JP2007303966A - Microwave range finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove misidentification of a position of a detection object caused by reflection of a microwave at a connection part between an antenna and the circuit side for transmission/reception of the microwave. <P>SOLUTION: This microwave range finder wherein only a circulator is arranged close to the antenna, is equipped with: the antenna equipped with a probe used for both transmission and reception for transmitting the microwave and receiving a reflected microwave reflected by the detection object; a divider for dividing the microwave from a microwave oscillator, transmitting either to the antenna side, and transmitting the other to the mixer side as a reference signal; the circulator inserted between the antenna, and the divider and the mixer; the mixer for transmitting a mixing signal formed by mixing the reflected microwave with the reference signal to an operation circuit; and the operation circuit for operating the mixing signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microwave rangefinder that transmits a microwave from an antenna toward an object to be detected, receives a reflected microwave reflected by the object to be detected, and measures a distance to the object to be detected.

  Conventionally, a distance meter using laser light, infrared rays, or the like has been widely used to detect the position of a processed product in a factory. However, in such a system using light, for example, in a use environment where steam mist, oil mist, etc. exist, such as a blast furnace, a coke oven, an incinerator, etc., the sensitivity is remarkably lowered and detection becomes difficult. Therefore, as a distance detection means in such an environment, a microwave distance meter using a microwave as a detection medium is used.

  FIG. 3 is a block diagram showing main components of a conventional microwave rangefinder (see, for example, Patent Document 1). The microwave oscillator 1 is connected to the divider 2, and the divider 2 demultiplexes the oscillating microwave from the microwave oscillator 1 and sends one of them to the antenna 3 via the circulator 20. The antenna 3 includes a probe (not shown) that is used for transmission and reception in order to transmit microwaves and receive microwaves reflected by an object to be detected (not shown). M1 is transmitted toward the detected object, and the reflected microwave M2 reflected by the detected object is received. Then, the reception microwave M <b> 2 is sent to the mixer 4 via the circulator 20. The other oscillation microwave demultiplexed by the divider 2 is input to the mixer 4, the other oscillation microwave and the received reflected microwave M <b> 2 are mixed, and the mixing signal is input to the arithmetic circuit 5. Sent. In the arithmetic circuit 5, a microwave detector (not shown) detects the oscillating microwave from the divider 2 and the received reflected microwave M2 in the mixing signal, and the object to be detected is based on the phase difference between the two detection signals. For example, as shown in FIG. 4, the reflection peak (R) due to the detected object is displayed as position information on a chart with the horizontal axis as the distance.

  However, in the above microwave distance meter, the transmitting / receiving probe of the antenna 3 and the circulator 20 are connected by the single coaxial cable 30, so that the oscillating microwave output from the circulator 20 and propagating through the coaxial cable 30 is Reflected by the end face of the coaxial cable 30 at the connection portion A with the transmission / reception probe, as shown in FIG. 4, in addition to the reflection peak (R) due to the detected object, the reflection peak (A at the end face of the coaxial cable 30 (A) ) Appears. In addition, the reflected microwave M2 from the detected object is attenuated because it propagates in the air, whereas the microwave reflected by the end face of the coaxial cable 30 is less attenuated. The reflection peak (A) due to the end face of the coaxial cable 30 is larger than the reflection peak (R) due to the object to be detected and appears on the chart, and erroneous measurement is likely to occur.

  Further, depending on the installation location, only the antenna 3 is arranged in the vicinity of the object to be detected, and other components such as the microwave oscillator 1, the divider 2, the circulator 20, the mixer 4, and the arithmetic circuit 5 are arranged away from the antenna 3. Things have been done. For example, when measuring the amount of high-temperature contents deposited such as in a blast furnace or an incinerator, it is common to mount the antenna 3 on the top of the furnace and place other components away from the furnace. It is. Therefore, the reflection peak (A ′) at the cable end surface appears at a distance that is a multiple of the cable length of the coaxial cable 30 together with the reflection peak (R) due to the content within the measurement range, and the amount of content accumulation is erroneously measured. Sometimes.

JP 2001-91640 A

  The present invention has been made in view of such a situation, and eliminates misidentification of the position of an object to be detected, which is caused by reflection of microwaves at a connection portion between an antenna and a microwave transmission / reception circuit side. For the purpose.

In order to achieve the above object, the present invention provides the following first and second microwave rangefinders.
(1) In a microwave rangefinder that transmits a microwave from an antenna toward an object to be detected, receives a reflected microwave reflected by the object to be detected, and measures a distance to the object to be detected.
A microwave oscillator,
An antenna including a transmission / reception probe for transmitting a microwave oscillated from a microwave oscillator and receiving a reflected microwave reflected by an object;
A divider that demultiplexes the microwaves oscillated from the microwave oscillator, sends one of them to the antenna via the circulator, and sends the remainder to the mixer as a reference signal;
A circulator inserted between the divider and the antenna and connected by a first coaxial cable, and connected by a mixer and a second coaxial cable;
A mixer that receives a reflected microwave received by an antenna and is input via a circulator and a reference signal from a divider, and sends the mixed signal to an arithmetic circuit;
An arithmetic circuit that calculates the distance to the object to be detected by calculating the mixing signal from the mixer, and
A first microwave rangefinder characterized in that only a circulator is disposed close to an antenna.
(2) In a microwave rangefinder that transmits a microwave from an antenna toward an object to be detected, receives a reflected microwave reflected by the object to be detected, and measures a distance to the object to be detected.
A microwave oscillator,
An antenna including a transmission probe for transmitting microwaves oscillated from a microwave oscillator, and a reception probe for receiving reflected microwaves reflected by an object to be detected;
A divider that divides the microwave oscillated from the microwave oscillator, sends one of them to the antenna side, and sends the remainder to the mixer side as a reference signal;
A mixer that mixes the reflected microwave received by the antenna and the reference signal from the divider, and sends the mixing signal to the arithmetic circuit;
An arithmetic circuit that calculates the distance to the object to be detected by calculating the mixing signal from the mixer, and
2. A second microwave rangefinder, wherein an antenna transmission probe and a divider are connected by a first coaxial cable, and a reception probe and a mixer are connected by a second coaxial cable.

  In the first microwave rangefinder according to the present invention, since the circulator and the antenna are arranged close to each other, the microwave reflected from the end face of the coaxial cable at the connection portion with the antenna appears at a very short distance on the chart representing the distance. Therefore, it can be easily determined that the reflection is not caused by the object to be detected. Further, in the second microwave rangefinder, the circulator is eliminated, the antenna transmission probe and the divider are connected by the first coaxial cable, and the antenna reception probe and the mixer are connected by the second coaxial cable. Even if the oscillating microwave propagating through the first coaxial cable is reflected at the end face of the cable at the connection portion with the antenna, the reflected microwave is not sent to the mixer, and the chart shows the distance on the chart. It is never displayed. Thus, according to the 1st microwave rangefinder and the 2nd microwave rangefinder concerning the present invention, the reflected microwave by a detected object can be recognized correctly.

  Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.

(First microwave rangefinder)
FIG. 1 is a block diagram showing main components of a first microwave rangefinder according to the present invention. As shown in the figure, the microwave oscillator 1 is connected to the divider 2, and the divider 2 demultiplexes the oscillating microwave from the microwave oscillator 1 and sends one of them to the antenna 3 via the circulator 20. The divider 2 and the circulator 20 are connected by the first coaxial cable 10. The antenna 3 includes a probe (not shown) for transmitting and receiving in order to transmit microwaves and receive the microwave reflected by the object to be detected (not shown). The probe and the circulator 20 are connected by a single coaxial cable 30. The antenna 3 transmits the transmission microwave M1 toward the detection object, and receives the reflected microwave M2 reflected by the detection object. Then, the reception microwave M <b> 2 is sent to the mixer 4 via the circulator 20. The circulator 20 and the mixer 4 are connected by a second coaxial cable 11. The other oscillation microwave demultiplexed by the divider 2 is input to the mixer 4, the other oscillation microwave and the received reflected microwave M <b> 2 are mixed, and the mixing signal is input to the arithmetic circuit 5. Sent. The arithmetic circuit 5 calculates the distance to the detected object, and displays the reflection peak due to the detected object on a chart having the horizontal axis as shown in FIG. 4, for example.

  The above-described component configuration is the same as that of the microwave distance meter in which the conventional circulator 20 and the antenna 3 shown in FIG. 3 are connected by the coaxial cable 30, for example, the microwave oscillator 1, the divider 2, the antenna 3, the mixer 4 and Any of the coaxial cables 30 may be known. The configuration of the arithmetic circuit 5 is not limited. Also, the microwave oscillation method is not limited, and for example, the FM / CW method can be used. Furthermore, various filters may be inserted.

  However, the present invention is characterized in that the circulator 20 and the antenna 3 are arranged close to each other, that is, the cable length of the coaxial cable 30 is shortened. Accordingly, the peak (A) of the microwave reflected at the end face of the coaxial cable 30 in the connection portion A appears at a very short distance on the chart, so that it can be determined that it is clearly different from the reflection peak due to the detected object. Therefore, it is preferable to shorten the cable length of the coaxial cable 30 as much as possible.

  Further, since other components such as the microwave oscillator 1, the divider 2, the mixer 4, and the arithmetic circuit 5 except the circulator 20 do not input the reflected microwave signal to the mixer 4, they are unitized (reference numeral 100). However, the antenna 3 and the circulator 20 can be arranged apart from each other. Thereby, the freedom degree of installation increases and it becomes useful especially in application to a blast furnace, an incinerator, etc. Since most parts of the circulator 20 are made of metal, the operation is not affected even if the circulator 20 is installed at the top of the furnace together with the antenna 3 and the ambient temperature is high.

(Second microwave rangefinder)
FIG. 2 is a block diagram showing the main components of the second microwave rangefinder according to the present invention. As shown in the figure, the second microwave rangefinder removes the circulator 20 from the first microwave rangefinder or the conventional microwave rangefinder shown in FIG. 3, and connects the divider 2 and the antenna 3 to the first microwave rangefinder. The antenna 3 and the mixer 4 are connected by a second coaxial cable 11 and connected by a coaxial cable 10. The antenna 3 includes a transmission probe (not shown) for transmitting the transmission microwave M1 and a reception probe (not shown) for receiving the reflected microwave M2, and the first coaxial. The cable 10 connects the divider 2 and the transmission probe, and the second coaxial cable 11 connects the mixer 4 and the reception probe.

  According to such a configuration, even if the oscillating microwave from the divider 2 propagates through the first coaxial cable 10 and is reflected by the cable end surface at the connection portion A with the antenna 3, the reflected microwave is transmitted to the mixer 4. Never sent. Therefore, only the oscillation microwave demultiplexed by the divider 2 and the reflected microwave M2 by the detected object received by the antenna 3 are input to the mixer 4, and only the reflected peak by the detected object is displayed on the chart. Is done.

  In the second microwave rangefinder, other components such as the microwave oscillator 1, the divider 2, the mixer 4, and the arithmetic circuit 5 may be unitized (reference numeral 100) and arranged away from the antenna 3. it can. Furthermore, in order to suppress the attenuation of the microwave, it is advantageous that the coaxial cables 10 and 11 have a short cable length, and only the divider 2 and the mixer 4 are unitized (reference numeral 50) and arranged close to the antenna 3. Also good.

It is a block diagram which shows the main components of the 1st microwave rangefinder which concerns on this invention. It is a block diagram which shows the main components of the 2nd microwave rangefinder which concerns on this invention. It is a block diagram which shows the main components of the conventional microwave rangefinder. It is a schematic diagram which shows an example of the measurement result by the conventional microwave rangefinder.

Explanation of symbols

1 Microwave Oscillator 2 Divider 3 Antenna 4 Mixer 5 Arithmetic Circuit 10 First Coaxial Cable 11 Second Coaxial Cable 20 Circulator

Claims (5)

In the microwave rangefinder that transmits the microwave from the antenna toward the object to be detected, receives the reflected microwave reflected by the object to be detected by the antenna, and measures the distance to the object to be detected.
A microwave oscillator,
An antenna including a transmission / reception probe for transmitting a microwave oscillated from a microwave oscillator and receiving a reflected microwave reflected by an object;
A divider that demultiplexes the microwaves oscillated from the microwave oscillator, sends one of them to the antenna via the circulator, and sends the remainder to the mixer as a reference signal;
A circulator inserted between the divider and the antenna and connected by a first coaxial cable, and connected by a mixer and a second coaxial cable;
A mixer that receives a reflected microwave received by an antenna and is input via a circulator and a reference signal from a divider, and sends the mixed signal to an arithmetic circuit;
An arithmetic circuit that calculates the distance to the object to be detected by calculating the mixing signal from the mixer, and
A microwave rangefinder characterized in that only the circulator is placed close to the antenna.   2. The microwave distance according to claim 1, wherein the antenna is disposed in the vicinity of the object to be detected together with the circulator, and other components including a microwave oscillator, a divider, a mixer, and an arithmetic circuit are disposed apart from the antenna. Total In the microwave rangefinder that transmits the microwave from the antenna toward the object to be detected, receives the reflected microwave reflected by the object to be detected by the antenna, and measures the distance to the object to be detected.
A microwave oscillator,
An antenna including a transmission probe for transmitting microwaves oscillated from a microwave oscillator, and a reception probe for receiving reflected microwaves reflected by an object to be detected;
A divider that divides the microwave oscillated from the microwave oscillator, sends one of them to the antenna side, and sends the remainder to the mixer side as a reference signal;
A mixer that mixes the reflected microwave received by the antenna and the reference signal from the divider, and sends the mixing signal to the arithmetic circuit;
An arithmetic circuit that calculates the distance to the object to be detected by calculating the mixing signal from the mixer, and
A microwave rangefinder, wherein an antenna transmission probe and a divider are connected by a first coaxial cable, and a reception probe and a mixer are connected by a second coaxial cable.   4. The microwave rangefinder according to claim 3, wherein the antenna is disposed in the vicinity of the object to be detected, and other components including a microwave oscillator, a divider, a mixer, and an arithmetic circuit are disposed apart from the antenna.   3. An antenna is attached to the top of the furnace, microwaves are transmitted toward the contents in the furnace, and the amount of deposition in the furnace is measured by detecting reflected microwaves from the contents. Or the microwave rangefinder of 4.

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