JPH0627809B2 - Lath radar device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lath radar apparatus for remotely measuring wind direction wind speed and altitude distribution of temperature using radio waves and sound waves.

(Prior Art and its Problems) As a conventional device of this type, there is one shown in FIG.
In the figure, a sound wave transmitting antenna 1, a radio wave transmitting antenna 2,
Since the receiving antenna groups 3 are attached to the same outdoor frame, they have the same height.

When a pulse sound wave is directed upward from the sound wave transmitting antenna 1 at a constant period and is emitted with directivity, it becomes a spherical compression wave surface 5 and propagates. At the same time, when a radio wave is emitted from the radio wave transmitting antenna 2 toward the spherical compression wavefront 5 at an incident angle θ, the density of the atmospheric density created by the spherical compression wavefront 5 causes fluctuations in the inductive rate of the atmosphere, that is, the refractive index of the radio wave. , But is reflected by the spherical compression wavefront 5 although it is weak.

The reflected radio wave reflected by the spherical compression wave surface 5 returns to the receiving antenna as a spot-shaped focusing region 6 having a reflection angle θ because the incident angle is equal to the reflection angle.

Here, since the reflected radio wave from the spherical compression wavefront 5 is weak, the wavelength ratio of the pulse sound wave to the radio wave is set to 1: 2.
By satisfying the diffraction condition of g, the spherical compression wave front 5
The reflected radio waves reflected at are added in the same phase on the lower side of the wavefront to make them stronger.

Note that the focusing area 6 is point-symmetric with the position of the radio wave transmitting antenna 2 about the position of the sound wave transmitting antenna 1 when there is no wind, that is, when the center position of the spherical compression wave surface 5 is equal to the position of the sound wave transmitting antenna 1. It has the property of coming to the position of.

Further, the incident reflection angle θ is large at the reflection point 20 located near the sound wave transmitting antenna 1 from the reflection point 21 on the spherical compression wave front 5, and is small at the reflection point 22 located far away.
The reflected radio waves can be received as an intensity distribution using the receiving antenna group 3, the altitude distribution of the wind direction wind speed of the atmosphere above is measured from the maximum intensity of this intensity distribution, and the Doppler frequency corresponding to the sound velocity is detected. It measures the altitude distribution of temperature. Here, the receiving antenna group 3 has M × M receiving antennas arranged in a grid and has a wide receiving area.
The receiving antennas are arranged at intervals d of several tens of cm.

As an example, the receiving antenna with an antenna diameter of about 1 m is 6 rows x 6
In the case of the receiving antenna group 3 which is arranged in a grid with the arrangement interval d of about 20 cm, the reflected radio waves returned as the focusing area 6 should be received by only a few receiving antennas. become. The velocity of the sound wave is given as a function of temperature, and when the pulse sound wave emitted from the sound wave transmitting antenna 1 with directivity propagates as the spherical compression wave front 5, the propagation speed of the spherical compression wave front 5 depends on the temperature of the atmosphere. Only changes. That is, only the proportion of the spherical compression wavefront that spreads over time changes, and the spread of the focusing region 6 does not change.

Further, the spherical compression wave front 5 moves to the leeward side by the wind in the sky, but at this time, the apparent sound source position 7 with respect to the spherical compression wave front 5 is the sound wave transmitting antenna 1 in the horizontal direction as shown in FIG. The extent of the focusing area 6 does not change due to the wind in the sky because it is considered that the focus area 6 has moved to.

In this type of device, the position of the focused area 6 of the reflected radio wave is. Since the spherical compression wave front 5 changes by twice the distance swept by the wind in the sky, it is necessary to arrange many receiving antennas densely over a wide area. However, even if they are densely arranged, the spot-shaped focusing area 6 has the maximum strength at its center and becomes weaker as it spreads outwards. Therefore, when the center of the focusing area 6 reaches between the receiving antennas, it becomes remarkably large. The reception level became small and it became difficult to measure the wind direction and air temperature.

Further, if the receiving antennas are closely spaced, the reception range of the reflected radio waves becomes narrow, and the reflected radio waves may not be received in the strong wind. On the contrary, when many receiving antennas are densely arranged, not only the cost becomes high, but also a large site is required.

(Means for Solving the Problems) The present invention aims to solve the problems of the above-mentioned conventional techniques, and in order to achieve the object, a sound wave transmitting antenna and a radio wave transmitting antenna arranged at the same height are provided. Position the receiving antenna group at a high position or a low position, or place the radio wave transmitting antenna and the receiving antenna group at a high position or a low position with respect to the sound wave transmitting antenna to spread the reflected radio waves outside the focusing area. By receiving at a certain part, the reception area can be expanded and measurement can be performed even if the reception antennas are not closely spaced.
The present invention also provides a lath radar device that can reliably receive even in strong winds.

Embodiment An embodiment of the present invention will be described in detail below with reference to FIG. In the figure, 11 is the ground surface, and the sound wave transmitting antenna 1
Also, the radio wave transmitting antenna 2 is installed on the ground surface 11. The pulse sound wave emitted from the sound wave transmission antenna 1 propagates as a spherical compression wave surface 5 and propagates to the radio wave transmission antenna 2
When radio waves are continuously emitted from the reflected radio waves, the reflected radio waves are returned to the ground surface 11 as a spot-shaped focusing area 6. By arranging the receiving antenna group 3 at a position higher than the focusing area 6, the reflected radio wave has a wider area than the focusing area 6 in which the central portion of the receiving antenna group 3 has the maximum intensity and becomes weaker as it spreads outward. It can be received as a reception area 9 that it has.

On the contrary, when the receiving antenna group 3 is arranged at a position lower than the sound wave transmitting antenna 1 and the radio wave transmitting antenna 2, the reflected radio waves are collected and then spread radially, so that the reception area has a wider area than the focusing area 6. Can be received.

Further, another embodiment will be described in detail with reference to FIG. In FIG. 2, the radio wave transmitting antenna 2 and the receiving antenna group 3 are arranged at a low position with respect to the sound wave transmitting antenna 1. The pulse sound wave emitted from the sound wave transmission antenna 1 propagates as a spherical compression wave surface 5, and when a radio wave is emitted from the radio wave transmission antenna 2 at an incident angle θ, it returns as a reflected radio wave with a reflection angle θ. come. At this time, since the radio wave transmission antenna 2 is installed at a position lower than the sound wave transmission antenna 1, at the reflection point 20 located near the sound wave transmission antenna 1 from the reflection point 21 of the spherical compression wave front 5, the incident reflection angle θ thereof. ₁ is larger than the conventional _one . On the contrary, at the reflection point 22 located far from the sound wave transmitting antenna 1, the incident reflection angle θ ₃ becomes smaller than in the conventional case. As a result, the locus of the reflected radio wave at the reflection point 20 is in a direction further away from the sound wave transmitting antenna 1 than the locus of the reflected radio wave at the reflection point 21. On the contrary, in the case of the reflection point 22, the direction is closer to the sound wave transmission antenna 1 than the trajectory of the reflected radio wave at the reflection point 21. Therefore, the reflected radio wave from the spherical compression wavefront 5 is centered on the position of the sound wave transmission antenna 1 above the ground surface 11, and the radio wave transmission antenna 2
Returned as a reflected radio wave having a spot-shaped focusing area 6 at a position substantially point-symmetrical to the position of. After that, the reflected radio waves become radial and can be received as a receiving area 9 having a wider area than the focusing area 6 where the central portion of the receiving antenna group 3 has the maximum intensity and becomes weaker as it spreads outward.

On the contrary, when the radio wave transmitting antenna 2 and the receiving antenna group 3 are arranged at a high position with respect to the sound wave transmitting antenna 1, the focusing area 6 is centered on the position of the sound wave transmitting antenna 1 and the position of the radio wave transmitting antenna 2. Since the reflected radio waves are focused at a point-symmetrical position, that is, below the reception antenna group 3, the reception antenna group 3 can be received as a wide reception area.

Next, the above-mentioned embodiment will be described by a calculation formula. That is, the third
In the secondary coordinates shown in the figure, the position of the radio wave transmitting antenna 2 (O, y _e ), the position of the sound wave transmitting antenna 1 (x _a , y _a ), the speed of sound
Let Ca be time t. Now, the acoustic wavefront emitted at t = O becomes the spherical compression wavefront 5 and propagates, so that the following equation is satisfied.

(xx _a ) ² + (yy _a ) ² = (Ca · t) ² − (1) Ca · t represents the distance from the acoustic wave transmitting antenna 1 to the spherical compression wavefront 5. The equation of the radio wave path transmitted from the radio wave transmitting antenna 2 at the angle ψ _e is as follows.

y = x · tan ψ _e + y _e − (2) The reflection point 12 of the radio wave on the spherical compression wave front 5 is (x _O , y _O ).
Then, x _O and y _O must satisfy both formulas (1) and (2). Calculating x _O and y _O from equations (1) and (2) gives the following.

The relation with the incident / reflection angle θ is that the sound wave transmitting antenna 1 and the reflection point 12
If the angle of the straight line connecting to and is ψ _a , then it becomes as follows.

θ = ψ _a − ψ _e − (5) where tan ψ _a is expressed as follows.

Finally, the path of the reflected radio wave is represented by a straight line passing through the reflection point 12 (x _O , y _O ) and having an inclination of tan (ψ _e + 2θ), and thus the following equation is obtained.

y = (x-x _O ) tan (ψ _e + 2θ) + y _O − (7) Substituting equation (6) into equation (7), X _R when the receiving point 13 and (x _R, y _R), and a constant y _R
Is as follows from Eq. (8).

From equations (3), (4), (6), and (9), the angle ψ _{e of the} radio wave transmitting antenna 2
Is varied within the range of the radio wave beam, x _R of the receiving point 13 at that time is calculated, and the spread of the receiving area 9 is shown in the graphs from the maximum and minimum values of x _R in FIGS. Shown in the figure. In FIG. 4, when the receiving antenna group 3 is installed at a position of about 1 m from the surface of the earth, the receiving area 9 is expanded to a circular area having a diameter of about 35 cm compared with the focusing area 6 received as a point. Further, in FIG. 5, when the sound wave transmitting antenna 1 is installed at a position about 1 m from the surface of the earth, the receiving area 9 is expanded to a circular area having a diameter of about 77 cm compared with the focusing area 6 having a diameter of several cm.

(Effect of the Invention) According to the present invention described above, the receiving antenna group is arranged at a high position or a low position with respect to the sound wave transmitting antenna and the radio wave transmitting antenna arranged at the same height in the conventional technique, or Since the reception area in the reception antenna group can be expanded with a simple configuration in which the radio wave transmission antenna and the reception antenna group are arranged at high or low positions with respect to the transmission antenna, there is no need to arrange the reception antennas densely. It is possible to receive reflected radio waves and reliably measure the wind direction and wind speed and the air temperature. Further, the remarkable effect that the reflected radio waves can be received even in the strong wind without arranging many receiving antennas to increase the site area is exhibited.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a sectional view showing one embodiment, FIG. 2 is a sectional view showing another embodiment, and FIG.
The figure is a two-dimensional coordinate diagram, and FIGS. 4 and 5 are characteristic diagrams of the spread of the reception area. FIG. 6 is a perspective view showing a conventional lath radar apparatus. 1 ... Sound wave transmitting antenna, 2 ... Radio wave transmitting antenna, 3 ...
Receiving antenna group, 5 ... Spherical compression wavefront, 6 ... Focusing area, 9
…… Reception area, 11 …… Ground surface, 12,20,21,22…
… Reflection point, 13 …… Reception point.

Claims (1)

[Claims] 1. A pulsed sound wave is emitted from a sound wave transmitting antenna (1) toward the atmosphere above, and a radio wave is continuously emitted from a radio wave transmitting antenna (2) to a spherical compression wave surface (5) formed by the sound wave. Then, the radio wave reflected from the spherical compression wavefront (5) is received as an intensity distribution using the reception antenna group (3), and the altitude distribution of the wind direction wind speed of the atmosphere above is measured from the maximum intensity of the intensity distribution. A lath radar apparatus for measuring the altitude distribution of air temperature by detecting the Doppler frequency corresponding to the speed of sound, comprising: a focusing area (6) of reflected radio waves from the spherical compressional wavefront (5).
The reception antenna group (3) is located at a high position or a low position with respect to the sound wave transmission antenna (1) and the radio wave transmission antenna (2) which are arranged at the same height so as to be received by a portion having a spread. Or the radio wave transmitting antenna (2) and the receiving antenna group (3) are arranged at a high position or a low position with respect to the sound wave transmitting antenna (1).