EP2331917A1

EP2331917A1 - Filling level measuring device operating with microwaves

Info

Publication number: EP2331917A1
Application number: EP09781721A
Authority: EP
Inventors: Peter KLÖFER; Winfried Mayer
Original assignee: Endress and Hauser SE and Co KG
Current assignee: Endress and Hauser SE and Co KG
Priority date: 2008-10-10
Filing date: 2009-08-12
Publication date: 2011-06-15
Also published as: CN102177420B; US20110193567A1; US8884632B2; WO2010040580A1; CN102177420A; DE102008050329A1

Abstract

The invention relates to a filling level measuring device operating with microwaves according to the propagation time principle for measuring the filling level of filling materials (5) in containers (3), with which microwave signals (S_M, S_N, S_L) can be sent into the container (3) on several different signal paths and the associated echo signals (E_M, E_N, E_L) of said microwave signals can be recorded and the measurement results obtained on the different signal paths can be evaluated separately from each other, having measuring device electronics (7), having a microwave generator (9) for successively generating microwave signals (S_M, S_N, S_L) having different usable frequencies (f_m, f_n, f_l), and having a frequency-selective passive antenna arrangement (11a, 11b, 11c, 11d, 11e) which is connected thereto and which comprises several antennas, which are used to send the different microwave signals (S_M, S_N, S_L) into the container (3) consecutively, and to receive the echo signals (E_M, E_N, E_L) thereof reflected back to the antenna arrangement (11a, 11b, 11c, 11d, 11e), which comprises several frequency selective elements (F_M, F_N, F_L), particularly band-pass filters, through which one of the different usable frequencies (f_m, f_n, f_l) can pass in each case, in which a uniquely associated signal path is specified for each of the different microwave signals (S_M, S_N, S_L) and the echo signal (E_M, E_N, E_L) thereof through the antennas and the frequency-selective elements (F_M, F_N, F_L), said microwave signal being sent into the container (3) through said uniquely associated signal path and the echo signal (E_M, E_N, E_L) thereof reflected back to the antenna arrangement being received and fed to the measuring device electronics (7) through said uniquely associated signal path, and a device (21) provided in the measuring device electronics (7) which associates the consecutively incoming echo signals (E_M, E_N) to the associated signal path.

Description

Microwave level gauge

The invention relates to a working according to the transit time Füilstandsmessgerät for level measurement of in-container products, sent with the signal paths on different signal microwave signals into the container and their associated on the

Füllgutoberfiäche reflected echo signals are received again after a dependent on the level run time and based on their maturities, the levels are determined.

Such non-contact meters are used in a variety of industries, e.g. in the processing industry, in chemistry or in the food industry.

Typically, the level gauge is mounted above the medium and its antenna aligned with the contents.

To determine the transit times, all known methods can be used which make it possible to measure relatively short distances by means of reflected microwaves. The best known examples are the pulse radar and the FMCW radar.

When Puisradar short microwave transmission pulses are periodically sent, which are reflected by the Füllgutoberfläche and received after a distance-dependent run time again. An echo function is derived on the basis of the received signal, which reproduces the received signal amplitude as a function of time. Each value of this echo function corresponds to the amplitude of an echo reflected at a certain distance from the antenna.

In the FMCW method, a microwave signal which is periodically linearly frequency-modulated, for example after a sawtooth function, is transmitted continuously. The frequency of the received echo signal therefore has a frequency difference which differs from the instantaneous frequency which the transmission signal has at the time of reception Microwave signal and its echo signal depends. The frequency difference between the transmitted signal and the received signal, which can be obtained by mixing both signals and evaluating the Fourier spectrum of the mixed signal, thus corresponds to the distance of the reflecting surface from the antenna. Furthermore, the amplitudes of the spectral lines of the frequency spectrum obtained by Fourier transformation correspond to the echo amplitudes. This Fourier spectrum therefore represents the echo function in this case,

At least one useful echo is determined from the echo function, which corresponds to the reflection of the transmission signal at the product surface. From the duration of the useful echo results in a known propagation speed of the microwaves directly the distance that the microwaves (your way from the measuring instrument to the full product surface and back again) Based on the installation height of the fullness measuring instrument above the container, the required level can be calculated directly

However, there are a variety of applications in which this form of Fulistandsmessung is insufficient

An example of this are full level measurements in storage containers for debris. Debris normally forms a debris cone. The above classical Fulistandsmessung provides here, however, the full height in a certain predetermined by the antenna position and their alignment area of the debris cone, a more accurate determination of the contents achievable In these cases, so-called multi-point measurements are regularly carried out. Several Fulistandsmessgerate are arranged side by side above the contents and determines the levels in the individual detected by the respective measuring devices areas in the container The use of several Fulistandsmessgerate is in the

Usually very expensive and expensive Alternatively, a Fuilstandsmessgerat can be equipped with several arranged at different locations on the product antennas that are switched individually, for example, arranged in the field electronic switches The use of multiple switchable via electronic switch antennas, however, is less expensive, but has the Disadvantage that this usually directly to the antenna in the field arranged switches must be supplied with energy This is not only expensive, but is esp in applications in which for reasons of explosion protection special security must be complied with a security risk

Another example is applications in which there are Storer in the container, such as Ruhrwerke or other internals, where the transmitted microwave signals are also reflected. In this case, the echo signal recorded with the Fuilstandsmessgerat contains both the sought on a reflection on the Vollgutoberflache Therefore, it is very difficult or even impossible under certain circumstances to determine the wanted echo and thus the level to be measured by means of the echo signal. To overcome this problem, so-called multi-lobe measurements are frequently carried out the transmission signals are thereby aligned, for example, in such a way that each transmission lobe reaches the fuligut. The echo signals of the individual transmission lobes are recorded and, for example, the transmission signals are transmitted in a plurality of transmission lobes with different orientation Based on the known orientation of the different emission lobes obtained additional information, based on which the echoes contained in all echo signals can be determined much more accurate and reliable Examples thereof are described in EP 1 431 724 A1 There is described among other things, the useful echo on the basis of the amplitudes of Whereas the amplitude of the useful echo is equal in all echo signals in terms of angle, the storechos in the different echo signals have different amplitudes due to the different alignment of the associated transmitting lobes

Both in the multipoint measurement and in the multi-lobe measurement, it is necessary to transmit microwave signals on different signal paths into the container and to evaluate their echo signals separately from one another

For this purpose, several parallel operated transmission and / or receiving arrangements and / or electronic switches can be used in DE 10 2004 034 429 an example is described, which is used in the automotive industry as a distance sensor There is a microwave generator via a switch successively to different transmitting antennas connected to each of the receiving antennas, a separate reception branch is connected, via which the echo signal recorded by the respective receiving antenna is received and fed to a signal processing. The assignment of the individual measuring signals to the individual signal paths takes place here via the respective switch positions and the separate receiving forces

It is an object of the invention to provide a full-range measuring device operating with microwaves after the transit time pnnip, with which microwave signals can be transmitted to the container on a plurality of different signal paths and their associated echo signals can be recorded and the measurement results obtained on the different signal paths can be evaluated separately from one another

For this purpose, the invention consists in a working with microwaves on the runtime principle Fullstandsmessgerat for Fulistandsmessung of in-container products, with

- A meter electronics with a microwave generator for the successive generation of different payloads having micro dome signals, and

a frequency-selective passive antenna arrangement connected thereto,

having a plurality of antennas which serve to successively transmit the different microwave signals into the container and to receive the echo signals reflected back to the antenna arrangement, the plurality of frequency-selective elements each having one of the different useful frequencies, in particular bandpass fifters, - In the over the antennas and the frequency-selective elements for each of the different micro Wehensignaie and its echo signal is a uniquely assigned signal path pretending that this Mikrowellensigna! sent to the container and its back to the antenna array reflected echo signal and the meter electronics is supplied, and

a device provided in the measuring device electronics, which assigns the consecutively incoming echo signals to the associated signal path.

According to a first variant, the invention consists in a level gauge in which

one of the antennas is a transmitting antenna serving to transmit the different microwave signals into the container,

- The other antennas are receiving antennas, which serve to reflected by reflections in the container back to the antenna array echo signals of the different

To receive microwave signals, - in the antenna arrangement of each receiving antenna for each of the different useful frequencies durchiässiges frequency-selective element, esp. A band-pass filter, is connected downstream, which serves, from that of the respective

Receive antenna received signal received to filter the useful frequency having echo signal out, and

- The device assigns the successively transmitted from the antenna assembly to the meter electronics echo signals of the receiving antenna from which they were received.

According to a second variant, the invention consists in a level gauge in which

- One of the antennas is a receiving antenna, which serves to receive the reflections reflected in the container back to the antenna arrangement echo signals of the different microwave signals,

the remaining antennas are transmitting antennas which serve to send one of the different microwave signals into the container,

- in the Antennenanordnuπg each transmitting antenna a for a frequency-selective element permeable to the different useful frequencies, in particular a band-pass filter, which serves to filter out from the microwave signals generated by the microwave generator that which is transmitted in the measurement mode via the respective transmitting antenna, and

- The device assigns the successively transmitted from the antenna array to the meter electronics echo signals of the respective transmitting antenna, from which the associated MikroweJIensignale has been sent.

According to a third variant, the invention consists in a level measuring device in which

the antennas are transmitting and receiving antennas which serve to transmit the different microwave signals into the container and to receive their echosigna reflected back to the antenna arrangement by reflections in the container,

- In the antenna arrangement of each transmitting and receiving antenna for one of the different useful frequencies permeable frequency-selective element, esp. A bandpass filter is assigned, which serves to from the from

Microwave generator generated the antenna array supplied microwave signals to filter out the one and the transmitting and receiving antenna, which via this

Transmitting and receiving antenna is sent, and which serves to filter out of the received from this transmitting and receiving antenna received signal, the associated this useful frequency having echo signal, and

- The device assigns the successively transmitted from the antenna array to the meter electronics echo signals of the transmitting and receiving antenna over which the associated microwave signal was sent and its echo signal was received.

According to a development of the invention, the measuring device electronics are connected to the antenna arrangement exclusively via a single waveguide,

via which the different microwave signals are transmitted from the measuring device electronics to the antenna arrangement and the echo signals are transmitted from the antenna arrangement to the measuring device electronics, and - Is connected via a provided in the antenna arrangement transmitting-receiving separation to all transmitting antennas and to aile Empfangarttennen.

According to an alternative development

the measuring device electronics are connected to the antenna arrangement via a transmitting conductor, via which the transmitting antennas are fed with the different microwave signals, and the measuring device electronics are connected to the antenna arrangement via a receiving waveguide via which the echo signals are transmitted from the antenna arrangement to the measuring device electronics.

According to one embodiment of the first variant

- The receiving antennas are arranged in a group spatially adjacent to each other, and

- The transmitting antenna is spatially located outside the group.

According to one embodiment of the second variant

the transmitting antennas are arranged in a group spatially adjacent to one another, and

- The receiving antenna is spatially located outside of the group.

According to another embodiment of the first variant

the receiving antennas surround the transmitting antenna spatially,

- the transmitting antenna is aligned with the contents in the container,

the receiving antennas each have an orientation which is inclined with respect to the orientation of the transmitting antenna, and the receiving areas of the individual receiving antennas which are predetermined by the orientations of the receiving antennas and which are covered by the respective receiving antenna partially overlap.

According to another embodiment of the second variant, the transmitting antennas surround the receiving antenna spatially,

- the receiving antenna is aligned with the contents in the container,

the transmitting antennas each have an orientation which is inclined with respect to the orientation of the receiving antenna, and

- Given by the orientations of the transmitting antennas Transmission areas of the individual transmission antennas are at least partially in the reception area of the reception antenna and partly overlap.

The fill level measuring devices according to the invention have the advantage that, due to the arrangement of the antennas in the antenna arrangement, their integration into the transmitting antenna a! S

Receiving antenna or as transmitting and receiving antenna and the frequency-selective elements for each of the different microwave signals and the echo signal is a unique defined exclusively by passive components signal path is clearly specified. The passive components do not require any power supply. Electronic switches or other active power supply requiring components are therefore no longer needed. The assignment of the obtained measurement results to the individual signal paths is thus automatically given over the useful frequency of both the respective transmitted microwave signal and the associated echo signal. The individual echo signals arrive one after the other in the measuring device electronics and can there be processed and evaluated separately in knowledge of the associated signal path in one and the same signal processing.

The invention and its advantages will now be explained in more detail with reference to the figures of the drawing, in which five embodiments are shown; like parts are provided in the figures with the same reference numerals.

1 shows a filling level measuring device according to the invention with a measuring device electronics and a frequency-selective antenna arrangement connected thereto via a single micro-conductor and having a transmitting antenna and a plurality of receiving antennas;

Fig. 2 shows an inventive level measuring device with a

Meter electronics and connected thereto via a transmitting conductor and a Empfangsieiter frequency selective antenna arrangement with a transmitting antenna and several

Receiving antennas;

Fig. 3 shows an inventive level measuring device in which the

Antenna arrangement comprises a plurality of transmitting and receiving antennas;

4 shows a fill level measuring device according to the invention with a measuring device electronics and a frequency-selective one connected thereto via a single microwave conductor Antenna arrangement comprising a receiving antenna and a plurality of transmitting antennas, and

Fig. 5 shows a erfuldaßaß Fulistandsmessgerat with a meter electronics and connected thereto via a transmitting conductor and a receiving conductor frequency-selective antenna arrangement with a receiving antenna and a plurality of transmitting antennas

1 shows a schematic diagram of a first variant of the filling level measuring device according to the invention

1 The level gauge 1 is a working with microwaves on the transit time principle Fulistandsmessgerat, eg an FMCW radar level gauge or a pulse radar Fulistandsmessgerat and is used for level measurement of contained in containers 3 filling 5. It includes a Messgeratelektronik 7, which has a microwave generator 9, the successive generation of at least two different useful frequencies f _m , f _n having

Mikroweilensignalen SM, S _N is microwave generators 9, as can be used in level gauges are known from the prior art. The generation of the different useful frequencies f _m , f _n having microwave signals S _M , S _N can be effected for example by a corresponding control of digitally controllable electronic tuning elements of the microwave generator 9, in modern microwave generators 9, such. B in direct digital synthesizers (DDS) or voltage-controlled oscillators (VCO), are provided regularly anyway. The Nutzfrequenzeinstellung then takes place for example via a varactor used in a resonant circuit of a transmission oscillator. Alternatively, a synthesizer structure may be used in the transmit oscillator, and the pay frequency modifier may be made by changing values of an adjustable frequency divider. Likewise, a direct digital synthesizer with variable output frequency can be used, or the useful frequencies can be effected by the targeted adjustment of the operating points of active components of a transmission oscillator

To the meter electronics 7 according to the invention is a frequency-selective passive

Antenna array 11 connected. The antenna arrangement 11 has a number of antennas which serve to successively transmit the different microwave signals S _M , S _N into the container 3, and to receive the echo signals E _M , E _N to which they are reflected back to the antenna arrangement 11 The antenna arrangement illustrated in FIG For this purpose, 11a comprises a transmitting antenna 13, which serves to transmit the different microwave signals SM, S _N into the container 1, and a plurality of receiving antennas 15, 17, which serve to return the echo signals E _M , E _{N of} the different reflected back to the antenna arrangement 11a To receive microwave signals S _M , S _N. The antenna arrangements 11 according to the invention have a plurality of each one of the different wanted frequencies f _m, f _n permeable frequency selective Eiemente F _M, FN, in particular, band pass filter, at. The essence of the invention is that in the antenna _assembly 11 via the antennas and the frequency-selective elements F _Ml F _N for each of the different microwave signals S _M , S _N and its echo signal E _M , EN a uniquely assigned signal path is given over this Microwave signal S _M , S _{N sent} into the container 3 and the antenna array 11 back reflected echo signal E _M , EN received and the meter electronics 7 is supplied. As a result of this frequency selectivity of the antenna arrangement 11, an unambiguous assignment of the consecutively transmitted microwave signals SM, S _N and their associated successively in the memory is obtained via the different useful frequencies f _m , f _n

Meter electronics 7 incoming echo signals E _M , EN given to the associated signal path.

In the variant illustrated in FIG. 1, this is realized in that each receiving antenna 15, 17 has a frequency-selective element F _M , F _N , änsb which is permeable to one of the different useful frequencies f _m , f _n . a band-pass filter is connected downstream, which serves to filter out the echo signal Ey, E _N having this useful frequency f _m , f _n , from the received signals received by the respective receiving antenna 15, 17.

In the exemplary embodiment illustrated in FIG. 1, the microwave generator 9 successively generates two different microwave signals S _M , S _N , which are transmitted via the transmitting antenna 13. For receiving the associated echo signals E _M , E _N two receiving antennas 15, 17 are provided accordingly. From the reception signal of the reception antenna 15, the frequency-selective element F _M connected downstream of the reception antenna 15 is filtered out for the echo signal E _M associated with the micro-presence signal S _M. From the received signal of the receiving antenna 17, the frequency response to the receiving antenna 17 downstream frequency selective element F _M to Mikroweilensignai S _N associated echo signal E _{N is} filtered out.

On the basis of the different useful frequencies of the echo signals E _M , E _N , the echo signals E _M , EN can be unambiguously assigned to the respective receiving antenna 15, 17. For this purpose, the measuring device electronics 7 comprises a device 21 which assigns the incoming echo signals E _M , E _N based on their different useful frequencies f _m , f _{n to} the respective receiving antennas 15, 17 or to the signal path extending over these receiving antennas 15, 17. For this purpose, the device 21 comprises, for example, a memory connected to a signal processor 23, in which this assignment is stored. Since the microwave generator 9 successively generates the individual different microwave signals S _M , S _N , and these are sent successively, the useful frequencies f _m , f _{n of} the echo signals E _M , E _N need not be measured. As long as the microwave generator 9 generates the micro dimming signal S _M , the receiving antennas 15, 17 exclusively receive its echo signal EM. The pertinent echo signal E _M reflected back by reflection in the container 3 to the antenna arrangement 11a is indeed of both Reception antennas 15, 17 received, but this can happen only for its useful frequency f _m permeable to the receiving antenna 15 downstream frequency-selective element F _M.

As long as the microwave generator 9 generates the microwave signal S _N , receive the receiving antennas 15, 17 exclusively its echo signal E _N The associated by reflection in the container 3 to Anteπnenanordnung 11 a back reflected echo signal! Although E _N is received by both receiving antennas 15, 17, however, this can pass only the frequency-selective element FN arranged downstream of the receiving antenna 17 for its useful frequency f _n . The individual successive incoming echo signals E _M , E _N from the signal processing are used to determine the filling level 23 processed by, for example, based on the echo signals E _M , EN an echo function is derived, which reproduces the received Signaiamplitude as a function of Signalzeitaufzeit For this, the known from the prior art both Pulse Radar Fullstandsmessgerate and FMCW Radar Fullstandsmessgerat be used The invention Fullstandsmessgerat in this case has the advantage that the relevant for the transit time determination of the respective echo signal E _M , E _N sent sent

Microwave signal S _M , S _N in the meter electronics 7 via the microwave generator 9 of the signal processing 23 is always time correct available

By correspondingly increasing the number of different microwave signals and the receiving antennas, of course, three or more echo signals recorded by different receiving antennas can be distinguished

In the variant shown in FIG. 1, the measuring device electron 7 is connected to the antenna arrangement 11 exclusively via the single waveguide 19. This is via a transmitting-receiving separation 25, eg a circulator or a directional coupler, both to the transmitting antenna

13 and to the receiving antennas 15, 17 connected via this waveguide 19, the antenna arrangement 1 1 with the different Mtkroweliensignalen S _M , S _N fed in the reverse direction, the filtered out from the received signals of the receiving antennas 15, 17 echo signals E _M , E _N over transmit this microwave conductor 19 from the antenna arrangement 11 to the measuring device electronics 7

This offers the advantage that only a single connection between the Meßgerateiektromk 5 and the antenna assembly 11a is required Another advantage is that this is a permanent connection that causes no change and / or impairment of the signal transmission

2 shows a second variant of the inventive Fullstandsmessgerats in contrast to the variant shown in Figure 1, the Messgeratelektronik 7 here via two microwave conductors, namely a transmitting conductor 27 and a receiving conductor 29 to the antenna assembly 1 1 b connected. The transmission conductor 27 leads from the microwave generator 9 of the measuring device electronics 7 to the transmitting antenna 13. The transmitting antenna 13 is fed with the microwave signals S _M> S _N via them. Via the reception conductor 29, the echo signals E _M , E _N filtered out of the received signals of the receiving antennas 15, 17 are fed to the measuring device electronics 7. For this purpose, all receiving antennas 15, 17 are connected to the second Empfangsieiter 29, which in turn is connected to the meter electronics 7. Again, the Sendieiter 27 and the receiving conductor 29 permanent connections that unlike electronic switches cause no change and / or impairment of signal transmission. In contrast to the variant shown in FIG. 1, no transmitting / receiving separation 25 is required in the antenna arrangement 1 1b shown in FIG.

3 shows a third variant of the level gauge according to the invention, which has the measuring device electronics 7 already explained with reference to FIGS. 1 and 2 and a frequency-selective passive antenna arrangement 11c connected thereto. In contrast to the previously described antenna arrangements 1a and 11b, the antenna arrangement 11c has transmission and reception

Receiving antennas 31, 33, 35, ie each of the antennas serves both as a transmitting antenna and as a receiving antenna. Each of these transmit and receive antennas 31, 33, 35 is each assigned a frequency-selective element F _M , F _N , F _L which is permeable to one of the different useful frequencies f _m , f _n ,,, and which respectively serves for this purpose from the different successive microweighing generators 9 generated the antenna array 11 c supplied microwave signals SM; SN; SL, the respective useful frequency f _m , f _n , fι having microwave signal S _M ; S _N ; S _L out, which is then sent in each case exclusively via the associated transmitting and receiving antenna 31, 33 and 35 in the container 3. In the reverse direction, the respective frequency-selective element F _M , F _N , F _{L is} used, from the recorded with the respective transmitting and receiving antenna 31, 33, 35 received signal, the associated this useful frequency f _m , f _n . fι having echo signal E _M ; E _N ; To filter out e _l . In the illustrated Ausführungsbetspiel the Mikroweliengenerator 9 generates three different microwave signals SM; SN; SL- cause the frequency-selective elements F _M , F _N , F _L that the microwave signal S _{M is sent} exclusively via the transmitting and receiving antenna 31 and filtered out of the received signal exclusively the associated echo signal E _M and to

Meter electronics 7 is transmitted. Accordingly, the Mäkrowellensignal S _{N is sent} exclusively via the transmitting and receiving antenna 33 and filtered out of the received signal, only the associated echo signal E _N and transmitted to the meter electronics 7. Likewise, the Mikrowellensägnai S _{L is sent} exclusively via the transmitting and receiving antenna 35 and filtered out of the received signal, only the associated echo signal E _L and the

Meter electronics 7 transmit.

Analogous to the exemplary embodiment illustrated in FIG. 1, the antenna arrangement 11c is also connected exclusively via the single microwave conductor 19 to the measuring device electronics 7, via which the antenna arrangement 11c is supplied with the microwave signals S _M , S _N , SL, and via which the echo signals E _M , E _N , E _L associated with the received signals of the transmitting and receiving antennas 31, 33, 35 are supplied to the measuring device electronics 7 become

In the antenna arrangement 11c, the microwave conductor 19 is connected in parallel via the transmitting and receiving separation 25 to the three frequency-selective elements F _M , F _N , F _L , which in turn are connected to the transmission elements assigned to the respective element F _M , F _N , F _L. and receiving antenna 31, 33, 35 are connected

FIGS. 4 and 5 show two further full-range measuring devices according to the invention, each having a frequency-selective antenna arrangement 1 1d, 11e connected to the measuring device electronics 7 in contrast to the exemplary embodiments described above, these antenna arrangements 11d, 11e have only one receiving antenna 37 and several transmitting antennas 39, 41 Each of the transmitting antennas 39, 41 serves to transmit one of the different micro-woke signals S _M , S _N into the container 3, and the receiving antenna 37 serves for this purpose the echo signals E _M reflected back by reflections in the container 3 to the antenna arrangement 11d, 11e To E _{N of} the different microwave signals S _M , S _{N to} receive each transmit antenna 39, 41 is one for one of the different useful frequencies f _m , f _n permeable frequency-selective element F _M , F _N , esp a bandpass filter, upstream, which serves from the micro-wave signals S _M , S _N d generated by the microwave generator 9 To filter out as that is sent in Messbetπeb on the respective transmitting antenna 39, 41

For this purpose, the measuring device electronics 7 can either be connected via a single microwave conductor 19 to the antenna arrangement 11d, as shown in FIG. 4, via which the antenna arrangement 11d is supplied with the different micro-cavity signals SM, S _N , and via which the associated antenna arrangement 11 d received echo signals e _M> e _N of Messgeratelektronik are supplied to 7 in the case of the microwave conductor 19 is connected analogous to that shown in Figure 1 example, via the transmitter-receiver separation 25 to the transmitting antennas 39, 41 and to the receiving antenna 37, the frequency selective elements F _M , F _N are in this case respectively between the transmitting-receiving separation 25 and the respective transmitting antenna 39, 41 are arranged

Alternatively, the measuring device electronics 7 analogous to the exemplary embodiment shown in Figure 2 via a transmission line 27 and a receiving line 29 to be connected to antenna array 11e This variant is shown in Figure 5. The transmission line 27 is here in the antenna assembly 11e via the frequency-selective element FM to the transmitting antenna 41 connected and connected via the frequency-selective element F _N to the transmitting antenna 39 Due to the upstream frequency-selective elements F _M , F _N sends the transmitting antenna 41 exclusively the microwave signal S _M and the transmitting antenna 39th only the microwave signal! S _N. Since the microwave generator 9 successively generates the different microwave signals S _M , S _N , either one or the other transmitting antenna 39, 41 transmits. On the basis of the frequency f _m , f _{n of} the respective current generated microwave signal S _M , S _N and / or on the basis of Frequency f _m , f _{n of} the current received echo signal E _M , E _N thus inevitably results in the assignment to the transmitting antenna 39, 41 was transmitted via the.

The respective currently transmitted microwave signal S _M , S _N , S _L and the associated echo signal E _Mt E _N , E _L are each in pairs at the associated level-dependent run time offset in time to each other in the meter electronics 7 are available, so that the succession of the different measurement quantities obtained by the respective antenna arrangement signal paths, esp. The associated dependent of the signal delay time echo functions of one and the same signal processing 23 can be determined sequentially.

With the level measuring devices according to the invention can a variety of different

Measuring method are performed. In this case, the different Sägnalwege on which the microwave signals S _M , S _N , S _{1 are} sent and associated echo signals E _M , E _N , E _{L are} received by the positioning of the individual antennas of the antenna assemblies 11 a, 11 b, 11 c, 11 d, 11 e, the Alignment and their use as a transmitting antenna, as a receiving antenna or as a transmitting and receiving antenna within wide limits predetermined. In FIGS. 1 to 5, the individual signal paths predetermined by the respective antenna arrangement 11a, 11b, 11c, 11d, 11e via the frequency-selective elements F _M , F _N , F _L are shown by arrows.

For carrying out the multi-point measurement described above, the antennas of the respective antenna arrangement 11a, 11b, 11c, 11d, 11e can be arranged, for example, next to each other in a row. In the embodiment shown in FIG. 3, this results in parallel orientation of the individual transmitting and receiving antennas 31, 33, 35 on the medium 5 via each of the individual transmitting and receiving antennas 31, 33, 35 respectively the current level at the location of the respective Transmitting and receiving antenna 31, 33, 35.

In the case of the other exemplary embodiments, the measuring locations at which filling levels are measured in the course of a multi-point measurement are shown by the marked signal paths, which lead from one of the transmitting antennas 13, 39, 41 to one of the receiving antennas 15, 17, 37. In this case, preferably antenna arrangements, such as the arrangement 11 b of FIG. 2, are selected in which a plurality of receiving antennas 15, 17 are arranged in a group spatially adjacent to one another, and a transmitting antenna 13 is arranged spatially outside the group, or antenna arrangements, such as the arrangements 11d, 11e are selected in which a plurality of transmitting antennas 39, 41 are arranged in a group spatially adjacent to each other, and a receiving antenna 31 is arranged outside the group. The Individual antennas are preferably aligned depending on their position relative to each other such that the signal efficiency on the individual signal paths is maximaf.

Antenna arrangements, such as the antenna arrangement 11a of FIG. 1, are preferably selected for carrying out the multi-lobe measurement described above, in which a plurality of receive antennas 15, 17 spatially surround a single transmit antenna 13. For this purpose, the transmitting antenna 13 positioned in the center of the antenna arrangement 11a is preferably aligned directly with the filling material 5 in the container, and the receiving antennas 15, 17 each have an orientation which is inclined relative to the orientation of the transmitting antenna 13 and which is selected such that the light emitted through the Ausrächtungen the receiving antennas 15, 17 predetermined by the respective receiving antenna 15, 17 covered receiving areas at least partially cover the transmission range of the transmitting antenna 13 and the reception areas of the individual receiving antennas 15, 17 partially overlap.

Analogously, of course, it is also possible to use an antenna arrangement 11e shown in FIG. 4 with respect to the signal paths, in which the receiving antenna 37 positioned in the center of the antenna arrangement 11d is spatially surrounded by a plurality of transmitting antennas 39, 41. in this case, the receiving antenna 37 is preferably aligned directly with the filling material 5, and the transmitting antennas 39, 41 each have an orientation which is inclined relative to the orientation of the receiving antenna 37 and which is selected such that the directions defined by the dimensions of the transmitting antennas 39, 41 Transmission areas of the transmission antennas 39, 41 partially overlap and at least partially lie in the reception area of the reception antenna 37.

LIST OF REFERENCE NUMBERS

1 level gauge

3 containers

5 contents

7 Meter electronics

9 microwave generator

11 Antennenanordnuπg

13 transmitting antenna

15 receiving antenna

17 receiving antenna

19 microwave line

21 device

23 signal processing

25 transmission and reception separation

27 transmission ladder

29 receptionist

31 receiving antenna

33 transmitting antenna

35 transmitting antenna

37 receiving antenna

39 transmitting antenna

41 transmitting antenna

Claims

claims

1. Microwaves operating on the transit time principle level gauge (1) for level measurement of goods in containers, with

- A measuring device electronics (7) with a microwave generator (9) for the successive generation of different useful frequencies (f _m , f _n , f |) exhibiting micro dome signals (S _M , S _N , S _L ) ₁ and

a frequency-selective passive antenna arrangement (11a, 11b, 11c, 11d, 11e) connected thereto,

- Which has a plurality of antennas, which serve to transmit the different microwave signals (SM, S _N , SL) successively in the container (3), and whose back to the antenna arrangement (11 a, 11 b, 1 1c, Hd ₁ 11e) Echo signals (E _M , E _N , E _L ) to receive, - the more each for one of the different

Useful frequencies (f _m , f _n , fι) permeable frequency-selective elements (F _M , F _N , F _L ), esp. Bandpass filter has,

in the via the antennas and the frequency-selective elements (F _M , F _N , FL) for each of the different microwave signals (S _M , S _N , S _L ) and its echo signal (E _M , E _N , E _L ) a unique associated Prescribe signal path is transmitted via which this microwave signal in the container (3) and the antenna arrangement (S _M , S _N , S _L ) back reflected echo signal (E _M , E _N , E _L ) and supplied to the meter electronics (7) is, and - in the meter electronics (7) provided device (21), which assigns the successive incoming echo signals (E _M , E _N ) the associated Sägnalweg.

2. Level gauge according to claim 1, in which - one of the antennas is a transmitting antenna (13) which serves to transmit the different microwave signals (SM, S _N ) into the container (3),

- The other antennas are receiving antennas (15, 17), which serve, by Reffektionen in the container (3) to the antenna assembly (11 a, 11 b) back reflected echo signals (E _M , E _N ) of the different

To receive microwave signals (S _M , S _N ),

in the antenna arrangement (11a, 1b) of each receiving antenna (15, 17) a frequency-selective element (F _M , F _N ) permeable to one of the different useful frequencies (f _m , f _n ), in particular a bandpass filter, which serves to filter out from the received signal received by the respective receiving antenna {15, 17) the echo signal (E _M , E _N ) having this useful frequency (f _m , f _n ), and - the device (21) successively assigning the echo signals (E _M , E _N ) transmitted by the antenna arrangement (11a, 11b) to the measuring device electronics (7) to the receiving antenna (15, 17) from which they were received,

3. level measuring device according to claim 1, wherein - one of the antennas is a receiving antenna (37), which serves, by the reflections in the container (3) to the antenna arrangement (1 Id ₁ 11e) back reflected echo signals (E _M) E _N ) receive the different microwave signals (SM, S _N ),

- The remaining antennas transmit antennas (39, 41), which serve, each one of the different Microweüensignale (S _M , S _N ) in the

To send containers (3),

- In the antenna arrangement (11d, 11e) of each transmitting antenna (39, 41) for one of the different useful frequencies (f _m , f _n ) durchfässiges frequency-selective element (F _M , F _N ), esp. A band pass filter is connected upstream, the serves, from those generated by the microwave generator (9)

Microwave signals (S _M , S _N ) filter out the one that is sent in the measuring mode via the respective transmitting antenna (39, 41), and

the device (21) assigns the echo signals (EM, E _N ) successively transmitted from the antenna arrangement (11d, 11e) to the measuring device electronics (7) to the respective transmitting antenna (39, 41), from which the associated microwave signals (S _M , S _N ) was sent.

4. level gauge according to claim 1, wherein

- The antennas are transmitting and receiving antennas (31, 33, 35), which serve to send the different microwave signals (S _M , S _N , S _L ) in the container (3) and whose by reflections in the container (3) to receive back reflected echo signals (E _M , E _N , E _L ) to the antenna arrangement (11c),

- in the antenna arrangement (11c) of each transmitting and receiving antenna (31, 35, 37) for one of the different useful frequencies (f _m , f _n , f |) permeable frequency-selective element (F _M , F _N , F _L ), esp is assigned. a Bandpassfiiter, which serves from the microwave generator (9) of the antenna array generated (11c) supplied microwave signals (S _M, S _N, S _L) to filter out the one and the transmitting and receiving antenna (31, 33, 35) that is transmitted via this transmitting and receiving antenna (31, 33, 35), and which serves, from the from this transmitting and receiving antenna (31, 33, 35) received signal, the associated this useful frequency (f _m , f _n , fι) having echo signal (E _M , E _N , E _L ) out to filter, and

- The device (21) the successively from the antenna assembly (1 1 c) to the measuring device electronics (7) transmitted echo signals (E _M) E _N , EJ the transmitting and receiving antenna (31, 33, 35) assigns, via which the associated microwave signal (S _M , SN, S _L ) and its echo signal (E _M , E _N , EJ was received.

5. level gauge (1) according to claim 1, wherein the

Measuring device electronics (7) with the antenna arrangement (1 1a, 11c, 11d) is connected exclusively via a single waveguide (19), - via which the different micro dwell signals (S _M , SN, SJ of the

Meter electronics (7) to the antenna assembly (11a, 11 c, 11d) are transmitted and the echo signals (E _M , E _N , E _L ) from the antenna assembly (11 a, 11 c, 11 d) to the meter electronics (7) are transmitted, and

- the one in the antenna assembly (11 a, 11 c, 1 1 d) provided transceiver separation (25) to all transmitting antennas (13, 31, 33, 35, 39,

41) and to all receiving antennas (15, 17, 31, 33, 35, 37) is connected.

6 level gauge (1) according to claim 2 or 3, wherein

- the Messgeratelektronik (7) with the antenna assembly (11 b, 1 1e) via a Sendewelienieiter (27) is connected, via which the transmitting antennas (13, 39, 41) with the different micro Weilensignale (S _M , S _N ) are fed and

- The meter electronics (7) to the antenna assembly (11 b, 1 1 e) via a receiving waveguide (29) is connected via which the echo signals (E _M , E _N ) from the antenna assembly (11 b, 11 e) to the measuring device electronics ( 7)

7. level gauge according to claim 2, wherein

- The receiving antennas (15, 17) are arranged in a group spatially adjacent to each other, and - the transmitting antenna (13) is arranged spatially outside the group

8 Fullstandsmessgerat according to claim 3, wherein

- The transmit antennas (39, 41) are arranged in a group spatially adjacent to each other, and - the receiving antenna (37) is arranged spatially outside the group.

9. Fuillstandsmessgerat according to claim 2, wherein

the receiving antennas (15, 17) spatially surround the transmitting antenna (13),

- The transmitting antenna (13) on the contents (5) in the container (3) is aligned, - The receiving antennas (15, 17) each have a relation to the orientation of the transmitting antenna (13) inclined orientation, and

- The by the orientations of the receiving antennas (15, 17) predetermined by the respective receiving antenna (15, 17) covered receiving areas of the individual receiving antennas (15, 17) partially overlap.

10. level gauge according to claim 3, wherein

the transmitting antennas (39, 41) spatially surround the receiving antenna (37),

- The receiving antenna (37) is aligned with the filling material (5) in the container (3),

- The transmit antennas (39, 41) each have a relative to the orientation of the receiving antenna (37) inclined orientation, and

- The by the orientations of the transmitting antennas (39, 41) predetermined transmission ranges of the individual transmitting antennas (39, 41) at least partially lie in the receiving area of the receiving antenna (37) and partially overlap.