JP2009068932A - Method and apparatus for measuring system parameter of linear multi-port, measuring method using vector network analyzer, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a computation time of a system parameter corresponding to a 5-port connection, a 6-port connection or the like used in a vector network analyzer (VNA) etc. , and simplify the configuration of its measuring circuit. <P>SOLUTION: The system parameter is required to measure a DUT (Device Under Test) by using the VNA. In a conventional method, a complicated procedure such as a well-known integral calculus is needed, since the system parameter is computed from center-point positions and radii of three circles on a complex plane at the input port complex amplitude ratio W=a2/a1. In this method, the computation is carried out based on intersection points of the three circles on the complex plane of a system parameter k. For example, three waves having phases shifted from another by 120° are sequentially input to an input port of the 5-port connection, and the system parameter is computed based on an output power value which is normalized by a predetermined reference power. The computation is made simple in comparison with the conventional integral calculus, and no phase shifter is needed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for measuring a signal amplitude ratio and a phase difference in a high frequency region (particularly, a microwave band, a millimeter wave band, a submillimeter wave band) and an optical region (infrared ray, visible ray, ultraviolet ray).

  For research and development of devices, circuits, and devices that operate in a high frequency region, it is essential to measure the phase difference between input and output signals of the devices, circuits, and devices. Conventionally, VNA (Vector Network Analyzer) has played its role. The VNA is a device for measuring an amplitude ratio and a phase difference (S parameter: scattering matrix element) of an incident wave and a reflected wave, or an incident wave and a transmitted wave of a DUT (Device Under Test).

U.S. Pat. No. 4,104,583 discloses a six-port reflectometer. This is to derive the amplitude ratio and phase difference (vector quantity) of two waves from hardware information (calibration parameters) specific to the system obtained by calibration and a plurality of power measurement values (scalar quantities). According to this apparatus and a measurement method using the same, the phase difference, which is difficult to measure with high accuracy as the frequency increases in the conventional method, is a basic measurement amount in electromagnetic wave measurement, and the measurement accuracy is almost equal to the frequency. It can be obtained based on the measurement of the scalar value, which is an independent power value. According to the technique described in Patent Document 1, it is freed from the demand for conventional high-precision hardware, and is characterized in that four power measurements and hardware imperfections are corrected by software (system parameters) called calibration. It is.

  The reflectometer is a device for comparing the incident wave and the outgoing wave with respect to one wave (signal).

  The inventor of the present application has devised a method capable of calibrating a 6-port type reflectometer with high accuracy using only one movable load calibrator with unknown complex reflection coefficient and one standard with known complex reflection coefficient. Furthermore, the above system was developed and a 6-port correlator (Six-Port based Wave-Correlator) was devised. The 6-port correlator is configured so that the complex amplitude ratio W = a2 / a1 of the waves a1 and a2 input to the two input ports can be calculated from the power values of the remaining four ports. The calibration operation of the 6-port type correlator is relatively simple because it is only necessary to obtain the power value at each step while moving it for one cycle from an arbitrary position of the phase shifter (Phase Shifter).

  A correlator (Wave-Correlator) is a device that compares two independent waves (having the same frequency), that is, measures a complex amplitude ratio.

  According to the 6-port correlator, the 6-port reflectometer can use information of two independent waves for measurement, and the calibration accuracy is improved because it is simpler than the calibration operation of the 6-port reflectometer. Benefits arise.

  However, in the actual measurement by the 6-port type correlator, there is a problem that the measurement accuracy deteriorates when the balance of the amplitude of the two independent waves input to the two ports is lost. In order to improve this point, the present inventor has devised a 7-port correlator (Patent Document 2).

JP, 2003-215183, A In addition to a port (reference port) for monitoring the amplitude value of one wave, another wave reference port was added. As a result, measurement can be performed while maintaining the balance between the amplitudes of two independent waves. The 7-port correlator corresponds to a combination of two 6-port correlators.

Other related arts include Patent Documents 3 and 4 below.
JP, 2005-221375, A By using a well-known correlator, the complex amplitude ratio of two waves (electromagnetic waves) can be obtained with high accuracy. A procedure to calculate is needed. However, when a BPSK (Binary Phase Shift Keying) demodulator or a QPSK (Quadrature Phase Shift Keying) demodulator is configured using a known correlator, it is sufficient to know the phase difference. A method for directly measuring the phase difference from simple calibration and comparison of power values (voltage values) suitable for such applications is disclosed. JP, 2005-326308, A Although calibration of VNA is performed by connecting several kinds of standard devices (short, open, load, through, line, etc.), there is a problem that a calibration procedure is complicated. Also, it is necessary to connect and remove several types of standard devices during calibration, which causes a problem of reduced measurement accuracy. A one-port variable load device with a known complex reflection coefficient that can solve these problems is disclosed.

As a prior art regarding improvement of the conventional VNA, there is Patent Document 5 below.
The calibration method for VNA, which is the mainstream of high-frequency measurement systems, requires the connection and removal of several types of standard devices during calibration, and causes human error. There was a problem of reduced accuracy. A VNA that can solve this problem and includes only one phase shifter and one standard device with a known complex reflection coefficient is disclosed.

  In a conventional VNA using a 6-port junction, there are very many system parameters (calibration parameters) for calibration. For this reason, the calibration work is complicated, requiring a lot of labor, and causes human error.

  Conventionally, system parameters have been obtained by an integral calibration method. In the integral calibration method, the power of each port is measured while changing the phase by at least one period, the complex Fourier coefficient of the nth harmonic is calculated for the graph obtained as a result, and the calibration is performed based on the complex Fourier coefficient. The parameter is determined. Due to the principle of the integral calibration method, it is necessary to provide a phase shifter in the VNA, and the configuration is complicated. Further, since the Fourier transform is performed when obtaining the system parameters, it takes time for the processing.

  The present invention has been made in view of the above problems, and realizes a measurement method and program using a vector network analyzer capable of greatly reducing system parameters and simplifying the configuration and speeding up the processing, and An object of the present invention is to provide a method and apparatus for measuring the system parameters.

The present invention is a linear circuit having two input ports such as a 5-port junction and a 6-port junction and three or more output ports, and a wave line in which a wave coming out from each output port enters the two input ports. A method for measuring a system parameter, which is a value specific to the linear multiport, with respect to a linear circuit expressed in a form (hereinafter referred to as “linear multiport”),
A first wave, a second wave, and a third wave having different phases are prepared, and a predetermined wave (hereinafter referred to as “reference wave a1”) is set in one input port 1 of the linear multiport. The first wave, the second wave, or the third wave (hereinafter referred to as “measurement wave a2”) when the other input port 2 is put into the first wave, the first wave with respect to the reference wave a1. A phase setting step for setting the complex amplitude ratios of the first wave, the second wave, and the third wave to W0, W1, and W2 (W = a2 / a1), respectively;
A reference power measurement preparation step of putting the reference wave a1 into one input port 1 of the linear multi-port and matching-terminating the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,
The matching termination of the other input port 2 is removed, the first wave, the second wave, and the third wave are sequentially added to the other input port 2, and the power of each output port corresponding to each wave { P30, P40, P50... {P31, P41, P51...} {P32, P42, P52.
The power {P30, P40, P50...} {P31, P41, P51...} {P32 measured for the first wave, the second wave, and the third wave. , P42, P52...} With the reference powers P3r, P4r, P5r.
The system parameter kh is calculated based on the normalized power of each output port and the complex amplitude ratios W0, W1, and W2, or the normalized power of each output port, the first Calculating a ratio hki of the system parameters kh based on the phase difference ψ01 between the wave and the second wave and the phase difference ψ02 between the first wave and the third wave; It is to be prepared.

The present invention is a method for measuring a system parameter that is a value inherent to a linear multiport, comprising:
A reference power measurement preparation step of putting a reference wave a1 into one input port 1 of the linear multi-port and matching-terminating the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,
The matching termination of the other input port 2 is removed, a short standard is connected to the other input port 2, and the power of each output port with respect to the first reflected wave at that time {P30, P40, P50. } And normalizing the measured power with the reference powers P3r, P4r, P5r,...
A first fixed phase shifter is connected to the other input port 2, and a short standard is connected to this, and the power of each output port with respect to the second reflected wave at that time {P31, P41, P51,. A second power measurement normalization step that normalizes the measured power with the reference powers P3r, P4r, P5r,.
A first fixed phase shifter and a second fixed phase shifter connected in series to the other input port 2 are connected to the other input port 2, and a short standard is connected to the second fixed phase shifter. And a third power measurement normalizing step for measuring the power {P32, P42, P52...} Of each output port with respect to and normalizing the measured power with the reference powers P3r, P4r, P5r. ,
Calculating the system parameter kh based on the normalized power of each output port and the reflection coefficients Γ0, Γ1, and Γ2 of the first reflected wave, the second reflected wave, and the third reflected wave; Or based on the normalized power of each output port, the phase difference ψ01 between the first reflected wave and the second reflected wave, and the phase difference ψ02 between the first reflected wave and the third reflected wave And a system parameter calculation step for performing any one of calculating the ratio hki of the system parameters kh.

For example, in the system parameter calculation step, the system parameter kh is calculated by the following equation (19).

For example, in the system parameter calculation step, the ratio hki of the system parameters kh is calculated by the following equation (20-1).

A linear multi-port system parameter measuring apparatus according to the present invention includes at least two power supplies for generating a high frequency signal such as a microwave band, a millimeter wave band, a submillimeter wave band, infrared rays, visible rays, and ultraviolet rays, and outputs of the power sources. A power divider that distributes to the power, a variable phase device that receives one of the waves distributed by the power distributor, adds at least two phase differences ψ01 or ψ02 to the wave, and outputs the wave, and a processing unit that calculates system parameters And
One input port 1 of the linear multi-port to be measured receives the other wave distributed by the power distributor, and the other input port 2 receives the wave from the variable phase device,
The processing unit calculates the system parameter kh or the ratio hki of the system parameters kh based on the power of the output port of the linear multi-port and the phase differences ψ01 and ψ02.

The present invention is a method for measuring a system parameter that is a value inherent to a linear multiport, comprising:
A reference power measurement preparation step for applying a wave to one input port 1 of the linear multi-port and matching termination of the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,
A power measuring step of removing the matching termination of the other input port 2, applying a wave to the other input port 2, and measuring the power {P 3, P 4, P 5.
A normalization step of normalizing the measured power {P3, P4, P5...} Of each output port with the reference powers P3r, P4r, P5r;
A phase shifting step of changing the phase of the wave entering the other input port 2;
The power measurement step, the normalization step, and the phase shift step are repeated a plurality of times, and based on the obtained normalized powers, the phase of the wave entering the other input port 2 is used as a variable. A function identification step for identifying a power function;
A system parameter calculation step of calculating a system parameter kh or a ratio hki of the system parameters kh by integrating the identified function.

For example, in the system parameter calculation step, the ratio hki of the system parameters kh is calculated by the following equation (24).

The present invention divides a wave from a power source that generates a high frequency signal such as a microwave band, a millimeter wave band, a submillimeter wave band, an infrared ray, a visible ray, and an ultraviolet ray into two, one of which is two input ports and three or more. The input port 1 of the linear multiport having the output port is input to the device under test, and the wave passing through the device under test or the wave reflected by the device under test is input to the linear multiport In this state, the detection output of each of the three or more output ports for power measurement of the linear multi-port is measured, and a vector network analyzer that measures the vector quantity related to the device under test based on the result is used. A measuring method,
Measure the power P3d, P4d, P5d... Of each output port and normalize it with the pre-measured reference powers P3r, P4r, P5r... Or either one of the output ports. A DUT measurement step for measuring one of the power ratios 3P4d, 3P5d, 3P6d,... Of the other three output ports as a reference;
Instead of the device to be measured, a standard device whose transmission characteristic or reflection characteristic is known is connected, and the power P3s, P4s, P5s... Of each output port is measured with respect to the standard device, and this is measured in advance. Normalized with the reference powers P3r, P4r, P5r, etc., or the power ratio of the other three output ports when any one of the output ports is used as a reference 3P4s, 3P5s, 3P6s,. A standard measurement step that performs any of the following:
Based on the normalized power or the power ratio and the pre-determined system parameter kh or system parameter ratio hki of the linear multi-port, a criterion that enters the port 1 for the device under test and the standard device respectively. Calculating a complex amplitude ratio Wd and Ws between the wave a1 and the measurement wave a2 entering the port 2, and calculating a ratio sWd = Wd / Ws between them,
And an S parameter calculation step of calculating an S parameter of the device under measurement based on the ratio sWd and the S parameter of the standard device.

For example, the linear multiport is a 5-port junction;
In the complex amplitude ratio calculation step, the ratio sWd is calculated by the following equation (14).

For example, the linear multi-port is a 6-port junction,
In the complex amplitude ratio calculation step, the complex amplitude ratios Wd and Ws are calculated by the following equation (616).

The present invention divides a wave from a power source that generates a high frequency signal such as a microwave band, a millimeter wave band, a submillimeter wave band, an infrared ray, a visible ray, and an ultraviolet ray into two, one of which is two input ports and three or more. The input port 1 of the linear multiport having the output port is input to the device under test, and the wave passing through the device under test or the wave reflected by the device under test is input to the linear multiport In this state, the detection output of each of the three or more output ports for power measurement of the linear multi-port is measured, and a vector network analyzer that measures the vector quantity related to the device under test based on the result is used. A program for causing a computer to execute a measurement method,
Measure the power P3d, P4d, P5d... Of each output port and normalize it with the pre-measured reference powers P3r, P4r, P5r... Or either one of the output ports. A DUT measurement step for measuring one of the power ratios 3P4d, 3P5d, 3P6d,... Of the other three output ports as a reference;
When a standard device with known transmission characteristics or reflection characteristics is connected instead of the device under test, the power P3s, P4s, P5s,... Of each output port is measured for the standard device, and this is measured in advance. Normalize with the reference powers P3r, P4r, P5r, etc., or power ratios of the other three output ports when any one of the output ports is used as a reference 3P4s, 3P5s, 3P6s .. a standard measurement step for measuring one of
Based on the normalized power or the power ratio and the pre-determined system parameter kh or system parameter ratio hki of the linear multi-port, a criterion that enters the port 1 for the device under test and the standard device respectively. Calculating a complex amplitude ratio Wd and Ws between the wave a1 and the measurement wave a2 entering the port 2, and calculating a ratio sWd = Wd / Ws between them,
An S parameter calculation step of calculating an S parameter of the device under measurement based on the ratio sWd and the S parameter of the standard device is executed by a computer.

The program according to the present invention is recorded on a recording medium, for example.
Examples of the medium include EPROM device, flash memory device, flexible disk, hard disk, magnetic tape, magneto-optical disk, CD (including CD-ROM and Video-CD), DVD (DVD-Video, DVD-ROM, DVD- RAM), ROM cartridge, RAM memory cartridge with battery backup, flash memory cartridge, nonvolatile RAM cartridge, and the like.

  A medium is a medium in which information (mainly digital data, a program) is recorded by some physical means, and allows a processing device such as a computer or a dedicated processor to perform a predetermined function. is there.

Hereinafter, description will be added in the following order.
1. System Parameter Measurement Method 1.1 Correlator System Parameter Measurement Method Using 5-Port Junction 1.2 Correlator System Parameter Measurement Method Using 5-Port Junction (Integration Method)
1.3 Method of measuring system parameters of correlator using 6-port junction 1.4 Method of measuring system parameters of reflectometer using N-port junction DUT measurement method 2.1 VNA using 5-port correlator and measurement method using the same 2.1.1 Description of measurement system 2.1.2 Description of DUT S-parameter measurement procedure 2.2 6-port correlator 2. A VNA using the above and a measuring method using the same. 3.1 Measurement Theory of the Case 3.1 5 Port Correlator 3.1.1 Principle of 5 Port Correlator 3.1.2 Measurement of DUT S-parameters with 5 Port Correlator 3.1.3 Linear Solution of System Parameters 3.1.4 System parameter product decomposition 3.2 6-port correlator 3.3 Reflectometer

1. Measuring system parameters

1.1 Correlator system parameter measurement method using 5-port junction Correlator (Wave-Correlator) compares two independent waves (with the same frequency), that is, measures their complex amplitude ratio It is a device to do.

  A correlator using a 5-port junction is a device that performs the above measurement by a 5-port junction including two input ports and three output ports. The 5-port junction is one of linear multi-ports (linear circuits), and is a circuit in which output waves of three output ports are expressed by a linear expression of input waves from two input ports. That is, the correlator is a linear circuit system that measures the correlation between the magnitude and phase of a sine wave entering two input ports from the power values of the waves exiting from three output ports.

  An example of a 5-port junction is shown in FIG. In the figure, 5PJ indicates a 5-port junction. Q is a known 90 ° hybrid, and PD is a known distributor. Port 1 and port 2 are input ports. 3 to 5 are power measurement ports. In the 90 ° hybrid, when a high-frequency signal is input to one port on one side, a high-frequency signal having half the amplitude of the high-frequency signal is output to the opposite port on the opposite side, and the other half is on the other port on the opposite side. The phase difference of the high-frequency signal output to the port and the opposite port and the other port is 90 °.

  The operation of the 5-port junction 5PJ will be described later in detail (see “3.1.1 Principle of 5-port correlator”).

  In order to perform measurement using a correlator having a 5-port junction 5PJ, the power value of the wave at each output port is measured, and the power value and system parameters are substituted into a predetermined mathematical formula. The system parameter is a value unique to the 5-port junction 5PJ. Specifically, it is the ratio of the coefficients of a linear expression describing the relationship between two input ports and three output ports. System parameters need to be obtained in advance prior to measurement.

  FIG. 2 is a flowchart of a method for measuring a system parameter of a correlator using a 5-port junction 5PJ. Hereinafter, the measurement method will be described with reference to FIG.

(1) Three waves (the first wave, the second wave, and the third wave) having the same amplitude and different phases are set. A reference wave a1 is input to the input port 1 of the 5-port junction, and the first wave, the second wave, and the third wave (measurement wave a2) are sequentially input to the input port 2 with respect to the reference wave a1. The complex amplitude ratios of the first wave, the second wave, and the third wave are set as W0, W1, and W2 (W = a2 / a1), respectively (STEP 1 in FIG. 2). For example, W1 and W2 can be obtained by passing the wave W0 through fixed phase shifters having different phase shift amounts.
In the following description, the first wave, the second wave, and the third wave are referred to as a wave W0, a wave W1, and a wave W2, respectively, within a range where there is no possibility of misunderstanding. The same applies to the description of the drawings.

(2) The reference wave a1 is input to one input port (for example, port 1) of the 5-port junction 5PJ (STEP 2 in the figure). The other input port (for example, port 2) is terminated in a matching manner, and the wave entering the input port is set to zero (STEP 2 in the figure).

(3) In the state of (2) above, the power of each output port is measured, and the result is {P3r, P4r, P5r} (subscripts 3, 4, and 5 are assigned to output ports 3, 4, and 5, respectively) Corresponding, and so on) These are used as the reference power (STEP 3 in the figure).

(4) Remove the matching termination of port 2 (STEP 4 in the figure).

(5) The wave W0 is input to the port 2 of the 5-port junction 5PJ as the measurement wave a2.

(6) In the state of (5) above, the power of each output port is measured, and the result is {P30, P40, P50} (STEP 6 in the figure).

(7) The wave W1 is input as the measurement wave a2 to the port 2 of the 5-port junction 5PJ. However, the wave W1 is a wave having the same amplitude and a different phase as the wave W0. For example, it is assumed that the wave W1 is delayed from the wave W0, and the phase difference is −ψ01 (ψ01 is a positive real number). The complex amplitude ratio W1 of the wave is expressed by the following equation. However, 0W1 = W1 / W0.

(8) In the state of (7) above, the power of each output port is measured, and the result is {P31, P41, P51} (STEP 6 in the figure).

(9) The wave W2 is input as the measurement wave a2 to the port 2 of the 5-port junction 5PJ. However, the wave W2 is a wave having the same amplitude and a different phase as the wave W0. The wave W2 is different in phase from the wave W1. For example, it is assumed that the wave W2 is behind the wave W0, and the phase difference is −ψ02 (ψ02 is a positive real number, ψ01 ≠ ψ02). The complex amplitude ratio W2 of the wave is expressed by the following equation. However, 0W2 = W2 / W0.

(10) In the state of (9), the power of each output port is measured, and the result is set to {P32, P42, P52} (STEP 6 in the figure).

(11) Divide {P30, P40, P50} {P31, P41, P51} {P32, P42, P52} by the reference power {P3r, P4r, P5r}, respectively (STEP 7 in the figure). The result is the normalized port power. / Ph0 = Ph0 / Phr (h = 3,4,5), / Ph1 = Ph1 / Phr (h = 3,4,5), / Ph2 = Ph2 / Phr (h = 3,4,5). However, / Ph0 indicates that a superscript bar is attached to the symbol Ph0. Similarly, in the following description, the symbol “/” represents “superscript bar”.

(12) The system parameter ratio hki is calculated according to the following equation (STEP 10 in the figure). Here, for example, h = 3 and i = 4,5.

  The system parameters of the correlator using the 5-port junction can be measured by the above procedures (1) to (12).

FIG. 3 shows an example of a measurement circuit for executing the measurement method described above.
In FIG. 3, VS is a power source (signal source) that supplies a signal of a predetermined frequency. The PD is a power distributor that distributes waves from the power supply VS into two. Although not shown, the apparatus shown in FIG. 3 receives a detector for measuring the power at the output port, an amplifier for amplifying the output of the detector, and the output of the amplifier (that is, three of the five-port junction 5PJ). (A detection output of the output ports P3 to P5) may be provided with a personal computer (computer) that calculates system parameters.

  The apparatus of FIG. 3 further includes two fixed phase shifters FPS1 and FPS2 and a switch SW for turning them on and off. These constitute the variable phase device VP. The switch SW is a rotary switch and selects one of the contacts u, v, and w. The contact u is connected to the input of the fixed phase shifter FPS1, that is, the output of the power distributor PD, the contact v is connected to the output of the fixed phase shifter FPS1 (input of the fixed phase shifter FPS2), and the contact w is the output of the fixed phase shifter FPS2. It is connected to the. The common of the switch SW is the output of the variable phase device VP and is connected to the input port 2 of the 5-port junction 5PJ. The phase shift amounts of the fixed phase shifters FPS1 and FPS2 are ψ1 and ψ2, respectively, and they are connected in series. Therefore, by selecting the switch SW, one of phase shift amount = 0 (contact point u), phase shift amount = −ψ1 (contact point v), and phase shift amount = − (ψ1 + ψ2) (contact point w) can be selected.

  At the positions of the contacts v and w, the following occurs.

  Since ψ1 and ψ2 are not constant due to the frequency characteristics of the fixed phase shifter, it is necessary to accurately measure the amount of phase shift with a standard measuring instrument. Although it is sufficient to select 0W1 and 0W2 under the condition that the regularity of the system parameter determination determinant is maintained, it is desirable that the absolute value is 1 and the phase difference is close to 120 ° and 240 °.

  The measurement of STEP 6 in FIG. 2 may be performed while switching the switch SW in FIG. 3 in order of u, v, and w.

  It supplements about the measuring method of the system parameter of the correlator using 5 port junction 5PJ mentioned above.

  When the normalization reference power is measured in (3) above, in FIG. 3, a matching termination as a standard device is connected to port 2 of the 5-port junction 5PJ, port M is matched termination, and port R is changed to port 1 A reference power (for example, 0 dBm) is applied, and port outputs P3r, P4r, and P5r are measured. In the subsequent port power measurement, it is desirable to keep the reference power constant.

  Then, fixed phase shifters FPS1 and FPS2 having a phase delayed by approximately 120 ° at the center frequency are used. The frequency vs. phase characteristics of the phase shifters FPS1 and FPS2 are measured and stored with a usable measuring instrument (standard VNA).

  According to this measurement method, system parameters can be obtained without using a known integral calibration method, so that it is not necessary to provide a phase shifter in the VNA, and the configuration of the VNA can be simplified. In addition, since the Fourier transform process is unnecessary, the processing time can be shortened.

1.2 Correlator system parameter measurement method using 5-port junction (integration method)
FIG. 4 shows an example of a measurement circuit for executing the integration method. 4, parts that are the same as those in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted.

  In FIG. 4, DC1 and DC2 are directional couplers. Two ends on one side of the directional coupler DC1 are connected to the first switch SW1 and the second switch SW2, and one end on the other side is a two-port device under test (hereinafter referred to as “DUT”). And the other end is terminated. The same applies to the directional coupler DC2. SW1 is a switch that puts the wave from the phase shifter PS into either of the two directional couplers DC1 or DC2. SW2 is a switch that selects either one of the two directional couplers DC1 or DC2 and sends a wave from the selected one to port 2 of the 5-port junction 5PJ.

  The first switch SW1, the second switch SW2, and the directional couplers DC1 and DC2 are switching mechanisms that realize connections for measuring the four S parameters (S11, S12, S21, and S22) of the DUT (described in detail later). ).

  The apparatus of FIG. 4 includes a phase shifter PS between the power distributor PD and the input terminal of the first switch SW1. A phase shifter PS is used to change the phase relationship between two waves. System parameters are measured using this device.

  FIG. 5 is a flowchart of the integration method. Hereinafter, the measurement method will be described with reference to FIG.

(1) A predetermined reference wave is input to port 1 of the 5-port junction 5PJ. Port 2 is matched and terminated, and the wave entering the input port is set to zero (STEP 11 in FIG. 5).

(2) In the state (1), the power of each output port is measured, and the result is {P3r, P4r, P5r}. These are used as the reference power (STEP 12 in the figure).

(3) Remove the matching termination of port 2 (STEP 13 in the figure).

(4) A signal is applied to ports 1 and 2 (STEP 14 in the figure).

(5) In the state of (4) above, the phase shifter PS is discretely changed from an arbitrary starting position θc (STEP 18 in the figure).

(6) The port powers P3, P4, and P5 are measured and normalized by P3r, P4r, and P5r, respectively (STEP 16 in the figure).

(7) Repeat (5) and (6) above (STEP 17 in the figure). The number of iterations is such that a function can be specified by Curve Fitting, and in fact, only a few times are sufficient.

(8) A function is determined by Curve Fitting based on the measurement data obtained by the above procedure (STEP 19 in the figure). Curve Fitting is a well-known technique and will not be described.

  The function is given by the following equation. If the amplitude, phase, and offset amount can be specified, the function is determined. Since the function form is known, the fitting ends with several points of data obtained including the measurement error.

(9) The system parameter hki (h = 3, i = 4, 5) is calculated by performing integral calculation of the function / Ph (θ) determined in the above (8) according to the following equation (STEP 20 in the figure). This equation is the same as equation (24) described later).

  The numerical integration operation of the product of normalized power and exponential function / Ph (θ) exp j (θ−θc) is / Ph (θc) exp j (0) at the start position of the phase shifter, and so on. Since θc + δ) exp j (δ), / Ph (θc + 2δ) exp j (2δ),..., the integration start position can be arbitrarily set.

1.3 Method for measuring system parameters of correlator using 6-port junction Even if 6-port junction is provided as a linear multi-port (linear circuit), the procedure is the same as in the case of 5-port junction except that one output port is added. And system parameters can be measured by calculation formulas. The system parameters of the 6-port junction are expressed as 3ki = ki / k3 (i = 4, 5, 6) as in the case of the 5-port junction.

  An example of a 6-port junction is shown in FIG. In the figure, 6PJ indicates a 6-port junction. Q is a known 90 ° hybrid, and Z is a matched termination.

  The same is true for the N-port junction, and the system parameters can be measured by the same procedure and calculation formula as in the case of the 5-port junction.

1.4 Method for Measuring System Parameters of Reflectometer Using N-Port Junction A reflectometer is a device for comparing incident waves and outgoing waves of one wave (signal).

  N-port reflectometer (N-port reflectometer) has a signal source connected to port 1 of N-port junction and a DUT connected to port 2, and the complex amplitude ratio of the wave coming out of port 2 and the wave coming in is taken as the reflection coefficient of DUT. The system measures from the remaining N-2 port power values. If the wave entering the DUT is b2 and the reflected wave exiting the DUT is a2, the complex reflection coefficient Γ = a2 / b2.

  The N port junction includes the above-described 5-port junction and 6-port junction. The N-port junction is a linear multi-port (linear circuit) in which the output wave of the (N-2) output port is expressed by a linear expression of the input waves from the two input ports.

  In order to perform measurement using a reflectometer having an N-port junction, the power value of the wave at each output port is measured, and the power value and the system parameter are substituted into a predetermined mathematical formula. The system parameter needs to be obtained in advance prior to measurement, but can be obtained in the same manner as the above-described correlator. That is, if the complex amplitude ratio W in the correlator is replaced with the complex reflection coefficient Γ, the reflectometer can handle the same (refer to “3.3 Reflectometer” for details).

  FIG. 7 is a flowchart of a method for measuring a system parameter of a reflectometer using an N-port junction. Hereinafter, the measurement method will be described with reference to FIG.

(1) Set three reflected waves with the same amplitude and different phases (first reflected wave, second reflected wave, and third reflected wave), and set their reflection coefficients to Γ0, Γ1, and Γ2, respectively. (STEP 1 in FIG. 7). For example, a first reflected wave is set by attaching a short standard device to the port 2 of the N port junction, and a second standard device is attached to the port 2 by attaching a fixed phase shifter with a phase shift amount ψ1 and a short standard device. A reflected wave is set, and a third reflected wave is set by attaching a fixed phase shifter with a phase shift amount ψ1, a fixed phase shifter with a phase shift amount ψ2 and a short standard to port 2. Note that, unlike the case of the correlator (for example, FIG. 3), the wave b2 returning from the port 2 reciprocates the line connected thereto, so that the amount of phase shift is doubled.
In the following description, the first reflected wave, the second reflected wave, and the third reflected wave are referred to as a reflected wave Γ0, a reflected wave Γ1, and a reflected wave Γ2, respectively, within a range where there is no possibility of misunderstanding. . The same applies to the description of the drawings.

(2) A constant wave is input to one input port (for example, port 1) of the N-port junction (STEP 2 in the figure). The other input port (for example, port 2) is terminated in a matching manner, and the wave entering the input port is set to zero (STEP 2 in the figure).

(3) In the state of (2) above, the power of each output port is measured, and the result is {P3r, P4r, P5r, ...} (subscripts 3, 4, 5,. Corresponding to the output ports 3, 4, 5,. These are used as the reference power (STEP 3 in the figure).

(4) Remove the matching termination of port 2 (STEP 4 in the figure).

(5) Connect a short standard to port 2 of the N port junction. The reflection coefficient of the reflected wave entering the port 2 (first reflected wave) is Γ0.

(6) In the state of (5) above, the power of each output port is measured, and the result is {P30, P40, P50,...} (STEP 6 in the figure).

(7) Connect a fixed phase shifter and a short standard to port 2 of the N port junction. When the amount of phase shift is ψ1, the reflected wave Γ1 entering the port 2 is delayed by 2ψ1 from the reflected wave Γ0.

(8) In the state of (7) above, the power of each output port is measured, and the result is {P31, P41, P51,...} (STEP 6 in the figure).

(9) Connect two fixed phase shifters and a short standard to port 2 of the N port junction. When the amount of phase shift is ψ1 + ψ2, the reflected wave Γ2 entering the port 2 is delayed by 2 (ψ1 + ψ2) from the reflected wave Γ0.

(10) In the state of (9) above, the power of each output port is measured, and the result is {P32, P42, P52,...} (STEP 6 in the figure).

(11) {P30, P40, P50, ...} {P31, P41, P51, ...} {P32, P42, P52, ...} are used as reference powers {P3r, P4r, P5r,. Divide by .. (STEP 7 in the figure). The result is the normalized port power.

(12) The system parameter hki is calculated according to the above equation (20-1) (STEP 10 in the figure). Here, for example, h = 3, i = 4, 5,. Note that, as described above, the amount of phase shift is doubled because the line travels back and forth. For example, when measured with the apparatus of FIG. 8, ψ01 and ψ02 in the equation (20-1) are −2ψ1 and −2 (ψ1 + ψ2), respectively.

  The system parameters of the reflectometer using the N-port junction can be measured by the above procedures (1) to (12).

FIG. 8 shows an example of a measurement circuit for executing the measurement method described above.
8, parts that are the same as those in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted. In FIG. 8, the wave from the power supply VS is input to the port 1 of the N-port junction NPJ without being divided into two. In addition, a short standard device is connected to one end of the variable phase device VP.

  The amount of phase shift of the reflected wave can be varied by selecting the switch SW. If the phase shift amount at the point of contact u is the reference (0), the phase shift amount = −2ψ1 (contact point v) and the phase shift amount = −2 (ψ1 + ψ2) (contact point w).

  The measurement of STEP 6 in FIG. 7 may be performed while switching the switch SW in FIG. 8 in order of u, v, and w.

2. 2. Measurement method of DUT 2.1 VNA using 5-port correlator and measurement method using the same 2.1.1 Description of measurement system FIG. 9 shows a high-frequency signal measurement system (vector network analyzer Vector) according to an embodiment of the invention. A block diagram of Network Analyzer (VNA) is shown. This is a vector network analyzer device for 2-port device measurement using a 5-port junction.

The VS is a power source (signal source) that supplies a signal having a predetermined frequency.
The PD is a power distributor that distributes waves from the power supply VS into two.

The DET is a detector that detects waves from the three output ports 3 to 5 of the 5-port junction 5PJ.
The AMP is an amplifier that amplifies the output of the detector DET and supplies the amplified output to the personal computer PC.

  The PC is a personal computer (computer) that receives the output of the amplifier AMP and obtains the S parameter of the DUT based on the output (that is, the detection output of the three output ports P3 to P5 of the 5-port junction 5PJ).

  SW1 is a switch that sends one wave distributed by the power distributor PD to either one of the two directional couplers DC1 or DC2. When one of the switches SW1 is selected, a matching load (non-reflection termination) (not shown) is connected to the other side that is not selected, so that unnecessary reflection does not occur. This also applies to the switch SW2.

A switching mechanism 20 connects the power source VS (power distributor PD), the DUT, and the port P2 of the 5-port junction 5PJ through a predetermined path. The switching mechanism 20 performs one of the following operations.
(1) One of the waves distributed by the power distributor PD is input to one port of the DUT, and the wave output from the port is input to the port 2 of the 5-port junction 5PJ.
(2) One of the waves distributed by the power distributor PD is input to one port of the DUT, and the wave output from the other port is input to the port 2 of the 5-port junction 5PJ.
(3) One of the waves distributed by the power distributor PD is input to the other port of the DUT, and the wave output from the one port is input to the port 2 of the 5-port junction 5PJ.
(4) One of the waves distributed by the power distributor PD is input to the other port of the DUT, and the wave output from the port is input to the port 2 of the 5-port junction 5PJ.

The switching mechanism 20 includes switches SW1 and SW2 and directional couplers DC1 and DC2.
SW2 is a switch that selects either one of the two directional couplers DC1 or DC2 and sends a wave from the selected one to port 2 of the 5-port junction 5PJ.

  DC1 and DC2 are directional couplers. Two ends (reference numerals A and C in the figure) of one side of the directional coupler DC1 are connected to the first switch SW1 and the second switch SW2, and one end (reference numeral D in the figure) on the other side. Is connected to one end of a two-port device under test DUT, and the other end (symbol B in the figure) is terminated. The same applies to the directional coupler DC2. Directional couplers DC1 and DC2 are devices that couple the other ends only to waves traveling in a specific direction. Waves traveling in the opposite direction are eliminated. Referring to the reference numeral in FIG. 9, the input from point A is output to points B and D, but not to point C (the same applies to the input of point C). Since it is bilaterally symmetric, the input from point D is output to point A and point C.

  The first switch SW1, the second switch SW2, and the directional couplers DC1 and DC2 constitute a switching mechanism 20 that realizes connections for measuring the four S parameters (S11, S12, S21, and S22) of the DUT. . Specifically, when the two ports of the DUT are PA and PB, the switching mechanism 20 performs any of the following connection operations (1) to (4).

(1) First connection (see FIG. 10)
In order to measure S11, the first switch SW1 supplies the wave from the power distributor PD to the point C of the directional coupler DC1 (that is, the port PA of the DUT), and the second switch SW2 is directional coupled. A wave from point A of the unit DC1 (that is, port PA of the DUT) is supplied to port 2 of the 5-port junction 5PJ. At this time, the port PB of the DUT is connected to an unselected end of the first switch SW1 and the second switch SW2, but as described above, a matching load (non-reflective termination) (not shown) is connected to the end. Therefore, there is no wave entering port PB.

(2) Second connection (see FIG. 11)
In order to measure S12, the first switch SW1 supplies the wave from the power distributor PD to the point C of the directional coupler DC2 (that is, the port PB of the DUT), and the second switch SW2 is directional coupled. A wave from point A of the unit DC1 (that is, port PA of the DUT) is supplied to port 2 of the 5-port junction 5PJ.

(3) Third connection (see FIG. 12)
In order to measure S21, the first switch SW1 supplies the wave from the power distributor PD to the point C of the directional coupler DC1 (that is, the port PA of the DUT), and the second switch SW2 is directional coupled. A wave from point A of the unit DC2 (that is, port PB of the DUT) is supplied to port 2 of the 5-port junction 5PJ.

(4) Fourth connection (see FIG. 13)
In order to measure S22, the first switch SW1 supplies the wave from the power distributor PD to the point C of the directional coupler DC2 (that is, the port PB of the DUT), and the second switch SW2 A wave from point A of the unit DC2 (that is, port PB of the DUT) is supplied to port 2 of the 5-port junction 5PJ. At this time, the port PA of the DUT is connected to the unselected end of the first switch SW1 and the second switch SW2, but as described above, a matching load (non-reflective termination) (not shown) is connected to the end. There is no wave entering port PA.

2.1.2 Description of DUT S Parameter Measurement Procedure A measurement method using the apparatus according to the embodiment of the invention will be described. It should be noted that the system parameters and the reference according to the above-mentioned “1.1 Measuring method of system parameters of correlator using 5-port junction” or “1.25 Measuring method of system parameters of correlator using 5-port junction (integration method)” It is assumed that the power measurement has been completed.

  As described above, there are four types of DUT connection, the first to the fourth connection. FIG. 14 shows the relationship between these, the S parameter, and the standard used.

  There are two standard devices: Short and Thru. These equivalent circuits and S parameters are shown in FIG.

  FIG. 15A shows a short standard. In this method, the input wave is phase-inverted and totally reflected to the input end. The S parameters are S11 = S22 = −1 and S12 = S21 = 0.

  FIG. 15B shows a through standard. This transmits the input wave as it is to the other end. The S parameters are S11 = S22 = 0 and S12 = S21 = 1.

  As shown in FIG. 14, the DUT connection is switched in four ways, and the power of each port is measured for each. First, the measurement of S11 will be described. In addition, since the measurement of S22 is the same, the description is omitted.

  FIG. 16 shows a measurement flowchart of S11. Note that FIG. 16 is an example, and other procedures (for example, after the DUT is measured, the DUT may be replaced with a standard device) may be performed.

STEP 21: The switching mechanism 20 is set to the first connection shown in FIG.
STEP 22: A short standard device is connected to the switching mechanism 20 of FIG.
STEP 23: The power {P3s, P4s, P5s} of the output ports 3, 4, 5 of the 5-port junction 5PJ is measured. Here, s indicates a standard.
STEP 24: The measured power {P3s, P4s, P5s} is normalized with the normalization reference power {P3r, P4r, P5r}.
STEP25: Remove standard device and connect DUT instead.
STEP 26: The power {P3d, P4d, P5d} of the output ports 3, 4, 5 of the 5-port junction 5PJ is measured. Here, d indicates a DUT (device).
STEP 27: The measured power {P3d, P4d, P5d} is normalized with the normalization reference power {P3r, P4r, P5r}.
STEP 28: sWd is calculated based on the equation (14) (refer to “3.1.2 Measurement of S-parameter of DUT by 5-port correlator” for derivation of the equation).

STEP 29: S11 is calculated with Ss = −1 in equation (9).

FIG. 17 shows a measurement flowchart of S21. Differences from FIG. 16 will be described. In addition, since the measurement of S12 is the same, the description is omitted.
STEP 21: The switching mechanism 20 is set to the third connection shown in FIG.
STEP 22: A through standard device is connected to the switching mechanism 20 of FIG.
STEP 29: S21 is calculated with Ss = 1 in equation (9).

  According to the measurement method described above, in the measurement of the S-parameters S11, S12, S21, and S22 of the DUT, the parameters to be determined for the measurement are two complex numbers (3k4, 3k5), and a total of four real values. is there. In a conventional VNA using a 6-port correlator, there are as many as 35 system parameters. However, according to the embodiment of the invention, the number can be greatly reduced. For this reason, the calibration work is simplified, the processing time can be shortened, and the occurrence of human error can be suppressed.

2.2 VNA using 6-port correlator and measurement method using the same The circuit of the apparatus used for measurement is the same as in FIG. Since the relationship between the connection of the switching mechanism 20 and the standard device is the same as in FIGS. 14 and 15, the description thereof is also omitted.

  The measurement method using the apparatus according to the embodiment of the invention will be described. It is assumed that the system parameters and the reference power have been measured according to the above-described “1.3 Method for Measuring System Parameters of Correlator Using 6-Port Junction”.

  As shown in FIG. 14, the DUT connection is switched in four ways, and the power of each port is measured for each. First, the measurement of S11 will be described. In addition, since the measurement of S21, S12, and S22 is the same, the description is omitted.

  FIG. 18 shows a measurement flowchart of S11. Note that FIG. 18 is an example, and other procedures (for example, after the DUT is measured, the DUT may be replaced with a standard device) may be performed.

STEP 31: The switching mechanism 20 is set to the first connection shown in FIG.
STEP 32: A short standard device is connected to the switching mechanism 20 of FIG.
STEP 33: The power of the output ports 3, 4, 5, 6 of the 6-port junction 6PJ is measured, and the power ratio {3P4s, 3P5s, 3P6s} with respect to the port 3 is obtained. Here, s indicates a standard.
STEP 34: Remove the standard device and connect the DUT instead.
STEP 35: The power of the output ports 3, 4, 5, 6 of the 6-port junction 6PJ is measured, and the power ratio {3P4d, 3P5d, 3P6d} with respect to the port 3 is obtained. Here, d indicates a DUT (device).
STEP 36: Ws and Wd are calculated based on the equation (616) (refer to “3.2 6-port correlator” for derivation of the equation). Then, sWd = Wd / Ws is calculated.

STEP 37: S11 is calculated with Ss = -1 in the equation (621).

  According to the measurement method described above, in the measurement of the S-parameters S11, S12, S21, and S22 of the DUT, the parameters to be determined for the measurement are three complex numbers (3k4, 3k5, and 3k6). It is a numerical value. Although there are 35 conventional system parameters, according to the embodiment of the invention, the number can be greatly reduced.

3. 3.1 Measurement Theory of this Case 3.1 5 Port Correlator 3.1.1 Principle of 5 Port Correlator The 5 port correlator is the correlation between the magnitude and phase of the sine wave entering the two ports. It is a linear circuit system that measures from the power value coming out of one port.
In the linear 5-port junction of FIG. 19, assuming that the complex amplitudes of the waves entering from the input ports 1 and 2 are a1 and a2, the power of the waves coming out from the side arm ports 3, 4 and 5 can be written as follows.

Here, Ah and Bh are complex constants inherent to the 5-port junction, and αh is a conversion coefficient.
The correlator measures the complex amplitude ratio W of the measurement wave with respect to the reference wave, using the wave a1 entering from the port 1 as a reference wave and the wave a2 entering from the port 2 as a measurement wave.
Therefore, as shown in FIG. 20, port 2 is matched and terminated, a2 = 0, the side arm port power with only the reference wave input is defined as reference port power Phr, and equation (1) is rewritten as follows.

Expanding the normalized port power of equation (2)

式（６）から、入力複素振幅比Wの線形解を与える方程式（７）、およびＷ平面上の円の方程式（８）が得られる。これらから、システムパラメータが既知であれば、サイドアーム正規化ポート電力の測定によって、基準波に対する測定波の大きさと位相が決定できる。
未知数Ｗの線形方程式は式（７）で与えられる。

From equation (6), equation (7) that gives a linear solution of the input complex amplitude ratio W and equation (8) of the circle on the W plane are obtained. From these, if the system parameters are known, the magnitude and phase of the measurement wave relative to the reference wave can be determined by measuring the side arm normalized port power.
The linear equation of the unknown W is given by equation (7).

  Equation (6) is also an equation of a circle on the complex W plane, and can be transformed as Equation (8).

  The linear solution of W is the intersection of three circles. When three circles intersecting at one point are given, instead of solving simultaneous equations consisting of three circle equations to calculate the intersection, 2 for each of the three pairs extracted from the three circles. A straight line passing through two intersections of two circles may be obtained, and an intersection of the three obtained straight lines may be obtained. The linear solution of W in equation (7) is the radical center of the three circles thus determined. The formulas that give radical centers are known.

3.1. 2 Measurement of DUT S-parameters using a 5-port correlator A comparative measurement method with a standard device will be described. In this method, the S parameter Sd of the 2-port DUT is compared with the S parameter Ss of the standard device and measured. (See Figure 14)

  As shown in FIG. 9, the reference port R (Reference port, output signal bs1) of the signal source (Source) is set to port 1 of 5 ports, the measurement port M (Measurement port, output signal bs2) is switched to a switching mechanism 20 including a DUT. Connect to port 2 via The measurement wave entering port 2 is proportional to the S-parameter of the 2-port DUT (proportional coefficient τ), and the S-parameters of the DUT and standard device are Sd and Ss, and W when they are connected is Wd and Ws. (Subscript d: device, s: standard). Then, Formula (9) is materialized.

Equation (9) indicates that if sWd is known, the S parameter Sd of the DUT can be calculated by calculating the product of this and the S parameter Ss of the standard device. Therefore, a comparative measurement method with a standard device, that is, a method of measuring the S parameter Sd of the 2-port DUT by comparing it with the S parameter Ss of the standard device will be described.
The transmission coefficient of the test set (switching mechanism 20) and the S parameter of the DUT are as shown in equations (10) to (12).

  From equation (7)

  If the system parameters k3, k4, k5 or the system parameter ratios 3k4, 3k5 are known, sWd = Wd / Ws can be calculated by equation (14), and sWd by the equation (9) and the known S parameter Ss of the standard device Is the SUT S parameter Sd of the DUT to be obtained.

  According to this measurement method, the system parameters to be identified in the S-parameter measurement of the 2-port DUT are only two complex numbers (3k4, 3k5), that is, a total of four real values.

  In a conventional VNA using a 6-port correlator, there are as many as 35 system parameters. However, according to the embodiment of the invention, the number can be greatly reduced. For this reason, the calibration work is simplified, the processing time can be shortened, and the occurrence of human error can be suppressed.

3.1.3 Linear Solution of System Parameters Focusing on the normalized port power equation (2), it can be seen that the role of the system parameter kh and the input complex amplitude ratio W on the port power is the same. Therefore, the positions of the system parameter kh and the input complex amplitude ratio W can be interchanged.

That is, since the input complex amplitude ratio W can be measured from the port power value by making the system parameter kh known, it is suggested that the system parameter kh can be identified by setting the known amount W.
In equation (2), h = 3, 4, 5, and W = Wn (n = 0, 1, 2) are rewritten as follows.

  Equation (16) is an equation of a circle having a center point qn = −1 / Wn and a radius Rn = √ / Ph / | Wn | on the complex number kh plane which is a system parameter of the port h.

  FIG. 21 shows that the system parameter kh is determined as the intersection of three circles corresponding to different Wn {W0, W1, W2}. In particular, if three Wn having the same absolute value and different phases are set, the centers of the three circles {q0, q1, q2} will be placed on the circumference centered at the origin on the complex number kh plane, If the phase difference is 120 °, it is arranged at the apex of an equilateral triangle. In order to reduce the error in actual measurement, it is preferable that the centers of the three circles are evenly distributed.

  Focusing again on the expansion formula (6) of the side arm port power ratio, a linear solution of kh is obtained using three different Wn (W0, W1, W2) as parameters.

If two 0W1 and 0W2 whose relative values are known are set for an arbitrary input complex amplitude ratio W0, the system parameter ratio can be obtained.
Here, 0W1 and 0W2 are set as follows.

  Substituting the above 0W1 and 0W2 into the equation (20) yields the following.

  When the right end side of the above expression is expanded, Expression (20-1) used in the calculation of “1.1 Method for Measuring System Parameters of Correlator Using 5-Port Junction” is obtained.

3.1.4 Product Parameter Decomposition Connect the reference port R (Reference port) of the signal source to the input port 1 of the 5-port correlator, and connect between the measurement port M (Measurement port) and the input port 2. An arbitrary DUT and a phase shifter PS are inserted, and the input complex amplitude ratio W is set to an arbitrary constant value. Since the port power periodically changes with respect to the lagging phase angle θ of the phase shifter, system parameters are obtained by paying attention to this periodicity.

  The above formula is as follows.

  According to the above equation, / Ph (θ) is a sine wave and does not include a harmonic component. Therefore, in order to obtain / Ph (θ), a complicated calculation such as Fourier transform is not necessary, and a simple method such as a known curve fitting can be applied. Fitting is an analysis method in which parameters included in a theoretical expression expressing a model are changed to best fit a measured value. For example, plot the measured data and change the parameters in the above formula to best match those data. Since the function form is known, the fitting ends with several points of data obtained including the measurement error.

  If the phase shifter is moved for one wavelength (θ = 2π) from an arbitrary starting position (θ = θc) and multiplied by exp j (θ−θc) on both sides,

  Therefore, the system parameter ratio determining formula is expressed by formula (24).

  The system parameter ratio hki (3k4, 3k5) is a value unique to the five ports and does not depend on the starting position (θc) of the phase shifter or the value of the complex amplitude ratio W of the input port.

3.2 6-port correlator Even in the case of 6-port junction, which is another linear multi-port (linear circuit), the same mathematical formula as in the case of 5-port junction is established except that one output port is added. For example, the above formulas (1) to (5) are established. The same can be said for the N-port junction.

  In the 6-port correlator, one of the side arm ports is used as a reference dedicated port in order to cancel the effect of the amplitude fluctuation of the reference wave on the measurement result. When the ratio of the remaining three port powers Pi to any one side arm port power Ph is hPi, the following equations (66) and (67) are established.

The hPir defined by the equation (67) can be measured as a ratio of the reference power and is a known amount.
When formula (66) is expanded with h = 3, i = 4,5,6

  Formula (68) can be rearranged as Formula (610) by parameter conversion like Formula (69).

  From equation (610), an equation (611) that gives a linear solution of the input complex amplitude ratio W and an equation (612) of a circle on the W plane are obtained. From these, if the system parameters are known, the magnitude and phase of the measurement wave relative to the reference wave can be determined by measuring the side arm port power.

  The equation of the circle with the center point qi and radius Ri on the complex W plane is as follows.

  The linear solution of W is a radical center of three circles.

  Therefore, the S parameter of the DUT is expressed by the equation (621) (this corresponds to the equations (9) and (14) in the case of the 5-port junction).

  The system parameters {k3, k4, k5, k6} are values unique to the 6-port junction, and the proportionality coefficient of the test set is irrelevant to the system parameters. Therefore, the system parameters are determined for each type of S11, S21, S12, and S22. There is no need.

  In measuring the S-parameters {S11, S21, S12, S22} of the 2-port DUT, the system parameters to be determined are three complex numbers {3k4, 3k5, 3k6}, that is, a total of six real values.

  Although there are 35 conventional system parameters, according to the embodiment of the invention, the number can be greatly reduced. For this reason, the calibration work is simplified, the processing time can be shortened, and the occurrence of human error can be suppressed.

The physical meaning of system parameters will be described.
The system parameter kh (h = 3, 4, 5,...) Is a normalized measurement wave output normalized by the normalized reference port output. Here, the normalized reference port output is the complex amplitude of the wave output from the side arm port when only the reference wave with complex amplitude 1 (a1 = 1) is input from port 1, and the normalized measurement wave output is the port. 2 is a complex amplitude of a wave coming out from the side arm port when only a measurement wave having a complex amplitude of 1 (a2 = 1) is input.

  The system parameter ratio hki (h = 3, i = 4, 5,...) Is the measured wave normalized by the ratio of the reference wave port h output to the port i output, as shown in the following equation. It is the ratio of port h output to port i output.

3.3 Reflectometer A reflectometer is a device for comparing incident waves and outgoing waves of one wave (signal).

  N-port reflectometer (N-port reflectometer) has a signal source connected to port 1 of N-port junction and a DUT connected to port 2, and the complex amplitude ratio of the wave coming out of port 2 and the wave coming in is taken as the reflection coefficient of DUT. The system measures from the remaining N-2 port power values.

  In FIG. 22, if the complex amplitudes of the wave coming out of port 2 and the incoming wave are b2 and a2, the power of the wave coming out of the side arm port can be expressed by the equation (1) for 5 ports by replacing a1 with b2. It is expressed similarly. If the wave entering the DUT is b2 and the reflected wave exiting the DUT is a2, the complex reflection coefficient is Γ = a2 / b2.

  In the reflectometer, as shown in FIG. 23, the side arm port power when the port 2 is matched and terminated and a2 = 0 is defined as the reference port power Phr, and Equation (1) is rewritten as follows.

  If W is replaced with Γ in the basic expression of normalized port power in the correlator, the relational expression of the reflectometer can be obtained. Therefore, the system parameter identification method proposed here can be directly applied to the reflectometer.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

It is an internal block diagram of 5 port joining. It is a measurement flowchart of the system parameter of the correlator using 5 port junction. It is a block diagram of the measurement circuit of a 5-port correlator. It is a block diagram of the measurement circuit for performing an integration method. It is a measurement flowchart of an integration method. It is an internal block diagram of 6 port junction. It is a flowchart of the measuring method of the system parameter of the reflectometer using N port junction. It is a block diagram of the measurement circuit of a reflectometer. It is a block diagram of a vector network analyzer (VNA). It is a figure which shows the circuit connection of S11 measurement. It is a figure which shows the circuit connection of S12 measurement. It is a figure which shows the circuit connection of S21 measurement. It is a figure which shows the circuit connection of S22 measurement. It is a figure which shows the relationship of S11, S12, S21, S22, the connection of the switching mechanism for those measurements, and the standard device to be used. 15A shows the S parameter of the short standard device, and FIG. 15B shows the S parameter of the through standard device. It is a measurement flowchart of S11 using VNA provided with 5 port junction. It is a measurement flowchart of S21 using VNA provided with 5 port junction. It is a measurement flowchart of S11 using VNA provided with 6 port junction. It is explanatory drawing of 5 port joining. It is explanatory drawing (port 2 is a matching termination | terminus) of 5 port joining. It is explanatory drawing of how to obtain | require a system parameter. It is explanatory drawing of N port joining (reflectometer). It is explanatory drawing (port 2 is a matching termination | terminus) of N port junction.

Explanation of symbols

20 switching mechanism 5PJ 5 port junction 6PJ 6 port junction AMP amplifier NPJ N port junction DC1, DC2 directional coupler DET detector DUT device under test FPS1, FPS2 fixed phase shifter PC personal computer PD power distributor PS phase shifter SW1, SW2 High frequency switch VP Variable phase device VS Power supply

Claims (12)

A linear circuit having two input ports, such as a 5-port junction and a 6-port junction, and three or more output ports, and a wave output from each output port is represented in a linear form of waves entering the two input ports. A system parameter, which is a value inherent to the linear multiport, for a linear circuit (hereinafter referred to as “linear multiport”),
A first wave, a second wave, and a third wave having different phases are prepared, and a predetermined wave (hereinafter referred to as “reference wave a1”) is set in one input port 1 of the linear multiport. The first wave, the second wave, or the third wave (hereinafter referred to as “measurement wave a2”) when the other input port 2 is put into the first wave, the first wave with respect to the reference wave a1. A phase setting step for setting the complex amplitude ratios of the first wave, the second wave, and the third wave to W0, W1, and W2 (W = a2 / a1), respectively;
A reference power measurement preparation step of putting the reference wave a1 into one input port 1 of the linear multi-port and matching-terminating the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,
The matching termination of the other input port 2 is removed, the first wave, the second wave, and the third wave are sequentially added to the other input port 2, and the power of each output port corresponding to each wave { P30, P40, P50... {P31, P41, P51...} {P32, P42, P52.
The power {P30, P40, P50...} {P31, P41, P51...} {P32 measured for the first wave, the second wave, and the third wave. , P42, P52...} With the reference powers P3r, P4r, P5r.
The system parameter kh is calculated based on the normalized power of each output port and the complex amplitude ratios W0, W1, and W2, or the normalized power of each output port, the first Calculating a ratio hki of the system parameters kh based on the phase difference ψ01 between the wave and the second wave and the phase difference ψ02 between the first wave and the third wave; A linear multi-port system parameter measurement method. A method for measuring a system parameter that is a value inherent to a linear multiport,
A reference power measurement preparation step of putting a reference wave a1 into one input port 1 of the linear multi-port and matching termination of the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,
The matching termination of the other input port 2 is removed, a short standard is connected to the other input port 2, and the power of each output port with respect to the first reflected wave at that time {P30, P40, P50. } And normalizing the measured power with the reference powers P3r, P4r, P5r,...
A first fixed phase shifter is connected to the other input port 2, and a short standard is connected to this, and the power of each output port with respect to the second reflected wave at that time {P31, P41, P51,. A second power measurement normalization step that normalizes the measured power with the reference powers P3r, P4r, P5r,.
A first fixed phase shifter and a second fixed phase shifter connected in series to the other input port 2 are connected to the other input port 2, and a short standard is connected to the second fixed phase shifter. And a third power measurement normalizing step for measuring the power {P32, P42, P52...} Of each output port with respect to and normalizing the measured power with the reference powers P3r, P4r, P5r. ,
Calculating the system parameter kh based on the normalized power of each output port and the reflection coefficients Γ0, Γ1, and Γ2 of the first reflected wave, the second reflected wave, and the third reflected wave; Or based on the normalized power of each output port, the phase difference ψ01 between the first reflected wave and the second reflected wave, and the phase difference ψ02 between the first reflected wave and the third reflected wave A system parameter calculation step for calculating one of the ratios hki of the system parameters kh, and a linear multiport system parameter measurement method. The linear multi-port system parameter measurement method according to claim 1, wherein the system parameter calculation step calculates the system parameter kh according to the following equation (19).

The system parameter measurement method according to claim 2, wherein the system parameter calculation step calculates the system parameter kh according to the following equation (19).

3. The linear multi-port system parameter measurement method according to claim 1, wherein the system parameter calculation step calculates a ratio hki of the system parameters kh by the following equation (20-1).

A power source that generates a high-frequency signal such as a microwave band, a millimeter wave band, a sub-millimeter wave band, an infrared ray, a visible ray, and an ultraviolet ray, a power distributor that distributes at least two outputs of the power source, and a power distributor A variable phase device that receives and outputs at least two phase differences ψ01 or ψ02 to the wave, and a processing unit that calculates system parameters,
One input port 1 of the linear multi-port to be measured receives the other wave distributed by the power distributor, and the other input port 2 receives the wave from the variable phase device,
The processing unit calculates a system parameter kh or a ratio hki of the system parameters kh based on the power of the output port of the linear multiport and the phase differences ψ01 and ψ02. System parameter measuring device. A method for measuring a system parameter that is a value inherent to a linear multiport,
A reference power measurement preparation step for applying a wave to one input port 1 of the linear multi-port and matching termination of the other input port 2;
A reference power measurement step of measuring the power of each output port of the linear multi-port and setting them as reference powers P3r, P4r, P5r,.
A power measuring step of removing the matching termination of the other input port 2, applying a wave to the other input port 2, and measuring the power {P 3, P 4, P 5.
A normalizing step of normalizing the measured power {P3, P4, P5...} Of each output port with the reference powers P3r, P4r, P5r;
A phase shifting step of changing the phase of the wave entering the other input port 2;
The power measurement step, the normalization step, and the phase shift step are repeated a plurality of times, and based on the obtained normalized powers, the phase of the wave entering the other input port 2 is used as a variable. A function identification step for identifying a power function;
A system parameter calculation step of calculating a system parameter kh or a ratio hki of the system parameters kh by integrating the identified function, and a linear multi-port system parameter measurement method. 8. The linear multi-port system parameter measuring method according to claim 7, wherein the system parameter calculating step calculates a ratio hki of the system parameters kh by the following equation (24).

Microwave, millimeter-wave, sub-millimeter-wave, and waves from power sources that generate high-frequency signals such as infrared rays, visible rays, and ultraviolet rays are divided into two. One is divided into two input ports and three or more output ports. The other input to the device under test is input to the input port 1 of the linear multiport, and the wave that has passed through the device under test or the wave reflected by the device under test is input to the input port 2 of the linear multiport, In this state, the detection output of each of the three or more output ports for power measurement of the linear multi-port is measured, and based on the measurement result, a vector network analyzer that measures a vector quantity related to the device under measurement is used. And
Measure the power P3d, P4d, P5d... Of each output port and normalize it with the pre-measured reference powers P3r, P4r, P5r... Or either one of the output ports. A DUT measurement step for measuring one of the power ratios 3P4d, 3P5d, 3P6d,... Of the other three output ports as a reference;
Instead of the device to be measured, a standard device whose transmission characteristic or reflection characteristic is known is connected, and the power P3s, P4s, P5s,... Of each output port is measured with respect to the standard device, and this is measured in advance. Normalized with the reference powers P3r, P4r, P5r, etc., or the power ratio of the other three output ports when any one of the output ports is used as a reference 3P4s, 3P5s, 3P6s,. A standard measurement step that performs any of the following:
Based on the normalized power or the power ratio and the pre-determined system parameter kh or system parameter ratio hki of the linear multi-port, a reference to enter the port 1 for the device under test and the standard respectively. Calculating a complex amplitude ratio Wd and Ws between the wave a1 and the measurement wave a2 entering the port 2, and calculating a ratio sWd = Wd / Ws between them,
A measurement method using a vector network analyzer comprising: an S parameter calculation step of calculating an S parameter of the device under measurement based on the ratio sWd and an S parameter of the standard device. The linear multi-port is a 5-port junction;
10. The measurement method using a vector network analyzer according to claim 9, wherein in the complex amplitude ratio calculation step, the ratio sWd is calculated by the following equation (14).

The linear multiport is a 6-port junction;
10. The measurement method using a vector network analyzer according to claim 9, wherein the complex amplitude ratio calculation step calculates the complex amplitude ratios Wd and Ws by the following equation (616).

Microwave, millimeter-wave, sub-millimeter-wave, and waves from power sources that generate high-frequency signals such as infrared rays, visible rays, and ultraviolet rays are divided into two. One is divided into two input ports and three or more output ports. The other input to the device under test is input to the input port 1 of the linear multiport, and the wave that has passed through the device under test or the wave reflected by the device under test is input to the input port 2 of the linear multiport, In this state, the detection method of each of the three or more output ports for power measurement of the linear multi-port is measured, and a measurement method using a vector network analyzer that measures a vector quantity related to the device under test based on the result is calculated by a computer. A program to be executed,
Measure the power P3d, P4d, P5d... Of each output port and normalize it with the reference powers P3r, P4r, P5r... Previously measured, or either one of the output ports. A DUT measurement step for measuring one of the power ratios 3P4d, 3P5d, 3P6d,... Of the other three output ports as a reference;
When a standard device with known transmission characteristics or reflection characteristics is connected instead of the device under test, the power P3s, P4s, P5s,... Of each output port is measured for the standard device, and this is measured in advance. Normalize with the reference powers P3r, P4r, P5r, etc., or power ratios of the other three output ports when any one of the output ports is used as a reference 3P4s, 3P5s, 3P6s .. a standard measurement step for measuring one of
Based on the normalized power or the power ratio and the pre-determined system parameter kh or system parameter ratio hki of the linear multi-port, a reference to enter the port 1 for the device under test and the standard respectively. Calculating a complex amplitude ratio Wd and Ws between the wave a1 and the measurement wave a2 entering the port 2, and calculating a ratio sWd = Wd / Ws between them,
A program for causing a computer to execute an S parameter calculation step of calculating an S parameter of the device under measurement based on the ratio sWd and the S parameter of the standard device.

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