JPH07333269A - Impedance measurement device - Google Patents

Abstract

PURPOSE:To instantly measure impedance with high precision by detecting voltage and current components allowed to flow in an object to be measured by a directional coupler mode or a impedance sensor mode. CONSTITUTION:A voltage detection circuit 7 connects resistances 11, 14 by a relay 13 and functions as a directional coupler. The resistance 14 and a capacitor 12 are connected to each other by the relay 13 and function as an impedance sensor. Measurement reference signals of a preset frequency and voltage produced by an oscillation circuit or the like are taken in from an input terminal 9. This is supplied to load (for instance, an antenna for a medium wave radio or the like) which indicates an impedance measurement object through an output terminal 10. At this time a current value allowed to flow in the load and a voltage value (the voltage value obtained by the directional coupler or by the impedance sensor) applied to the load are detected. These detection results are calculated and processed by a high frequency operation part 3 or the like and the impedance of the load can be found.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to antenna impedance measurement for medium-wave radio, impedance measurement of short-wave band antenna, impedance measurement of high-frequency circuit network using frequencies in the medium- and short-wave band, passing power measurement, L inductance, C The present invention relates to an impedance measuring device used for measuring capacitance and the like.

SUMMARY OF THE INVENTION The present invention is an impedance measuring apparatus for measuring the antenna impedance of a medium-wave radio, the input impedance of a high-frequency circuit, and the like, and a measuring method using a directional coupler and an impedance previously developed. The impedance of a load is measured with high accuracy and without adjustment and digitally displayed by combining each advantage with the measurement method using a sensor, thereby facilitating the impedance measurement.

[0003]

2. Description of the Related Art As one of impedance measuring devices for measuring the antenna impedance of a medium-wave radio and the input impedance of a high-frequency circuit network, the device shown in FIG. 6 is conventionally known (for example, Meguro radiometer ( Antenna constant measuring instrument (bridge), "MZ-811").

The impedance measuring device 20 shown in this figure
1 is a preset frequency range, for example 500 kHz
a frequency signal of z to 1650 kHz at 40 Hz (or
80 Hz) and a measurement reference signal obtained by modulating the signal and a frequency range higher than the frequency signal by a preset frequency, for example, an oscillation circuit 202 for generating a local oscillation signal of 955 kHz to 2105 kHz, and an antenna to be measured. A bridge circuit 204 that outputs a measurement signal corresponding to the impedance of the antenna 203 when the measurement reference signal output from the oscillation circuit 202 is applied, and a measurement output from the bridge circuit 204. The reception circuit 205 receives a signal and a local oscillation signal output from the oscillation circuit 202 and outputs a display or sound indicating whether or not the bridge circuit 204 is balanced and balanced.

The human system checks whether or not the bridge circuit 204 is balanced and balanced by the display and sound of the receiving circuit 205, and checks the measurement reference signal and the local oscillation signal output from the oscillating circuit 202. The antenna 203 is adjusted by adjusting the frequency and the frequency of the measurement signal that can be captured by the receiving circuit 205.
Measure the impedance of.

In addition to the impedance measuring device 201, an impedance sensor "KIM-" developed by NHK and commercialized by Kyoritsu Electronics Industry Co., Ltd.
There is also known one such as "3301" which measures the load impedance of the broadcaster output and the broadcaster output power.

[0007]

However, the above-mentioned conventional impedance measuring device has the following problems.

That is, in the case of the bridge type, such as the impedance measuring device 201 shown in FIG. 6, it is necessary to operate a human system in order to obtain a balanced balance, and it is necessary to perform measurement depending on the skill and experience of the measurer. The time required for measurement and the measurement error will differ, and each time the frequency is changed,
There is a problem that calibration is required, operation is difficult, and measurement takes too long.

Further, since the impedance measuring device using an impedance sensor or the like is intended to measure the output of the broadcaster, not only is it difficult to measure the impedance in a wide range, but it is relatively difficult to measure the impedance. There is a problem that a large amount of passing power is required.

Further, such an impedance measuring device has a problem that basically only one frequency determined by the constant of the detecting section can be used as the measuring frequency.

In view of the above-mentioned circumstances, the present invention instantaneously determines the impedance of the object to be measured, from low impedance to high impedance, at low level and high level, with high accuracy without requiring human operation. In addition, it is an object of the present invention to provide an impedance measuring device capable of performing measurement and displaying the measurement result in a digital format.

[0012]

In order to achieve the above object, the present invention provides a measuring object by detecting a voltage component signal and a current component signal of a signal flowing through the measuring object in claim 1. In an impedance measuring device for measuring the impedance of, a voltage detection circuit for detecting a voltage component signal of a signal flowing to the measuring object by a directional coupler mode or an impedance sensor mode, and a current component of the signal flowing to the measuring object. A current detection circuit for detecting,
A signal converter that obtains a plurality of signals to be processed by combining the voltage component signal obtained by the voltage detection circuit and the current component signal obtained by the current detection circuit, and a directional coupler obtained by this signal converter. An arithmetic unit that obtains the impedance of the object to be measured by performing a preset operation based on each processing target signal in the mode and each processing target signal in the impedance sensor mode; And a display unit for displaying the impedance of the measurement object.

According to a second aspect of the present invention, in the impedance measuring device according to the first aspect, the signal conversion unit combines the voltage component signal obtained by the voltage detection circuit and the current component signal obtained by the current detection circuit. To generate an addition signal and a subtraction signal, and the addition component and the subtraction signal together with the voltage component signal and the current component signal as processing target signals, and each of these processing target signals is a high linear detection having an ideal diode characteristic. The circuit is characterized in that it is converted into a DC processing target signal and output.

According to a third aspect of the present invention, in the impedance measuring device according to the first or second aspect, the voltage detection circuit changes from the directional coupler mode to the impedance sensor mode and the impedance based on a preset condition. It is characterized by switching from the sensor mode to the directional coupler mode.

[0015]

In the above structure, according to the first aspect of the present invention, in the impedance measuring device for measuring the impedance of the measuring object by detecting the voltage component signal and the current component signal of the signal flowing through the measuring object, the voltage detecting circuit is provided. Detects the voltage component signal of the signal flowing to the measurement object in the directional coupler mode or the impedance sensor mode, and detects the current component of the signal flowing to the measurement object by the current detection circuit, and further by the signal conversion unit. A plurality of processing target signals are obtained by combining the voltage component signal and the current component signal obtained by the voltage detection circuit and the current detection circuit, and at the time of the directional coupler mode obtained by the calculation unit by the signal conversion unit. Based on each signal to be processed and each signal to be processed in the impedance sensor mode, preset After obtaining the impedance of the measurement object by performing the calculation is performed, by displaying the impedance of the measurement object obtained by the calculation unit by the display unit, without the need for human operation, With high accuracy, from low impedance to high impedance, at low level and high level, the impedance of the measurement target is instantaneously measured, and the measurement result is displayed in digital format.

According to a second aspect of the present invention, in the impedance measuring device according to the first aspect, the signal conversion unit converts the voltage component signal obtained by the voltage detection circuit and the current component signal obtained by the current detection circuit. Combined to generate addition signal and subtraction signal, these addition signals,
Along with the subtraction signal, the voltage component signal, the current component signal and the processing target signal, by converting each of these processing target signals to a DC processing target signal by a high linear detection circuit having an ideal diode characteristic, and outputting, Without requiring human operation, with high accuracy, from low impedance to high impedance, at low level and high level, the impedance of the measurement target can be instantaneously measured and the measurement result can be displayed in digital format. indicate.

According to a third aspect of the present invention, in the impedance measuring device according to the first or second aspect, the voltage detection circuit is switched from the directional coupler mode to the impedance sensor mode based on a preset condition. By automatically switching from the impedance sensor mode to the directional coupler mode, with high precision, from low impedance to high impedance, and at low level, high level, without requiring human operation, The impedance of the object to be measured is instantly measured and the measurement result is displayed in digital form.

[0018]

1 is a circuit diagram showing an embodiment of an impedance measuring device according to the present invention.

The impedance measuring apparatus 1 shown in this figure comprises a voltage / current detecting section 2, a high frequency calculating section 3, a high linear detector 4, an A / D / CPU section 5 and an LCD display 6. Load a measurement reference signal of a preset frequency and voltage value generated by an oscillating circuit (not shown) etc., and load this on the impedance measurement target (for example, antenna for medium-wave radio) At this time, the value of the current flowing through the load and the value of the voltage applied to the load (the value of the voltage obtained by the directional coupler or the value of the voltage obtained by the impedance sensor) are supplied to the load. Upon detection, the detection results are arithmetically processed to obtain the impedance of the load, which is displayed in digital form.

The voltage / current detection section 2 includes a voltage detection circuit 7 and
A current detection circuit 8 and is in phase with the voltage (main line voltage) of the measurement reference signal that flows through the route (main line system) that is input to the RF input terminal 9 and is output to the load via the output terminal 10. Alternatively, a signal (voltage component signal) having a phase advanced by 90 degrees and a signal (current component signal) in phase with the current of the measurement reference signal flowing through the main line system are detected and supplied to the high frequency operation unit 3. .

The voltage detection circuit 7 is switched when a resistor 11 which is a component of the directional coupler, a capacitor 12 which is a component of the impedance sensor, and either the directional coupler or the impedance sensor is selected. The relay 13 is provided with a resistor 14 which is a common component of the directional coupler and the impedance sensor and is set to a value sufficiently smaller than the reactance of the capacitor 12, and the relay 13 connects the resistors 11 and 14 to each other. , When it functions as a directional coupler, it detects the voltage of the measurement reference signal of the route (main line system) that is input to the RF input terminal 9 and is output to the load (voltage component in phase with the main line system). This is supplied to the high frequency operation unit 3, and the relay 13 also connects the resistor 14 and the capacitor 12 to each other.
Are connected to each other and function as an impedance sensor, a signal in which the phase of the measurement reference signal output to the load is advanced by 90 degrees from the voltage of the main line system is detected, and this is detected by the high frequency operation unit 3. Supply.

Further, the current detection circuit 8 is input to the RF input terminal 9 and divides the current of the measurement reference signal supplied to the load, and a current transformer (CT) 15 and a secondary winding of the current transformer 15. And a resistor 16 having a resistance value sufficiently smaller than the reactance of the line and converting the value of the current output from the current transformer 15 into a voltage value, and the current of the measurement reference signal output to the load ( A signal in phase with the current of the main line system),
This is supplied to the high frequency operation unit 3.

The high frequency operation unit 3 includes a voltage component amplifier circuit 17
And a current component amplification circuit 18, an addition circuit 19, and a subtraction circuit 20. The voltage component signal output from the voltage / current detection unit 2 and the current component signal are taken in and the amplification factor is obtained. In addition to amplifying by "1" times or 10 times, the amplified voltage component signal and current component signal are added and subtracted to generate an addition signal and a subtraction signal, and these addition signal, subtraction signal, The amplified voltage component signal and the amplified current component signal are supplied to the high linear detector 4.

The voltage component amplifying circuit 17 determines an operational amplifier 21 for performing differential amplification, a resistor 22 for guiding a high frequency signal (voltage component signal) output from the voltage detecting circuit 7 to the operational amplifier 21, and an amplification factor. Two resistors 23, 24
And the output signal of the operational amplifier 21 or each of the resistors 2
The signal divided by 3, 24 is the operational amplifier 21.
2 which is fed back to operate the operational amplifier 21 as a voltage buffer or a voltage amplifier having a voltage amplification factor of 10 times.
5 and the operational amplifier 21 by the relay 25.
When the output signal of is selected, the voltage detection circuit 7
The voltage component signal output from the high linear detector 4 and the adder circuit 19;
When the signal which is supplied to the subtraction circuit 20 and which is divided by the resistors 23 and 24 by the relay 25 is selected, the voltage component signal output from the voltage detection circuit 7 is taken in, and this is taken as the voltage amplification degree. The signal is amplified 10 times and supplied to the high linear detector 4, the adder circuit 19, and the subtractor circuit 20.

The current component amplifier circuit 18 outputs the high frequency signal (current component signal) output from the current amplifier circuit 26 and the operational amplifier 2 which performs differential amplification.
A resistor 27 leading to 6 and two resistors 2 that determine the amplification factor
8 and 29, and the output signal of the operational amplifier 26 or the signal divided by the resistors 28 and 29 is fed back to the operational amplifier 26 to make the operational amplifier 26 a voltage buffer or a voltage amplifier having a voltage amplification factor of 10 times. When the output signal of the operational amplifier 26 is selected by the relay 30, the current component signal output from the current detection circuit 8 is fetched, and the current component signal is buffered to obtain the high voltage. Linear detector 4 and adder circuit 1
9 and the subtraction circuit 20, and when the signal divided by the resistors 28 and 29 by the relay 30 is selected, the current component signal output from the current detection circuit 8 is taken in, and this is output. Amplify with 10 times voltage amplification,
The high linear detector 4, the adder circuit 19, and the subtractor circuit 2
Supply to 0 and.

The adder circuit 19 includes an operational amplifier 31 for performing differential amplification, and an input resistor 3 for guiding the voltage component signal output from the voltage component amplifier circuit 17 to the operational amplifier 31.
2 and a resistor 33 for input for guiding the current component signal output from the current component amplifier circuit 18 to the operational amplifier 31.
And the output signal of the operational amplifier 31 from the operational amplifier 3
1 is provided for feedback to the input side, and the voltage component signal output from the voltage component amplification circuit 17 and the current component signal output from the current component amplification circuit 18 are added. To generate an addition signal, which is supplied to the high linear detector 4.

The subtraction circuit 20 further includes an operational amplifier 35 for performing differential amplification, a pull-down resistor 36 for applying a ground potential to the operational amplifier 35, and the current component amplification circuit 1.
And a resistor 37 for transmitting a current component signal output from the signal amplifier 8 to the operational amplifier 35, and the voltage component amplifier circuit 1
It has an input resistor 38 for guiding the voltage component signal output from the operational amplifier 35 to the operational amplifier 35, and a feedback resistor 39 for returning the output signal of the operational amplifier 35 to the input side of the operational amplifier 35. , The voltage component signal output from the voltage component amplifier circuit 17, and the current component amplifier circuit 18
The difference with the current component signal output from is calculated to generate a subtraction signal, which is supplied to the high linear detector 4.

The high linear detector 4 is provided with four high linear detector circuits 40, 41, 42 and 43 as shown in FIG. 2, and the high linear detector circuits 40 to 43 output these from the high frequency operation unit 3. Added signal, subtracted signal,
The amplified voltage component signal and the amplified current component signal are respectively taken in, and they are linearly detected with high accuracy to form a DC addition signal, subtraction signal, voltage component signal, current component signal, and the A / D -Supply to the CPU unit 5.

Each of the high linear detection circuits 40 to 43 has four resistors 44 to 47 for adjusting the characteristics of the input signal.
Detection circuit 52 including one coil 48, two capacitors 49 and 50, and one diode 51
And a linear correction circuit 5 composed of one diode 53, one resistor 54 and one operational amplifier 55.
6 and two resistors 57 for adjusting the characteristics of the output signal,
And an output circuit 60 composed of one capacitor 59, and outputs an addition signal, a subtraction signal, an amplified voltage component signal, and an amplified current component signal, which are output from the high frequency operation unit 3, respectively. After capturing and adjusting these characteristics, linear detection is performed with high accuracy to obtain a DC addition signal, a subtraction signal, a voltage component signal, and a current component signal, and these characteristics are adjusted to
It is supplied to the D / CPU unit 5.

As shown in FIG. 3, the A / D / CPU unit 5 takes in the DC addition signal, the subtraction signal, the voltage component signal and the current component signal output from the high linear detector 4, and A / D converts them. A / D converter circuit 65 for
Based on the addition signal, the subtraction signal, the voltage component signal, and the current component signal of the digital signal format fetched by the D converter circuit 65, a control signal necessary for performing a specified calculation or controlling each part of the device is generated. A CPU circuit 66 for generating, a P-ROM circuit 67 for storing an OS and software for defining the operation of the CPU circuit 66, a software for defining the operation of the CPU circuit 66, constant data, etc. are stored. It has an EEP-ROM circuit 68 and an S-RAM circuit 69 used as a work area of the CPU circuit 66.

Further, the A / D / CPU section 5 performs a time counting operation or the like to supply a time data to the CPU circuit 66, and a calendar clock circuit 70 and the CPU circuit 66.
A PPI circuit (Pe circuit) that takes in control data output from the PIC circuit and switches the relay 13 of the voltage / current detection unit 2 and the relays 25 and 30 of the high frequency operation unit 17
ripheral Interface) 71
When the power is turned on or a reset switch (not shown) is operated, the CPU circuit 6
6, a reset IC circuit 72 for resetting 6, and the CPU
The display data etc. output from the circuit 66 are fetched and transmitted to the LCD display 6 or the operation signal output from the operation panel (not shown) is fetched and supplied to the CPU circuit 66. RS-232C circuit 73 and a battery 7 as a backup power source
4 and the power supply voltage obtained by the battery 74 and the charged voltage, the S-RAM circuit 6
9 and a calendar clock circuit 70, and a battery backup circuit 75 that prevents data from being erased even when the power switch is turned off.

Then, in accordance with a pre-programmed measurement procedure, the voltage / current detection unit is switched while switching the relay 13 of the voltage / current detection unit 2 and the relays 25 and 30 of the high frequency operation unit 3. 2 detects the voltage component signal or the current component signal of the measurement reference signal supplied to the load, and the high frequency operation unit 3 and the high linear detector 4 detect the DC addition signal or the subtraction signal from the voltage component signal or the current component signal. Signal, voltage component signal, current component signal are generated, and these addition signal, subtraction signal, voltage component signal, current component signal are processed by a preset arithmetic expression to calculate the impedance value of the load. Is supplied to the LCD display 6.

The LCD display 6 is the A / D / CPU section 5
The A / D / CPU unit is provided with a display data generation circuit that takes in a transmission signal output from the display data generation circuit and an LCD display element that digitally displays the display data output from the display data generation circuit. The transmission signal indicating the impedance of the load output from 5 is taken in and displayed digitally.

Next, with reference to the circuit diagrams shown in FIGS. 1 and 2, the block diagram shown in FIG. 3, and the schematic diagrams shown in FIGS. 4 and 5, the operation of this embodiment is directed to the voltage detection circuit 7. The method when used as a sex coupler, the method when the voltage detection circuit 7 is used as an impedance sensor, and the method when these methods are combined will be described separately.

<Method when the voltage detection circuit 7 is used as a directional coupler> First, the two resistors 11 and 14 are connected by the relay 13 which constitutes the voltage detection circuit 7, and the voltage detection circuit 7 is directed. When used as a sex coupler, the voltage detection circuit 7 detects a voltage component signal in phase with the voltage of the main line system, and this is amplified by the voltage component amplification circuit 17 of the high frequency operation unit 3 to an amplification factor “1” or 10 times. Is supplied to the high linear detector 4, and a current component signal of the same phase as the current of the main line system is detected by the current detection circuit 8, and this is amplified by the current component amplification circuit 18 of the high frequency operation unit 3 by an amplification factor of "1". Alternatively, it is amplified 10 times and supplied to the high linear detector 4.

In parallel with this operation, the voltage component signal output from the voltage component amplification circuit 17 and the current component output from the current component amplification circuit 18 are added by the adder circuit 19 of the high frequency operation unit 3. And the signal is added,
The addition signal is generated, and the voltage component signal output from the voltage component amplification circuit 17 and the current component amplification circuit 18 are generated by the subtraction circuit 20 of the high frequency operation unit 3.
The subtraction signal is generated by subtracting the current component signal output from the subtraction signal, and the addition signal and the subtraction signal are supplied to the high linear detector 4.

The voltage component signal, the addition signal, the subtraction signal, and the current component signal output from the high frequency operation unit 3 by the high linear detection circuits 40 to 43 of the high linear detector 4 are linearly detected with high accuracy. And converted into a DC voltage component signal, an addition signal, a subtraction signal, and a current component signal.
It is supplied to the D / CPU unit 5.

Regarding the voltage detection circuit 7 and the current detection circuit 8, circuit constants are set so that the voltage component signal and the current component signal become equal when a reference load (50Ω) is connected to the output side.

As shown in FIG. 4, if the value of the voltage component signal input to the high linear detector 4 is V'and the value of the current component signal is I ', the high linear detector 4 outputs it. The value V _v of the DC voltage component signal and the value V _i of the current component signal have the values shown in the following expressions.

V _v = k · | V ′ | (1) V _i = k · | I '| (2) where k is a constant indicating a high frequency / DC conversion ratio. Also, input to the high linear detector 4. Assuming that the value of the addition signal to be generated is A and the value of the subtraction signal is B, this high linear detector 4
The value of the direct current of the addition signal output from the V _A, the value V _B of the subtraction signal becomes values shown in the following equation.

V _A = k · | A | = k · | V ′ + I ′ | = (V _v ² + V _i ² + 2 · V _v · V _i · cos θ) ^1/2 (3) V _B = k · | B | = k · | V'-I '| = (V v 2 + V i 2 -2 · V v · V i · cos θ) 1/2 ... (4) where, theta: voltage reference axis and the current Angle with Component Signal I ′ Then, by rearranging these equations (3) and (4), the angle θ between the voltage component signal and the current component signal becomes a value shown in the following equation, and cos θ = ( _VA ²⁻ V _B ² ) / (4 · V _v · V _i ) ... (5) From this equation (5), the value of sin θ is determined based on the following equation.

Sin θ = (1−cos ² θ) ^1/2 (6) Here, when the voltage of the main line is V and the current is I, the magnitude | Z | of the impedance of the load is expressed by the following equation. .

| Z | = | V / I | = 50 · (V _v / V _i ) ... (7) From the equation (7) and the equations (5) and (6), the R component and the X component of the load Are the values shown in the following equations.

R = | Z | · cos θ (8) X = | Z | · sin θ (9) Then, as shown in the above equation (5), the value V _{v of} the voltage component signal and the current component signal value V _i, the value V _a addition signal, from a value V _B of the subtraction signal cos theta directly can be determined,
Based on this cos θ, the R component and the X component of the load can be directly obtained.

However, with this method alone, (6)
Since the expression is always a positive number, the polarity of the X component of the load cannot be known, and it is impossible to determine whether the load is capacitive or inductive.

Furthermore, from the limit of the measurement resolution of cos θ, si
When the value of n θ is small, for example, 0.2 or less,
It is difficult to accurately obtain the value of sin θ. For example,
When the impedance Z of the load is | Z | = 100Ω and the magnitude of the X component of the load is 20Ω or less, this cannot be accurately measured.

<Method when the voltage detection circuit 7 is used as an impedance sensor> Further, the resistor 14 and the capacitor 12 are connected by the relay 13 which constitutes the voltage detection circuit 7, and the voltage detection circuit 7 is used as an impedance sensor. If used, the voltage detecting circuit 7 detects a voltage component signal having a phase advanced by 90 degrees from the phase of the voltage of the main line system, and this is amplified by the voltage component amplifying circuit 17 of the high frequency operation unit 3 by an amplification factor "1" or 10 times. Is supplied to the high linear detector 4, and the current detection circuit 8 detects a current component signal of the same phase as the current of the main line system. The signal is amplified “× or 10 times” and supplied to the high linear detector 4.

In parallel with this operation, the voltage component signal output from the voltage component amplifier circuit 17 and the current component output from the current component amplifier circuit 18 are added by the adder circuit 19 of the high frequency operation unit 3. And the signal is added,
The addition signal is generated, and the voltage component signal output from the voltage component amplification circuit 17 and the current component amplification circuit 18 are generated by the subtraction circuit 20 of the high frequency operation unit 3.
The subtraction signal is generated by subtracting the current component signal output from the subtraction signal, and the addition signal and the subtraction signal are supplied to the high linear detector 4.

Then, the voltage component signal, the addition signal, the subtraction signal, and the current component signal output from the high frequency operation unit 3 by the respective high linear detection circuits 40 to 43 of the high linear detector 4 are linear with high accuracy. The signals are detected and converted into a DC voltage component signal, an addition signal, a subtraction signal, and a current component signal.
It is supplied to the / D / CPU unit 5.

Regarding the voltage detection circuit and the current detection circuit,
When a reference load (50Ω) is connected to the output side, the circuit constants are set so that the voltage component signal and the current component signal are equal.

Now, as shown in FIG. 5, if the value of the voltage component signal input to the high linear detector 4 is V'and the value of the current component signal is I ', the high linear detector 4 outputs it. The value V _v of the DC voltage component signal and the value V _i of the current component signal have the values shown in the following expressions.

V _v = k · | V ′ | (10) V _i = k · | I ′ | (11) where k is a constant indicating a high frequency / DC conversion ratio. Also, it is input to the high linear detector 4. Assuming that the value of the addition signal to be generated is A and the value of the subtraction signal is B, this high linear detector 4
The value of the direct current of the addition signal output from the V _A, the value V _B of the subtraction signal becomes values shown in the following equation.

V _A = k · | A | = k · | V ′ + I ′ | = (V _v ² + V _i ² + 2 · V _v · V _i · sin θ) ^1/2 (12) V _B = k · | B | = k · | V'-I '| = (V v 2 + V i 2 -2 · V v · V i · sin θ) 1/2 ... (13) However, theta: voltage reference axis and the current Angle with Component Signal I ′ Then, by rearranging these equations (12) and (13), the angle θ between the voltage component signal and the current component signal becomes the value shown in the following equation, sin θ = (V _A ²⁻ V _B ² ) / (4 · V _v · V _i ) ... (14) From this equation (14), the value of cos θ is determined based on the following equation.

Cos θ = (1-sin ² θ) ^1/2 (15) Here, the magnitude | Z | of the impedance of the load is expressed by the following equation.

| Z | = | V / I | = 50 (V _v / V _i ) ... (16) From the equation (16) and the equations (14) and (15),
The R component and the X component of the load have the values shown in the following equations, respectively.

R = | Z | · cos θ (17) X = | Z | · sin θ (18) Then, as shown in the above equation (14), the value V _{v of} the voltage component signal and the current component signal Value V _i , the value of the addition signal VA,
The sin θ can be directly obtained from the value V _{B of the} subtraction signal, and the R component and the X component of the load can be directly obtained based on this sin θ.

Further, in this method, si is calculated from the equation (14).
Since the value of nθ can be directly obtained including the polarity, the polarity of the X component of the load can also be determined.

However, with this method, it is difficult to accurately obtain the value of cos θ when the value of cos θ is small, for example, 0.2 or less, due to the limit of the measurement resolution of sin θ. Therefore, for example, when the impedance Z of the load is | Z | = 100Ω and the magnitude of the R component of the load is 20Ω or less, this cannot be accurately measured.

<Method of Combining these Methods> Therefore, in the impedance measuring apparatus 1 according to the present invention, the method of using the voltage detecting circuit 7 described above as a directional coupler and the method of detecting the voltage detecting circuit 7 described above. By combining with the method when using as an impedance sensor, while taking advantage of the characteristics of these two methods, the drawbacks are covered, and even when the value of cos θ is small, si
Even when the value of nθ is small, the values of the R component and the X component of the load can be accurately obtained.

The impedance measuring method performed by the impedance measuring apparatus 1 according to the present invention will be described in detail below.

First, in the impedance measuring apparatus 1 according to the present invention, the A / D / CPU section 5 controls the relay 13 constituting the voltage detecting circuit 7 to use the above-mentioned voltage detecting circuit 7 as a directional coupler. Method of cos θ
Is calculated and sin θ is calculated by the method when the voltage detection circuit 7 described above is used as an impedance sensor, and then the angle θ is corrected by the calculation shown in the following equation.

Θ ₀ = tan ⁻¹ (sin θ / cos θ) (19) where θ ₀ : angle after correction Then, the magnitude | Z | of the impedance of the load is calculated by the following equation. | Z | = | V / I | = 50 (V _v / V _i ) ... (20) Using the equation (20) and the equation (19), the operation shown in the following equation is performed to calculate the load. Find the R and X components,
This is transmitted to the LCD display 5 for digital display.

R = | Z | · cos θ ₀ (21) X = | Z | · sin θ ₀ (22) By this method, when the value of sin θ or cos θ is small, for example, 0.2 or less. Even in the case of, the smaller one can be predominant and the angle θ ₀ with a small error can be obtained, whereby the R component and the X component of the load can be accurately measured.

As described above, in this embodiment, the relay 13 constituting the voltage detecting circuit 7 is controlled, and the voltage detecting circuit 7 is used as a directional coupler in the cos method.
After obtaining θ and also obtaining sin θ by the method when the voltage detection circuit 7 is used as an impedance sensor, these tan ⁻¹ are obtained to obtain an angle θ ₀ with a small error, and this angle θ ₀ is used. Then, the R component and the X component of the load are obtained, and these are digitally displayed. Therefore, it is possible to perform with high accuracy, from low impedance to high impedance, and even at a low level without requiring human operation. Even at a high level, the impedance of the object to be measured can be measured instantaneously and the measurement result can be displayed in digital form.

Further, although the present apparatus is of a power-passing type, the high-frequency operation unit 3 has an operational amplifier 21, which operates at high speed,
Since 26, 31, 35 are used, the measurement can be performed at a low level. In the implemented example, the frequency band of 0.5 MHz to 2 MHz in the medium wave band is adjusted without adjusting | Z.
Impedance measurement could be performed with high accuracy (error ± 5%) for | = 0 to 1000Ω. In addition, it was possible to measure the L inductance of a single element as the load and the C capacitance.

Not only the impedance but also 10 m
Since it can also be used as a pass-type power meter that can measure low power as low as W, it monitors the output of the transmitter, monitors the load impedance, and measures the actual input power,
It can also be used as a multifunctional measuring device, such as in the case of obtaining the input circuit impedance of a high frequency power amplifier.

Further, in terms of economy, by using the high linear detector 4, it is only necessary to handle the detected DC voltage signal in the A / D converter circuit 65, which is an expensive high speed A / D converter. From not needing
The entire device can be kept low in cost.

In addition, by using the two methods, the other parts can be used almost in common by simply switching the voltage detection circuit 7 despite the fact that the measurement is performed, which greatly simplifies the entire apparatus. Therefore, it can be manufactured at low cost.

Further, in the above-mentioned embodiment, the adder circuit 19 and the subtractor circuit 20 of the high frequency operation unit 3 are constituted by the operation circuit using the operational amplifier.
The addition circuit 19 and the subtraction circuit 20 of the high frequency operation unit 3 may be configured by using another operation circuit, for example, an operation circuit using a ferrite core.

Further, in the above-mentioned embodiment, the angle θ ₀ is obtained by using the equation (19), and the R component and X component of the load are obtained by using this angle θ ₀ . , Cos θ or sin θ, with the angle θ at 45 degrees as the boundary, using either one of cos θ or sin θ, the R component and X component of the load can be obtained. good.

In this case, for example, cos θ obtained by the method when the voltage detection circuit 7 is used as a directional coupler and sin θ obtained by the method when the voltage detection circuit 7 is used as an impedance sensor Of which, about 0.
Using the angle θ that is less than or equal to 7, the R component of the load, X
Find the ingredients.

[0072]

As described above, according to the present invention, it is possible to measure with high accuracy, from low impedance to high impedance, and at low level and high level without requiring human operation. The impedance of an object can be instantaneously measured, and the measurement result can be displayed in digital form.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of an impedance measuring device according to the present invention.

FIG. 2 is a circuit diagram showing a detailed circuit configuration example of the high linear detector shown in FIG.

3 is a block diagram showing a detailed circuit configuration example of an A / D / CPU unit shown in FIG.

FIG. 4 is a schematic diagram showing an operation example of an impedance measuring device when the voltage detection circuit shown in FIG. 1 is used as a directional coupler.

5 is a schematic diagram showing an operation example of the impedance measuring device when the voltage detection circuit shown in FIG. 1 is used as an impedance sensor.

FIG. 6 is a block diagram showing an example of a conventionally known impedance measuring device.

[Explanation of symbols]

 1 Impedance measuring device 2 Voltage / current detection unit 3 High frequency calculation unit (signal conversion unit) 4 High linear detector (Signal conversion unit) 5 A / D / CPU unit (Calculation unit) 6 LCD display (Display unit) 7 Voltage Detection circuit 8 Current detection circuit 9 RF input terminal 10 Output terminal 11 Resistance 12 Capacitor 13 Relay 14 Resistance 17 Voltage component amplification circuit 18 Current component amplification circuit 19 Addition circuit 20 Subtraction circuit 40-43 High linear detection circuit 56 Linear correction circuit

Claims (3)

[Claims] 1. An impedance measuring apparatus for measuring an impedance of the measurement object by detecting a voltage component signal and a current component signal of a signal flowing through the measurement object, wherein the impedance measurement device uses the directional coupler mode or the impedance sensor mode. A voltage detection circuit that detects a voltage component signal of a signal that flows in the measurement target, a current detection circuit that detects a current component of the signal that flows in the measurement target, and a voltage component signal and the current obtained by the voltage detection circuit. A signal conversion unit that obtains a plurality of processing target signals by combining the current component signals obtained by the detection circuit, each processing target signal obtained by this signal conversion unit in the directional coupler mode, and each of the processing target signals in the impedance sensor mode. The impedance of the measurement target is measured by performing a preset calculation based on the processing target signal. A calculation unit for obtaining the Nsu, impedance measurement device for a display unit for displaying the impedance of the measurement object obtained by the arithmetic unit, comprising the. 2. The impedance measuring device according to claim 1, wherein the signal conversion unit combines the voltage component signal obtained by the voltage detection circuit and the current component signal obtained by the current detection circuit to obtain an addition signal, A subtraction signal is generated, and the voltage component signal and the current component signal are processed together with the addition signal and the subtraction signal, and each of these processing signals is subjected to DC processing by a high linear detection circuit having an ideal diode characteristic. An impedance measuring device characterized by converting to a target signal and outputting it. 3. The impedance measuring device according to claim 1, wherein the voltage detection circuit is based on a preset condition,
An impedance measuring device characterized by switching from a directional coupler mode to an impedance sensor mode and from the impedance sensor mode to a directional coupler mode.