JPH0545393A - Measuring method of strength of scattered wave in radio wave darkroom - Google Patents

Abstract

PURPOSE:To obtain a measuring method of the strength of a scattered wave in a radio wave darkroom which makes it unnecessary to move an antenna for reception, which makes therefore the precision in measurement high and also makes the construction of a supporting device of the antenna for reception simple and which shortens the time for measurement. CONSTITUTION:An antenna 2 for transmission and an antenna 3 for reception are disposed in stationary states in the radio wave darkroom 1, and the antenna 3 is constructed by combining a first antenna 3A with a second antenna 3B so that main beams thereof form an angle thetaR. A direct wave from the antenna 2 for transmission is received by the second antenna 3B, while a scattered wave from the wall surface of the radio wave darkroom 1 is received by the first antenna 3A, and output signals of these antennas are synchronized to be a synchronized output signal by a synchronizer 4. The strength of the scattered wave is measured on the basis of the synchronized output signal obtained when the frequency of a transmission wave from the antenna for transmission is swept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring scattered wave intensity in an anechoic chamber.

[0002]

2. Description of the Related Art As a method of measuring scattered wave intensity in an anechoic chamber, a standing wave measurement is performed by a spatial standing wave method, in which direct wave reception intensity is lowered by utilizing directivity of a receiving antenna,
A method called an off-peak method that relatively increases the amplitude of a scattered wave is used. The ratio of the main lobe to the side rope of the receiving antenna is the off-peak amount a, which depends on the directivity of the antenna. With the transmitting antenna stationary in the anechoic chamber, the receiving antenna mounted on the antenna scanning device is placed in the center of the measurement area (quinit zone), and the transmitting antenna is directed in any direction (angle) of the wall surface of the dark chamber. The direct wave from the is received by the side lobe, the scattered wave from the wall is received by the main lobe, and the standing wave is measured by moving the receiving antenna in the direction of the main lobe.

[0003]

In the conventional measurement by the off-peak method, since the off-peak amount depends on the directional characteristics of the antenna, it is possible to obtain the optimum off-peak amount that becomes a standing wave with a large amplitude at an arbitrary angle. Since the off-peak amount “a” fluctuates greatly by linearly moving the antenna with a small amount, the received direct wave component largely changes and becomes a distorted standing wave, and the accuracy of reading the standing wave ratio may be poor. There was a problem that there were many. Further, in the conventional measurement by the off-peak method, the positional accuracy of the linear movement is high in order to reduce the distortion of the standing wave waveform (for example, in the case of the measurement of 10 GHz, the positional accuracy is ± 1 mm at the moving distance of 25 cm). An antenna scanning device was needed. An object of the present invention is to disperse an anechoic chamber that does not need to move the receiving antenna and therefore has high measurement accuracy and a simple supporting device for the receiving antenna, and that can shorten the measurement time. It is to provide a wave intensity measuring method.

[0004]

According to the present invention, a transmitting antenna and a receiving antenna are arranged stationary in an anechoic chamber, and the receiving antenna includes a first antenna and a second antenna. These main beams are combined so as to form an angle θ _R, and the second antenna receives the direct wave from the transmitting antenna and the first antenna receives the scattered wave from the wall surface of the anechoic chamber. , The respective output signals are combined by a combiner to form a combined output signal, and the scattered wave intensity is measured based on the combined output signal obtained when the frequency of the transmission wave from the transmitting antenna is swept. A method for measuring the intensity of scattered waves in an anechoic chamber is obtained.

[0005]

The first antenna having a low gain of the receiving antenna receives the direct wave from the transmitting antenna, and the second antenna having a high gain of the receiving antenna receives the scattered wave from the wall surface in an arbitrary direction. To receive. The variable attenuator which synthesizes both output signals of the first and second antennas of the receiving antenna and inserts them into the first and second antennas respectively sets an appropriate off-peak amount a by adjusting the attenuation amount. To enable. Sweeping the frequency of the transmitted wave gives the resultant output signal as an interference waveform of the direct and scattered waves.

[0006]

1 is a schematic view of an example of a measuring apparatus according to the present invention. A transmission antenna 2 and a reception antenna 3 are arranged inside the anechoic chamber 1. The transmitting antenna 2 is stationary at a predetermined position. The receiving antenna 3 is stationary at a predetermined position of the measurement area (quiet zone) (one of the five outermost areas in the front, rear, left, and right toward the center and the transmitting antenna 2. In the figure, the center). The receiving antenna 3 is a combination of a first antenna 3A and a second antenna 3B such that their main beams form an angle θ _R. First antenna 3A
Has a gain of 5 to 20 dB, and the transmitting antenna 2
And the direct wave E _d from the transmitting antenna 2 is received. The second antenna 3B has the first gain.
It is higher than the antenna 3A. For example, it is 10 to 40 dB and receives the scattered wave E _S from the wall surface of the dark room 1.

The output signals of the first antenna 3A and the second antenna 3B are variable attenuators R _A and R respectively.
It is combined via the Y branch circuit of the combiner 4 via _B and is given to the spectrum analyzer 5. In the transmission example, the transmission antenna 2 is connected to the tracking generator 6. The spectrum analyzer and tracking generator 6 are connected to the computer 7. Angle θ
_{When R} is set and the frequency of the transmission wave from the transmission antenna 2 is swept, the standing wave waveform is displayed on the spectrum analyzer 5, and the computer 7 calculates it by the following formula 1 or formula 2. Scattered wave intensity E _s /
It is constructed so that the absolute value of E _d ′ is displayed.

[0008]

[Equation 1]

[0009]

[Equation 2]

In FIG. 2, the receiving antenna 3 is stationary at the center of the measurement area and the angle θ _R is set to 120 degrees.
The standing wave waveform and the scattered wave intensity obtained when a transmitted wave with a frequency of ± 1 GHz) is transmitted are shown. The first antenna 3A has an opening surface of 12 cm × 7 cm, and the second antenna 3
B is the case where the aperture surface is 22 × 17 cm, the attenuators R _A and R _B are adjusted, and the off-peak amount a is set to 26 dB.

FIG. 3 shows the results of measuring the directional characteristics of the receiving antenna 3 with the combination of the first antenna 3A and the second antenna 3B while changing the attenuation amount of the attenuator R _A. In FIG. 3, the difference between the main lobes of the first antenna 3A and the second antenna 3B is the off-peak amount a, and when the attenuator R _A is adjusted to 5 dB, the off-peak amount a can be increased from about 16 dB to about 23 dB. It is shown. It has been confirmed that the off-peak amount a can also be changed by adjusting the attenuator R _B. Since the off-peak amount a of the receiving antenna 3 can be set by the attenuators R _A and R _{B in} this way, the amplitude can be changed from 2 dB to 10 dB by several setting trials.
A standing wave waveform in the range of dB can be obtained, and if the off-peak amount a is increased by this setting trial, the amplitude Δ
It can also be understood that if L increases, Formula 1 is applied, and if the amplitude ΔL decreases, Formula 2 is applied to calculate the scattered wave intensity.

FIG. 4 is a schematic view of a supporting device for the receiving antenna 3. The second antenna 3B is fixed to a support rotary shaft 8, and the shaft 8 is rotatably supported by a support base 9. A motor 10 is mounted on the support 9, and the power of the motor 10 is transmitted to the shaft 8 by a gear 11. The support base 9 is fixed to the upper end of the rotary shaft 12. Axis 12
The first antenna 3A is fixed in the middle of, and the base box 13 is arranged in the lower part. An opening cylinder 14 is provided in the upper part of the pedestal box 13, and the lower part of the shaft 12 is inserted into the opening cylinder 14 and rotatably supported. Stand 13
A motor 15 is disposed inside the motor and is connected to the shaft 12 via a gear 16. When the shaft 8 is rotated by the motor 10, the angle θ _R formed by the main beams of the first antenna 3A and the second antenna 3B can be changed. The shaft 12 is rotated by the motor 15 to set the first antenna 3A at a position facing the transmitting antenna 2. Motor 1
0 and 15 are controlled by the controller 17. The receiving antenna 3 is placed at the center of the measurement area and is stationary, and the angle θ _{R is set.}
Change every 10 degrees from 0 to 180 degrees,
By obtaining an easily readable real wave similar to that shown in FIG. 2, it is possible to measure the intensity of scattered waves coming from all directions of the wall surface of the dark room 1 in the measurement region.

[0013]

According to the present invention, since it is not necessary to move the receiving antenna, the measurement accuracy is high, and the supporting device of the receiving antenna is simple in construction, and the transmitted wave from the transmitting antenna is sufficient. Since the frequency sweep of can be performed at high speed, the measurement time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a measuring apparatus for carrying out the present invention.

FIG. 2 is a diagram showing an actual waveform and a scattered wave intensity obtained by the measuring device shown in FIG.

FIG. 3 is a diagram showing directional characteristics of a receiving antenna used in the present invention.

FIG. 4 is a schematic view showing a receiving antenna used in the present invention and a supporting device for the receiving antenna.

[Explanation of symbols]

1 anechoic chamber 2 transmitting antenna 3 receiving antenna 3A first antenna 3B second antenna R _A, R _B variable attenuator 4 synthesizer 5 spectrum analyzer 6 tracking generator 7 computer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yuro Sato, 398, Komokuchi, Takatsu-ku, Kawasaki-shi, Kanagawa In stock company Tokin (72) Inventor, Kenichi Hatakeyama 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation In the company

Claims (1)

[Claims] 1. A transmitting antenna and a receiving antenna are arranged stationary in an anechoic chamber, and the receiving antenna comprises a first antenna and a second antenna whose main beams form an angle θ _R. The second antenna receives the direct wave from the transmitting antenna, the first antenna receives the scattered wave from the wall of the anechoic chamber, and the output signals of these are received by the combiner. Scattered waves in an anechoic chamber characterized by measuring a scattered wave intensity based on the combined output signal obtained when the frequency of the transmitted wave from the transmitting antenna is swept in a combined output signal. Strength measurement method.