JP3743225B2 - Transmission characteristic measuring probe and transmission characteristic measuring apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission characteristic measurement probe and a transmission characteristic measurement apparatus, and in particular, to measure high-frequency signal transmission characteristics of information processing equipment and metal casings and metal joint plates of various electric and electronic devices in order to take measures against electromagnetic waves. The present invention relates to a transmission characteristic measurement probe and a transmission characteristic measurement apparatus.
[0002]
[Prior art]
Conventionally, current transformers and capacitively coupled probes that observe common mode noise have been used as probes used to measure transmission characteristics for taking measures against electromagnetic noise radiated from equipment.
[0003]
As a high-frequency measurement probe, a high-frequency measurement probe described in Japanese Utility Model Application No. 2-30062 has been proposed. This high-frequency measurement probe forms a distributed capacity by arranging conductive cylinders and rods on concentric circles, and an inductance core material is arranged on the concentric circles of the cylinders and rods to generate inductance components. High frequency measurements can be made by forming and using distributed capacitance and inductance components as circuit constants.
[0004]
[Problems to be solved by the invention]
However, transmission characteristic measurement using a network analyzer or standard signal generator using a current transformer or a capacitive coupling probe for observing common mode noise and a field strength meter is usually performed as shown in FIG. A signal return (grounding) structure that becomes the reference ground plane is required, and when measuring information processing devices and electrical / electronic devices with large volumes, not only the reference ground plane becomes large, but also at any point, The signal cannot be injected. Furthermore, there is a problem that the signal transmission characteristic of the metal structure incorporated in the device cannot be measured.
[0005]
When measuring transmission characteristics using the high-frequency measurement probe disclosed in Japanese Utility Model Application No. 2-30062, as shown in FIG. 11, the probe is brought into contact with any point of the device without requiring a reference ground plane. Thus, the current can be measured, but the impedance frequency characteristic of the probe varies when the contact terminal is brought into contact with the object to be measured. In addition, this probe is intended for current extraction, and since the ground line does not have a termination structure (the probe circuit is an open circuit), the arrangement of the coaxial line connected to the probe and the human and adjacent metal Therefore, there is a problem that the reproducibility of measurement cannot be ensured and a problem occurs in measurement accuracy.
[0006]
For this reason, the measurement in the special electromagnetic environment measurement place called the shield room which can become a large standard ground plane was required.
[0007]
The present invention has been made to solve the above problems, and provides a transmission characteristic measuring probe and a transmission characteristic measuring apparatus that can easily measure the transmission characteristic of an object to be measured without selecting a measurement location. Objective.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 is a measurement for measuring a transmission part of a contact part to be in contact with the object to be measured, a first winding to which the contact part is connected, and the object to be measured. A transformer including a second winding connected to a device, and a resistance element connected in series between the second winding and the measuring device are provided.
[0009]
According to the first aspect of the present invention, by providing a resistance element in series between the second winding and the measuring device, the transmission end impedance (impedance on the transmission characteristic measuring probe side) and the measuring device (for example, Therefore, it is possible to match the impedance of the coaxial line connecting the measuring device and the transmission characteristic measuring probe, and the impedance can be kept substantially constant over a wide frequency range. That is, impedance fluctuations between the transmission characteristic measuring probe and the measuring device (for example, a coaxial line) can be suppressed, so that measurement at an arbitrary point of the object to be measured is possible without requiring a large reference plane. That is, the transmission characteristics of the device under test can be easily measured without selecting a measurement location.
[0010]
Note that a capacitor may be connected in parallel to the resistor. By doing so, the inductance component specific to the transformer and the resistance element can be canceled, and a more stable impedance characteristic can be obtained at a wide frequency range.
[0011]
Further, an insulating member may be provided, and a biasing means such as a spring may be inserted into the insulating member, and the contact portion may be disposed on the biasing means. By doing so, the transmission characteristic measurement probe is pressed to bring the contact portion into contact with the object to be measured, and the insulating member is pressed until it comes into contact with the object to be measured. The pressure becomes the urging force of the urging means, and the contact pressure is always constant. Therefore, it is possible to prevent the contact resistance between the contact portion and the object to be measured from changing every measurement, and to ensure the reproducibility of the measurement.
[0012]
According to a second aspect of the present invention, in the first aspect of the present invention, the first winding and the second winding are connected in series by a capacitive element.
[0013]
According to a second aspect of the present invention, in the first aspect of the present invention, a standing wave can be suppressed by providing a capacitive element in series between the first winding and the second winding. The impedance fluctuation when the contact portion is brought into contact with the object to be measured can be suppressed.
[0014]
For example, a standing wave can be suppressed by connecting a capacitive element in series between the first winding and the second winding and connecting to the outer sheath of the coaxial line, and the contact portion is measured. Impedance fluctuation when brought into contact with an object can be suppressed.
[0015]
Therefore, measurement at an arbitrary point of the object to be measured is possible without requiring a large reference plane. That is, the transmission characteristics of the device under test can be easily measured without selecting a measurement location.
[0016]
In addition, a variable resistor and a variable capacitor may be used for the resistor and the capacitor of claims 1 and 2.
[0017]
According to a third aspect of the present invention, the transmission characteristic measuring probe according to the first or second aspect is connected as a first probe, and a signal is sent to the device under test via the contact portion of the first probe. A signal generating means for applying and a transmission object measuring probe according to claim 1 or 2 different from the first probe as a second probe and different from the first probe And an analysis means for analyzing the frequency of a signal obtained through the contact portion.
[0018]
According to a third aspect of the present invention, the signal generating means applies the signal to the object to be measured through the contact portion of the first probe using the transmission characteristic measuring probe as the first probe. Further, the analysis means uses a transmission characteristic measurement probe different from the first probe as the second probe, and contacts the contact portion of the second probe with a part of the object to be measured different from the first probe. The analysis means measures the impedance frequency variation and the resonance frequency of the object to be measured by performing frequency analysis on the signal obtained through the contact portion of the second probe. Here, when the transmission characteristic measuring probe is used as described above, impedance fluctuation is small and stable impedance characteristics can be obtained at a wide frequency range. For this reason, impedance fluctuations due to adjacent metal objects and people between the probe, the signal generating means and the analyzing means (for example, connection by a coaxial line) are suppressed, measurement reproducibility can be ensured, and measurement accuracy can be improved. Can be improved.
[0019]
In addition, since the frequency analysis of the object to be measured can be performed by bringing the first probe and the second probe into contact with different parts of the object to be measured, the object to be measured can be measured regardless of the size of the object to be measured and the measurement location. Frequency analysis of objects can be easily performed.
[0020]
According to a fourth aspect of the present invention, there is provided the transmission signal measuring probe according to the first or second aspect and the transmission characteristic measuring probe connected to each other and a measurement signal via a contact portion of the transmission characteristic measuring probe. Is transmitted to the device under test based on a return signal obtained from the device under test via the contact portion of the probe for measuring transmission characteristics and the signal generating means for applying the signal to the device under test. And measuring means for measuring the characteristics.
[0021]
According to the fourth aspect of the present invention, the signal generated by the signal generating means is injected into the object to be measured via the transmission characteristic measuring probe. The return signal from the object to be measured can be measured by the measuring means by extracting the injected signal through the object to be measured by the transmission characteristic measuring probe. The measuring means can measure transmission characteristics such as impedance and resonance frequency of the device under test based on the signal generated by the signal generating device and the return signal extracted via the device under test. As described above, when the transmission characteristic measuring probe is used, the impedance fluctuation is small and a stable impedance characteristic can be obtained at a wide frequency range. For this reason, impedance fluctuations due to adjacent metal objects and people between the transmission characteristic measurement probe and the signal generation means and measurement means (for example, coaxial line) are suppressed, ensuring measurement reproducibility and improving measurement accuracy. Can do.
[0022]
The same transmission characteristic measuring probe connected to the signal generating means and the measuring means can be used, and any of them may be used as long as a plurality of the transmission characteristic measuring probes are prepared.
[0023]
The transmission characteristic measuring probe can measure the transmission characteristic by contacting an arbitrary point of the object to be measured.
[0024]
Each transmission characteristic measuring probe in the transmission characteristic measuring device is brought into contact with an arbitrary point on the object to be measured, so that the signal generated by the signal generating means is injected into the object to be measured through the transmission characteristic measuring probe. Then, the return signal can be transmitted to the measuring means through the device under test and from the transmission characteristic measuring probe. Therefore, it is possible to easily measure the transmission characteristics of the object to be measured regardless of the size of the object to be measured and the measurement location.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0026]
FIG. 1 shows a schematic diagram of a transmission characteristic measuring probe according to an embodiment of the present invention.
[0027]
In the figure, a transmission characteristic measuring probe 10 is formed on a core material 12 in which a NiZn-based ferrite, a MnZn-based ferrite sintered body, or a sintered body obtained by mixing them is formed in a ring shape (a donut shape having a so-called hollow portion). The secondary conductor (secondary coil) 16 around which the coil wire is wound, and the primary conductor (primary coil) 14 around which the coil wire is wound at the opposite position on the same core as the secondary coil 16. It is mainly composed by.
[0028]
A coaxial line 18 is provided at the center of the core material 12, and the central conductor 20 of the coaxial line 18 is connected to the primary coil 14 via a resistor 22 and a capacitive element 24. The primary coil 14 is further connected to a grounding line (shield outer skin) 26 of the coaxial line 18.
[0029]
The coaxial line 18 is connected to a voltage source, a current source, an ammeter, an electric field strength meter, and a voltmeter, and transmits an electrical signal.
[0030]
The secondary coil 16 is connected to the shield sheath 26 of the coaxial line 18 via the capacitive element 28, and a contact terminal 30 that is brought into direct contact with the object to be measured is connected via a spring 32. The spring 32 is inserted into an insulator 34 on the cylinder. That is, the spring 32 is contracted by bringing the contact terminal into contact with the object to be measured, and the object to be measured and the insulator 34 are in contact with each other.
[0031]
FIG. 2 shows an equivalent circuit of the transmission characteristic measuring probe 10 configured as described above. Next, an equivalent circuit of the transmission characteristic measuring probe 10 configured as described above will be described.
[0032]
One end of the primary coil 14 has a resistance R connected in series to the central conductor 20 of the coaxial line 18. A capacitive element 24 is connected in parallel with the resistor 22. The other end of the primary coil 14 is connected to the grounded shield skin 26 of the coaxial line 18. The resistor 22 and the capacitive element 24 are connected to a resistor and a capacitive element having such a magnitude that the impedance generated by the core material 12 and the primary coil 14 and the impedance of the coaxial line 18 are substantially the same.
[0033]
The secondary coil 16 forms a short-circuited closed loop, and is connected to the shield sheath 26 of the coaxial line 18 via the capacitive element 28 and is connected to the contact terminal 30 via the spring 32.
[0034]
As shown in FIG. 3, the transmission characteristic measurement probe 10 is connected to the port 1 and the port 2 of the network analyzer 36 via the coaxial line 18 to transmit the transmission characteristic. By using the measuring apparatus 100, it is possible to measure transmission characteristics such as a resonance frequency output from a metal casing that protects an electric board or the like, various information processing devices, or the like.
[0035]
As shown in FIG. 4, the network analyzer 36 of the transmission characteristic measuring apparatus 100 mainly includes a signal generating means 38, a measuring means 40, an input means 48, and a monitor 50. The signal generating means 38, the measuring means. 40, the input means 48, and the monitor 50 are connected via an input / output bus 52, respectively.
[0036]
The signal generating means 38 injects a predetermined pulse signal into the object to be measured via one of the coaxial line 18 and the transmission characteristic measuring probe 10 (transmission characteristic measuring probe connected to the port 1), and measures the measuring means. Reference numeral 40 denotes a signal transmitted from the signal generator 38 and injected into the device under test via the transmission characteristic measurement probe 10 connected to the coaxial line 18 and the port 1. The signal is extracted through the transmission characteristic measurement probe and the coaxial line 18 connected to each other. Then, the transmission characteristic of the device under test is measured by comparing the signal generated by the signal generating means 38 with the signal extracted via the device under test.
[0037]
The network analyzer 36 can be operated by inputting information for adjusting the signal generated by the signal generating means 38 and information for instructing calibration of the network analyzer 36 to the input means 48. The measurement result can be displayed on the monitor 50. Note that the measurement result may be printed.
[0038]
For example, the signal generator 38 of the network analyzer 36 generates a pulse current having a predetermined frequency and injects the pulse current into the object to be measured. Then, the measuring means 40 measures the loss due to the impedance of the object to be measured from the pulse current generated by the signal generating means 38 and the pulse current extracted through the object to be measured. It is possible to measure the resonance frequency of electromagnetic noise generated from the device under test.
[0039]
The values of the resistor 22 and the capacitive element 24 of the transmission characteristic measuring probe 10 are obtained by connecting one transmission characteristic measuring probe 10 to a network analyzer and using the S parameter S11 (input reflection coefficient). The impedance obtained by the network analyzer 36 can be determined based on the Smith chart. For example, it is possible to determine the values of the resistor 22 and the capacitive element 24 by decomposing the impedance obtained by the network analyzer 36 into an inductance component and a capacitance component on a Smith chart.
[0040]
Next, the operation of the transmission characteristic measurement probe 10 will be described.
[0041]
Since the transmission characteristic measuring probe 10 is connected so that the impedance of the coaxial line 18 and the impedance generated by the core material 12 and the primary coil 14 become substantially the same impedance by the resistor 22 and the capacitive element 24, the coaxial line 18. And impedance matching with the transmission characteristic measuring probe serving as the transmitting end. Since the capacitive element 24 is connected in parallel to the resistor 22, the impedance frequency characteristic becomes substantially the same impedance stable at a wide frequency range, and a stable impedance frequency characteristic can be obtained.
[0042]
The secondary coil 16 is for injecting a signal into the object to be measured and extracting the injected signal in order to measure the transmission characteristic of the object to be measured by bringing it into contact with the object to be measured. By doing so, the impedance of the probe circuit (equivalent circuit of the transmission characteristic measuring probe 10) may fluctuate. However, since the secondary coil 16 and the shield sheath 26 connected to the ground of the coaxial line 18 are connected by the capacitive element 28, the standing wave can be suppressed, and the impedance of the probe circuit is not changed. Impedance characteristics are ensured with frequency. Therefore, the fluctuating impedance can be suppressed by contacting the object to be measured.
[0043]
Further, when the transmission characteristic measuring probe 10 is brought into contact with an object to be measured, the contact terminal 30 is connected to the spring 32, and therefore receives the urging force of the spring 32. Further, the object to be measured comes into contact with the insulator 34 by further pressing the object to be measured. That is, the contact terminal 30 comes into contact with the object to be measured in a state where a predetermined pressure corresponding to the urging force of the spring 32 is applied. Therefore, by pressing the transmission characteristic measuring probe 10 against the object to be measured until the insulator 34 comes into contact, the contact resistance between the object to be measured and the contact terminal 30 is always the same, and the measurement is reproduced by the contact resistance. It is possible to prevent the property from being impaired.
[0044]
As described above, the transmission characteristic measurement probe 10 according to the present embodiment can perform simple and stable signal injection and extraction.
[0045]
Next, an operation in the case where frequency characteristics are measured as transmission characteristics of a device in which an electric / electronic circuit is incorporated in a device such as an information processing device by the above-described transmission property measuring apparatus 100 will be described.
[0046]
As shown in FIG. 3, the transmission characteristic measuring probe 10 is connected to the port 1 and the port 2 of the network analyzer 36, and any point of the device under test is used as a signal injection point and a signal extraction point. The contact terminal 30 is brought into contact.
[0047]
Subsequently, when a predetermined pulse signal generated by the signal generating means 38 is injected from the port 1 of the network analyzer 36 through the signal injection point of the object to be measured, it is connected to the port 2 of the network analyzer 36 and the signal extraction point of the object to be measured. The signal which is output from the signal generating means 38 connected to the transmission characteristic measuring probe 10 in contact with the signal and inputted to the object to be measured through the transmission characteristic measuring probe 10 in contact with the signal injection point is extracted, It is transmitted to the measuring means 40 of the network analyzer 36.
[0048]
The measuring means 40 of the network analyzer 36 compares the signal generated by the signal generating means 38 with the signal extracted by the measuring means 40 via the device under test, and measures the signal lost by the device under test. . That is, the transmission characteristic of the device under test can be measured by analyzing the signal injected into the device under test and the signal extracted through the device under test. Here, by varying and injecting the frequency of the signal to be injected into the object to be measured, it is possible to measure the impedance frequency fluctuation and the resonance frequency of the object to be measured.
[0049]
Since the transmission characteristic measurement device 100 uses the transmission characteristic measurement probe 10 described above, the arrangement of the coaxial line 18 connected to the transmission characteristic measurement probe 10 and impedance fluctuations caused by nearby metals and people are suppressed. In addition to selecting a measurement location, any point of the object to be measured can be used as a signal injection point and an extraction point, and the transmission characteristics of the object to be measured can be easily measured.
[0050]
Further, since the transmission characteristic measuring apparatus 100 injects the signal generated by the signal generating means 38 into the object to be measured, the impedance frequency fluctuation of the object to be measured regardless of the operation of the object to be measured (operation of the electric / electronic device). And transmission characteristics such as resonance frequency can be measured.
[0051]
【Example】
Hereinafter, embodiments of a transmission characteristic measuring probe according to the present invention will be described in detail with reference to the drawings.
[0052]
The 50 Ω coaxial line 18 is connected to the transmission characteristic measuring probe 10, the transmission characteristic measuring probe 10 is connected to the transmission characteristic measuring device 100 when the resistor 22 is set to 51 Ω, and the capacitive element 24 and the capacitive element 28 are set to 33 pF. FIG. 5 shows the result (S parameter S21) of the loss measurement of the transmission characteristic measurement probe 10 itself (for two transmission characteristic measurement probes), and FIG. 6 shows the impedance frequency characteristic of the transmission characteristic measurement probe 10. The voltage standing wave ratio (VSWR) frequency characteristic is shown in FIG. 7 (S parameter S11).
[0053]
The loss measurement of the transmission characteristic measuring probe 10 itself is performed by connecting the transmission characteristic measuring probe 10 to the transmission characteristic measuring apparatus 100 and connecting the transmission characteristic measuring probe 10 connected to the signal generating means 38 and the measuring means 40 to the transmission characteristics. FIG. 5 shows a comparison between the signal generated by the signal generation means 38 and the signal returned to the measurement means 40 in a state in which the measurement probe 10 is in contact (short state). Is the magnitude of the return signal. From FIG. 5, the loss characteristic of the transmission characteristic measuring probe 10 is about 33 dB at 30 MHz, about 30 dB at 100 MHz, about 45 dB at 500 MHz, and about 43 dB at 1 GHz. It can be seen that the characteristics can be obtained.
[0054]
Further, as shown in FIG. 6, the impedance frequency characteristic of the transmission characteristic measurement probe 10 is 60 to 70 Ω, which is close to the impedance 50 Ω of the coaxial line 18 at a wideband frequency, and the transmission end impedance (transmission characteristic measurement probe 10). It can be seen that impedance matching between the antenna and the coaxial line 18 is achieved, and a stable impedance frequency characteristic can be obtained.
[0055]
Further, as shown in FIG. 7, in the voltage standing wave ratio frequency characteristics, the voltage standing wave ratio (VSWR) becomes 1: 1 to 1: 1.5, which is close to the ideal value 1: 1, at a wide frequency range. It can be seen that stable voltage standing wave ratio frequency characteristics can be obtained.
[0056]
Here, in FIG. 8, by using the transmission characteristic measuring probe 10 in the transmission characteristic measuring apparatus 100 of the present invention, a pulse signal (current) is injected into the measured apparatus such as an actual electronic device by changing the frequency, The measurement result of the signal (current) loss at each frequency of the signal extracted through the device under test is shown.
[0057]
As shown in FIG. 8, the signal loss varies depending on the injection frequency, and the point where the signal loss is large at each frequency can be measured as the resonance frequency of the device under test.
[0058]
In the above description, the resistor 22, the capacitive element 24, and the capacitive element 28 are fixed. However, like the equivalent circuit of the transmission characteristic measuring probe shown in FIG. 9, the variable resistor 42, the variable capacitive element 44, and the variable capacitive element 46 are used. May be used.
[0059]
By making it as shown in FIG. 9, it becomes possible to adjust the impedance fluctuation of the transmission characteristic measuring probe 10 when, for example, the transmission characteristic measuring probe 10 is replaced.
[0060]
Furthermore, the impedance frequency characteristics and voltage standing wave ratio frequency characteristics as shown in FIGS. 6 and 7 are not only stabilized in a wide frequency band, but also when, for example, a predetermined frequency band is precisely measured, only in the predetermined frequency band. Each characteristic can be further stabilized to a value close to an ideal value.
[0061]
In this embodiment, the transmission characteristic measuring apparatus 100 is configured by connecting two transmission characteristic measuring probes 10. However, the transmission characteristic measuring apparatus 10 is configured by connecting a plurality of transmission characteristic measuring probes 10. Also good.
[0062]
【The invention's effect】
As described above, according to the present invention, by providing a resistance element in series between the second winding and the measuring device, it is possible to match the sending end impedance and the impedance of the measuring device. Further, by providing the capacitive element in series between the first winding and the second winding, the standing wave can be suppressed, and the impedance fluctuation when the contact portion is brought into contact with the object to be measured can be suppressed. Can be suppressed. That is, a transmission characteristic measurement probe that enables measurement at an arbitrary point of the object to be measured without requiring a large reference plane, and can easily measure the transmission characteristic of the object to be measured without selecting a measurement location. And there is an effect that a transmission characteristic measuring device can be provided.
[Brief description of the drawings]
FIG. 1A is a schematic diagram of a transmission characteristic measuring probe according to an embodiment of the present invention. (B) is a figure which shows the AA cross section in (A).
FIG. 2 is a diagram showing an equivalent circuit of a transmission characteristic measuring probe according to an embodiment of the present invention.
FIG. 3 is a diagram showing a transmission characteristic measuring apparatus according to an embodiment of the present invention.
FIG. 4 is a block diagram showing a schematic configuration of a transmission characteristic measuring apparatus according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating loss frequency characteristics of a transmission characteristic measurement probe.
FIG. 6 is a diagram showing impedance frequency characteristics of a probe for measuring transmission characteristics.
FIG. 7 is a diagram showing a low standing wave ratio frequency characteristic of a transmission characteristic measuring probe;
FIG. 8 is a diagram illustrating an example of a measurement result obtained by a transmission characteristic measurement device.
FIG. 9 is a diagram showing an equivalent circuit of a modified example of the transmission characteristic measuring probe.
FIG. 10 is a diagram illustrating a conventional method for measuring transmission characteristics.
FIG. 11 is a diagram showing measurement using a conventional probe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Transmission characteristic measurement probe 12 Core material 14 Primary coil 16 Secondary coil 18 Coaxial line 20 Center conductor 22 Resistance 28 Capacitance element 30 Contact terminal 38 Signal generating means 40 Measuring means 100 Transmission characteristic measuring apparatus

Claims (4)

A contact portion for contacting the object to be measured;
A transformer comprising a first winding connected to the contact portion and a second winding connected to a measuring device for measuring transmission characteristics of the device under test;
A resistance element connected in series between the second winding and the measuring device;
A probe for measuring transmission characteristics, comprising: 2. The transmission characteristic measuring probe according to claim 1, wherein the first winding and the second winding are connected in series by a capacitive element. A signal generating means for connecting the transmission characteristic measuring probe according to claim 1 or 2 as a first probe and applying a signal to an object to be measured through a contact portion of the first probe;
3. The transmission characteristic measuring probe according to claim 1 or 2, which is different from the first probe, is connected as a second probe, and the second probe is attached to a part of an object to be measured different from the first probe. Analyzing means for contacting and frequency analyzing the signal obtained through the contact portion;
Transmission specific measuring device equipped with. 3. The transmission characteristic measuring probe according to claim 1 and the transmission characteristic measuring probe are connected, and a measurement signal is applied to an object to be measured via a contact portion of the transmission characteristic measuring probe. Signal generating means, and measuring means for measuring the transmission characteristics of the object to be measured based on a return signal connected to the transmission characteristic probe and obtained from the object to be measured through the contact portion of the transmission characteristic measuring probe. Equipped with a transmission characteristic measuring device.

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