JPH04155271A - Turntable for measuring emi - Google Patents

Abstract

PURPOSE:To enable grounding to be made, a worn part to be eliminated, and a stable operation to be secured for a long time by placing fixed electrodes which oppose each other with a gap at a turntable and then performing grounding through an electrostatic capacity between the turntable and the fixed electrodes. CONSTITUTION:When using a turntable, a bottom plate 19 contacts a metal ground surface which is laid on a ground surface so that an inner electrode 13 is contacted through a stay 18 and the bottom plate 19. A drive wheel 14 is fixed to a metal table 11 so that it is coaxial with an outer electrode 12 at a further inside of the inner electrode 13. Then, the table 11 is rotated by a motor 16 through a drive roller 15 by driving this drive wheel 14. When EMI is measured using a turntable, difference in measurement value as compared with a case when the turntable 2 and a metal ground surface 6 is completely connected by a metal sheet and the turntable is completely grounded in terms of high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention is applicable to E-M generated from electronic and electrical equipment.
1 (Electro-Magnetic Inter
The present invention relates to a turntable for an EMI measurement device used when measuring electromagnetic interference waves that cause electromagnetic interference.

[Conventional technology] Regarding EMI in electronic and electrical equipment such as televisions, radios, and computers, the domestic standards of each country (for example, Japan's telecommunications technology S Congress Report Standards, FCC Standards in the United States, VDE Standards in West Germany, etc.) are established and regulated. Equipment regulated by these standards includes information technology equipment such as computers, word processors and facsimile machines, industrial, scientific and medical radio frequency equipment, televisions, radio receivers and related equipment, and household electrical equipment. .

Particularly, recently, the number of regulated devices has been increasing year by year, and today, many of the devices labeled as electronic or electrical devices are subject to EMI regulations.

EMI is divided into radiated interference, which is emitted from the target device into space and disturbs the operation of other devices, and conducted interference, which is transmitted through power cables and other external connection cables and interferes with the operation of other devices. There is.

Among these electromagnetic interferences, radiation interference is caused by rotating the device under test 1 mounted on the device under test installation stand 3 on a metal turntable 2, as shown in FIG.
is attached to the lifting device 5 and moved up and down, thereby measuring the maximum values of the horizontal and vertical polarization components of the electric field strength of the leakage radio waves radiated from the equipment under test 1.

At the radiation interference measurement site, a conductive plane such as a steel plate or wire mesh is installed as the metal ground plane 6 in order to equalize the influence of reflected radio waves from the ground surface, and a turntable, antenna elevator, and Place measuring instruments, etc.

The equipment under test on the turntable is installed at a distance of 0.8 to 1 m from the metal ground plane in the case of table-top equipment, and on the metal ground plane in the case of floor-mounted equipment.

By the way, in such radiation disturbance measurements, it is necessary that the turntable and the metal ground plane are completely connected in terms of high frequency in addition to the conductive connection, and if this is incomplete, the EMI of the equipment under test will increase. This will cause changes in radiation characteristics and disturbance of the radiated electromagnetic field, which will have a significant impact on ensuring the reproducibility and accuracy of measurements. To this end, in conventional technology, a plurality of sliding contact pieces are provided around the turntable to connect the turntable and the metal ground plane, but this method uses high-frequency connections. In addition, there were other inconveniences such as insufficient inspection and maintenance due to aging.

[Questions to be solved by the invention] This invention was made in view of the problems in the prior art described above, and aims to improve the high frequency characteristics of the connection part, as well as reduce the wear of the connection part and the need for inspection and maintenance. EMI without sex
The purpose is to provide a measurement turntable.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a turntable for EMI measurement with a fixed grounding electrode that faces the turntable with a gap therebetween, and connects this electrode with the turntable. The feature is that the turntable is grounded to the metal ground plane at high frequency through the capacitance between the two.

[Function and Effect] The turntable is connected to the metal ground plane through its rotating shaft by a conductive wire or a sliding contact piece, but this alone is insufficient for the required high-frequency connection. Therefore, in the conventional technology, a plurality of sliding contact pieces are provided around the turntable to connect it to the metal ground plane at the shortest possible distance, but even with this method, in the high frequency range, the wavelength Compared to this, the length of the contact portion cannot be ignored, resulting in characteristic deterioration due to residual inductance of the contact portion. In addition, in this method, the slide contact portion wears out as the turntable rotates, so constant inspection and maintenance are required to maintain good contact conditions.

In place of the grounding method of the turntable using sliding contact as described above, the present invention provides grounding through the capacitance between the turntable and the fixed electrode by arranging fixed electrodes facing the turntable at a distance. It is something to do.

According to this invention, the turntable is directly connected to the metal ground plane by capacitive coupling without going through a conductor, so its characteristics do not change even in the high frequency range, and since it is a non-contact type, there are no parts that wear out. Stable operation can be ensured for a long period of time.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a foot turntable for EMI foot measurement according to an embodiment of the present invention.

In the figure, 11 is a disk-shaped metal table, 12 is an outer electrode, 13 is an inner north pole, 14 is a drive wheel, 15 is a drive roller, and 16 is a motor.

The metal table 11 is rotatably supported on a horizontal plane by a bearing 17. The outer electrode 12 is integrally formed with the table 11 in a cylindrical shape centered on the thrust axis of the table 11, with the outer edge of the table 11 hanging down. The inner electrode 13 is formed into a cylindrical shape with a diameter of /11 smaller than the outer electrode 8i12, and has eight stays 18 coaxially inside the outer electrode 12 so as to face the outer electrode 8i12 with a gap therebetween.
is screwed to. Each stay 18 is screwed to the bottom plate 19°. Disc-shaped table 11, outer electrode 1
2. The inner antistatic 8i13, the stay 18, and the bottom plate 19 are all made of metal.

When this turntable is used, the bottom plate 19 comes into contact with a metal ground plane laid on the ground surface, so the inner electrode 13 is grounded via the stay 18 and the bottom plate 19.

In this example, the clearance between the outer electrode 12 and the inner electrode 13 was 5 mm, and the opposing area was 0.5 m'. In this case, the capacitance between the outer electrode 12 and the inner electrode 13 is calculated to be approximately 1000 pF, and the ground impedance at 100 MHz is approximately 1.6 Ω.

The drive wheel 14 is fixed to the metal table 11 so as to be located further inward and outward than the inner electrode 13 and coaxially with the side electrode 12 . The table 11 is rotated by driving this drive wheel 14 via a drive roller 15 with a motor 16.

When we conducted EMI measurements using the turntable 2 shown in Fig. 1 as the turntable 2 shown in Fig. 2, the measured values were stable and had good reproducibility. The difference between the measured values when fully connected was so small that it could not be detected by the measuring device, and it was confirmed that the turntable was completely grounded in terms of high frequency.

[Modified Example of Embodiment] In the above-described embodiment, an example was shown in which the metal table side electrode was used as the outer electrode and the fixed electrode was used as the inner electrode, but the inside and outside of these electrodes may be reversed. In addition, in the above, a metal stay was used for the fixed t8i grounding, but
It would also be a problem if the outer cover 20 etc. were also used. Furthermore, in this example, the poles and fixed electrodes on the metal table side 1 are arranged in a coaxial cylindrical shape, but the metal table side electrodes are the table surface itself, and the fixed electrodes are arranged on the surface opposite to this table surface, for example, on the surface concentric with the table. It can also consist of a disk or a portion thereof.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the configuration of an EMT measurement turntable according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a radiation disturbance measurement method. 1. Test device 2: Turntable 11: Metal table 12: Outer electrode (metal table anti-static 1) 13: Inner side as pole (fixed electrode) Patent applicant Abras Co., Ltd. Patent applicant Kyoritsu Denshi Kogyo Co., Ltd. Agent Person Patent Attorney Tetsuya ItoRepresentative Patent Attorney Tatsuo Ito

Claims (1)

[Claims] (1) When receiving and measuring electromagnetic interference signals radiated from the equipment under test with an antenna facing the equipment under test, a conductive conductor that mounts the equipment under test and holds it in a predetermined position rotates in a horizontal plane. 1. A turntable for EMI measurement, comprising: a magnetic turntable; and a fixed electrode placed opposite the table with a gap in order to ground the turntable at high frequencies.