Six-port test equipment and measurement device

Abstract

To provide a measurement device capable of measuring the amplitude and phase of a measured object using a modulated wave.SOLUTION: A measurement device 1B supplies the modulated wave generated by modulated signal generating means 40 to an object to be measured 2 as a measurement signal, and causes the object to be measured 2 to output a signal to be measured. The measurement signal and the signal to be measured are input to the first and second ports P1 and P2, respectively, of six-port test equipment 10, and are output from the third and fourth ports P3 and P4 as output signals S3 and S4 containing first and second amplitude information. Moreover, output signals S5 and S6 containing first and second phase information are obtained from the fifth and sixth ports P5 and P6. Measurement results of the amplitude ratio and phase difference of the object to be measured 2 are obtained by measurement result acquisition means 20 that receives these output signals S3 to S6.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a six-port measuring instrument with a simple structure that obtains information for measuring the amplitude ratio and phase difference that indicate the characteristics of a device under test, and a measuring apparatus that measures the amplitude ratio and phase difference using this six-port measuring instrument. [Background technology]

[0002] A six-port correlator for measuring the amplitude ratio and phase difference between a reference signal and a signal under test is known (see, for example, Non-Patent Document 1). The amplitude measurement section of the six-port correlator described in Non-Patent Document 1 is configured to be able to measure power that depends only on the input signal by distributing the input signal to the output ports using a power distributor. The phase measurement section measures the power of two outputs that combine the reference signal and the signal under test. A VNA (Vector Network Analyzer) is known as a measurement device that uses the functions of such a six-port correlator to measure the amplitude ratio and phase difference between an incident wave and a reflected wave, or an incident wave and a transmitted wave, of an object under test. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Toshiyuki Yagabe, Makoto Yoshida, and Masahiro Hanazawa, “Simple 6-port correlator calibration method and 2-port device under test measurement method”, Published on July 8, 2021, IEICE Technical Report, vol. 121, no. 107, MW2021-14, pp. 11-15 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the six-port correlator described in Non-Patent Document 1, the power of each signal is attenuated by half in the power divider, so the power measured in the amplitude measurement unit and the phase measurement unit approaches the noise floor. Furthermore, the other signal may leak into the power divider. Therefore, the measurement accuracy may decrease, and the dynamic range may be limited.

[0005] In addition, conventional VNAs use continuous waves (CW) to measure the characteristics of the DUT, and cannot measure the amplitude and phase of the DUT using modulated waves used in the field of communications. In particular, nonlinear elements such as transistors and diodes have different output response characteristics to continuous waves and modulated waves, so there is a demand for a measurement device that can measure the amplitude and phase of the DUT using modulated waves.

[0006] Therefore, an object of the present invention is to provide a six-port measuring instrument that can improve measurement accuracy while expanding the dynamic range of measurement, and a measuring apparatus that can measure the amplitude and phase of a device under test using a modulated wave using this six-port measuring instrument. [Means for solving the problem]

[0007] A six-port measuring instrument for solving the above problem includes a first port to which a first input signal is input, a second port to which a second input signal is input, a third port to which an output signal including first amplitude information is output, a fourth port to which an output signal including second amplitude information is output, a fifth port to which an output signal including first phase information and second phase information is output, a sixth port to which an output signal including the first phase information and the second phase information is output, a phase correlator that generates an output signal including the first phase information and an output signal including the second phase information based on the first input signal and the second input signal, and a switching means that selectively switches a connection destination of the first port to either the third port or the phase correlator, and by connecting the first port to the third port by the switching means, the first input signal is converted into an output signal including the first amplitude information. and a second amplitude measurement unit that outputs the second input signal from the fourth port as an output signal including the second amplitude information by connecting the second port to the fourth port using the switching means, wherein the phase correlator receives the first input signal and the second input signal from the first amplitude measurement unit and the second amplitude measurement unit, respectively, and generates two types of output signals including the first phase information and the second phase information by combining the first input signal and the second input signal with different phase differences, and outputs one of the generated output signals to the fifth port and the other generated output signal to the sixth port.

[0008] In order to solve the above problem, a measurement device that measures an amplitude ratio and a phase difference that indicate characteristics of a device under test using a six-port measuring instrument having the above configuration is characterized in that it comprises: a measurement signal generating means that generates a measurement signal that is at least a modulated wave; a first input adjusting means that supplies the measurement signal generated by the measurement signal generating means to the device under test and the first port of the six-port measuring instrument as the first input signal; a second input adjusting means that supplies an output of the device under test to which the first input signal has been input as the second input signal to the second port of the six-port measuring instrument; and a measurement means that performs a sweep measurement in which the frequency and / or signal level of the measurement signal is changed by a predetermined reference amount, acquires each output signal from the third port, the fourth port, the fifth port and the sixth port of the six-port measuring instrument, and acquires measurement results of the amplitude ratio and phase difference of the device under test by performing a predetermined calculation.

[0009] In the above configuration, the measurement means may be provided with a calibration function for improving the phase measurement accuracy by setting a term gate of a time width that can be regarded as a stable output region with little error due to switching of phase modulation based on a baseband signal used by the measurement signal generation means to generate the modulated wave, and capturing output signals from the third port to the sixth port of the 6-port measurement instrument within the term gate.

[0010] In addition, in the above configuration, a bandpass means for spectrum masking may be provided to limit the second input signal or the output signals from the fifth port and the sixth port of the six-port measuring instrument to an occupied bandwidth in order to accommodate the device under test in which distortion occurs in the output when operated in a nonlinear region.

[0011] Furthermore, in the above configuration, the measurement signal generating means may have a continuous wave generating function for generating a continuous wave which is a sine wave having a constant frequency and amplitude, and a modulated wave generating function for generating multiple types of QPSK modulated waves having different peak to average power ratios, and the measurement means may be capable of performing measurement control for acquiring characteristics of the device under test using the continuous wave as a measurement signal, and measurement control for acquiring characteristics of the device under test using each of the multiple types of QPSK modulated waves as the measurement signal.

[0012] In order to achieve the above object, a measurement apparatus for measuring an amplitude ratio and a phase difference that indicate characteristics of a device under test using a six-port measuring instrument having the above configuration includes a measurement signal generating means for generating a measurement signal that is at least a modulated wave, a frequency conversion means for mixing an LO signal having a higher frequency than the measurement signal generated by the measurement signal generating means with the measurement signal to generate a frequency converted measurement signal, a first input adjustment means for supplying the frequency converted measurement signal as the first input signal to the device under test and the first port of the six-port measuring instrument, and a second input adjustment means for supplying an output of the device under test to which the first input signal has been input as the second input signal to the second port of the six-port measuring instrument. a second input adjustment means for supplying the signal to a first input port; a frequency restoration means for mixing an LO signal having the same frequency as that of the frequency conversion means with each output signal from the first port to the sixth port of the six-port measuring instrument, and passing a signal in the same frequency band as the measurement signal as a frequency restored output signal; and a measurement means for performing a sweep measurement in which the frequency of each of the LO signals used in the frequency conversion means and the frequency restoration means is changed by a predetermined reference amount, obtaining each frequency restored output signal based on each output signal from the third port to the sixth port of the six-port measuring instrument, and performing a predetermined calculation to obtain measurement results of the amplitude ratio and phase difference of the device under test.

[0013] In the above configuration, the measurement means may be provided with a calibration function for improving the phase measurement accuracy by setting a term gate of a time width that can be regarded as a stable output region with little error due to switching of phase modulation based on a baseband signal used by the measurement signal generation means to generate the modulated wave, and capturing output signals from the third port to the sixth port of the 6-port measurement instrument within the term gate.

[0014] In addition, in the above configuration, a bandpass means for spectrum masking may be provided to limit the second input signal or the output signals from the fifth port and the sixth port of the six-port measuring instrument to an occupied bandwidth in order to accommodate the device under test in which distortion occurs in the output when operated in a nonlinear region.

[0015] Furthermore, in the above configuration, the measurement signal generating means may have a continuous wave generating function for generating a continuous wave which is a sine wave having a constant frequency and amplitude, and a modulated wave generating function for generating multiple types of QPSK modulated waves having different peak to average power ratios, and the measurement means may be capable of performing measurement control for acquiring characteristics of the device under test using the continuous wave as the measurement signal, and measurement control for acquiring characteristics of the device under test using each of the multiple types of QPSK modulated waves as the measurement signal.

[0016] Furthermore, in the above configuration, the measurement means may use a 4-input 1-output high-frequency switch to switch output signals from the third port to the sixth port of the 6-port measuring device in a time series manner and input them to a power detector, and obtain a signal including amplitude information or phase information from the power detector in a time series manner.

[0017] In order to achieve the above object, a six-port measuring instrument having the above configuration is provided, comprising a first receiving means arranged so as to be able to receive incoming radio waves, a second receiving means arranged at a predetermined distance from the first receiving means in the direction of arrival of the radio waves, and a calculation means for acquiring an output signal from the six-port measuring instrument and performing a predetermined calculation, wherein a first received power signal obtained from the first receiving means is input to the first port, and a second received power signal obtained from the second receiving means is input to the second port, the first amplitude measurement unit switches the connection destination of the first port to the phase correlator, the second amplitude measurement unit switches the connection destination of the second port to the phase correlator, and the phase correlator calculates the first amplitude measurement unit and the second amplitude measurement unit. When the first received power signal and the second received power signal are input from a measurement unit, the first received power signal and the second received power signal are combined with different phase differences to generate two types of output signals including first phase information and second phase information, and one of the generated output signals is output to the fifth port and the other generated output signal is output to the sixth port. The calculation means calculates the phase difference between the first received power signal and the second received power signal based on the two types of output signals generated by the phase correlator, and calculates the angle of arrival of the radio wave based on this phase difference and a known arrangement distance between the first receiving means and the second receiving means.

[0018] In the above configuration, the calculation means may be provided with a conversion table and / or an approximation formula for correcting the discrepancy between the radio wave arrival angle calculated by the calculation and the actual radio wave arrival angle, and may calculate the corrected radio wave arrival angle.

[0019] In order to solve the above problem, the present invention is characterized in that it comprises a first receiving means arranged so as to be able to receive incoming radio waves, a second receiving means arranged at a predetermined distance from the first receiving means in the direction of arrival of the radio waves, a phase correlator that generates two types of output signals including first phase information and second phase information by combining a first input signal from the first receiving means and a second input signal from the second receiving means with different phase differences, and a calculation means that calculates the phase difference of the second input signal relative to the first input signal based on the two types of output signals generated by the phase correlator, and calculates the arrival angle of the radio waves based on this phase difference and the known arrangement distance between the first receiving means and the second receiving means.

[0020] In the above configuration, a conversion table and / or an approximation formula for correcting the difference between the radio wave arrival angle calculated by calculation and the actual radio wave arrival angle may be provided in advance to calculate the corrected radio wave arrival angle. Effect of the Invention

[0021] The six-port measuring device according to the present invention can improve the measurement accuracy while expanding the dynamic range. Also, a measuring device using the six-port measuring device can measure the amplitude and phase of a device under test using a modulated wave. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic configuration diagram of a measurement device according to a first embodiment. [Diagram 2] FIG. 1 is a schematic diagram showing the configuration of an embodiment of a six-port measuring device. [Diagram 3] FIG. 2 is a schematic diagram showing an example of a configuration of a variable gain means; [Figure 4](A1) is a characteristic diagram showing an amplitude measurement result obtained by measuring the amplitude characteristics of a bandpass filter without performing level adjustment by a variable gain means in the measurement device of the first embodiment. (A2) is a characteristic diagram showing an amplitude measurement result obtained by measuring the amplitude characteristics of a bandpass filter after performing level adjustment by a variable gain means in the measurement device of the first embodiment. (B1) is a characteristic diagram showing a phase measurement result obtained by measuring the phase characteristics of a bandpass filter without performing level adjustment by a variable gain means in the measurement device of the first embodiment. (B2) is a characteristic diagram showing a phase measurement result obtained by measuring the phase characteristics of a bandpass filter after performing level adjustment by a variable gain means in the measurement device of the first embodiment. [Diagram 5] FIG. 11 is a schematic configuration diagram of a measurement device according to a second embodiment. [Figure 6] 13 is a diagram illustrating a calibration operation in the measurement device according to the second embodiment. FIG. [Figure 7] FIG. 4 is a functional explanatory diagram of a detection filter. [Figure 8] (A1) to (A3) are characteristic diagrams comparing the results of measuring the amplitude characteristics of a coaxial cable using a conventional VNA and a six-port measuring instrument. (B1) to (B3) are characteristic diagrams comparing the results of measuring the phase characteristics of a coaxial cable using a conventional VNA and a six-port measuring instrument. [Figure 9] FIG. 11 is a schematic configuration diagram showing a modified example of the measurement device according to the second embodiment. [Figure 10] 10A and 10B are characteristic diagrams showing gain and phase characteristics of an amplifier measured using a modified example of the measurement device according to the second embodiment; [Figure 11] 10A and 10B are characteristic diagrams showing amplitude and phase characteristics resulting from a power sweep measurement of an amplifier using a modified example of the measurement device according to the second embodiment; [Figure 12] FIG. 11 is a schematic configuration diagram of a measurement device according to a third embodiment. [Figure 13](A) is a schematic diagram of a measurement device according to a fourth embodiment. (B1) is an explanatory diagram of the phase difference when a radio wave (radio wave arrival angle = 0°) arriving in a direction perpendicular to the antenna arrangement surface is received by the first antenna and the second antenna. (B2) is an explanatory diagram of the phase difference when a radio wave (radio wave arrival angle = 45°) arriving at an angle of 45° from a direction perpendicular to the antenna arrangement surface is received by the first antenna and the second antenna. (B3) is an explanatory diagram of the phase difference when a radio wave (radio wave arrival angle = 60°) arriving at an angle of 60° from a direction perpendicular to the antenna arrangement surface is received by the first antenna and the second antenna. [Figure 14] 13A is a schematic diagram of a measurement device according to a fifth embodiment, and FIG. 13B is a schematic diagram of a phase correlator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Next, an embodiment of a six-port measuring device and a measuring apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

[0024] 1 shows a measurement apparatus 1A including the measurement apparatus according to the first embodiment, and this measurement apparatus 1A uses a six-port measurement apparatus 10 according to the first embodiment. The measurement apparatus 1A functions as a VNA and is an apparatus capable of measuring the transmission characteristics and reflection characteristics of a device under test 2. Examples of the device under test 2 include a cable, a filter, and an attenuator. The measurement apparatus 1A includes, for example, the six-port measurement apparatus 10, a measurement result acquisition means 20, a measurement control means 30, an oscillator 41, a first directional coupler 51, a second directional coupler 52, a first test port TP1, and a second test port TP2.

[0025] The first test port TP1 is connected to a first connection port 2a which is one connection port of the device under test 2, and the second test port TP2 is connected to a second connection port 2b which is the other connection port of the device under test 2. As a result, a measurement signal is input from the measurement device 1A to the device under test 2 via the first test port TP1, and an output signal from the device under test 2 is input to the measurement device 1A via the second test port TP2.

[0026] The oscillator 41 is a measurement signal generating means that generates a reference signal as a measurement signal. A continuous wave (CW), which is a sine wave with a constant frequency and amplitude, can be used as the reference signal. When this reference signal is used as the measurement signal, it can be output as is to the first test port TP1. As will be described later, when a modulated wave is used as the measurement signal, it can be generated from the reference signal from the oscillator 41 and a separately prepared baseband signal, and output to the first test port TP1.

[0027] The first directional coupler 51 extracts a traveling wave traveling from the oscillator 41 toward the first test port TP1 and blocks a reflected wave traveling in the opposite direction. Specifically, the first directional coupler 51 extracts a measurement signal having energy according to the degree of coupling, etc., and provides it as a first input signal to the first port P1 of the six-port measuring instrument 10, which will be described in detail later. In other words, the first directional coupler 51 functions as a first input adjustment means that supplies the measurement signal generated by the oscillator 41 as a first input signal to the device under test 2 and the first port P1 of the six-port measuring instrument 10.

[0028] On the other hand, the second directional coupler 52 extracts a traveling wave of the signal under test obtained from the device under test 2 traveling from the second test port TP2 to the terminator, and blocks a reflected wave in the opposite direction. Specifically, the second directional coupler 52 extracts a measurement signal having energy according to the degree of coupling, etc., and provides it to the second port P2 of the six-port measuring instrument 10 as a second input signal. In other words, the second directional coupler 52 functions as a second input adjustment means that supplies the output of the device under test 2 to which the first input signal has been input, as a second input signal, to the second port P2 of the six-port measuring instrument 10.

[0029] The six-port measuring device 10 is a device for measuring the amplitude ratio and phase difference between a first input signal S1 and a second input signal S2. The six-port measuring device 10 includes a first port P1 to which the first input signal S1 is input, a second port P2 to which the second input signal S2 is input, a third port P3 to which an output signal S3 including first amplitude information is output, a fourth port P4 to which an output signal S4 including second amplitude information is output, a fifth port P5 to which an output signal S5 including first phase information and second phase information is output, and a sixth port P6 to which an output signal S6 including first phase information and second phase information is output. A detailed structure of the six-port measuring device 10 will be described later.

[0030] Measurement result acquisition means 20 to which output signals S3-S6 output from 6-port measuring device 10 are input has a function as a power measuring device that measures the power of output signals S3-S6, and a function that acquires measurement results of the amplitude ratio and phase difference of device under test 2 by performing a predetermined calculation from the measured power values ​​of output signals S3-S6. For the power measurement function, a power detector (power sensor) using a detection method with a large time constant (a detection element in which even if a signal power fluctuates rapidly, it is averaged due to the large response time) such as diode detection or thermocouple detection can be used.

[0031] The measurement control means 30 is a controller that comprehensively controls each function of the measurement device 1A (for example, the 6-port measurement device 10, the measurement result acquisition means 20, the oscillator 41, etc.). The measurement control means 30 can realize the functions of the measurement control means 30 by loading a required computer program into a microcomputer that includes a processor such as a CPU (Central Processing Unit), memories such as a RAM (Random Access Memory) and a ROM (Read Only Memory), input devices such as a touch panel, a mouse, and a keyboard, input / output devices (I / O) such as a display, etc.

[0032] For example, the measurement control means 30 outputs a switching signal to the six-port measuring device 10 to switch the measurement mode, or sends a control signal to the measurement result acquisition means 20 to control the timing of acquiring the output signals S3 to S6 from the six-port measuring device 10. Furthermore, the measurement control means 30 can output a control signal to the oscillator 41 to perform a sweep measurement in which the frequency or signal level of the reference signal is changed by a predetermined reference amount.

[0033] In the measurement device 1A of this embodiment, the measurement result acquisition means 20 and the measurement control means 30 work together to function as "a measurement means that performs a sweep measurement in which the frequency and / or signal level of the measurement signal is changed by a predetermined reference amount, acquires the output signals S3 to S6 from the third port P3 to the sixth port P6 of the six-port measuring device 10, and performs a predetermined calculation to acquire the measurement results of the amplitude ratio and phase difference of the device under test 2", but a measurement means that integrates the measurement result acquisition means 20 and the measurement control means 30 may be used. Alternatively, the measurement result acquisition means 20 may be configured with a four-channel power sensor or the like and have only the function of measuring the power of the output signals S3 to S6 from the six-port measuring device 10, and each measurement data may be output to the measurement control means 30 (indicated by a dashed arrow in FIG. 1), so that the measurement control means 30 determines the amplitude ratio and phase difference of the device under test 2.

[0034] Here, one embodiment of the six-port measurement device 10 will be described with reference to Fig. 2. The six-port measurement device 10 is composed of a first amplitude measurement section 11, a second amplitude measurement section 12, and a phase correlator 13, for example.

[0035] The first amplitude measurement unit 11 includes a switching means 111 that selectively switches the connection destination of the first port P1 to either the third port P3 or the phase correlator 13 side, and by connecting the first port P1 to the third port P3 by this switching means 111, the first input signal S1 input from the first port P1 can be output from the third port P3 as an output signal S3 including first amplitude information. Also, by connecting the first port P1 to the phase correlator 13 side by the switching means 111, the first input signal S1 input from the first port P1 can be input to the phase correlator 13.

[0036] The second amplitude measurement unit 12 includes a switching means 121 that selectively switches the connection destination of the second port P2 to either the fourth port P4 or the phase correlator 13 side, and by connecting the second port P2 to the fourth port P4 by this switching means 121, the second input signal S2 input from the second port P2 can be output from the fourth port P4 as an output signal S4 including second amplitude information. Also, by connecting the second port P2 to the phase correlator 13 side by the switching means 121, the second input signal S2 input from the second port P2 can be input to the phase correlator 13.

[0037] The phase correlator 13 generates two types of output signals (one is called a fifth output signal S5 and the other is called a sixth output signal S6) including the first phase information and the second phase information by combining the first input signal S1 and the second input signal S2 with different phase differences, and outputs the output signal S5 to the fifth port P5 and outputs the output signal S6 to the sixth port P6. The phase correlator 13 includes a power divider 131 with phase difference, a power divider 132, a power combiner 133, and a power combiner 134.

[0038] The power splitter with phase difference 131 generates a phase signal S1a (first phase signal) and a phase signal S1b (second phase signal) having mutually different phases from each other from the input signal S1. The power splitter with phase difference 131 can be configured by a 90-degree hybrid. In this case, the phase signal S1a lags the input signal S1 by 90 degrees, and the phase signal S1b lags the input signal S1 by 180 degrees. Therefore, the phase difference between the phase signal S1a and the phase signal S1b is 90 degrees. The power of the phase signal S1a and the power of the phase signal S1b are half that of the input signal S1. The power splitter with phase difference 131 outputs the phase signal S1a to the power combiner 133, and outputs the phase signal S1b to the power combiner 134.

[0039] The power distributor 132 generates a divided signal S2a (first divided signal) and a divided signal S2b (second divided signal) by dividing the power of the input signal S2. A known power distributor can be used as the power distributor 132. The power distributor 132 divides the power of the input signal S2 evenly. The power of the divided signal S2a and the power of the divided signal S2b are half that of the input signal S2. The power distributor 132 outputs the divided signal S2a to the power combiner 133, and outputs the divided signal S2b to the power combiner 134.

[0040] The power combiner 133 generates an output signal S5 including the first phase information and the second phase information by combining the phase signal S1a and the divided signal S2a. The power combiner 133 can be configured by a 90-degree hybrid. The power combiner 133 outputs the output signal S5 to a fifth port P5.

[0041] The power combiner 134 generates an output signal S6 including the first phase information and the second phase information by combining the phase signal S1b and the divided signal S2b. The power combiner 134 may be configured with a 90-degree hybrid. The power combiner 134 outputs the output signal S6 to a sixth port P6.

[0042] A measurement method in the above-mentioned measurement device 1A will be described. First, a user of the measurement device 1A sets a desired frequency range and measurement granularity in the measurement control means 30. For example, a start frequency and an end frequency are set as the frequency range. For example, a unit frequency is set as the measurement granularity. When a measurement start operation is performed by the user, a frequency sweep measurement is started.

[0043] First, the measurement control means 30 outputs a control signal to the oscillator 41 to set the frequency of the reference signal to the start frequency, and causes the oscillator 41 to start supplying the measurement signal to the device under test 2 .

[0044] Next, the measurement control means 30 outputs a switching signal to the first amplitude measurement unit 11 and the second amplitude measurement unit 12, causing the switching means 111 to connect the first port P1 to the third port P3, and the switching means 121 to connect the second port P2 to the fourth port P4. As a result, the power of the output signal S3 including the first amplitude information output from the third port P3 and the power of the output signal S4 including the second amplitude information output from the fourth port P4 are measured by the measurement result acquisition means 20, and an amplitude ratio measurement step is executed to calculate the amplitude ratio.

[0045] Next, the measurement control means 30 outputs a switching signal to the first amplitude measurement unit 11 and the second amplitude measurement unit 12, connects the first port P1 to the phase correlator 13 side by the switching means 111, and connects the second port P2 to the phase correlator 13 side by the switching means 121. As a result, the power of the output signal S5 including the first phase information output from the fifth port P5 and the power of the output signal S6 including the second phase information output from the sixth port P6 are measured by the measurement result acquisition means 20, and a phase difference measurement step is executed to calculate the phase difference.

[0046] Next, the measurement control means 30 judges whether the frequency of the reference signal is the end frequency or not, and if the frequency of the reference signal is not the end frequency, outputs a control signal to the oscillator 41 to increase the frequency of the reference signal by a predetermined reference amount, and performs the above-mentioned amplitude ratio measurement process and phase difference measurement process again. The same process is repeated until the frequency of the reference signal becomes the end frequency, and the sweep measurement of the frequency sweep is completed. Note that the sweep measurement of the power sweep can also be performed by increasing the output value of the reference signal by a predetermined reference amount at a time until the output value of the reference signal becomes the end output value.

[0047] In the six-port measuring instrument 10 described above, the first port P1 is connected to the third port P3 by the switching means 111, the second port P2 is connected to the fourth port P4 by the switching means 121, and power is measured at the third port P3 and the fourth port P4. That is, the power of the input signal S1 is output as the output signal S3 from the third port P3 with almost no attenuation, and the input signal S2 is output as the output signal S4 from the fourth port P4 with almost no attenuation, so that it is possible to reduce the possibility that the power of the output signal S3 and the output signal S4 will approach the noise floor, and it is possible to improve the measurement accuracy while expanding the dynamic range of the measurement.

[0048] In addition, in the phase correlator 13, phase signals S1a and S1b, which have different phases from each other, are generated at the same timing from the input signal S1. Therefore, even if the frequency or amplitude of the input signal S1 varies with time, the output signals S5 and S6 can be generated based on the input signal S1, which has the same frequency and amplitude. Therefore, it is also possible to use a modulated wave or the like as the measurement signal.

[0049] In the measurement device 1A of this embodiment, the input signals S1 and S2 are input to the six-port measuring instrument 10 using the first and second directional couplers 51 and 52, and if the coupling rates are approximately the same, an extreme difference in gain between the input signals S1 and S2 is unlikely to occur. However, when a device with a high signal attenuation rate is used as the device under test 2, an extreme difference in gain between the input signals S1 and S2 may cause a decrease in measurement accuracy. Therefore, in the six-port measuring instrument 10 of this embodiment, variable gain means 14 (VGB: Variable Gain Block) is provided at required locations to enable the gain of the input signals S1 and S2 to be adjusted.

[0050] 2, variable gain means 14 are provided at four locations: in the line from first port P1 to switching means 111, in the line from second port P2 to switching means 121, in the line from switching means 111 to power divider with phase difference 131 of phase correlator 13, and in the line from switching means 121 to power divider 132 of phase correlator 13. By adjusting these variable gain means, the gains of output signals S3 to S6 from six-port measuring instrument 10 can be adjusted.

[0051] 3 shows an example of the configuration of the variable gain means 14. The variable gain means 14 includes gain paths GP1 to GP3 and selectors SL1 and SL2. The gain path GP1 includes an amplifier. The gain path GP2 includes a pass-through wiring in which attenuation can be ignored. The gain path GP3 includes an attenuator. The gain paths GP1 to GP3 have different gains from each other. The gain of the gain path GP2 is 1. The gain of the gain path GP1 is greater than 1, and the gain of the gain path GP3 is less than 1, and is set appropriately.

[0052] The selector SL1 is a changeover switch that selects one of the gain paths GP1 to GP3 to be connected to the input terminal 14a. The selector SL2 is a changeover switch that selects one of the gain paths GP1 to GP3 to be connected to the output terminal 14b. The selectors SL1 and SL2 operate in conjunction with each other to select the same gain path. The selectors SL1 and SL2 are controlled by a changeover signal from the measurement control means 30.

[0053] The variable gain means 14 may not include any of the gain paths GP1 to GP3. The variable gain means 14 may include four or more gain paths having mutually different gains. The amplifier of the gain path GP1 may be a variable amplifier, and the attenuator of the gain path GP3 may be a variable attenuator.

[0054] As a pre-measurement calibration process, the measurement control means 30 adjusts the signal level of the input signal S1 (or the input signal S2) based on the amplitude ratio W (=S2 / S1) between the input signal S1 and the input signal S2. For example, the measurement control means 30 calculates the amplitude ratio W from the measured power value of the output signal S3 and the measured power value of the output signal S4 measured in the amplitude ratio measurement process. Then, when the amplitude ratio W is out of a predetermined range, the measurement control means 30 sets the gain of the variable gain means 14 so that the amplitude ratio W approaches 1. For example, when the amplitude ratio W is smaller than the lower limit of the predetermined range (when the signal level of the input signal S1 is larger than the signal level of the input signal S2 and the difference between them is larger than a predetermined value), the measurement control means 30 selects the gain path GP3 of the variable gain means 14 on the first amplitude measurement unit 11 side to reduce the signal level of the input signal S1. Alternatively, the measurement control means 30 selects the gain path GP1 of the variable gain means 14 on the second amplitude measurement section 12 side to increase the signal level of the input signal S2.

[0055] In the phase correlator 13, the output signal S5 and the output signal S6 are generated based on the input signal S1 and the input signal S2. Specifically, the output signal S5 is generated by combining the phase signal S1a generated from the input signal S1 and the divided signal S2a generated from the input signal S2, and the output signal S6 is generated by combining the phase signal S1b generated from the input signal S1 and the divided signal S2b generated from the input signal S2. Therefore, if the difference between the signal level of the input signal S1 and the signal level of the input signal S2 is large, the signal with the large signal level becomes dominant in the output signals S5 and S6. As a result, the phase difference between the input signal S1 and the input signal S2 cannot be accurately calculated, and the phase measurement accuracy may be reduced. Therefore, as in the six-port measuring instrument 10 of this embodiment, if variable gain means 14 is provided in the line from the switching means 111 to the power divider with phase difference 131 of the phase correlator 13, and in the line from the switching means 121 to the power divider 132 of the phase correlator 13, it becomes possible to make adjustments to further reduce the difference between the signal level of the input signal S1 input to the power divider with phase difference 131 and the signal level of the input signal S2 input to the power divider 132.

[0056] FIG. 4 shows the results of measuring the amplitude ratio and phase difference of the device under test 2 (bandpass filter) using the measurement device 1A of the first embodiment, together with a comparative example. The comparative example is a case where a network analyzer N5242A manufactured by Keysight Technologies, Inc. is used as the measurement device. FIG. 4(A1) shows the amplitude measurement result in measurement example 1, in which the characteristics of the bandpass filter are measured using the measurement device 1A without level adjustment using the variable gain means 14. It can be seen that in this measurement example 1, a measurement result that is comparable to the amplitude measurement result of the comparative example is obtained. (B1) shows the phase measurement result in measurement example 1, in which the phase characteristics of the bandpass filter are measured using the measurement device 1A without level adjustment using the variable gain means 14. It can be seen that this measurement example 1 contains a considerable error compared to the phase measurement result of the comparative example. (A2) shows the amplitude measurement result in measurement example 2, in which the characteristics of the bandpass filter are measured using the measurement device 1A with level adjustment using the variable gain means 14. It can be seen that in this measurement example 2, a measurement result that is comparable to the amplitude measurement result of the comparative example is also obtained. (B2) shows the phase measurement result in measurement example 2, in which the phase characteristics of the bandpass filter were measured by performing level adjustment using variable gain means 14 in measurement device 1A. It can be seen that in measurement example 2, the error is reduced compared to measurement example 1, and a measurement result close to the phase measurement result in the comparative example is obtained. Thus, it can be seen that adjusting the gain of input signals S1 and S2 in six-port measuring instrument 10 is effective in improving measurement accuracy.

[0057] Next, a measurement device 1B according to a second embodiment will be described with reference to Fig. 5. The measurement device 1B is significantly different from the measurement device 1A according to the first embodiment in that a modulated signal is used as a measurement signal. In the measurement device 1B, the same reference numerals are used to designate components having the same functions as those in the measurement device 1A according to the first embodiment, and descriptions thereof will be omitted.

[0058] The measurement device 1B includes a modulated signal generating means 40, and the modulated signal generated by the modulated signal generating means 40 is supplied to the device under test 2 as a measurement signal. The modulated signal generating means 40 modulates a reference wave (CW signal) generated by an oscillator 41 with an I signal and a Q signal supplied from a baseband signal generator 42 in a quadrature modulator 43, and outputs a QPSK modulated wave modulated signal. Note that the quadrature modulator 43 is provided with a band-limiting filter, which causes a difference in peak to average power ratio (PAPR) compared to an unmodulated CW signal. The peak to average power ratio (PAPR) is the ratio between the maximum transmission power and the average transmission power of a modulated signal, and is an index indicating the magnitude of the transmission power at the peak. For example, the quadrature modulator 43 is provided with multiple types of band-limiting filters, and by changing the band-limiting filter used when generating a modulated signal, modulated signals with different PAPRs can be used as measurement signals.

[0059] As described above, the modulated signal generated by the modulated signal generating means 40 is supplied to the device under test 2 as a measurement signal, the signal under test is output from the device under test 2, and an input signal S1 corresponding to the measurement signal and an input signal S2 corresponding to the signal under test are supplied to the six-port measuring instrument 10. As described above, since the input signals S1 and S2 are input to the six-port measuring instrument 10 from the first port P1 and the second port P2 almost simultaneously, even if the frequency and amplitude change over time, the amplitude ratio and phase difference can be measured with high accuracy by measuring the output signals S3 to S6 obtained from the third to sixth ports P3 to P6 by the measurement result acquiring means 20.

[0060] Furthermore, when performing a sweep measurement using a frequency sweep in the measuring device 1B, the frequency of the reference wave output by the oscillator 41 is changed by a predetermined reference amount. Similarly, when performing a sweep measurement using a power sweep in the measuring device 1B, the output value of the reference signal is increased by a predetermined reference amount until the output value of the reference signal reaches the end output value. Methods for changing the output value of the reference signal for a power sweep include changing the levels of the I and Q signals input to the quadrature modulator 43, providing a variable attenuator or variable gain amplifier on the output side of the quadrature modulator 43, or combining both methods.

[0061] When the characteristics of the device under test 2 are measured by the measurement device 1B that uses a modulated wave as a measurement signal, the measurement accuracy can be further improved by performing various calibrations.

[0062] 6, a delay Δt may occur between a measurement signal that is input to six-port measuring instrument 10 as input signal S1 and a signal under measurement that is input to six-port measuring instrument 10 as input signal S2. If this delay Δt is negligible relative to the wavelengths of the measurement signal and the signal under measurement, it does not significantly reduce the measurement accuracy. However, if a delay Δt that cannot be ignored occurs due to the characteristics of device under test 2, the delay of the signal under measurement can be offset by delaying input signal S1 by Δt before inputting it to six-port measuring instrument 10.

[0063] 6, when the modulation signal generating means 40 modulates the CW wave based on the baseband signal used to generate the modulation wave, an error occurs in the amplitude of the measurement signal due to switching of the phase modulation, resulting in an unstable state. Therefore, the measurement control means 30 sets a term gate of a time width that can be considered as a stable output region in which there is little error due to switching of the phase modulation within the output timing from the six-port measuring device 10, generates a gate signal for capturing the output signals S3 to S6 from the third port P3 to the sixth port P6 of the six-port measuring device 10 within the term gate, and transmits the gate signal to the measurement result acquiring means 20. Then, the measurement result acquiring means 20 captures the output signals S3 to S6 in accordance with the on / off timing of the gate signal, thereby improving the phase measurement accuracy.

[0064] Furthermore, when using the measurement device 1B to measure a device under test 2 that generates distortion in the output when operated in a nonlinear region, such as a transistor or a diode, it is desirable to provide a detection filter 60 (shown by a dashed line in FIG. 5). As shown in FIG. 7, this detection filter 60 functions as a bandpass means for spectrum masking that limits the input signal S2 input to the second port P2 to an occupied bandwidth. Alternatively, the detection filter 60 may be provided to limit the output signals from the third port P3 to the sixth port P6 (including at least the fifth port P5 and the sixth port P6) of the six-port measuring instrument 10 to an occupied bandwidth. Note that instead of the detection filter 60 made up of an analog filter, a digital filter may be used that band-limits the output signals S3 to S6 from the third port P3 to the sixth port P6 of the six-port measuring instrument 10 after A / D conversion.

[0065] 8(A1) to 8(A3) are characteristic diagrams comparing the amplitude characteristics when a coaxial cable is used as the DUT 2 and measured using a conventional VNA (comparative example shown by a solid line in the figure) with the amplitude characteristics when measured using a six-port measuring device 10 (measurement example shown by a dashed line in the figure). In FIG. 8(A1), CW is used as the measurement signal, and the output from the six-port measuring device 10 is acquired using an existing spectrum analyzer as the measurement result acquisition means 20 of the measuring device 1A according to the first embodiment of FIG. 1 (measurement example 3-1). In FIG. 8(A2), a QPSK modulated wave is used as the measurement signal, and the output from the six-port measuring device 10 is acquired using an existing spectrum analyzer as the measurement result acquisition means 20 of the measuring device 1B according to the second embodiment of FIG. 5 (measurement example 3-2). In FIG. 8(A3), a QPSK modulated wave was used as a measurement signal, and the output from the 6-port measuring device 10 was acquired using a power sensor as the measurement result acquisition means 20 of the measuring device 1B according to the second embodiment of FIG. 5 (measurement example 3-3). It can be seen that in these measurement examples 3-1 to 3-3, measurement results comparable to those obtained using a conventional VNA (comparative example) can be obtained. In particular, in the measuring device 1B according to the second embodiment using a QPSK modulated wave, by performing average power measurement using a detection element with a large time constant such as a power sensor, rather than an existing spectrum analyzer, as the measurement result acquisition means 20, it can be seen that the fine ripples seen in the amplitude characteristics of FIG. 8(A2) are suppressed as shown in FIG. 8(A3), and the influence of the PAPR in the QPSK modulated wave can be eliminated as much as possible. Note that the conventional VNA (heterodyne method) only supports CW, and the characteristics of the coaxial cable do not change whether it is CW or QPSK modulated wave, so all the comparative examples in FIG. 8(A1) to (A3) used CW.

[0066] 8(B1)-(B3) are characteristic diagrams comparing the phase characteristics (measurement example shown by dashed lines in the figures) when a coaxial cable is used as the DUT 2 and a conventional VNA (comparative example shown by solid lines in the figures) is used to measure the coaxial cable as the DUT 2, and the six-port measuring device 10 is used to measure the coaxial cable as the DUT 2. In FIG. 8(B1), CW is used as the measurement signal, and the output from the six-port measuring device 10 is acquired using an existing spectrum analyzer as the measurement result acquisition means 20 of the measuring device 1A according to the first embodiment of FIG. 1 (measurement example 3-1). In FIG. 8(B2), a QPSK modulated wave is used as the measurement signal, and the output from the six-port measuring device 10 is acquired using an existing spectrum analyzer as the measurement result acquisition means 20 of the measuring device 1B according to the second embodiment of FIG. 5 (measurement example 3-2). In FIG. 8(B3), a QPSK modulated wave was used as the measurement signal, and the output from the 6-port measuring device 10 was acquired using a power sensor as the measurement result acquisition means 20 of the measuring device 1B according to the second embodiment of FIG. 5 (measurement example 3-3). It can be seen that in these measurement examples 3-1 to 3-3, measurement results comparable to those obtained using a conventional VNA (comparative example) can be obtained. In particular, in the measuring device 1B according to the second embodiment using a QPSK modulated wave, by performing average power measurement using a detection element with a large time constant such as a power sensor, rather than an existing spectrum analyzer, as the measurement result acquisition means 20, it can be seen that the fine ripples seen in the phase characteristic of FIG. 8(B2) are suppressed as shown in FIG. 8(B3), and the influence of the PAPR in the QPSK modulated wave can be eliminated as much as possible. Note that the conventional VNA (heterodyne method) only supports CW, and the characteristics of the coaxial cable do not change whether it is CW or QPSK modulated wave, so all the comparative examples used CW.

[0067] The measurement device 1B of the second embodiment described above can output a modulated wave as a measurement signal, but does not have a function to output a continuous wave as a measurement signal. However, in the case of an object to be measured 2 such as an amplifier, which has different response outputs to a continuous wave and a modulated wave, it is desirable to be able to use both a continuous wave and a modulated wave as a measurement signal in order to precisely evaluate the upper limit of the linear region. Therefore, the measurement device 1B', which is a modified example of the second embodiment shown in FIG. 9, is provided with a measurement signal generating means 40' having a continuous wave generating function for generating a continuous wave that is a sine wave with a constant frequency and amplitude, and a modulated wave generating function for generating multiple types of QPSK modulated waves with different peak power to average power ratios. Then, the measurement control means 30 can perform measurement control for acquiring the characteristics of the object to be measured 2 using a continuous wave as a measurement signal and measurement control for acquiring the characteristics of the object to be measured 2 using multiple types of QPSK modulated waves as measurement signals by instructing the measurement signal generating means 40'. The measurement signal generating means 40' can generate a plurality of types of modulated waves by outputting measurement signals with different peak-to-average power ratios (PAPR) using, for example, different band-limiting filters.

[0068] FIG. 10 shows an example of characteristics obtained by the measuring device 1B′ using an amplifier as the DUT 2. FIG. 10(A) shows the gain characteristics of an amplifier using a continuous wave (CW) and two types of QPSK modulated waves (QPSK with a PAPR of 5 dB and QPSK with a PAPR of 7 dB) as measurement signals. This result shows that it is necessary to set the upper limit of the linear region to a lower input signal level than the upper limit of the linear region when the amplifier is operated with a continuous wave. FIG. 10(B) shows the phase characteristics of an amplifier using a continuous wave (CW) and two types of QPSK modulated waves (QPSK with a PAPR of 5 dB and QPSK with a PAPR of 7 dB) as measurement signals. This result also shows that it is necessary to set the upper limit of the linear region to a lower input signal level than the upper limit of the linear region when the amplifier is operated with a continuous wave. In this way, by using the measuring device 1B′, it is possible to precisely evaluate the upper limit of the linear region of the DUT 2, which has different response outputs to a continuous wave and a modulated wave. Fig. 11 shows an example of characteristics acquired by performing a power sweep using the measurement apparatus 1B' with an amplifier as the DUT 2. A 5 GHz QPSK modulated signal actually used for communications was used here. Fig. 11(A) shows the gain characteristics of the amplifier, and Fig. 11(B) shows the phase characteristics of the amplifier. As such, it can be seen that the measurement apparatus 1B' of this embodiment, as well as the measurement apparatuses 1A and 1B described above, can also perform measurements with a high degree of accuracy using a power sweep that uses a modulated wave.

[0069] In the above-mentioned measuring devices 1A, 1B, 1B', when performing a sweep measurement by frequency sweep, the frequency of the measurement signal must be changed by a predetermined reference amount, so that the generation of the measurement signal is complicated. In addition, the measurement result acquisition means 20 that receives the output signals S3 to S6 from the 6-port measuring device 10 is required to have a high-speed sampling capability that can follow the high-frequency measurement signals.

[0070] Therefore, in the third embodiment of the measuring device 1C shown in Figure 12, a so-called heterodyne detection method is combined to efficiently perform frequency sweep measurements and to acquire output signals S3 to S6 from the six-port measuring device 10 in the same frequency band as the measurement signals.

[0071] In the measuring device 1C, the measuring signal output from the modulation signal generating means 40, which generates the measuring signal, which is a modulated wave, is mixed with the LO signal by the frequency converting means 70 to produce a frequency-converted measuring signal, which is then output. The LO signal is a signal with a higher frequency than the measuring signal, and the mixer 71 mixes the measuring signal with the LO signal generated by an oscillator (not shown) to generate two frequencies, which are the sum and difference of the two frequencies, and the filter 72 blocks the frequency band which is the difference between the two frequencies and the LO signal, and passes only the frequency band which is the sum of the two frequencies as the frequency-converted measuring signal. This frequency-converted measuring signal is supplied to the device under test 2 and the first port P1 of the six-port measuring instrument 10 as a first input signal via the first directional coupler 51. The output from the device under test 2 to which the first input signal has been input is supplied to the second port P2 of the six-port measuring instrument 10 as a second input signal via the second directional coupler 52.

[0072] Since the frequency of the frequency-converted measurement signal generated by the frequency conversion means 70 is determined by the frequency of the measurement signal generated by the modulation signal generation means 40 and the frequency of the LO signal, for example, the frequency of the frequency-converted measurement signal can be changed simply by changing the frequency of the LO signal. That is, a sweep measurement using a frequency sweep can be performed by simple control in which the frequency of the measurement signal generated by the modulation signal generation means 40 is fixed and the frequency of the LO signal mixed by the mixer 71 is changed in increments of a predetermined unit frequency.

[0073] On the other hand, the output signals S3 to S6 output from the third port P3 to the sixth port P6 of the six-port measuring instrument 10 are selected by the high-frequency switch 80 and sequentially supplied to the frequency restoration means 90. In this frequency restoration means 90, the output signals S3 to S6 selected by the high-frequency switch 80 are mixed with an LO signal generated by an oscillator (not shown), and output as a frequency restoration output signal to the measurement result acquisition means 20. The LO signal used in the frequency restoration means 90 is a signal of the same frequency as the LO signal used in the frequency conversion means 70, and by mixing the output signals S3 to S6 with the LO signal by the mixer 91, two frequencies that are the sum and difference of the two frequencies are generated, and the frequency band that is the sum of the two frequencies and the LO signal are blocked by the filter 92, and only the frequency band that is the difference between the two frequencies is passed as the frequency restoration output signal.

[0074] The frequency restoration output signal generated by the frequency restoration means 90 is a signal in the same frequency band as the measurement signal generated by the modulation signal generation means 40. That is, even if the frequency conversion means 70 changes the frequency of the LO signal by a predetermined unit frequency in order to perform a sweep measurement by frequency sweep, a signal in the same frequency band as the measurement signal generated by the modulation signal generation means 40 is obtained as the frequency restoration output signal without being affected by the frequency change. Therefore, the measurement result acquisition means 20 that receives the frequency restoration output signal can be supported by an inexpensive and relatively slow sampling function, thereby reducing the cost of the measurement device 1C.

[0075] Moreover, when the CH power (channel power) is measured with spectrum masking, the measured value of the CH power fluctuates due to the PAPR of the QPSK modulated signal. However, if a diode or thermocouple type power sensor is used as the detector of the measurement result acquisition means 20, the response speed of the detector is slow, so that the fluctuation due to the PAPR is filtered and the detector functions as an average detector. In other words, in the detection by the measurement result acquisition means 20, the influence of the fluctuation due to the PAPR according to the sampling point on the time axis can be eliminated as much as possible, so that the detection of four output signals can be performed in a short time with a single detector by switching the four output ports at high speed with the high frequency switch 80 by sequential control, which has the advantage of realizing high measurement accuracy. In the first place, one of the factors that deteriorates the measurement accuracy is that the use of multiple detectors results in the influence of individual differences and temperature drifts of each detector, so if the influence of the time difference in the detection timing can be eliminated with a single detector, the measurement accuracy can be improved. Therefore, as in the measuring device 1C of this embodiment, the output signals from the third port P3 to the sixth port P6 of the six-port measuring device 10 are switched in time series by a four-input one-output high-frequency switch 80, input to a power detector with a slow response speed for measuring power, and a signal including amplitude information or phase information is obtained in time series from this power detector, thereby improving the measurement accuracy. In addition, since the measuring device 1C of this embodiment does not need to be provided with four detection functions, the number of parts is reduced, which is also useful for reducing costs.

[0076] Also, by carrying out the various calibrations described above on the measurement device 1C, the measurement accuracy can be further improved. For example, if a delay Δt occurs between the measurement signal input to the six-port measurement device 10 as the input signal S1 and the signal under measurement input to the six-port measurement device 10 as the input signal S2, the delay of the signal under measurement can be offset by delaying the input signal S1 by Δt before inputting it to the six-port measurement device 10.

[0077] Furthermore, if the measurement control means 30 sets a term gate of a time width that can be regarded as a stable output region with little error due to phase modulation switching within the output timing from the six-port measuring device 10, generates a gate signal for capturing the output signals S3 to S6 from the third port P3 to the sixth port P6 of the six-port measuring device 10 within the term gate and sends it to the high-frequency switch 80, and the high-frequency switch 80 selects and sends out the output signals S3 to S6 in accordance with the on / off timing of the gate signal, the phase measurement accuracy can be improved.

[0078] Furthermore, when using the measurement apparatus 1C to measure a device under test 2 that generates distortion in its output when operated in a nonlinear region, such as a transistor or a diode, a detection filter 60 (shown by a dashed line in FIG. 12) may be provided to limit the input signal S2 input to the second port P2 to an occupied bandwidth. Alternatively, the detection filter 60 may be provided so as to limit the output signals from the third port P3 to the sixth port P6 (including at least the fifth port P5 and the sixth port P6) of the six-port measuring instrument 10 to an occupied bandwidth. Note that instead of the detection filter 60 made up of an analog filter, a digital filter may be used that band-limits the frequency restored output signal output from the frequency restoration means 90 after A / D conversion.

[0079] Furthermore, so that both continuous waves and modulated waves can be used as measurement signals, the measurement device 1C may be provided with a measurement signal generating means having a continuous wave generating function for generating a continuous wave that is a sine wave with a constant frequency and amplitude, and a modulated wave generating function for generating multiple types of QPSK modulated waves with different peak power to average power ratios.

[0080] The above-mentioned measuring devices 1A, 1B, 1B', and 1C are measuring devices that measure the amplitude ratio and phase difference that indicate the characteristics of the device under test 2, but it is also possible to estimate the arrival angle of the radio wave from the phase difference when the radio wave is received at two locations by using only the function of outputting phase information of the six-port measuring device 10. Therefore, the measuring device 1D shown in Fig. 13(A) is equipped with a first receiving means 3a arranged to be able to receive the arriving radio wave (for example, wavelength λ), a second receiving means 3b arranged at a predetermined interval (for example, λ / 2) so as to have the same reception angle as the first receiving means 3a with respect to the arrival direction of the radio wave, and a calculation means 100 that acquires the output signal from the six-port measuring device 10 and performs a predetermined calculation, thereby determining the arrival angle of the radio wave.

[0081] In the measurement device 1D, the first received power signal obtained from the first receiving means 3a is input to the first port P1 of the six-port measuring device 10, and the second received power signal obtained from the second receiving means 3b is input to the second port P2 of the six-port measuring device 10, and phase information is acquired in the six-port measuring device 10. In the six-port measuring device 10, the switching means 111 of the first amplitude measuring unit 11 keeps the connection destination of the first port P1 switched to the phase correlator 13, and the switching means 121 of the second amplitude measuring unit 12 keeps the connection destination of the second port P2 switched to the phase correlator 13. Then, when the phase correlator 13 receives the first received power signal and the second received power signal from the first amplitude measuring unit 11 and the second amplitude measuring unit 12, respectively, it generates two types of output signals including the first phase information and the second phase information by combining the first received power signal and the second received power signal with different phase differences, and outputs one of the generated output signals to the fifth port P5 and the other generated output signal to the sixth port P6.

[0082] The two types of output signals output from the six-port measuring device 10 are supplied to a calculation means 100 having a function of a measurement result acquisition means, and the calculation means 100 calculates the phase difference between the first received power signal and the second received power signal based on the two types of output signals including the first phase information and the second phase information, and calculates the arrival angle of the radio wave based on this phase difference and the known arrangement interval (λ / 2) between the first receiving means 3a and the second receiving means 3b. If the cable length connecting the antenna input of the first receiving means 3a to the first port P1 of the six-port measuring device 10 and the cable length connecting the antenna input of the second receiving means 3b to the second port P2 of the six-port measuring device 10 are different, a phase difference will occur between the signal received by the first receiving means 3a and the signal received by the second receiving means 3b. In addition, a phase difference may occur due to the transmission characteristics of the connection cable itself. Therefore, it is desirable to measure the phase difference caused by the cable length etc. in advance and provide the calculation means 100 with a function to correct (offset) the phase difference. Also, the phase difference caused by the cable length etc. may be corrected by setting the variable gain means 14 of the six-port measuring instrument 10 to an appropriate gain.

[0083] As shown in Fig. 13(B1), when radio waves arrive perpendicular to the antenna arrangement surface PS, they are incident on the first receiving means 3a and the second receiving means 3b at the same time. In this case, the received waves at the first receiving means 3a and the received waves at the second receiving means 3b are in phase with each other, so the phase difference is 0. In other words, if the phase difference based on the phase information from the first receiving means 3a and the phase information from the second receiving means 3b is 0, the radio waves arrive from a direction perpendicular to the antenna arrangement surface PS, so the radio wave arrival angle is 0°.

[0084] As shown in FIG. 13(B2), when radio waves arrive in a direction inclined with respect to the antenna arrangement surface PS, the first receiving means 3a receives the radio waves later than the timing when the second receiving means 3b, which is closer to the radio wave arrival direction, receives the radio waves. This difference can be obtained as a phase difference between the received waves at the first receiving means 3a and the received waves at the second receiving means 3b. For example, when the first receiving means 3a receives the radio waves later than the timing when the second receiving means 3b receives the radio waves by √2λ / 4, cosθ=(√2λ / 4) / (λ / 2)=1 / √2, so θ=45°. If this is replaced with the radio wave arrival angle based on the direction perpendicular to the antenna arrangement surface PS, 90°-45°=45°, and the radio wave arrival angle is estimated to be 45° on the second receiving means 3b side. However, the radio wave arrival angle may differ from the angle (phase difference=wavelength difference) detected by the six-port measuring instrument 10 and the actual angle, so correction is required. For example, the calculation means 100 has a function of calculating a corrected radio wave arrival angle based on a conversion table or an approximation formula for correcting the difference between the calculated radio wave arrival angle and the actual radio wave arrival angle (function of the radio wave arrival angle correction means). With this function of the radio wave arrival angle correction means, the radio wave arrival angle can be corrected to 45° when the phase difference is 63°.

[0085] As shown in Fig. 13(B3), when the first receiving means 3a receives radio waves with a delay of √3λ / 4 from the timing of reception by the second receiving means 3b, cosθ=(√3λ / 4) / (λ / 2)=√3 / 2, so θ=30°. If this is replaced with the radio wave arrival angle based on the direction perpendicular to the antenna arrangement surface PS, 90°-30°=60°, and the radio wave arrival angle is estimated to be 60°, but the radio wave arrival angle correction means can correct the radio wave arrival angle to 60° when the phase difference is 78°. Note that the radio wave arrival angle correction means may use only one of the conversion table or approximation formula for correction, or the conversion table may be used for a range that cannot be properly corrected by the approximation formula.

[0086] In this way, the measurement device 1D can estimate the arrival angle of the radio wave. For the sake of simplicity, the measurement device 1D of this embodiment has been described on the assumption that the arrangement direction of the first receiving means 3a and the second receiving means 3b coincides with the traveling direction of the radio wave, but it is also possible to arrange three or more receiving means on the two-dimensional coordinate system of the antenna arrangement surface PS and obtain the three-dimensional angle of the radio wave arrival direction. The measurement device 1D can also be used not only to obtain the arrival angle of the incoming radio wave, but also to know the phase characteristics of the power supplied to the antenna.

[0087] Conventionally, portable communication devices such as mobile phones are battery-powered, and therefore the efficiency of transmission power is an issue. To address these issues, power efficiency has been improved by using multiple amplifiers such as the Doherty amplifier. This Doherty amplifier combines the output of a main amplifier that always operates and a sub-amplifier that operates when the output power is large. The transmission line lengths from each amplifier to the power combiner are not equal, and a phase difference occurs, so there is a problem that the phase of the combined power varies greatly when the sub-amplifier operates. In the case of the Doherty amplifier, the phase changes dramatically depending on whether only the main amplifier operates, only the sub-amplifier operates, or the main amplifier and the sub-amplifier operate simultaneously, so the issue is how to generate a correction table for the phase adjuster according to the power supplied to the antenna element.

[0088] In addition, in millimeter wave communications, etc., technology is used that dynamically changes the antenna directivity by adaptive phased array antennas, and by changing the amplitude and phase of the wireless communication signal fed to each antenna element, it is possible to perform beamforming that gives directivity in any direction. Therefore, in the case of adaptive phased array antennas, the challenge is to generate a correction table for the phase adjuster so as to offset the fluctuations in the relative phase characteristics of each antenna element.

[0089] Therefore, if the power signals for the two antenna outputs are input from the first and second receiving means 3a and 3b in the measuring device 1D of this embodiment, the phase difference between the two signals can be measured, and a correction table for the phase adjuster can be generated. Moreover, since modulated waves such as QPSK used in actual wireless communication can be input to the first and second receiving means 3a and 3b, the phase can be measured with high accuracy, and the error when generating the correction table is reduced. If a highly accurate correction table is used in the Doherty amplifier, appropriate phase adjustment can be performed depending on the case where the main amplifier is switched to the sub-amplifier or the main amplifier and the sub-amplifier are used together. Furthermore, if a highly accurate correction table is used in the adaptive phased array antenna, the phase difference of each antenna element constituting the adaptive phased array antenna can be appropriately corrected, and highly accurate directional control can be performed.

[0090] In the above-mentioned measuring device 1D, when the power ratio of the two signals is significantly biased because the received power of the signal acquired by the first receiving means 3a is different from the received power of the signal acquired by the second receiving means 3b, the power ratio of the two signals can be made close to 1 by using the variable gain means 14. However, when the propagation distance of the radio waves is sufficiently long in the far field, the power ratio input to the two antennas is close to 1, so that the radio wave arrival angle can be measured with sufficient accuracy by using only the phase correlator 13, which is one component of the six-port measuring instrument 10. Therefore, the measuring device 1E shown in FIG. 14(A) is provided with the first receiving means 3a arranged to be able to receive the arriving radio waves (for example, wavelength λ), the second receiving means 3b arranged at a predetermined interval (for example, λ / 2) from the first receiving means 3a in the direction of the arrival of the radio waves, and the calculation means 100 that acquires two types of output signals from the phase correlator 13′ and performs a predetermined calculation, thereby determining the arrival angle of the radio waves.

[0091] The phase correlator 13' has a first input port IP1 for receiving a first input signal from the first receiving means 3a, a second input port IP2 for receiving a second input signal from the second receiving means 3b, a first output port OP1 for extracting a first output signal to the calculation means 100, and a second output port OP2 for extracting a second output signal to the calculation means 100.

[0092] A first input signal inputted from a first input port IP1 is generated in a 90° hybrid 135 as a first phase signal delayed by 90° and a second phase signal delayed by 180°. A second input signal inputted from a second input port IP2 is generated in a power divider 136 as a first divided signal and a second divided signal of equal power. A first power combiner 137 receives the first phase signal from the 90° hybrid 135 and the first divided signal from the power divider 136, and generates a first output signal by combining the two signals, which is outputted from a first output port OP1. A second power combiner 134 receives the second phase signal from the hybrid 135 and the second divided signal from the power divider 138, and generates a second output signal by combining the two signals, which is outputted from a second output port OP2.

[0093] The first and second output signals output from the phase correlator 13' each contain phase information of the first input signal and the second input signal, and are supplied to a calculation means 100 having a function of a measurement result acquisition means, and the calculation means 100 calculates the phase difference of the second input signal relative to the first input signal based on the first and second output signals, and calculates the arrival angle of the radio wave based on this phase difference and the known arrangement interval (λ / 2) between the first receiving means 3a and the second receiving means 3b. Note that, in the measurement device 1E of this embodiment as well, it is desirable to measure in advance the phase difference caused by the cable length, etc., and provide the calculation means 100 with a function of correcting (offsetting) the phase difference.

[0094] If the circuit configuration is such that the received signals from the two antennas (first and second receiving means 13a and 13b) are directly input to the phase correlator 13' as in the measuring device 1E of this embodiment, the first and second amplitude measuring units 11 and 12 and the variable gain means 14 are not required, so the circuit configuration is simplified and the number of parts that cause errors can be reduced, which is effective in improving the measurement accuracy of the radio wave arrival angle. However, the measuring device 1E can be applied to measure the radio wave arrival angle only when the communication distance is long and the amplitude difference between the received signals by the first and second receiving means 13a and 13b is small, so when the amplitude difference between the received signals by the first and second receiving means 13a and 13b is significant, it is useful to measure the radio wave arrival angle using the measuring device 1D equipped with the variable gain means 14.

[0095] The above describes the six-port measuring instrument and measurement devices according to the present invention based on several embodiments, but the present invention is not limited to these embodiments and encompasses within its scope all six-port measuring instruments and measurement devices that can be realized as long as the configuration described in the claims is not changed. [Explanation of symbols]

[0096] 1A Measuring device 2 Object to be measured 10 6-port measuring instrument 20 Measurement result acquisition means 30 Measurement Controller 41 Oscillator 51 1st directional coupler 52 Second directional coupler

Claims

1. a first port to which a first input signal is input; a second port to which a second input signal is input; a third port to which an output signal including the first amplitude information is output; a fourth port to which an output signal including the second amplitude information is output; a fifth port for outputting an output signal including the first phase information and the second phase information; a sixth port for outputting an output signal including the first phase information and the second phase information; a phase correlator that generates an output signal including the first phase information and an output signal including the second phase information based on the first input signal and the second input signal; a first amplitude measurement unit including a switching means for selectively switching a connection destination of the first port to the third port or the phase correlator, and connecting the first port to the third port by the switching means, thereby outputting the first input signal from the third port as an output signal including the first amplitude information; a second amplitude measurement unit including a switching means for selectively switching a connection destination of the second port to either the fourth port or the phase correlator, and connecting the second port to the fourth port by the switching means, thereby outputting the second input signal from the fourth port as an output signal including the second amplitude information; Equipped with when the first input signal and the second input signal are input from the first amplitude measurement unit and the second amplitude measurement unit, respectively, the phase correlator generates two types of output signals including the first phase information and the second phase information by combining the first input signal and the second input signal with different phase differences, and outputs one of the generated output signals to the fifth port and the other generated output signal to the sixth port. A six-port measuring instrument characterized by:

2. A measurement apparatus for measuring an amplitude ratio and a phase difference that indicate characteristics of a device under test by using the six-port measuring device according to claim 1, A measurement signal generating means for generating a measurement signal which is at least a modulated wave; a first input adjusting means for supplying the measurement signal generated by the measurement signal generating means as the first input signal to the device under test and the first port of the six-port measuring instrument; a second input adjusting means for supplying an output of the device under test to which the first input signal has been input as the second input signal to the second port of the six-port measuring instrument; a measurement means for performing a sweep measurement in which the frequency and / or the signal level of the measurement signal is changed by a predetermined reference amount, acquiring output signals from the third port, the fourth port, the fifth port, and the sixth port of the six-port measuring instrument, and performing a predetermined calculation to acquire measurement results of the amplitude ratio and the phase difference of the device under test; A measuring device comprising:

3. The measurement device according to claim 2, characterized in that the measurement means has a calibration function for setting a term gate of a time width that can be regarded as a stable output region with little error due to switching of phase modulation based on a baseband signal used by the measurement signal generating means to generate the modulated wave, and for improving phase measurement accuracy by capturing output signals from the third port to the sixth port of the six-port measuring instrument within the term gate.

4. 4. The measurement apparatus according to claim 2 or 3, further comprising a bandpass means for spectrum masking that limits the second input signal or the output signals from the fifth port and the sixth port of the six-port measuring instrument to an occupied bandwidth so as to correspond to the device under test in which distortion occurs in the output when operated in a nonlinear region.

5. the measurement signal generating means has a continuous wave generating function for generating a continuous wave which is a sine wave having a constant frequency and amplitude, and a modulated wave generating function for generating a plurality of types of QPSK modulated waves having different peak power to average power ratios; The measurement device according to claim 4, characterized in that the measurement means is capable of performing measurement control to acquire characteristics of the device under test using the continuous wave as a measurement signal, and measurement control to acquire characteristics of the device under test using each of the multiple types of QPSK modulated waves as the measurement signal.

6. A measurement apparatus for measuring an amplitude ratio and a phase difference that indicate characteristics of a device under test by using the six-port measuring device according to claim 1, A measurement signal generating means for generating a measurement signal which is at least a modulated wave; a frequency conversion means for mixing an LO signal having a higher frequency than the measurement signal generated by the measurement signal generation means with the measurement signal to generate a frequency-converted measurement signal; a first input adjustment means for supplying the frequency converted measurement signal as the first input signal to the device under test and the first port of the six-port measuring instrument; a second input adjusting means for supplying an output of the device under test to which the first input signal has been input as the second input signal to the second port of the six-port measuring instrument; a frequency restoration means for mixing an LO signal having the same frequency as that of the frequency conversion means with each output signal from the first port to the sixth port of the six-port measuring device, and passing a signal having the same frequency band as that of the measurement signal as a frequency restored output signal; a measurement means for performing a sweep measurement in which the frequency of each of the LO signals used in the frequency conversion means and the frequency restoration means is changed by a predetermined reference amount, acquiring each frequency restored output signal based on each output signal from the third port to the sixth port of the six-port measuring instrument, and performing a predetermined calculation to acquire measurement results of the amplitude ratio and phase difference of the device under test; A measuring device comprising:

7. The measurement device according to claim 6, characterized in that the measurement means has a calibration function for setting a term gate of a time width that can be regarded as a stable output region with little error due to switching of phase modulation based on a baseband signal used by the measurement signal generating means to generate the modulated wave, and for improving phase measurement accuracy by capturing output signals from the third port to the sixth port of the six-port measuring instrument within the term gate.

8. 8. The measurement apparatus according to claim 6 or 7, further comprising a bandpass means for spectrum masking that limits the second input signal or the output signals from the fifth port and the sixth port of the six-port measuring instrument to an occupied bandwidth so as to correspond to the device under test in which distortion occurs in the output when operated in a nonlinear region.

9. the measurement signal generating means has a continuous wave generating function for generating a continuous wave which is a sine wave having a constant frequency and amplitude, and a modulated wave generating function for generating a plurality of types of QPSK modulated waves having different peak power to average power ratios; The measurement device according to claim 8, characterized in that the measurement means is capable of performing measurement control to acquire characteristics of the device under test using the continuous wave as the measurement signal, and measurement control to acquire characteristics of the device under test using each of the multiple types of QPSK modulated waves as the measurement signal.

10. The measurement device according to claim 9, characterized in that the measurement means uses a 4-input 1-output high-frequency switch to switch output signals from the third port to the sixth port of the 6-port measuring device in a time series manner and inputs them to a power detector, and acquires a signal including amplitude information or phase information from the power detector in a time series manner.

11. The six-port measuring device according to claim 1 ; a first receiving means arranged to be able to receive incoming radio waves; a second receiving means disposed at a predetermined distance from the first receiving means in the direction of arrival of the radio wave; A calculation means for acquiring an output signal from the six-port measuring device and performing a predetermined calculation; Equipped with inputting a first received power signal obtained from the first receiving means to the first port; inputting a second received power signal obtained from the second receiving means to the second port; the first amplitude measurement unit switches the connection destination of the first port to the phase correlator; the second amplitude measurement unit switches the connection destination of the second port to the phase correlator; when the first received power signal and the second received power signal are input from the first amplitude measurement unit and the second amplitude measurement unit, respectively, the phase correlator generates two types of output signals including first phase information and second phase information by combining the first received power signal and the second received power signal with different phase differences, and outputs one of the generated output signals to the fifth port and the other generated output signal to the sixth port, the calculation means calculates a phase difference between the first received power signal and the second received power signal based on the two types of output signals generated by the phase correlator, and calculates an arrival angle of the radio wave based on this phase difference and a known arrangement distance between the first receiving means and the second receiving means. A measuring device comprising:

12. The measuring device according to claim 11, characterized in that the calculation means is provided with a conversion table and / or an approximation formula for correcting a deviation between the calculated radio wave arrival angle and an actual radio wave arrival angle, and calculates a corrected radio wave arrival angle.

13. a first receiving means arranged to be able to receive incoming radio waves; a second receiving means disposed at a predetermined distance from the first receiving means in the direction of arrival of the radio wave; a phase correlator that generates two types of output signals including first phase information and second phase information by combining a first input signal from the first receiving means and a second input signal from the second receiving means with different phase differences; a calculation means for calculating a phase difference between the first input signal and the second input signal based on the two types of output signals generated by the phase correlator, and for calculating an arrival angle of a radio wave based on the phase difference and a known arrangement distance between the first receiving means and the second receiving means; A measuring device comprising:

14. The measuring device according to claim 13, characterized in that the calculation means is provided with a conversion table and / or an approximation formula for correcting a discrepancy between the calculated radio wave arrival angle and an actual radio wave arrival angle, and calculates a corrected radio wave arrival angle.

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