JPH11177370A - Microwave attenuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finely adjust attenuation and to attain zero reflection by forming whole three resistors of a T-type or a π-type with variable resistors. SOLUTION: Variable resistors 10a, 10b and 11 are mounted at a prescribed positions of a metal plating pattern 6 which is integrally provided in a T-form on a circuit board 5 with metal plating. Namely, the variable resistors 10a, 10b and 11 are fitted to the circuit board 5 by an adhesive or solder wherein an input voltage is changed instead of adjusting the resistance values of the variable resistors 10a, 10b and 11 so as to change output voltage, or the resistance values are changed by rotating the adjusting screws of the variable resistors 10a, 10b and 11 instead of the change of input voltage. Thus, they are connected so that attenuation and reflection can be adjusted. Thus, the resistance values of the variable resistors 10a and 10b are adjusted and the resistance value of the variable resistor 11 is adjusted, so that reflection can be set to zero even if attenuation is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attenuator used for a communication device such as a microwave circuit.

[0002]

2. Description of the Related Art FIG. 11 shows an equivalent circuit of a generally known conventional T-type attenuator. In FIG. 11, 1 is an input terminal, 2 is an output terminal, 3a and 3b are fixed resistors connected in series between the input terminal 1 and the output terminal 2, and 4 is connected in parallel between the fixed resistors 3a and 3b. Fixed resistance.

Next, the operation will be described. In FIG. 11, the input signal is attenuated by the fixed resistors 3a and 3b, and is output after obtaining a predetermined amount of attenuation. The fixed resistor 4 includes a fixed resistor 3a,
3b is reduced. Here, the fixed resistors 3a,
Assuming that the resistance value of the resistor 3b is R1, the resistance value of the fixed resistance value 4 is R2, the predetermined attenuation is K, and the load impedance of the input and output is Z0, the relational expression is: R1 = (1-K) .Z0 / (K + 1) (1) R2 = 2 · K · Z0 / (K ² −1) (2) By selecting R1 and R2 from the equations (1) and (2), a predetermined amount of attenuation can be obtained. The reflection amount S at this time
11 is: S11 = (2 · R1 · R2 + R1 ² -Z0 ² ) / (2 · Z0 · R2 + 2 · Z0 · R1 + 2 · R1 · R2 + R1 ² + Z0 ² ) (3) Become. Also, if R1 and R2 are determined such that R2 = (Z0 ² −R1 ² ) / (2 · R1) (4), the reflection amount becomes zero.

[0004]

Since the conventional attenuator has a configuration in which the amount of attenuation is fixed as described above, when the attenuator is used for adjusting the gain of a microwave circuit, the attenuator is used in accordance with product variations. You have to use them properly. Therefore, it is necessary to prepare many kinds of attenuators, and there is a problem that the manufacturing cost and the manufacturing time increase.

The present invention has been made to solve the above problems, and has as its object to provide a microwave attenuator capable of finely adjusting the amount of attenuation and reducing the amount of reflection to zero.

[0006]

According to a first aspect of the present invention, there is provided a microwave attenuator in which all three resistors constituting a T-type or a π-type are formed as variable resistors.

According to a second aspect of the present invention, there is provided a microwave attenuator having a λ / 4 line having an electrical length of １ ／ wavelength of a working frequency, and a series connection between an input side and an input terminal of the λ / 4 line. , A variable resistor connected in series between the output side and the output terminal of the λ / 4 line, and a variable resistor connected in parallel between the input terminal and the input side of the λ / 4 line. And a connected variable resistor.

According to a third aspect of the present invention, there is provided a microwave attenuator comprising: a λ / 4 line having an electrical length of 波長 wavelength of a working frequency; and a series connection between an input side of the λ / 4 line and an input terminal. , A variable resistor connected in series between the output side of the λ / 4 line and the output terminal, and a variable resistor connected between the input side of the λ / 4 line and the λ / 4 line. And a variable resistor connected in parallel.

According to a fourth aspect of the present invention, there is provided a microwave attenuator comprising: the output terminal according to any one of the second and third aspects;
A variable resistor is connected in parallel with the variable resistor on the output side of the line.

According to a fifth aspect of the present invention, in the microwave attenuator, a variable resistor is provided between the variable resistor on the output side of the λ / 4 line and the λ / 4 line. It is characterized by being connected in parallel.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, in which the same reference numerals are given to the same parts as in the prior art. Embodiment 1 of the Invention 1A and 1B show Embodiment 1 of the present invention, in which FIG. 1A shows an equivalent circuit of an attenuator, and FIG. 1B shows an external view of the attenuator. In FIG. 1A, 10a and 10b are variable resistors connected in series between the input terminal 1 and the output terminal 2, and 11 is a variable resistor connected in parallel between the variable resistors 10a and 10b. In FIG. 1B, reference numeral 5 denotes a circuit board made of a ceramic or organic material of an attenuator;
Is a gold-plated pattern integrally provided on the circuit board 5 in a T-shape by plating, and variable resistors 10a, 10b, and 11 are loaded at predetermined positions of the gold-plated pattern 6.
That is, the variable resistors 10a, 10b, 11
Is attached with adhesive or solder,
The output voltage is changed by changing the input voltage instead of changing the respective resistance values of the variable resistors 10a, 10b, 11 or the variable resistors 10a, 10b, 11 are changed instead of changing the input voltage.
The connection is made so that the amount of attenuation and the amount of reflection can be adjusted by rotating the respective adjustment screws 10b and 11 to change the resistance value.

Next, the operation will be described. By adjusting the resistance values of the variable resistors 10a and 10b and simultaneously adjusting the resistance values of the variable resistors 11 so that the expression (4) holds, the reflection amount is made zero even when the attenuation amount is changed. Can be.

Embodiment 2 of the Invention FIG. 2 shows an equivalent circuit of the attenuator according to the second embodiment of the present invention. In FIG. 2, 12
Is a variable resistor connected in series between the input terminal 1 and the output terminal 2, 13a is a variable resistor connected in parallel between the variable resistor 12 and the input terminal 1, and 13b is a variable resistor 12 and the output terminal 2. And a variable resistor connected in parallel. That is, in the second embodiment of the present invention, the three resistors of the π-type attenuator are formed as the variable resistors 12, 13a, and 13b.

Next, the operation will be described. Similarly to the T-type attenuator according to the first embodiment of the present invention, by adjusting the resistance value of the variable resistor 12 and simultaneously adjusting the resistance values of the variable resistors 13a and 13b, even if the amount of attenuation is changed, reflection can be prevented. The quantity can be zero. Now, assume that the resistance value of the variable resistor 12 is R1, the resistance values of the variable resistors 13a and 13b are R2, the impedance is Z0, and the reflection amount S1 on the input side.
When 1 is represented by R1 and R2

[0015]

(Equation 1)

From the condition that the amount of reflection becomes zero, R2 ² · R1-2 · Z0 ² · R2-Z0 ² · R1 = 0 (6) Also, if setting is made so that the expression (6) is satisfied,
Even if the amount of attenuation is changed, the amount of reflection can be constantly reduced to zero. Note that the impedance Z0 is obtained by calculating the F parameter before deriving the S parameter of the π-type variable attenuator,
When converting from F parameter to S parameter, π
This is the characteristic impedance applied to the type variable attenuator.

Embodiment 3 of the Invention FIG. 3 shows an equivalent circuit of the attenuator according to the third embodiment of the present invention. In FIG. 3, a variable resistor 14a, a .lambda.1 / 4 line 15 whose electrical length is a quarter wavelength of the operating frequency, and a variable resistor 14b are connected in series between an input terminal 1 and an output terminal 2, and the input terminal and the variable resistor 14b are connected. Resistance 14
A variable resistor 16 is loaded in parallel with the variable a.

Next, the operation will be described. The input signal is attenuated by the attenuator 14a, passes through the λ / 4 line 15, and is attenuated by the variable resistor 14b. λ / 4 line 15 is a variable resistor 14
a and 14b are reduced. Also, the variable resistor 16 corrects the deviation of the reflection of the variable resistors 14a and 14b while slightly attenuating. Now, assume that the resistance values of the variable resistors 14a and 14b are R1, the resistance value of the variable resistor 16 is R2, the impedance Z0 of the λ / 4 line 15, and the reflection amount S on the input side.
11 is represented by R1, R2 and Z0.

[0019]

(Equation 2)

From the condition that the amount of reflection becomes zero, R2
When are expressed as R1 and ^{Z0 R2 = (Z0 3 + Z0} 2 · R1 + Z0 · R1 2) / R1 2 ............... (8) , and the when the attenuation and K1, K1, R1, Z0 relationship The equation is as follows: K1 · R2 ² + K1 · Z0 · R1 + (K1-1) · ZO ² = 0 (9) Here, the attenuation K1 when Z0 = 50Ω is set.
The relationship between R1 and R1 and R2 is as shown in FIGS. When changing the amount of attenuation, a predetermined amount of attenuation can be obtained by adjusting the resistance values of the variable resistors 14a and 14b. Further, if the resistance value of the variable resistor 16 is adjusted so that the relationship of the expression (8) is established, the reflection amount can be constantly reduced to zero even if the attenuation amount is changed.

Embodiment 4 of the Invention FIG. 6 shows an equivalent circuit of the attenuator according to the fourth embodiment of the present invention. As shown in FIG.
The attenuator according to the fourth embodiment of the present invention has a variable resistor 17 loaded in parallel between the variable resistor 14a and the λ / 4 line 15 instead of the variable resistor 16 according to the third embodiment of the present invention. is there.

Next, the operation will be described. Now, assuming that the resistance value of the variable resistor 17 is R2, the reflection characteristic is

[0023]

(Equation 3)

From the condition that the reflection amount becomes zero, R2
When the R1, is represented by ^{Z0 R2 = (Z0 3 -Z0 2} · R1) / R1 2 ......... (11) , and the attenuation amount is K1, the relational expression of K1, R1, Z0 is R1 = (1- K1) · Z0 (12) When changing the attenuation, the variable resistor 14 is used.
A predetermined amount of attenuation can be obtained by adjusting the resistance values of a and 14b. Further, if the resistance value of the variable resistor 17 is adjusted so that the relationship of the expression (11) is established, the reflection amount can be constantly reduced to zero even if the attenuation amount is changed.

Embodiment 5 of the Invention FIG. 7 shows an equivalent circuit of the attenuator according to the fifth embodiment of the present invention. As shown in FIG.
The attenuator according to the fifth embodiment of the present invention is obtained by adding a variable resistor 18 to the third embodiment of the present invention, and the variable resistor 18 is loaded in parallel between the λ / 4 line 15 and the variable resistor 14b. Have been.

Next, the operation will be described. Now, assuming that the resistance value of the variable resistor 18 is R2, the condition that the amount of reflection becomes zero is (R2 ² -Z0 ² ) · R1 ² -2 · Z0 ² · R2 · R1-Z0 ⁴ = 0. ). When changing the attenuation, the variable resistor 14 is used.
A predetermined amount of attenuation can be obtained by adjusting the resistance values of a and 14b. Further, if the resistance values of the variable resistors 16 and 18 are adjusted so that the relationship of Expression (13) is established,
Even if the amount of attenuation is changed, the amount of reflection can be constantly reduced to zero.

Embodiment 6 of the Invention FIG. 8 shows an equivalent circuit of the attenuator according to the sixth embodiment of the present invention. As shown in FIG.
The attenuator according to the fifth embodiment of the present invention is obtained by adding a variable resistor 19 to the third embodiment of the present invention. The variable resistor 19 is mounted between the variable resistor 14b and the output terminal 2 in parallel. I have.

Next, the operation will be described. Now, assuming that the resistance value of the variable resistor 19 is R2, the condition that the reflection amount becomes zero is (R2 ² −Z0 · R2) · R1 ² −Z0 ³ · R1−Z0 ⁴ = 0... (14) To change the amount of attenuation, the variable resistors 14a, 14
By adjusting the resistance value of b, a predetermined amount of attenuation can be obtained. Further, if the resistance values of the variable resistors 16 and 19 are adjusted so that the relationship of the expression (14) is satisfied, the reflection amount can be constantly reduced to zero even if the attenuation amount is changed.

Embodiment 7 of the Invention FIG. 9 shows an equivalent circuit of the attenuator according to the seventh embodiment of the present invention. As shown in FIG.
The attenuator according to the seventh embodiment of the present invention is obtained by adding a variable resistor 18 in parallel between the variable resistor 14b and the output terminal 2 to the fourth embodiment of the present invention.

Next, the operation will be described. Now, assuming that the resistance value of the variable resistor 18 is R2, the condition that the reflection amount becomes zero is (R2 ² + Z0 · R2) · R1 ² + Z0 ³ · R1-Z0 ⁴ = 0... (15) To change the amount of attenuation, the variable resistors 14a, 14
By adjusting the resistance value of b, a predetermined amount of attenuation can be obtained. Further, if the resistance values of the variable resistors 17 and 18 are adjusted so that the relationship of the expression (15) is established, the reflection amount can be constantly reduced to zero even if the attenuation amount is changed.

Embodiment 8 of the Invention FIG. 10 shows an equivalent circuit of the attenuator according to the eighth embodiment of the present invention. As shown in FIG. 10, the attenuator according to the eighth embodiment of the present invention differs from the fourth embodiment in that the variable resistor 19 is replaced by the λ / 4 line 15 and the variable resistor 1.
4b and added in parallel.

Next, the operation will be described. Now, assuming that the resistance value of the variable resistor 19 is R2, the condition that the amount of reflection becomes zero is (R2 ² + Z0 ² ) · R1 ² + 2 · Z0 ² · R2 · R1-Z0 ⁴ = 0... ). When changing the attenuation, the variable resistor 14 is used.
A predetermined amount of attenuation can be obtained by adjusting the resistance values of a and 14b. Further, if the resistance values of the variable resistors 17 and 19 are adjusted so that the relationship of the expression (16) is established,
Even if the amount of attenuation is changed, the amount of reflection can be constantly reduced to zero.

[0033]

As described above, according to the first aspect of the present invention,
Since all three resistors constituting the T-type or the π-type are formed as variable resistors, the amount of attenuation can be finely adjusted by adjusting the resistance value of each variable resistor, and even if the attenuation is changed to cancel the reflection. The amount of reflection can be reduced to zero. Therefore, by adjusting the resistance value of each variable resistor according to the variation of the product, it is possible to appropriately adjust the gain of the microwave, and it is not necessary to prepare a wide variety of attenuators, and the production cost and This has the effect of reducing the production time.

According to the second aspect of the present invention, the λ / 4 line whose electric length is １ ／ wavelength of the working frequency, and the variable connected in series between the input side and the input terminal of the λ / 4 line. Resistance and
A variable resistor is connected in series between the output side and the output terminal of the λ / 4 line, and a variable resistor is connected in parallel between the input terminal and the input side variable resistor of the λ / 4 line. Therefore, the amount of attenuation can be finely adjusted by adjusting the resistance value of each variable resistor, and even if the amount of attenuation is changed to cancel the reflection, the reflection can be made zero.

According to the third aspect of the present invention, the λ / 4 line whose electric length is １ ／ wavelength of the operating frequency, and the variable connected in series between the input side and the input terminal of the λ / 4 line. Resistance and
a variable resistor connected in series between the output side and the output terminal of the λ / 4 line, and a variable resistor connected to the input side of the λ / 4 line and λ / 4
Since variable resistances are connected in parallel with the line, the amount of attenuation can be finely adjusted by adjusting the resistance value of each variable resistor, and even if the amount of attenuation is changed to cancel the reflection, the amount of reflection is zero. There is an effect that can be.

According to the fourth aspect of the present invention, the output terminal and the λ /
Since the variable resistors are connected in parallel with the variable resistors on the output side of the four lines, the amount of attenuation can be finely adjusted by adjusting the resistance value of each variable resistor. This has the effect of reducing the amount to zero.

According to the fifth aspect of the present invention, since the variable resistors are connected in parallel between the variable resistor on the output side of the λ / 4 line and the λ / 4 line, the resistance value of each variable resistor is adjusted. The amount of attenuation can be finely adjusted, and even if the amount of attenuation is changed to cancel the reflection, the amount of reflection can be reduced to zero.

[Brief description of the drawings]

1 shows a first embodiment of the present invention, in which (a) is an equivalent circuit diagram of an attenuator, and (b) is a perspective view of the attenuator.

FIG. 2 is an equivalent circuit diagram of an attenuator according to a second embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of an attenuator according to a third embodiment of the present invention.

FIG. 4 is a characteristic diagram illustrating a relationship between a resistance value R1 and an attenuation K1 according to the third embodiment of the present invention.

FIG. 5 is a characteristic diagram illustrating a relationship between a resistance value R2 and an attenuation K1 according to the third embodiment of the present invention.

FIG. 6 is an equivalent circuit diagram of an attenuator according to a fourth embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of an attenuator according to a fifth embodiment of the present invention.

FIG. 8 is an equivalent circuit diagram of an attenuator according to a sixth embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram of an attenuator according to a seventh embodiment of the present invention.

FIG. 10 is an equivalent circuit diagram of an attenuator according to an eighth embodiment of the present invention.

FIG. 11 is an equivalent circuit diagram of a conventional attenuator.

[Explanation of symbols]

1 input terminal, 2 output terminal, 10a, 10b, 11,
12, 13a, 13b, 14a, 14b, 16, 17,
18, 19 Variable resistance, 15 λ / 4 line.

Claims (5)

[Claims] 1. A microwave attenuator, wherein all three resistors constituting a T-type or a π-type are formed as variable resistors. 2. A λ / 4 line having an electrical length of １ ／ wavelength of a working frequency, a variable resistor connected in series between an input side and an input terminal of the λ / 4 line, and a λ / 4 line. And a variable resistor connected in parallel between the input terminal and the variable resistor on the input side of the λ / 4 line. And a microwave attenuator. 3. A λ / 4 line having an electrical length of 波長 wavelength of a working frequency, a variable resistor connected in series between an input side and an input terminal of the λ / 4 line, and a λ / 4 line. And a variable resistor connected in parallel between the variable resistor on the input side of the λ / 4 line and the λ / 4 line. A microwave attenuator characterized by the following. 4. The microwave attenuator according to claim 2, wherein a variable resistor is connected in parallel between the output terminal and a variable resistor on the output side of the λ / 4 line. . 5. The variable resistor on the output side of a λ / 4 line and λ / 4
4. The microwave attenuator according to claim 2, wherein a variable resistor is connected in parallel with the line.