating resistor installed at the end of a microwave coaxial line consisting of an inner conductor and an outer conductor.

[Prior Art] Conventionally, this type of terminating resistor is shown in Fig. 9 and Fig. 1.
There is one shown in Figure 0.

The one shown in FIG. 9 is a simple terminating resistor, in which a resistor 3 is extended and connected to the end of the inner conductor 1, and the end of the resistor 3 is closed off to the end of the outer conductor 2. A short-circuit is formed at a short-circuit portion 4 provided in the shape of .

On the other hand, in the case shown in FIG. 1O, a resistor 3 is extended and connected to the end of the inner conductor 1, similar to the case shown in FIG. 9 above. Moreover, this thing connects the terminal end 5 of the outer conductor 2 to the inner conductor 1.
From the connection part between the resistor 3 and the resistor 3 to the terminal end of the resistor 3, it is narrowed down to an exponential type, and is connected to the resistor 3 at a short-circuit part 6 provided in a shape that closes the terminal surface. .

However, these conventional termination resistors have the following drawbacks.

[Problems to be Solved by the Invention] The terminating resistor shown in FIG. 9 has a simple structure and can be easily manufactured. The disadvantage is that the characteristics deteriorate at frequencies above I GHz).

This drawback can be countered by devising a correction circuit in the case of a narrow band. However, there is a problem in that it cannot be used when wideband characteristics are required.

On the other hand, the terminating resistor shown in FIG. 10 has little deterioration in characteristics even at high frequencies, and can be used even when wideband characteristics are required. However, it requires processing to squeeze the outer conductor into a precise exponential shape, and has the disadvantage that it is not easy to manufacture.

Another drawback is that it is not easy to connect the short-circuited portion 6 of the external conductor 2, which has been narrowed down to an exponential shape, and the resistor 3 accurately and without problems at high frequencies.

The present invention was made to solve these problems, and it does not require shaping the outer conductor into a precise exponential shape that is difficult to process and connect to a resistor, and it is easy to manufacture. It is an object of the present invention to provide a microwave coaxial type line terminating resistor that has a simple form and can be used even when broadband characteristics are required at high frequencies.

[Means for Solving the Problems] The present invention is provided in a microwave coaxial type line consisting of an inner conductor and an outer conductor coaxially arranged at a constant interval, and a resistor is provided at the end of the inner conductor. Applicable to a terminating resistor formed by extending the resistor, covering the outside of the resistor by extending the outer conductor, and connecting the terminal end of the resistor to a short circuit provided on the termination surface of the outer conductor. be done. As a means for solving this problem, the distance between the resistor connected to the end of the inner conductor and the outer conductor covering the outside thereof is set narrower than the distance between the inner conductor and the outer conductor. .

[Function] By the way, when a coaxial type terminating resistor is actually assembled, the short circuit between the resistor and the outer conductor does not become electrically zero, but has a certain length. and,
Due to actance generated in this part, it becomes impossible to reduce reflection (loss) as a terminating resistor. Therefore, it is desirable to make the electrical effective length of this short circuit as small as possible.

The present invention reduces the characteristic impedance of the resistor portion by setting the distance between the resistor connected to the end of the inner conductor and the outer conductor covering the outside thereof to be narrower than the distance between the inner conductor and the outer conductor. are doing. As a result, the electrical effective length of the short-circuited portion is shortened, and reflection loss is reduced.

[Example] Embodiments of the present invention will be described with reference to the drawings.

Configuration of First Embodiment> As shown in FIG. 1, the first embodiment of the present invention is a microwave coaxial line consisting of an inner conductor 1 and an outer conductor 2 coaxially arranged with a constant interval. A resistor 3 is extended and connected to the terminal end of the inner conductor 1, and an extension 2a is provided on the outer conductor 2 to cover the outside of the resistor 3, and the terminal end of the resistor 3 is connected to the outer conductor 2. It is connected to a short-circuit portion 7 provided on the end surface of the extension portion 2a of the outer conductor 2.

The resistor 3 can be the same as the one conventionally used. For example, a cylindrical resistor having a uniform resistance film on the surface of a cylindrical ceramic cylinder can be used. This resistor 3 is
The inner conductor 1 and the outer conductor 2 are completely connected, for example, by soldering.

The extension portion 2a covering the outside of the resistor 3 is formed to be thicker than the outer conductor 2. Therefore, the distance d between the extension portion 2a and the outer peripheral surface 3a of the resistor is narrower than the distance between the inner conductor 1 and the outer conductor 2.

Operation of the first embodiment> The operation of the first embodiment configured as described above will be explained with reference to FIGS. 2 to 4.

To analyze the characteristics of the terminating resistor of the above embodiment, more precisely, a differential equation must be solved. Here, as a simple method, divide it into elements as shown in Figure 2, and create RlxRn
This is done by finding the characteristics of the individual elements of and adding them together. The individual resistive elements are n
/L and has a resistance of R/n as a lumped constant.

In order to improve the analysis accuracy, it is desirable to increase the number of divisions n. Here, n = IEI. In addition, the length L of the resistor is selected to be short in relation to the wavelength, so that L =
It is set to 0.5 mm. Furthermore, the inner diameter of the outer conductor 2 is set to 3.5 m, which is equivalent to ASP-3 and ASP-5, which are international standards for coaxial lines.

Under such conditions, the electrical effective length of the short-circuit portion 7 is approximately 0.
Approximately 5mm occurs.So, when calculating the reflection loss,
The result is as shown in FIG.

In the same figure, the characteristic impedance of the resistor part is Z
= 50Ω, a maximum reflection loss of -15 dB occurs. Therefore, by reducing the diameter of the outer conductor and setting the characteristic impedance of the resistor portion to Z=25Ω, the reflection loss becomes approximately −27 dB, which is improved by approximately 12 dB.

As described above, according to the present embodiment, the distance between the extension part 2a and the resistor 3 is narrowed by a simple method of thickening the extension part 2a, and the reflection loss can be reduced even in the high frequency range. can do.

Second Embodiment> The second embodiment of the present invention, as shown in FIGS. 5 to 7,
The inner shape of the extension part 2a is modified, and the other parts are constructed in the same manner as in the first embodiment. Therefore, only the differences will be explained.

In the example shown in FIG. 5, a taper 2b is provided on the inner circumferential portion on the terminal end side of the extension portion 2a.

In the example shown in FIG. 6, a stepped portion 2C is provided on the inner peripheral portion of the extension portion 2a, the inner diameter of which decreases toward the terminal end.

In the example shown in FIG. 7, a taper 2d is provided on the inner peripheral portion of the extension portion 2a, the inner diameter of which becomes smaller toward the terminal end.

In the case shown in FIGS. 5 and 6 above, the electrical effective length of the short circuit portion 7 connecting the resistor 3 and the outer conductor 2 is Q, 1
It becomes approximately mrx, and has the characteristics shown in the Is8 diagram. As is clear from the figure, if the characteristic impedance of the resistor 3 is approximately 20 to 30Ω, the reflection loss is approximately 30dB.
The properties are as follows, which is very excellent.

Further, the characteristic shown in FIG. 7 will have the characteristics shown in the graph of FIG. 8 if the average characteristic impedance of the resistor 3 is about 25Ω. In this case, from the two examples above,
It has even better characteristics.

In the second embodiment described above, the inner periphery of the extension part 2 is processed, but unlike the process of narrowing it into an exponential shape, it is only a matter of providing a taper or step, so it is relatively easy to process. be able to. In this embodiment, reflection loss is further reduced than in the first embodiment by simply adding such processing.

<Modification of Embodiment> In the embodiment described above, the extension portion 2a is configured to have a thick wall on the inner peripheral side thereof. In the present invention, since it is sufficient that the distance between the extension part and the resistor is narrow, it is not necessary to make the extension part thick. Therefore, the outer diameter of the extension part may be smaller than the outer circumference of the outer conductor.

〔Effect of the invention〕

As explained above, the present invention does not require narrowing the outer conductor into a precise exponential shape that is difficult to process and connect with a resistor, and has a simple form that is easy to manufacture. This has the effect of realizing a terminating resistor that can be used even when broadband characteristics are required.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts showing the configuration of the first embodiment of the terminating resistor of the present invention, Fig. 2 is an explanatory diagram for analyzing the characteristics of the above-mentioned first embodiment, and Fig. 3 shows the above-mentioned characteristics. An explanatory diagram showing one element of the resistor assumed for analysis, Figure 4 is the above wS1
Graph showing the reflection loss of the termination resistor according to the example, No. 5
6 and 7 are cross-sectional views showing each aspect of the second embodiment of the present invention, and FIG. 8 is a graph showing the reflection loss of the terminating resistor according to the second embodiment, and FIGS. FIG. 10 is a sectional view showing each conventional termination resistor. 1... Inner conductor 2... Outer conductor 2a...
Extension part 2b... Taper 2c... Step part
2d...Taper 3...Resistor 4.6.7...Short circuit part

Claims (1)

[Claims] A microwave coaxial line is provided in a microwave coaxial line consisting of an inner conductor and an outer conductor arranged coaxially at a constant interval, and a resistor is extended and connected to the terminal end of the inner conductor, and the resistor In a terminating resistor formed by extending and covering the outer conductor, and connecting the terminal end of the resistor to a short circuit provided on the termination surface of the outer conductor, the resistor and the outer side thereof are covered. A terminating resistor for a microwave coaxial line, characterized in that a distance between the outer conductor and the inner conductor is set narrower than a distance between the inner conductor and the outer conductor.