JPH06160450A - Plane scanning instrument for measuring electric field near antenna - Google Patents

Abstract

PURPOSE:To provide a plane scanning instrument for measuring electric fields near an antenna, which does not require any unechoic chamber nor large installation space and can be manufactured at a low cost. CONSTITUTION:A table 12 is set upward at the center of a space section surrounded by four vertical supports 10, 10, 10, and 10 and the surface of the table 12 is coated with a first wave absorber 14 and, at the same time, an antenna 16 to be measured is fixed on the surface of the table 12. A scanner 18 which scans in a plane is provided on the tops of the supports 10, 10, 10, and 10 and the surface of the mobile section 20 of the scanner 18 on the table 12 side is coated with a second wave absorber 22. Then probe antennas 24 and 26 are projected from the surface of the absorber 22. In addition, the circumference of the space section surrounded by the supports 10, 10, 10, and 10 is surrounded with third wave absorbers 28, 28, 28, and 28. An arithmetic processing means 38 calculates the remote radiating characteristic of the antenna 16 from the positional information of the probe antennas 24 and 26 and received electric field values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plane-scanning type near electric field measuring apparatus for measuring far-field radiation characteristics by measuring an electromagnetic field near an antenna.

[0002]

2. Description of the Related Art An antenna is measured in a free space with a measured antenna and a measuring antenna facing each other with a sufficient distance. However, there are reflections of electromagnetic waves from the ground and surrounding obstacles, which cause errors in measurement. Moreover, the required inter-antenna distance increases as the antenna becomes larger and the frequency becomes higher, and the restriction on measurement is significant.

Therefore, as a method of performing highly accurate measurement while avoiding the above-mentioned restriction due to the far electric field measurement, a technique for measuring the near electric field of the antenna for measuring the electromagnetic field in the vicinity of the antenna and obtaining the far radiation characteristic therefrom has been developed. I am doing it. These situations are detailed, and the Institute of Electronics and Communication Engineers, October 1979 issue (Vol. 62, No. 10) No. 1145 to No. 115.
It is shown on page 3.

An example of the near electric field measurement will be briefly described below. For example, JP-A-60-61664, JP-A-62-54175, and JP-A-3-4877.
6 and US Pat. No. 3,879,733, the electromagnetic field radiated from the antenna to be measured is measured by a probe antenna provided on a movable part of the scanner capable of scanning on a plane close to the antenna to be measured. Then, the far radiation characteristic of the measured antenna is calculated by the arithmetic processing means such as a computer from the position information of the probe antenna and the near electric field value measured at the position. Then, this measurement is performed in an anechoic chamber in order to eliminate the influence of reflection of electromagnetic waves and noise radio waves from the outside.

[0005]

In the near electric field measurement, since the measurement is performed in the anechoic chamber, there is an advantage that restrictions such as the far electric field measurement can be eliminated. However, an anechoic chamber having a volume large enough to accommodate the device under test, the probe antenna, and a device for scanning the probe antenna, such as a scanner, is required.

[0006] The construction cost of this anechoic chamber is
It is more expensive than a research building. Therefore, it has been a major obstacle to the development, evaluation and measurement of the antenna.

The present invention has been made in view of the circumstances of the prior art, and an object of the present invention is to provide a planar scanning type near electric field measuring apparatus which has a small installation space and can be manufactured at low cost.

[0008]

In order to achieve such an object, a plane scanning type near electric field measuring apparatus of the present invention is designed so that an electromagnetic field radiated from an antenna to be measured is placed on a plane close to the antenna to be measured. A plane which is measured by a probe antenna provided on a movable part of a scanner capable of scanning, and a far radiation characteristic of the antenna under measurement is calculated by arithmetic processing means from position information of the probe antenna and a near electric field value measured at the position. In the scanning type near electric field measuring apparatus, a first electromagnetic wave absorber is provided so as to cover a surface of a table on which the antenna to be measured is fixed, and a second electromagnetic wave absorber is provided so as to cover a surface of the movable portion of the scanner facing the table. A radio wave absorber is provided, and a third part is provided around the movable part of the table and the scanner except for the side where the table and the scanner are provided.
It is constructed by enclosing it with a radio wave absorber.

Then, the surface of the table is arranged so as to face upward, and the scanner is supported by four vertically standing columns so that the scanner can scan on the horizontal plane above the table, and is surrounded by the columns. The third surface on the peripheral surface of the space
You may arrange | position the radio wave absorber of.

[0010]

[Operation] The first and second electromagnetic wave absorbers are provided so as to cover the surface of the table to which the antenna to be measured is fixed and the surface of the movable portion of the scanner on which the probe antenna is projected, respectively, and the table and the scanner are provided. Since the surroundings are surrounded by the third electromagnetic wave absorber except for the side where is provided, the antenna to be measured and the probe antenna are not affected by reflection of electromagnetic waves and noise electromagnetic waves from the outside.

If the surface of the table is directed upward and the scanner is scanned in the horizontal plane above the table,
The movement of the movable portion of the scanner is not affected by gravity and the movement of the movable portion of the scanner can be controlled with high accuracy, and the measurement accuracy can be improved accordingly. Moreover, since the third electromagnetic wave absorber is arranged on the peripheral surface of the space surrounded by the columns supporting the scanner, the assembly structure of the third electromagnetic wave absorber is also simple.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical cross-sectional view showing the structure of one embodiment of the planar scanning type near-field measuring apparatus of the present invention, and FIG. 2 is a partially cutaway external perspective view of the entire apparatus.

In FIGS. 1 and 2, vertical (Z direction)
The table 12 with its surface facing upward is placed in the center of the space surrounded by the four columns 10, 10, 10, 10.
Are placed. The surface of the table 12 is covered with the first electromagnetic wave absorber 14, and the antenna 16 to be measured is appropriately placed.
Can be fixed. Moreover, the table 12 is configured to be movable up and down by a cylinder or the like. In addition, prop 1
A scanner 18 capable of scanning on a horizontal plane (X-Y direction) is arranged at the upper ends of 0, 10, 10, 10 and its movable part 2
The second electromagnetic wave absorber 22 is arranged so as to cover the surface of the table 0 facing the table 12. Further, the movable portion 20 is provided with two probe antennas 24 and 26 protruding from the second radio wave absorber 22. The two probe antennas 24 and 26 are arranged so as to be orthogonal to each other. Further, the third electromagnetic wave absorbers 28, 28, 28, 28 are provided on the circumferential surface of the space surrounded by the columns 10, 10, 10, 10.
It is supported and fixed by 0, 10, 10, 10. And
A coaxial cable connected to the probe antennas 24 and 26 is supported by the cable guide rail 30. Further, the control computer 34 controls the switching of the position of the scanner 18 in the XY direction, the position of the table 12 in the Z direction, and the switching of the coaxial relay 32 for switching the two probe antennas 24 and 26. The electric field values received by the probe antennas 24 and 26 controlled at the field and at the predetermined positions are measured by the measuring device 36. Further, the position information of the scanner 18 and the data measured by the measuring device 36 are further accumulated in the control computer 34, and the far radiation characteristic is calculated by the control computer 34 from the position information of the scanner 18 and the near electric field values by the probe antennas 24 and 26. To be done. The control computer 34 and the measuring device 36 combine the arithmetic processing means 38.
Is configured.

In such a configuration, the antenna under test 16
Electromagnetic field radiated from the third electromagnetic wave absorber 2 around the side
When it reaches 8, 28, 28, 28, it is not properly absorbed and reflected. In addition, the radiation to the rear side is the table 1
It is not absorbed and reflected by the first radio wave absorber 14 above. The radiation reaching the movable portion 20 of the scanner 18 is not absorbed and reflected by the second radio wave absorber 22, except for the radiation received by the probe antennas 24 and 26. In addition, noise radio waves from the outside are also the first and the second.
And the third electromagnetic wave absorbers 14, 22, 28, 28, 2
It is cut off at 8, 28. As a result, similar to the conventional electric field measurement in the anechoic chamber, the electric field measurement can be performed without being affected by the reflected electric wave and the noise electric wave from the outside.

In the structure of the present invention, the device is only partially surrounded by the electromagnetic wave absorber, and the installation space is smaller than that of the conventional anechoic chamber, and the manufacturing cost is low.

In the above embodiment, the antenna under test 1
6 to radiate an electromagnetic field, and probe antennas 24, 26
Although the one in which the electric field value in the vicinity is measured by receiving in, the electromagnetic field is radiated from one of the probe antennas 24 and 26, and the antenna 16 to be measured receives the electromagnetic field.
The far radiation characteristic may be calculated from the value of the near electric field. Further, in the embodiment, the scanner is arranged so that it can scan on the horizontal plane (X-Y direction), but the present invention is not limited to this, and the scanner is arranged so as to scan in the Z-X direction or the Z-Y direction. You can set it up.

[0017]

As is apparent from the above description, the plane scanning type near field measuring apparatus of the present invention has the following special effects.

First, in the plane scanning type near-field measuring apparatus according to the first and second aspects, the antenna to be measured and the probe antenna are surrounded by a radio wave absorber, and the radio wave absorber is radiated from the probe antenna or the antenna to be measured. The electromagnetic waves that reach the are not absorbed and reflected. Therefore, a simple anechoic chamber that provides the same measurement accuracy as the conventional anechoic chamber is configured. Moreover, the structure is simple, the manufacturing cost is low, and the installation space is small.

Further, in the plane scanning type near field measuring apparatus according to the third aspect, since the scanning of the movable portion of the scanner is not influenced by the gravity, the position of the probe antenna can be controlled accurately. Therefore, the far radiation characteristic can be calculated with high accuracy. In addition, the third radio wave absorber can be supported by using a pillar with a simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of an embodiment of a planar scanning type near-field measuring device of the present invention.

FIG. 2 is a partially cutaway external perspective view of the entire apparatus of the planar scanning type near electric field measuring apparatus of the present invention.

[Explanation of Codes] 10 Supports 12 Table 14 First Electromagnetic Wave Absorber 16 Antenna to be Measured 18 Scanner 20 Movable Part 22 Second Electromagnetic Wave Absorber 24, 26 Probe Antenna 28 Third Electromagnetic Wave Absorber 38 Calculation Processing Means

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Rinichi Hamada 1-6-19 Kami Kuramasaku, Hirano-ku, Osaka City, Osaka Prefecture Icom Co., Ltd. 6-19 No. Icom Co., Ltd. (72) Inventor Hitoshi Kita 1-6-19 Kami Kuramasaku Hirano-ku, Osaka City Osaka Prefecture Icom Co., Ltd.

Claims (3)

[Claims] 1. An electromagnetic field radiated from an antenna to be measured is measured by a probe antenna provided in a movable part of a scanner capable of scanning on a plane close to the antenna to be measured, and position information of the probe antenna is obtained. In a plane scanning type near field measuring device for calculating a far radiation characteristic of the antenna to be measured by an arithmetic processing means from a near electric field value measured at the position, a first surface covering a surface of a table fixing the antenna to be measured. A radio wave absorber is provided, and a second radio wave absorber is provided so as to cover a surface of the movable portion of the scanner facing the table, and the table and the scanner are provided except for the side where the table and the scanner are provided. A plane-scanning type near-field electric field measuring device characterized in that the movable part of the scanner is surrounded by a third radio wave absorber. 2. The plane scanning type near electric field measuring device according to claim 1, wherein an electromagnetic field is radiated from the probe antenna, and the electromagnetic field is received by the antenna to be measured, and the position information of the probe antenna and the object to be measured are received. A plane-scanning type near-field measuring apparatus, characterized in that the calculation processing means calculates the far-field radiation characteristic from the near-field value received by the measuring antenna. 3. The flat-scanning type near-field measuring apparatus according to claim 1, wherein the table is arranged with the surface of the table facing upward, and the scanner is constituted by four columns vertically erected. 2. A plane scanning type near electric field measuring device, characterized in that the third radio wave absorber is arranged so as to be supported so as to be able to scan on the upper horizontal plane, and the third radio wave absorber is arranged on the peripheral surface of the space surrounded by the columns.