JPH0619097Y2 - High frequency measurement probe - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention directly contacts an object such as an electric / electronic device that radiates radio noise to capture this radio noise, so-called interference wave, and measures it. The present invention relates to a high-frequency measurement probe, and more particularly to improvement of a high-frequency measurement probe used when searching for a source of an interfering wave.

(Prior Art) Generally, an interfering wave radiated from an electric / electronic device enters another electric / electronic device through the atmosphere or an electric wire,
It interferes with the normal operation of the device. In order to eliminate the influence of the interference wave, it has been conventionally required to measure the source of the interference wave, the frequency characteristic, the electric field strength, and the like, and various interference wave measuring instruments have been put to practical use from this request.

An example of this interfering wave measuring device is Toshio Nemoto, "Techno System Vol. 3 (Measurement), pp. 141-144" (1984 1
Month, published by Denki Shoin Co., Ltd.)
There is known a form in which an interfering wave is contactlessly input via an antenna and a predetermined process is performed on the input interfering wave to measure the interfering wave.

(Problems to be solved by the invention) However, as described above, when the input form of the interfering wave is the non-contact type via the antenna, the resolution within the measurement range is regulated by the size of the antenna. , The resolution is inferior to that of the direct contact type in which the interference wave is input by directly contacting the probe with the device without passing through the antenna, and as a result, the interference wave is specified by designating a specific point less than the size of the antenna. There was a problem that it was difficult to enter.

On the other hand, the conventional direct contact type of the interfering wave is excellent in that the interfering wave can be input by designating the specific point as described above, but It had the drawback of being difficult to measure.

The present invention has been made in view of the above circumstances, and provides a high-frequency measurement probe capable of inputting an interference wave by designating a specific point and having a flat frequency characteristic. The purpose is to provide.

(Means for Solving the Problems) In order to solve the above-mentioned object, the present invention has an inductance core material for adding an inductance component, which has a tip portion for directly contacting a detected object in order to detect a signal. A conductive rod-shaped member surrounded by an insulating member except for the tip and the end face, and an opening with one end open, and propagates the signal detected by the tip to the outside. However, it is partially surrounded by an inductance core material for adding an inductance component, and by incorporating the rod-shaped member so that the tip portion projects from the opening, a distributed capacitance is formed between the rod-shaped member and the member. A conductive tubular inner wall member to be formed and an opening portion whose one end is open are provided, and a gap is provided between the tubular inner wall member and the tubular inner wall member, and the tip portion is projected from the opening portion. Further, it is characterized in that it is configured by including the tubular inner wall member and a conductive tubular outer wall member that forms a distributed capacity between the tubular inner wall member and the tubular inner wall member.

In addition, a conductive rod-shaped member, which is partly surrounded by an inductance core material for propagating the detected signal to the outside and adding an inductance component, and is covered with insulating members except for both end surfaces, and one end is released. It has an opening and a tip for making direct contact with an object to be measured for measurement, and is partly surrounded by an inductance core material for adding an inductance component, and the rod-shaped member projects from the opening. As described above, the cylindrical inner wall member includes a conductive cylindrical inner wall member that forms a distributed capacitance between the rod-shaped member and the rod-shaped member, and an opening portion having one end opened. A conductive material for forming a distributed capacitance between the tubular inner wall member and the tubular inner wall member so that a gap is provided between the tubular inner wall member and the member, and the tip portion is projected from the opening. Cylindrical outside Characterized in that it is composed of a member.

(Operation) The distributed capacity formed between the rod-shaped member, the tubular inner wall member, and the tubular outer wall member, and the inductance core material disposed between the rod-shaped member and the tubular inner wall member The L-C filter is composed of the inductance and the low-frequency signal component unnecessary for the measurement by the L-C filter, so that only the interference waveform required for the measurement can be obtained.

(Example) The high-frequency measuring probe according to the present invention will be described below.
It will be described in detail with reference to the drawings.

FIGS. 1 and 3 (a) and (b) show an embodiment of a high-frequency measuring probe according to the present invention. The high-frequency measuring probe 1 has conductivity such as metal. Inside the outer shell 2 as a cylindrical tubular body made of a material and having one open end, the inner shell 3 as a cylindrical tubular body made of a material having conductivity, such as a metal, having an open end, A rod made of a conductive material such as a metal, which is provided concentrically with the outer shell 2 and at a predetermined interval, and an insulating member 4 having an electric insulating property is covered inside the inner shell 3 so as to cover the periphery thereof. A body 5 is provided with one end thereof exposed, and an inductance core material 6 such as a doughnut-shaped ferrite ring that generates an inductance component LP1 is arranged around the closed end side of the inner shell 3, and the insulating member 4 is provided. The doughnut-shaped inductance core material 7 for generating the inductance component LP2 is arranged around the open end side of the inner shell 3 in the rod body 5 covered with. This high-frequency measuring probe 1 is connected to a measuring device via a transmission path 8 such as a coaxial cable extending through an opening 2b formed in the closed wall 2a of the outer shell 2 and thereby, An interfering wave detected by directly contacting the tip portion 5a of the rod body 5 with the measurement target site is input to the measuring device.

An insulating member 4, which generally exhibits a high dielectric constant, is interposed between the rod body 5 and the inner shell 3 to form a feedthrough capacitor to form a capacitance CP1. Air having a low dielectric constant is interposed between the outer shell 2 and the inner shell 3 at a predetermined interval, and a capacitance CP2 is formed by this. By these capacitors CP1 and CP2, the measurement target part and the measuring device are AC-coupled, and the signals of the DC component and the low frequency component that interfere with the measurement are blocked. It should be noted that the capacitance CP2 is for electrostatically shielding the circuit, and is preferably sufficiently smaller than the capacitance CP1. Therefore, the ratio of the capacitances CP1 and CP2 can be adjusted by changing the distance between the rod 5 and the inner shell 3, the dielectric constant of the insulating member 4, or changing the predetermined distance.

As shown in FIG. 3 (a), the inductance core material 7 is arranged around the exposed portion 5 b of the rod body 5 covered with the insulating member 4, which is exposed from the open end side of the inner shell 3. Meanwhile, the inductance core material 6 is
As shown in FIG. 6B, the inner shell 3 is disposed around the space 5c on the closed end side where the rod 5 does not exist inside. The inductance core materials 6 and 7 are
Since the coupling impedance cannot be matched and the frequency characteristics of the interfering wave cannot be flattened only by coupling the interfering wave transmission line 8 in an alternating manner by CP1 and CP2, it is provided to correct this. . The inductance core materials 6 and 7 are not limited to the above-mentioned ferrite rings, and a material having an appropriate magnetic permeability may be appropriately selected according to the frequency band to be measured.

FIG. 2 shows an equivalent circuit diagram around the high-frequency measurement probe 1 configured as described above. Among these, the equivalent circuit of the high-frequency measurement probe 1 includes an inductance component LP1, a capacitance CP1, and The inductance component LP2 is connected in series, and the connection point X between the capacitance CP1 and the inductance component LP2 is grounded via the capacitance CP2. In FIG. 2, reference symbol E ₀ indicates the signal source output voltage of the measurement target, reference symbol Z ₀ indicates the signal source output impedance of the measurement target, and reference symbol Zin indicates the input impedance of the measuring device.

Next, the electrical characteristics of the high frequency measurement probe according to the present embodiment will be described with reference to FIG.

The interfering wave input through the tip 5a of the rod 5 is
The frequency characteristic is corrected by capacitively coupling the transmission line 8 by the CP1 and blocking excess DC component and low frequency signal component for measurement, and matching the coupling impedance by the inductance components LP1 and LP2. Therefore, as shown in FIG. 6, it is possible to obtain an interference waveform having a characteristic of following the input waveform and exhibiting a flat frequency characteristic.

4 is an embodiment of the present invention different from the embodiment of FIG. 1, in which the tip portion 5a is removed from the rod-shaped member of FIG. 1, and the tip portion 5a is formed into a cylindrical inner wall member. This is a high-frequency measurement probe when the functions of each of them have been replaced.

The high frequency measuring probe 10 has an open end made of a conductive material such as metal inside an outer shell 12 as a cylindrical body having an open end made of a conductive material such as metal. The inner shell 13 as a cylindrical body is provided on the outer shell 12 concentrically and at a predetermined interval. Inside the inner shell 13, an insulating member 1 having electrical insulation is provided.
4 is provided with a bar 15 made of a conductive material such as a metal, which is covered over the periphery, with one end thereof exposed. In addition, an inductance core material 16 such as a donut-shaped ferrite ring that generates an inductance component LP1 is provided around the tip portion 15a side of the inner shell 13 that directly contacts the object to be measured. On the other hand, a donut-shaped inductance core material 17 that generates an inductance component LP2 is arranged around the open end side of the inner shell 13 in the rod body 15 covered with the insulating member 14. The high-frequency measuring probe 10 is connected to a measuring device (not shown) via a transmission line 18 such as a coaxial cable that extends through an opening 12b formed in the closed wall 12a of the outer shell 12. As a result, the interference wave detected by directly contacting the tip portion 15a of the rod 15 with the measurement target site is input to the measuring device.

An insulating member 14, which generally exhibits a high dielectric constant, is interposed between the rod body 15 and the inner shell 13, which constitutes a feedthrough capacitor and has a capacitance CP1.
On the other hand, air having a low induction rate is interposed between the outer shell 12 and the inner shell 13 at a predetermined interval, and thereby a capacitance CP2 is formed. The capacitances CP1 and CP2 are used for AC coupling between the measurement target portion and the measuring device, and to reduce the signals of the direct current component and the low frequency component that interfere with the measurement. It should be noted that the capacitance CP2 is for electrostatically shielding the circuit, and is preferably sufficiently smaller than the capacitance CP1. Therefore, the ratio of the capacitances CP1 and CP2 can be adjusted by changing the distance between the rod 15 and the inner shell 13, the dielectric constant of the insulating member 14, or changing the predetermined distance.

An equivalent circuit diagram of the high-frequency measuring probe 10 according to the embodiment of the present invention of FIG. 4 configured as described above is the same as FIG. 2 which is an equivalent circuit diagram of FIG. 1 as shown in FIG. The same effect can be obtained because the equivalent circuit is obtained.

FIG. 5 shows an equivalent circuit diagram around the high-frequency measuring probe 1 according to another embodiment. Even with this configuration, the same effect as that of the above-described embodiments can be obtained.

Finally, in both of the embodiments described above, the shell may have a multiple structure in order to increase the value of the capacitance CP1.

(Effects of the Invention) As described in detail above, according to the present invention, the interference wave input by directly contacting the object to be measured with the cylindrical body or the rod body causes an AC wave in the transmission line due to the distributed capacitance. It is capacitively coupled to and the extra DC component and low frequency signal component are blocked for measurement, and the inductance component
Since the frequency characteristics are corrected by matching the coupling impedance, as a result, it is possible to obtain an interference waveform having a characteristic of following the input waveform and exhibiting a flat frequency characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a high frequency measuring probe according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram around the high frequency measuring probe, and FIG. 3 (a). , (b) is a sectional view of a main part of the high-frequency measuring probe, FIG. 4 is a sectional view of a high-frequency measuring probe according to another embodiment of the present invention, and FIG. 5 is a sectional view of the other embodiment. FIG. 6 is an equivalent circuit diagram around the high-frequency measuring probe, and FIG. 6 is a diagram showing frequency characteristics of an interference wave input using the present invention. 1, 10 ... High frequency measurement probe, 2, 12 ... Outer shell (cylindrical body), 2a, 12a ... Closure wall, 2b, 12b ... Open hole, 3, 13 ... Inner shell (cylindrical body), 5, 15 ... Rod Body, 5a, 15a ... Tip part, 6, 7, 16, 17 ... Inductance core material, 8, 18 ... Transmission line.

Claims (2)

[Scope of utility model registration request] 1. A tip portion (5a) for directly contacting a detected object for detecting a signal, which is partly surrounded by an inductance core material (7) for adding an inductance component, 5a) and a conductive rod-shaped member (5) covered with an insulating member (4) except the end surface, and an opening with one end opened, and the signal detected by the tip (5a) is externally By being incorporated in the rod-shaped member (5) so that the tip portion (5a) is projected from the opening part by being surrounded by the inductance core material (6) for adding an inductance component. The cylindrical inner wall member (3), which has a conductive cylindrical inner wall member (3) forming a distributed capacity with the rod-shaped member (5) and an opening whose one end is open,
(3) A space is provided between the inner wall member and the tubular inner wall member so that the tip portion (5a) projects from the opening.
(3) is built in, and is composed of an electrically conductive tubular outer wall member (2) that forms a distributed capacitance between the inner wall member (3) and the tubular inner wall member (3), for high frequency measurement probe. 2. An inductance core material (17) for propagating a detected signal to the outside and adding an inductance component.
It has a conductive rod-like member (15) that is partially surrounded by and is covered with insulating members (14) except for both end surfaces, and an opening with one end open, so that it directly contacts the DUT for measurement. The rod-shaped member having a tip portion (15a) to be brought into contact with, and partially surrounded by an inductance core material (16) for adding an inductance component, and the rod-shaped member (15) protruding from the opening. A cylindrical inner wall member (13) made of a conductive material that forms a distributed capacitance with the rod-shaped member (15) by incorporating (15), and an opening with one end open, Inner wall member (1
The cylindrical inner wall member is provided so that a gap is provided between the inner wall member and the distal end portion (15a) so as to protrude from the opening.
(13) is built in, and is composed of a conductive tubular outer wall member (12) that forms a distributed capacitance between the tubular inner wall member (13) and the tubular inner wall member (13), and for high frequency measurement probe.