JP4299401B2 - S-parameter test set and signal separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an S-parameter test set and a signal separator used when performing S-parameter measurement using a network analyzer or the like.
[0002]
[Prior art]
Conventionally, a network analyzer is used as a measuring instrument that inputs a predetermined sine wave signal and measures various parameters of a linear network. When actually measuring various parameters, a test set suitable for the parameter to be measured is prepared. By attaching this test set to the network analyzer, signals are input and output between the device under test and the network analyzer. This makes it possible to measure various parameters. Examples of measurable items include S-parameters, phase characteristics, voltage standing wave ratio (VSWR), and the like. Although the above-described test set may be built in the network analyzer, in this specification, it is assumed that a test set is prepared separately from the network analyzer.
[0003]
When measuring the S parameter of the device under measurement using the network analyzer described above, an S parameter test set prepared for S parameter measurement is used. FIG. 9 is a diagram showing a configuration of a conventional S-parameter test set, and shows a connection state between each component included in the S-parameter test set, a network analyzer, and a device under measurement.
[0004]
The network analyzer 90 includes one signal source 92 and three receiving circuits 94, 96, and 98, and the connection state between these and the device under test (DUT) 100 is switched by the S parameter test set 80. By means of two transmission coefficients S for the device under test 100 _{twenty one} , S ₁₂ And two reflection coefficients S ₁₁ , S _{twenty two} Is measured.
[0005]
The S parameter test set 80 includes a switch 82 that switches the connection destination of the signal source 92 and two signal separators 84 and 86 that separate signals input and output via the two ports 102 and 104, respectively. It is configured. For example, transmission coefficient S _{twenty one} , The switch 82 is switched to the contact a side, the signal output from the signal source 92 is input to the port 1 of the device under test 100 and the signal output from the port 2 is received by the receiving circuit 94. And detect. The signal output from the signal source 92 is always input to the receiving circuit 98 and detected, and the transmission coefficient S is obtained by obtaining the ratio of the power of the signals detected by the two receiving circuits 94 and 98. _{twenty one} Is measured. Similarly, transmission coefficient S ₁₂ Is measured, the switch 82 is switched to the contact b side so that the signal output from the signal source 92 is input to the port 2 of the device under test 100 and the signal output from the port 1 is received by the reception circuit 96. And detect. Then, by determining the ratio between the power of the signal detected by the receiving circuit 96 and the power of the signal detected by the receiving circuit 98 connected to the signal source 92, the transmission coefficient S ₁₂ Is measured.
[0006]
[Problems to be solved by the invention]
By the way, as described above, the two transmission coefficients S of the device under measurement 100 using the conventional S-parameter test set 80 are used. _{twenty one} , S ₁₂ , The two signal separators 84 and 86 are included in the transmission path of the signal output from the signal source 92, and loss occurs, so that the dynamic range is narrowed accordingly. . For example, one of the signal separators 84 is set so that a loss of a path for connecting the signal source 92 and the device under test 100 is reduced, and between the device under test 100 and the receiving circuit 96. It is assumed that the path loss is set to be large. The other signal separator 86 is set so that the loss of the path for connecting the signal source 92 and the device under test 100 is reduced, and between the device under test 100 and the receiving circuit 94. It is assumed that the path loss is set to be large. Using such two signal separators 84 and 86, the transmission coefficient S _{twenty one} , When the signal output from the port 2 of the device under test 100 is guided to the receiving circuit 94 side, a large attenuation occurs in the signal separator 86, so that the level of the signal input to the receiving circuit 94 is Decreases and the dynamic range deteriorates. Similarly, transmission coefficient S ₁₂ When the signal output from the port 1 of the device under test 100 is guided to the receiving circuit 96, a large attenuation occurs in the signal separator 84. Therefore, the level of the signal input to the receiving circuit 96 is Decreasing the dynamic range.
[0007]
The present invention was created in view of the above points, and an object of the present invention is to provide an S-parameter test set and a signal separator that can widen a dynamic range when measuring transmission coefficients. .
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, the S-parameter test set of the present invention includes a plurality of signal separators that connect each port of a device under measurement to a signal source and a receiving circuit, and sets the transmission coefficient of the device under measurement. A bypass path is provided that bypasses at least one of a plurality of signal separators existing on the signal transmission path during measurement. Therefore, a signal can be transmitted without going through a signal separator with a large loss of transmitted signal, and a wide dynamic range can be set when measuring a transmission coefficient.
[0009]
Further, the detour path described above is configured by a switch and a signal line, and by switching the switch, a signal line that connects between the receiving circuit and at least one of the signal source and the device to be measured without using a signal separator is provided. It is desirable to use as a detour route. Since it is possible to set a bypass route that does not go through the signal separator simply by operating the switch, switching control of the bypass route becomes easy.
[0010]
In addition, the signal separator described above has a through port with a small loss and a coupling port with a large loss, instead of a signal separator that transmits a signal through the coupling port when measuring a transmission coefficient. It is desirable to transmit a signal using a bypass route. When a signal is transmitted through a coupling port, a large loss occurs. Therefore, if a bypass path is used in such a case, the loss of the transmitted signal can be reduced, and a wide dynamic range can be obtained. Can be secured.
[0011]
The signal separator of the present invention connects each port of the device under measurement to the signal source and the receiving circuit, and also includes a high loss path existing on the signal transmission path when measuring the transmission coefficient of the device under measurement. There is a low-loss path that bypasses. Therefore, by using a low-loss path formed inside when transmitting a signal through the signal separator, a wide dynamic range can be set when measuring the transmission coefficient.
[0012]
In addition, a signal separator is configured by a bridge circuit having a plurality of resistors and a plurality of switches, and by switching the switches, the magnitude relationship between the resistance values of the two resistors facing each other is inverted, and a high loss path and low It is desirable to switch to the loss path. Alternatively, a signal separator is configured by a bridge circuit having a plurality of resistors and a plurality of switches, and by switching the switches, a low-loss path and a high-loss path as a short-circuit path that transmits a signal without using a resistor. It is desirable to switch between Signals can be transmitted through a low-loss path simply by operating a switch, and switching control between a low-loss path and a high-loss path becomes easy.
[0013]
Further, a signal separator is constituted by a coupler having a plurality of transmission conductors and a switch that are partially close to each other, and a switch formed by including the proximity portion of the plurality of transmission conductors by switching the switch. Switching between the loss path and the low-loss path as a short-circuit path formed by the switch may be performed. In this case as well, switching control between a short-circuit path and a high-loss path as a low-loss path formed in the coupler is facilitated, as in the case where the signal separator is configured using a bridge circuit.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an S parameter test set and a signal separator according to an embodiment to which the present invention is applied will be described with reference to the drawings. For example, a network analyzer that performs S-parameter measurement of a 2-port device is considered as a measuring instrument according to an embodiment to which the present invention is applied.
[0015]
[First Embodiment]
FIG. 1 is a diagram showing a configuration of a measuring instrument according to the first embodiment, and shows a state where an S-parameter test set for a 2-port device is connected to a network analyzer.
[0016]
The measuring instrument shown in FIG. 1 includes a network analyzer 10 that includes a signal source and a plurality of receiving circuits to measure S parameters, and an S parameter test set 20 that switches the connection state of a device under test (DUT) 40 to the network analyzer 10. It is comprised including.
[0017]
The network analyzer 10 includes a signal source 12 and three receiving circuits 14, 16 and 18. The signal source 12 generates a sine wave signal having a predetermined frequency. The receiving circuits 14, 16, and 18 perform vector detection on the sine wave signal transmitted via the S parameter test set 20. For example, each receiving circuit 14 or the like mixes a predetermined local oscillation signal with a high-frequency input signal to convert the low-frequency signal into a low-frequency signal that is the difference component, and converts the low-frequency signal to a predetermined resistance value. It is converted to a voltage by passing through a resistor having (for example, 50Ω).
[0018]
The S parameter test set 20 includes five change-over switches 21, 22, 23, 24, 25, three signal separators 26, 27, 28, and two test ports 30, 32. The two test ports 30 and 32 are connection terminals to which the device under measurement 40 as a two-port device is connected via a cable. The changeover switch 21 is for switching the output destination of the signal generated by the signal source 12 in the network analyzer 10 to one of the two test ports 30 and 32. Further, the two change-over switches 22 and 23 are for bypassing the signal separator 26, and by switching each to the contact b side, the signal line 34 with almost no loss is connected to the detour path of the signal separator 26. Set as Similarly, the two changeover switches 24 and 25 are for bypassing the signal separator 27, and by switching each to the contact b side, the signal line 36 with almost no loss is routed around the signal separator 27. Set as
[0019]
Each of the two signal separators 26 and 27 is for separating signals input / output via the corresponding test ports 30 and 32. For example, a bridge type or coupler type signal separator is used. In the signal separator 26, the path on the side connecting the test port 30 and the signal source 12 corresponds to a through port having a small loss, and the path on the side connecting the test port 30 and the receiving circuit 16 is a coupler port having a large loss. Corresponding to Similarly, in the signal separator 27, the path on the side connecting the test port 32 and the signal source 12 corresponds to a through port with a small loss, and the path on the side connecting the test port 30 and the receiving circuit 14 is lossy. Corresponds to a large coupler port. Further, the signal separator 28 sends a part of the signal transmitted via the transmission line extending from the signal source 12 to the receiving circuit 18.
[0020]
The S parameter test set 20 of this embodiment has such a configuration, and the operation thereof will be described next. FIG. 2 is a diagram illustrating a connection state of the switches (SW) 21 to 25 during S parameter measurement. As shown in FIG. 2, the transmission coefficient S _{twenty one} And reflection coefficient S ₁₁ Is measured, the connection states of the three switches 21 to 23 are set to the contact a side, and the connection states of the remaining two switches 24 and 25 are set to the contact b side. Therefore, the signal output from the signal source 12 is input to one port 1 of the device under measurement 40 via the signal separator 26 and the test port 30. Then, the signal reflected from the one port 1 passes through the signal separator 26 again to the receiving circuit 16 via the changeover switch 23, and is detected and reflected by the reflection coefficient S. ₁₁ Is measured. In addition, a signal output from the other port 2 of the device under test 40 is guided to the reception circuit 14 via the changeover switch 24, the signal line 36, and the changeover switch 25, and is detected and transmitted. _{twenty one} Is measured.
[0021]
Transmission coefficient S ₁₂ And reflection coefficient S _{twenty two} Is measured, the connection states of the three switches 21 to 23 are set to the contact b side, and the connection states of the remaining two switches 24 and 25 are set to the contact a side. Therefore, the signal output from the signal source 12 is input to the other port 2 of the device under measurement 40 via the signal separator 27 and the test port 32. Then, the signal reflected from the other port 2 passes through the signal separator 27 again to the receiving circuit 14 through the changeover switch 25, and is detected and reflected by the reflection coefficient S. _{twenty two} Is measured. In addition, a signal output from one port 1 of the device under test 40 is guided to the receiving circuit 16 via the changeover switch 22, the signal line 34, and the changeover switch 23, and is detected and transmitted. ₁₂ Is measured.
[0022]
Thus, the transmission coefficient S _{twenty one} , S ₁₂ When measuring the signal output from the device under test 40 to the receiving circuits 14 and 16, the signal lines 36 and 34 as bypass paths are used without passing through the signal separators 27 and 26. . Therefore, the signal is not transmitted via the coupling port of each of the signal separators 27 and 26 having a large loss, but instead, the signal is transmitted via the signal lines 36 and 34 having a small loss. Therefore, the level of the signal input to the receiving circuits 14 and 16 is increased, and the transmission coefficient S _{twenty one} , S ₁₂ The dynamic range when measuring can be expanded.
[0023]
[Second Embodiment]
By the way, in the first embodiment described above, when the transmission coefficient is measured, the signal is transmitted through the detour path instead of passing through the signal separator that causes a large loss of the signal. A function of switching the detour path as necessary may be incorporated in the signal separator.
[0024]
FIG. 3 is a diagram illustrating a detailed configuration of the signal separator according to the second embodiment. FIG. 4 is a diagram showing the correspondence between the ports of the signal separator 50 shown in FIG. As shown in FIG. 3, the signal separator 50 is realized by a bridge circuit, and includes five resistors 51 to 55 and four changeover switches 56 to 59.
[0025]
The two resistors 52 and 54 sandwiched between the two changeover switches 56 and 57 are alternatively selected. For example, by switching each of the switches 56 and 57 to the contact a side, the resistance value R ₁ On the contrary, the resistance value R is selected by switching to the contact b side. ₁ A resistor 54 having 'is selected.
[0026]
Similarly, two resistors 53 and 55 sandwiched between two changeover switches 58 and 59 are alternatively selected. For example, by switching each of the switches 58 and 59 to the contact a side, the resistance value R ₂ On the contrary, the resistance value R is selected by switching to the contact b side. ₂ A resistor 55 having ′ is selected.
[0027]
By the way, in the signal separator 50 described above, each resistance value R of the two resistors 52 and 53 selected when each of the four selector switches 56 to 59 is switched to the contact a side. ₁ , R ₂ In between, R ₁ <R ₂ There is a relationship. In such a connection state, there is a loss of signal that occurs when the path from the port BB ′ constituted by the terminals B and B ′ to the port A-A ′ constituted by the terminals A and A ′ is passed. Along with the decrease, the loss of the signal that occurs when the path from the port BB ′ to the port CC ′ constituted by the terminals C and C ′ is increased. Accordingly, the port A-A ′ functions as a through port for the port BB ′, and the port CC ′ functions as a coupling port for the port BB ′.
[0028]
Further, in the signal separator 50 described above, each resistance value R of the two resistors 54 and 55 selected when each of the four selector switches 56 to 59 is switched to the contact point b side. ₁ ', R ₂ Between ′, R ₁ ′ ＞ R ₂ There is a relationship of ′. In such a connection state, the loss of the signal generated when passing through the path from the port BB ′ to the port A-A ′ is large, and the path from the port BB ′ to the port CC ′ is passed. Signal loss that occurs when Therefore, the port AA ′ functions as a coupling port for the port BB ′, and the port CC ′ functions as a through port for the port BB ′.
[0029]
FIG. 5 is a diagram showing the configuration of the S-parameter test set configured using the signal separator 50 shown in FIGS. 3 and 4, and the connection state between the nutwork analyzer and the device under test (DUT). It is shown. The S parameter test set 20A shown in FIG. 5 includes a changeover switch 21 and three signal separators 50 and 50A. Each of the signal separators 50 and 50A has the detailed configuration shown in FIG.
[0030]
The signal separators 50 and 50A of this embodiment and the S parameter test set 20A using the signal separators 50A have such a configuration, and the operation thereof will be described next. FIG. 6 is a diagram illustrating a connection state of the switches 21 and 56 to 59 when the S parameter is measured.
[0031]
As shown in FIG. 6, the transmission coefficient S _{twenty one} And reflection coefficient S ₁₁ , The connection states of the changeover switch 21 included in the S parameter test set 20A and the four changeover switches 56 to 59 included in the signal separator 50 are set to the contact a side, and the signal separator 50A Each connection state of the included four changeover switches 56 to 59 is set to the contact b side. Therefore, the signal output from the signal source 12 passes through the path connecting the port A-A 'and the port BB' of the signal separator 50 set to low loss, and then is measured via the test port 30. Input to one port 1 of the device 40. Then, the signal reflected from the one port 1 is again guided to the receiving circuit 16 through the signal separator 50, detected and reflected by the reflection coefficient S. ₁₁ Is measured. Further, the signal output from the other port 2 of the device under test 40 connects the port BB ′ and the port CC ′ of the signal separator 50A set to low loss through the test port 32. After passing through the path, it is guided to the receiving circuit 14 and detected to transmit the transmission coefficient S. _{twenty one} Is measured.
[0032]
Transmission coefficient S ₁₂ And reflection coefficient S _{twenty two} , The connection states of the changeover switch 21 included in the S parameter test set 20A and the four changeover switches 56 to 59 included in the signal separator 50 are set to the contact b side, and the signal separator 50A Each connection state of the included four changeover switches 56 to 59 is set to the contact a side. Therefore, the signal output from the signal source 12 passes through the path connecting the port A-A 'and the port BB' of the signal separator 50A set to low loss, and then is measured via the test port 32. Input to the other port 2 of the device 40. Then, the signal reflected from the other port 2 is again guided to the receiving circuit 14 through the signal separator 50A, detected and reflected by the reflection coefficient S. _{twenty two} Is measured. Further, the signal output from one port 1 of the device under test 40 is connected to the port BB ′ and the port CC ′ of the signal separator 50 set to low loss via the test port 30. After passing through the path, it is guided to the receiving circuit 16 where it is detected and the transmission coefficient S ₁₂ Is measured.
[0033]
Thus, the transmission coefficient S _{twenty one} , S ₁₂ When the signal output from the device under test 40 is guided to the receiving circuits 14 and 16, the transmission paths in the signal separators 50 and 50A are set to low loss. Therefore, the level of the signal input to the receiving circuits 14 and 16 increases, and the transmission coefficient S _{twenty one} , S ₁₂ The dynamic range when measuring can be expanded.
[0034]
[Third Embodiment]
In the second embodiment described above, the transmission coefficient S is appropriately switched by appropriately switching the loss amounts of the two signal transmission paths in the signal separators 50 and 50A. _{twenty one} , S ₁₂ Although the dynamic range at the time of measurement was widened, focusing on the signal separator on the side where the transmitted signal is input, only the transmission path on the side to which the receiving circuit is connected is used, so this transmission path loss is further reduced. Then, the port BB ′ and the port CC ′ may be directly connected.
[0035]
FIG. 7 is a diagram illustrating a detailed configuration of the signal separator according to the third embodiment. As shown in FIG. 7, the signal separator 60 is realized by a bridge circuit, and includes three resistors 61, 62, 63 and two switches 64, 65.
[0036]
When the signal separator 60 is used as a normal bridge circuit, one switch 64 connected in series to the resistor 62 is turned on, and the other switch 65 connected in parallel to the resistor 63 is turned off. . Further, the resistance value R of the resistor 62 _Three And resistance value R of resistor 63 _Four R between _Three <R _Four There is a relationship. Therefore, the loss of the signal generated when passing through the path from the port BB ′ to the port A-A ′ is small, and the signal generated when passing through the path from the port BB ′ to the port CC-C ′ is reduced. Loss increases. Therefore, the port A-A ′ functions as a through port for the port BB ′, and the port CC ′ functions as a coupling port for the port BB ′.
[0037]
Transmission coefficient S _{twenty one} , S ₁₂ When the signal separator 60 is used to guide the transmitted signal to the receiving circuit when measuring the signal, one switch 64 connected in series to the resistor 62 is turned off and the resistor 63 is connected in parallel. The other switch 65 is turned on. Accordingly, the path from the port BB ′ to the port CC ′ is blocked, and the port BB ′ and the port CC ′ are directly connected, so that the receiving circuit is connected via the port CC ′. The signals input to 14 and 16 are hardly attenuated in the signal separator 60. For this reason, the level of the signal input to the receiving circuits 14 and 16 can be increased, and the transmission coefficient S _{twenty one} , S ₁₂ The dynamic range when measuring can be expanded.
[0038]
[Fourth Embodiment]
In the second and third embodiments described above, the signal separator 50 and the like are realized by a bridge circuit, but may be realized by a coupler. FIG. 8 is a diagram illustrating a detailed configuration of the signal separator according to the fourth embodiment. The signal separator 70 shown in FIG. 8 is realized by a coupler using a microstrip line, and a dielectric substrate 71 and five conductors 72-1, 72- serving as transmission conductors formed on the surface of the dielectric substrate 71. 2, 74, 77-1, 77-2, and four switches 73, 75, 76, 78 for switching the connection states of the three ports AA ′, BB ′, CC ′. It consists of For example, each switch 73 may be a micro relay switch or a semiconductor switch such as a pin diode. A grounding conductor is formed on the entire back surface of the dielectric substrate 71, and a termination resistor 79 having a predetermined resistance value is provided so that no signal is reflected at the fourth port DD '. Is connected.
[0039]
A switch 73 is connected between the conductors 72-1 and 72-2 formed between the port B-B 'and the port A-A'. By turning this switch 73 on, A transmission path connecting these two ports is formed. The conductor 77-1 connected to the port C-C 'is formed at a predetermined position partially approaching the conductor 72-1 connected to the port A-A'. When a signal is transmitted through the cable, a part of the signal leaks to the conductor 77-1 side. Accordingly, when a signal is input to the port BB ′, a part of the signal is output from the port A-A ′ via the conductors 72-2 and 72-1, and the rest is the conductor 77-1. Through the port CC-C '. Usually, the signal output from the port A-A ′ directly connected to the port BB ′ via the conductors 72-1 and 72-2 is larger than the signal output from the port CC ′. Therefore, the port A-A ′ side becomes a through port and the port CC-side becomes a coupling port.
[0040]
When used in such a state, the switch 78 connected between the conductor 77-1 and the conductor 77-2 is set to the on state, so that unnecessary reflection does not occur. Yes. Further, the switch 75 provided between the conductor 72-2 and the conductor 74 and the switch 76 provided between the conductor 77-2 and the conductor 74 are set in an off state.
[0041]
Transmission coefficient S _{twenty one} , S ₁₂ When the signal separator 70 is used to guide the transmitted signal to the receiving circuit when measuring the signal, the switch 73 formed between the conductors 72-1 and 72-2 is set to the OFF state. The other three switches 75, 76 and 78 are set to the ON state. Therefore, the conductor 72-2 connected to the port B-B 'and the conductor 77-1 connected to the port CC' are short-circuited through the conductor 74 and the three switches 75, 76, 78, and this transmission is performed. Path loss is reduced. For this reason, the level of the signal input to the receiving circuits 14 and 16 via the port CC ′ increases, and the transmission coefficient S _{twenty one} , S ₁₂ The dynamic range when measuring can be expanded.
[0042]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, in the above-described embodiment, the S parameter test set for ports and the signal separator included therein are described. However, the S parameter test set having a different number of ports (for example, for 3 ports) and the signal separator used therefor The present invention can be applied.
[0043]
【The invention's effect】
As described above, according to the present invention, when measuring the transmission coefficient of a device under test in an S-parameter test set having a plurality of signal separators connecting each port of the device under test with a signal source and a receiving circuit. A bypass path is provided for bypassing at least one of a plurality of signal separators existing on the signal transmission path. Therefore, a signal can be transmitted without going through a signal separator with a large loss of transmitted signal, and a wide dynamic range can be set when measuring a transmission coefficient.
[0044]
Further, according to the present invention, in the signal separator that connects each port of the device under measurement, the signal source, and the receiving circuit, the high loss existing on the signal transmission path when measuring the transmission coefficient of the device under measurement. A low-loss path that bypasses the path is provided. Therefore, by using a low-loss path formed inside when transmitting a signal through the signal separator, a wide dynamic range can be set when measuring the transmission coefficient.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a measuring instrument according to a first embodiment.
FIG. 2 is a diagram illustrating a connection state of each switch when measuring an S parameter.
FIG. 3 is a diagram illustrating a detailed configuration of a signal separator according to a second embodiment.
4 is a diagram illustrating a correspondence relationship between each port of the signal separator illustrated in FIG. 3; FIG.
FIG. 5 is a diagram illustrating a configuration of an S parameter test set configured using the signal separator illustrated in FIGS. 3 and 4;
FIG. 6 is a diagram illustrating a connection state of each switch when measuring an S parameter.
FIG. 7 is a diagram illustrating a detailed configuration of a signal separator according to a third embodiment.
FIG. 8 is a diagram illustrating a detailed configuration of a signal separator according to a fourth embodiment.
FIG. 9 is a diagram showing a configuration of a conventional S-parameter test set.
[Explanation of symbols]
10 Network analyzer
12 Signal source
14, 16, 18 Receiver circuit
20 S-parameter test set
21, 22, 23, 24, 25 changeover switch
26, 27, 28, 50, 50A, 60, 70 Signal separator

Claims (7)

A plurality of signal separators for connecting each port of the device under measurement to a signal source and a receiving circuit; An S-parameter test set, characterized in that a bypass path is provided to bypass at least one of the devices. In claim 1,
The detour path is configured by a switch and a signal line. By switching the switch, the detour path passes between at least one of the reception circuit, the signal source, and the device under test without passing through the signal separator. An S-parameter test set, wherein the signal line to be connected is used as the bypass path. In claim 1 or 2,
The signal separator has a low-loss through port and a high-loss coupling port. Instead of the signal separator, a signal is transmitted through the coupling port when measuring a transmission coefficient. An S-parameter test set, wherein a signal is transmitted using the detour path. In the signal separator that connects each port of the device under measurement to the signal source and the receiving circuit,
A signal separator comprising a low loss path that bypasses a high loss path existing on a signal transmission path when measuring a transmission coefficient of the device under measurement. In claim 4,
A bridge circuit having a plurality of resistors and a plurality of switches, and by switching the switches, the magnitude relationship between the resistance values of the two opposing resistors is reversed, and the high loss path and the low loss path are The signal separator characterized by switching. In claim 4,
A bridge circuit having a plurality of resistors and a plurality of switches, and switching between the low loss path and the high loss path as a short-circuit path for transmitting a signal without passing through the resistance by switching the switches A signal separator. In claim 4,
A coupler having a plurality of transmission conductors and a switch partially brought close to each other, wherein the high-loss path formed including the proximity portions of the plurality of transmission conductors by switching the switch; and A signal separator characterized by switching to the low-loss path as a short-circuit path formed by a switch.

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