DE102014212955A1 - High-frequency microwave barrier - Google Patents

Abstract

High-frequency microwave barrier for monitoring a security area, for counting events or for monitoring a level in a tank or silo using a microwave signal with a frequency above 24 GHz. As a result, the signal focus can be increased and the negative influence of soiling on the antenna or disturbances in the area to be monitored can be reduced.

Description

Field of the invention

The invention relates to devices for monitoring security areas, for counting events and for level monitoring in containers or silos. In particular, the invention relates to a high frequency microwave barrier and the use of a high frequency microwave barrier for monitoring a level in a container, for monitoring security areas and for counting events.

Technological background

Photocells can be used to monitor safety areas, to count events or to monitor a level in a container or silo. By an opposite arrangement of transmitter and receiver, a signal can be detected in the interruption of the light beam and a corresponding action, for. As the shutdown of a machine or the filling of a container triggered.

As radiation sources light-emitting diodes or laser diodes can be used, which allows a very good signal bundling. In this way, it is possible that the light barriers of objects that are close to the beam path, are not or only slightly affected.

Such light barriers can be susceptible to soiling on their optical systems and environmental influences in the area to be monitored, ie along the measuring path. In particular, dust, rain, snow or fog can lead to disturbances of the measurement, so that a reliable function under such environmental conditions is not guaranteed in every case.

Summary of the invention

It is an object of the invention to reduce the likelihood of misdetection in monitoring a security area, counting events or monitoring a level in a bin or silo in the event of contamination on the optical systems or disturbances in the area to be monitored.

This object is solved by the features of the independent claims. Further developments of the invention will become apparent from the dependent claims and the description below.

According to a first aspect of the invention, a high frequency microwave barrier is provided for monitoring a security area, for counting events and / or for monitoring a level in a bin or silo. The microwave barrier has a transmission module for emitting a microwave signal in the direction of a region to be monitored. Opposite the transmitter module is provided a receiver module which serves to receive the microwave signal after it has passed through the area to be monitored. The microwave signal in this case has a frequency of over 24 GHz.

The use of microwaves instead of light can reduce the influence of the measurement due to disturbing environmental influences and contamination on the antennas and lenses of the transmitting and receiving modules. In addition, by using a transmission frequency of over 24 GHz, a good focus of the transmitted microwave signals can be achieved.

Thus, it is possible, for example, to minimize or completely avoid disturbing reflections by metallic components which are located next to the optical axis of the transmitting module (for example outside the area of the main beam of the antenna of the transmitting module). Such disturbing reflections can make it difficult or even impossible to reliably monitor the given area.

According to one embodiment of the invention, the aperture angle of the microwave signal transmitted by the transmitter module is less than 10 degrees. In this case, the opening angle is to be understood as meaning the angular range in which the transmission module transmits the largest portion of the microwave signal. The opening angle defines the area outside of which the signal strength of the transmitted microwave signal has dropped by 3 dB. Accordingly, the so-called -3 dB point is the opening angle at which the energy is reduced to 50%.

According to a further embodiment of the invention, the aperture angle of the microwave signal transmitted by the transmitter module is less than 8 degrees, for example even less than 3 degrees.

Likewise it can be provided that the maximum opening angle of the receivable by the receiving module microwave signal is less than 10 °, less than 8 degrees, or even less than 3 degrees. Thus, it can be ruled out that signals are received that come from another direction.

According to another embodiment of the invention, the microwave signal has a frequency of 61 GHz or more. For example, the microwave signal has a frequency of 80 GHz or more, 122 GHz or more, or 244 GHz or more. The microwave signal may be in the K band (15-26.5 GHz), in the Ka band (50-75 GHz), in the Q band (33-50 GHz), in the U band (40-60 GHz), for example. , in the V band (50-75 GHz), in the W band (75-110 GHz), in the F band (90-140 GHz), in the D band (110-170 GHz) or in the V band ( 325-500 GHz).

According to a further embodiment of the invention, the transmission module is designed to emit the microwave signal in the form of a coded microwave signal, wherein in return the reception module is designed to decode the microwave signal encoded by the transmission module.

Thus, it can be ensured that the receiving module can assign the received microwave signal to the corresponding transmission module.

According to a further aspect of the invention, the use of a high-frequency microwave barrier described above and below for monitoring a fill level in a container or silo is indicated.

According to a further aspect of the invention, the use of a high-frequency microwave barrier described above and below for monitoring a security area is indicated.

According to a further aspect of the invention, the use of a high-frequency microwave barrier described above and hereinafter for counting events is indicated.

Embodiments of the invention will be described below with reference to the figures.

Brief description of the figures

1 shows a light barrier.

2 shows a microwave barrier.

3 shows a microwave barrier with a Störreflector.

4 shows a microwave barrier according to an embodiment of the invention.

Detailed description of embodiments

The illustrations in the figures are schematic and not to scale.

If the same reference numerals are used in different figures in the following description of the figures, these designate the same or similar elements. However, identical or similar elements can also be designated by different reference symbols.

1 shows the structure and the signal bundling of a light barrier 100 , The photocell 100 has a transmitter 101 and an opposite receiver 102 on. Both the transmitter 101 as well as the receiver 102 can with a lens system 103 . 104 be equipped. The transmitter 101 sends a beam of light 105 out, from the receiver 102 can be detected.

In this optical method can lead to interference or incorrect measurements, if the lens systems 103 . 104 Contaminants or the area to be monitored (the measuring section) is disturbed by dust, rain, snowfall and / or fog.

The use of microwaves instead of light can reduce the likelihood of a faulty measurement of a contaminated lens or the aforementioned disturbances in the area to be monitored.

2 shows a microwave barrier 200 which emits microwave signals at a frequency of, for example, 6 to about 24 GHz. The microwave barrier 200 has a transmitter module 201 on which a microwave module 202 and an attached antenna system 203 with a lens attached to it 204 includes. The transmission module 201 sends a microwave signal 205 in the direction of the area to be monitored and thus in the direction of the receiving module 206 off, which is opposite to the transmitter module on the other side of the area to be monitored.

The (main) beam of the transmitted microwave signal 205 has an aperture angle of about 20 degrees when using a frequency of about 24 GHz.

The receiving module 206 includes a microwave receiver 207 and an antenna system attached thereto 208 with upstream lens 209 ,

3 shows the microwave barrier 200 of the 2 , where in the area to be monitored a measurement object 304 located. In addition to the area to be monitored is a Störreflector 301 who in the example of the 3 is arranged outside the main beam.

This, for example, metallic, Störreflector 301 reflects a part of the microwave signal emitted by the transmitter module 302 , The reflected signal 303 is then received by the receiving module 206 receive. Is the receiving module 206 unable to decide which direction the received microwave signal comes from, it also can not decide if the received microwave signal is a jamming signal 303 from an interfering reflector 301 or actually around the measured, directly in the direction of the receiving module 206 radiated microwave signal 305 is.

In the example of 3 becomes the signal 305 from the measurement object 304 which is to be detected, blocked and thus does not reach the receiving module 206 , However, because the interfering signal 306 reaches the receiving module, the measured object 304 not detected by the measuring arrangement.

4 shows a high-frequency microwave barrier 400 according to an embodiment of the invention. The high-frequency microwave barrier 400 also has a transmission module 401 and a receiving module disposed opposite the transmitting module 406 on. The transmitter module has a microwave module 402 for generating the microwave signal to be transmitted 405 and an attached antenna system 403 with a lens 404 (Optional). The antenna system is, for example, a horn antenna.

Likewise, also the receiving module 406 an antenna system 408 with possibly a front mounted lens 409 which is on a microwave receiver 407 connected.

The dashed box 410 denotes the area to be monitored, through which the radiated microwave signal 405 running.

When using an antenna size of about 40 mm in diameter with a microwave signal frequency of 24 GHz, an opening angle of about 20 degrees (measured at the typical 3 dB point) can be achieved. With even smaller antennas, no practically usable signal bundling can be achieved in this frequency range.

By using higher frequencies of the microwave signal, for example in the frequency range around 80 GHz, a signal focusing of 7 to 8 degrees is possible with the same antenna size. With antenna sizes of approx. 80 mm diameter, a focusing of up to 3 degrees is achieved. By using even higher frequencies, for example of about 120 GHz, the signal focusing can be further increased. The possible frequency ranges are in particular the ranges 18-40 Ghz, 50-75 Ghz, 75-110 Ghz and 60-90 Ghz into consideration.

Improved signal bundling significantly reduces the effects of interfering reflections from installations, metal surfaces or container walls and significantly improves the operational reliability of the microwave barrier.

For example, the frequencies are chosen in an internationally approved frequency band. These frequency ranges are about 61 GHz, about 122 GHz or about 244 GHz. Another useful frequency band is around 80 GHz.

The use of high frequencies results in a combination of the advantages of the optical light barrier and the microwave measurement method. By using very high frequencies, a strong focusing of the radiated microwave signal is achieved. The use of microwaves instead of light makes the measuring system less dependent on soiling and environmental influences such as dust, rain, snow or fog.

The transmission module 401 the microwave barrier is therefore with a high-frequency microwave generator (microwave module 402 ), which may also be designed to emit a modulated continuous signal in one of the above-mentioned frequency ranges. The receiving module 406 has a receiving device (microwave receiver 407 , Antenna and lens system 408 . 409 ) with a high sensitivity detector tuned to the signals and frequency ranges of the transmitter module. In order to be able to unambiguously assign the transmission module to the reception module, it can be provided that the microwave signal to be transmitted is coded by a corresponding modulation.

The microwave signal to be transmitted is provided by an antenna adapted to the conditions of use and the conditions of use 403 . 404 focused and bundled. For different applications and measuring ranges, it is possible to adapt the antenna systems of the transmitting and receiving module to the respective requirements and, if necessary, to replace them.

In addition, it should be noted that "comprising" and "having" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. It should also be appreciated that features or steps described with reference to any of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

Claims (10)

High-frequency microwave barrier for monitoring a security area, for counting events or for monitoring a level in a tank or silo, comprising: a transmission module ( 401 ) for emitting a microwave signal ( 405 ) in the direction of an area to be monitored ( 410 ); a receiving module ( 406 ) for receiving the microwave signal after passing through the area to be monitored; wherein the microwave signal has a frequency of over 24 GHz. High-frequency microwave barrier according to claim 1, wherein an opening angle of the transmission module ( 401 ) emitted microwave signal is less than 10 °. High-frequency microwave barrier according to one of the preceding claims, wherein the opening angle of the transmission module ( 401 ) emitted microwave signal is less than 8 °, for example, less than 3 °. A high-frequency microwave barrier according to any one of the preceding claims, wherein the microwave signal has a frequency of 61 GHz or more. A radio frequency microwave barrier as claimed in any one of the preceding claims, wherein the microwave signal has a frequency of 80 GHz, 122 GHz, 244 GHz or more. High-frequency microwave barrier according to one of the preceding claims, wherein the transmission module ( 401 ) for emitting the microwave signal ( 405 ) in the form of a coded microwave signal; and wherein the receiving module ( 406 ) for decoding the microwave signal. High-frequency microwave barrier according to one of the preceding claims, wherein an opening angle of the receiving module ( 406 ) is less than 10 °. Use of a high-frequency microwave barrier according to one of claims 1 to 7 for monitoring a filling level in a container or silo. Use of a high-frequency microwave barrier according to one of claims 1 to 7 for monitoring a security area. Use of a high-frequency microwave barrier according to one of claims 1 to 7 for counting events.

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