WO2014090565A1 - Fill state measuring device - Google Patents

Abstract

The invention relates to an antenna, which can be produced inexpensively and which can be used in a versatile manner, for a fill state measuring device which operates according to the transit-time principle using microwaves or for a device for checking emission, reception, transmission, and/or signal generation properties of units (71) designed for microwaves. The antenna comprises at least one individual antenna which is provided on a flat dielectric support (11) and which has a dipole (15, 19, 21) provided on the support (11). The individual antenna has at least 10, in particular 20 - 40, linear directors (17) which are mounted upstream of the dipole (15, 19, 21) in an antenna (5, 57) emission direction (X) running perpendicularly to the surface normal on the support (11), which are arranged on the support (11) one behind the other in the emission direction (X) and in a mutually spaced manner, and which are oriented parallel to one another and perpendicular to the emission direction (X), and the individual antenna has reflectors (31, 33) arranged on a dipole (15, 19, 21) face opposite the emission direction (X).

Description

 level meter

The invention relates to an antenna for working with microwaves on the transit time principle level gauge for measuring a level of a filling material in a container or for a device for metrological detection of transmission, reception, transmission and / or signal generation properties of microwaves

designed units.

Level measuring devices operating with microwaves according to the transit time principle are used, for example, in measurement and control technology as well as in industrial applications

Process automation, used to measure fill levels of a product in a container.

The filling level determination according to the transit time principle is based on the fact that transmission signals are transmitted by means of an antenna in the direction of the product surface, and their signal components reflected at the product surface are received by means of an antenna as receiving signals after a runtime dependent on the level to be measured. In this case, the transit time is determined based on the transmit and receive signals, which have needed the signals for the way to the product surface and back. Based on the measured transit time and the propagation speed of the microwave signals, the distance between the level gauge and the product surface is calculated, from which then the level is determined at a known installation height of the measuring device above the container. To determine the transit times, all known methods can be used, which allow relatively short distances by means of reflected

To measure microwave signals. The best known examples are pulse radar and frequency modulation continuous wave (FMCW) radar. To the level measurement as unimpaired from the side in the container

built-in interferers, e.g. Container installations or other measuring devices to perform, antennas are preferably used, the emission characteristics have a single dominant main lobe with the smallest possible opening angle. Very often, horn antennas fed via a coaxial line are used for this purpose. These include a microwave to be fed via a coupling

Waveguide segment, usually a circular waveguide to which a in

Transmitting direction opening funnel connects. In this case, however, the opening angle of the forming main lobe is greater, the smaller the diameter of the

Waveguide segment is. To achieve a small opening angle of the main lobe Consequently, the waveguide segment must have a comparatively large diameter. The openings in the container into which the antenna is inserted must be correspondingly large. The operators of industrial plants, however, esp. For security reasons, strives to keep the required nominal widths of the container openings as low as possible.

Another disadvantage of horn antennas is that the couplings fed by horn antennas are comparatively large, typically metallic, components which must be machined with high precision in order to produce the desired ones

To ensure signal transmission characteristics. Couplings are accordingly expensive custom-made products.

In addition, it is known from level measurement to use antennas with planar antenna structures applied to a carrier, such as e.g. Patch antennas, use. In this case, the planar antenna structure is applied to an upper side of a dielectric substrate, the underside of which is provided with a metal coating lying regularly to ground. These antennas emit microwave signals perpendicular to the carrier plane to which the planar antenna structure is applied. They have the advantage that they can be manufactured inexpensively and mechanically with high precision. However, individual patch antennas regularly have a comparatively weak one

Directional effect, so that in order to achieve an improved directional characteristic regularly a large number of patch antennas operated in parallel must be used. For this parallel connection, a distribution network is required, which leads to additional losses, which increase proportionally per individual antenna with increasing number of parallel-operated patch antennas. This results in an asymptotic limit for the increase in the value achieved by interconnecting many individual patch antennas

Antenna gain.

Since the antenna structures are regularly mechanically sensitive, they are preferably inserted into a protective waveguide segment. Just like that

 Waveguide segments of horn antennas should also these waveguide segments have the largest possible diameter, so that a main lobe can be achieved with the smallest possible opening angle. Since the 1920s, a then developed by the Japanese Hidetsugu Yagi and Shinataro Uda antenna principle is known in which a dipole is used, which are preceded in the transmission direction, a number of parallel to the dipole, parallel to each other and perpendicular to the direction of transmission directors. These also known under the name Yagi-Uda antennas are usually wise in

Frequency ranges of 10 - 2500 MHz, used in amateur radio, for example. They only point a few directors, eg 3 to 5 directors, and are in the amateur radio area with

Dimensions on the order of one or several meters very large.

In addition, on a printed circuit board applied for frequencies of up to 2450 MHz designed undirected Yagi Uda antennas Kent Electronics on the market, which can be used for example in wireless transmission systems, RFID systems or satellite dishes. These have a force applied to the circuit board via an asymmetric line powered dipole, which are upstream of up to three directors.

However, these antennas are not used in level measurement, since there is a directed, preferably highly concentrated radiation of the microwave signals is required, and the microwave signals have significantly higher frequencies. typical

 Frequencies in the pulsed radar level measurement method today are in the range of 5 GHz - 80 GHz, e.g. at 6.3 GHz, 10 GHz, 25.5 GHz or 78 GHz. However, it is quite conceivable that as the development of high frequency technology progresses, even higher frequencies, e.g. 1 10 GHz, can be used.

It is an object of the invention to specify an antenna which can be produced cost-effectively and is suitable for use in level measurement technology.

For this purpose, the invention comprises an antenna for a microwave after

 Runtime principle working level gauge for measuring a level of a filling material in a container or for a device for checking transmission, reception, transmission and / or signal generation properties of a

 Microwaves designed unit, with

 at least one individual antenna provided on a planar dielectric support,

having a dipole provided on the support,

 having at least 10, in particular 20-40, the dipole in a direction perpendicular to the surface normal to the carrier extending transmission direction of the antenna upstream, in the transmission direction one behind the other and spaced on the support arranged, parallel to each other and perpendicular to the transmission direction aligned, line-shaped directors and

 - The arranged on one of the transmission direction opposite side of the dipole

 Reflectors has.

According to a first embodiment, the reflectors comprise

 - On a top and / or bottom of the carrier arranged electronic

Components, and / or - On the top and / or bottom of the carrier arranged electrically conductive or provided with a conductive coating, wall segments, esp. Metallic or metallized wall segments, sheets or housing wall portions of the respective individual antenna surrounding housing, and / or

- On the top and bottom of the carrier arranged line structures

 connecting vias.

According to a first variant of the invention

 the carrier consists of a carrier material having a dielectric constant less than or equal to 3.5, or

 the carrier has a base,

 - Is arranged on the one layer of a carrier material having a dielectric constant less than or equal to 3.5, and

 - The base has a recess in an area in which the directors are arranged on the carrier.

According to a second variant of the invention

 - The carrier consists of a carrier material having a dielectric constant greater than or equal to 4 and less than 10, and

 - The carrier points to its side facing away from the dipole side of the directors in front of the

 Directors an end region whose width decreases continuously in the transmission direction of the antenna.

Furthermore, the invention comprises embodiments in which

- The dipole a closed Faltdipol, esp. On a top of the carrier

 applied folding dipole, is, or

 - The dipole an open elongated dipole, especially one on an upper side of the carrier

 applied open elongated dipole, is. According to a first embodiment

 - Serves at least one of the individual antennas for transmitting microwave signals

 and / or for receiving received signals containing frequencies of a predetermined frequency range, and

 - At least one of these individual antennas is designed such that

- in whose carrier at the ends of the directors connected with the directors

 Vias are provided

- Are provided in the carrier at the ends of the directors located on the top of the carrier with the directors connected vias and the directors on the underside of the carrier to the vias the directors on the underside of the carrier end perpendicular to the transmission direction Fortsätze, esp. Fortsungen with a length of less than one-eighth of the

 Free space wavelengths of the microwave signals, are provided

 - the lengths of their directors and their distances from each other along the

 Transmit direction across the length of the antenna vary, or

- It is designed as a logarithmic antenna.

According to a second embodiment

 - At least one of the individual antennas for transmitting microwave signals of a predetermined frequency and / or for receiving received signals of the predetermined frequency, and

 - These individual antennas are designed such that

 - whose directors are the same length, and

 - the distances between each directly adjacent directors of these

 Single antennas are all the same size.

According to a development, two or more individual antennas are arranged on a common carrier next to each other or completely or partially overlapping.

According to another embodiment

- The individual antennas are juxtaposed parallel operated designed for the same frequency or the same frequency range individual antennas, or

- The individual antennas are juxtaposed individually operated for

 different frequencies or different frequency ranges designed individual antennas, or

- The individual antennas are wholly or partially overlapping arranged individually operated designed for different frequencies or different frequency ranges individual antennas.

In addition, the invention comprises a working with microwaves on the transit time principle level gauge with an antenna according to the invention.

According to a first development of this level gauge

 - The antenna is arranged in a housing, and

 - The housing is sealed in the transmission direction of the antenna to the outside through a dielectric window, esp. A window designed as a dielectric lens.

According to a second development of this level gauge

is on the support of the antenna, a high-frequency module, esp. A

High frequency assembly for receiving and / or processing with the antenna received signals received and / or for generating via the antenna to be transmitted microwave signals arranged.

According to a third development of this level gauge

- The antenna has a balanced antenna connection, and

 - The balanced antenna connection is via a balun to an asymmetric

 Connecting cable or an asymmetrical connection of the high-frequency module connected. According to a fourth development of this fill level measuring device, the antenna feeds a waveguide segment which, in the transmission direction, merges into a funnel which widens in the transmission direction.

 In addition, the invention comprises a device for the metrological detection of transmission, reception, transmission and / or signal generation properties of units designed for microwaves, in particular of high-frequency assemblies of

 Microwaves according to the transit time principle working level gauges or connected to a transmitting and / or receiving unit antennas of working with microwaves on the transit time principle level gauges, with

 - At least one antenna according to the invention, and

a receiving device for receiving the unit,

 - In which the receiving device and the antennas are arranged relative to each other such that the transmission directions of the antennas facing in the receiving unit in the direction of the unit. The antenna according to the invention has the advantage that the directivity of the antenna is essentially determined by the number of directors, and thus by their length. Accordingly, the antenna can have comparatively small dimensions perpendicular to the transmission direction, without its directional characteristic thereby being impaired. The antenna can thus be used in very small container openings.

In addition, can be very compact with the antenna according to the invention

Level gauges are built by the antenna and RF assembly are integrated in a compact module.

It is particularly advantageous that the radio-frequency module and the antenna can be arranged on a single carrier. This eliminates the need to connect antenna and high frequency assembly via usually expensive and sensitive connectors and / or high-frequency cables together. Due to the compared to connectors almost reflection-free connection of the antennas according to the invention to the high-frequency modules, the

Level measurement increases available power, and improves the signal-to-noise ratio. In addition, this significantly less affect the measurement impairing multiple reflections, as esp. By reflections on the

 Connections are on, and the signal paths are significantly shorter. Thus, in the vicinity of the antenna according to the invention, it is also possible to measure fill levels of contents which have a lower dielectric constant difference

Dielectric constant of the ambient atmosphere, and thus have a lower reflectivity.

Another advantage of the invention is that the antenna is inexpensive to produce compared to horn or rod antennas. In this case, only manufacturing steps are required for the production of the antenna, which in the manufacture of the

Hochfrequenzbaugrupe the level gauge are running anyway.

Another advantage is that the antenna structure, in particular the dipole and the directors, can not only be applied cost-effectively to the carrier, but above all can be manufactured with high precision.

The invention and further advantages will now be described with reference to the figures of the drawing, in which five embodiments of antennas according to the invention, a fill level measuring device according to the invention and a device according to the invention for the metrological detection of transmission, reception, transmission and / or

Signal generation properties of designed for microwave units are explained in more detail; like parts are provided in the figures with the same reference numerals.

Fig. 1 shows: a level measuring arrangement;

Fig. 2 shows: an upper side of a arranged on a support one

 Folding dipole comprehensive antenna;

Fig. 3 shows an underside of the carrier of Fig. 2;

Fig. 4 shows: an upper side of a arranged on a support one

 elongated dipole antenna;

5 shows an upper side of an alternative embodiment of one

a carrier arranged a folding dipole comprehensive Antenna;

Fig. 6 shows an underside of the carrier of Fig. 5;

Fig. 7 shows four each having a base and a layer applied thereon

 a carrier comprising carrier;

Fig. 8 shows a housing sealed by a dielectric window

 with an antenna located therein;

Fig. 9 shows: a horn fed by an antenna;

Fig. 10 shows: an antenna inserted into a waveguide segment of a horn; Fig. 1 1 shows: a four arranged on a support individual antennas

 having antenna;

Fig. 12 shows: a two nested on a support

 arranged single antenna antenna; and

FIG. 13 shows a device for metrological detection of transmission, transmission, reception, transmission and / or transmission

 Signal generation properties of microwaves

 designed units.

1 shows a schematic representation of a filling level measuring arrangement for measuring a filling level L of a filling material 1 in a container 3.

 It comprises a mounted on the container 3 in an installation height H related here with respect to the container bottom working with microwaves according to the transit time principle

Level Meter.

The fill level measuring device has an antenna 5 according to the invention, which serves to send microwave signals S in the direction of the medium 1 in the measuring device, and to receive the signal components reflected back on the product surface 7 back to the antenna 5 as received signals R after a time dependent on the filling level L. In the present case, the invention is described using the example of a measuring device which has a single antenna 5, which serves both to transmit the microwave signals S and to receive the received signals R. Alternatively, two separate antennas formed according to the invention could also be provided, one of which serves for transmission and the other for reception. The antenna 5 is connected to a high-frequency module 9, via which it is fed with the microwave signals S to be transmitted, and they are the incoming

Receiving signals R for further processing and / or processing supplies. to

Generation of the transmission signals S and for processing and / or processing of

Receiving signals R can be used from the prior art in connection with conventional pulse radar or FMCW level gauges known devices and methods. The microwave signals S have frequencies in the gigahertz range. Typical frequencies in the pulsed radar level measurement method today are in the range of 5 GHz - 80 GHz, e.g. at 6.3 GHz, 10 GHz, 25.5 GHz or 78 GHz. However, it is quite conceivable that even higher frequencies can be used as the development of high-frequency technology progresses.

According to the invention, the antenna 5 comprises at least one individual antenna, which has a dipole provided on a planar dielectric support, the transmission direction X of which extends perpendicular to the surface normal to the support

Single antenna at least 10, preferably 20-40, arranged one behind the other and spaced apart on the support, parallel to each other and perpendicular to the

Transmitting X aligned, line-shaped directors are upstream, and which has at least one arranged on one of the transmission direction X opposite side of the dipole reflector.

If the antenna 5 only comprises a single antenna, the transmission direction X corresponds to the individual antenna of the transmission direction of the antenna 5. If several individual antennas are used, these are to be aligned for use in a level gauge such that their transmission directions X are parallel to one another and thus parallel to the transmission direction of the entire antenna 5 lost.

Although the present description of antenna according to the invention mainly speaks of the transmission direction X, these antennas can of course also be used for reception, the reception direction then - as always with passive antennas always the case - in the direction of transmission X opposite direction.

The invention is first described with reference to several embodiments of each having only a single antenna antennas 5.

FIGS. 2 and 3 show a first exemplary embodiment of a single antenna arranged on the planar dielectric support 11. 2 shows a view of an upper side and FIG. 3 shows a view of an underside of the carrier 11. On the upper side of the carrier 11, a dipole 15, which is fed via a symmetrical antenna connection 13, is provided.

In the illustrated embodiments, the carrier 1 1 is provided isolated. However, the carrier 1 1 can also form a layer of a multilayer printed circuit board. In the case is above and / or under the carrier 1 1 at least one more

Printed circuit board layer.

The illustrated dipole 15 is a Faltdipol, which is applied in the form of correspondingly shaped conductor tracks on the support 1 1.

 On the side of the dipole 15 pointing in the transmission direction X of the antenna 5, line-shaped directors 17 aligned parallel to each other and parallel to the longitudinal axis of the dipole 15, designated here by Y, are arranged in front of the dipole 15. The directors 17 are preferably narrow straight on the carrier 1 1 applied conductor track sections. The dipole 15 and the directors 17 are preferably applied to the carrier 1 1 metallic structures, esp. Of copper, nickel-plated and then gold-plated copper or tinned copper. Metallic structures offer the advantage of being compatible with circuit board fabrication techniques, e.g. can be manufactured using etching processes, cost-effective and, above all, high-precision.

The dipole 15 and the directors 17 can - as shown here - be applied in a plane on the support 1 1. Alternatively, however, it would also be possible to apply them to different parallel, adjacent surfaces, e.g. on adjacent surfaces of individual

PCB layers of a multilayer printed circuit board, apply.

In the transmission mode, the directors 17 are excited by the radiation emitted by the dipole 15. With appropriate dimensioning takes place in the over the central regions of the directors 17 extending transmission direction X, a phase and direction-dependent superposition of the outgoing from the dipole 15 and the individual directors 17

Radiation shares instead, while the individual radiation components to the

Increasingly overshadowing the peripheral areas of the directors 17.

The resulting in the transmission direction X bundling the radiated

Microwave signals can be further increased to some extent by increasing the number of directors 17 placed one behind the other in the transmission direction X. This additional bundling causes a reduction of the opening angle of the main lobe. To achieve a sufficient for the level measurement bundling, according to the invention at least 10 directors 17, but preferably 20 - 40 directors 17, are provided. In contrast to conventionally used in the level measurement technology antennas in which a reduction of the antenna aperture regularly with a magnification required for the introduction of the antenna in the container

Cross-sectional area is connected, the individual antenna according to the invention is thereby only longer. However, this does not lead to an enlargement of the required for the introduction of a single antenna having inventive antenna 5 in the container 3 required nominal diameter of the opening in the container. 3

In contrast to patch antennas, no metallic coating is deliberately applied to the underside of the carrier 11 under the antenna structure here. Such a coating would lead to an enlargement of the parallel to the surface normal to the carrier 1 1 forming signal components and thus counteract the desired bundling of the signals in the transmission direction X of the antenna 5 and thus perpendicular to the surface normal to the carrier 1 1. Figures 4 to 6 show alternative embodiments of the antenna 5. Due to the broad agreement with the embodiment described above, only the existing differences are explained in more detail below.

4 shows an upper side of a first alternative exemplary embodiment of the antenna 5. In contrast to the exemplary embodiment illustrated in FIGS. 2 and 3, here an elongate dipole 19 applied to the upper side of the carrier 11 is provided.

Fig. 5 shows an upper side and Fig. 6 shows an underside of a second alternative

Embodiment. Just as in the illustrated in Figures 2 and 3

Embodiment, the dipole 21 provided here is designed as a folded dipole. in the

In contrast to the embodiment shown in Figures 2 and 3, this, however, does not run on the support 1 1, but in a direction perpendicular to the plane of the support 1 1 extending plane. For this purpose it comprises two perpendicular to the top

Transmission direction X extending line segments 23, whose center of the carrier facing ends over parallel and opposite to the transmission direction X extending

Line segments 25 are connected to the symmetrical antenna terminal 13, and the outer ends of the carrier facing each connected via a through the carrier 1 1 passing through hole 27 with a running on the underside of the support 1 1 perpendicular to the transmission direction X line segment 29, which are the two Through contacts 27 connects to each other. According to the invention, the individual antennas have reflectors arranged on the side of the respective dipole 15, 19, 21 facing away from the transmitting direction X on the top and / or bottom side, preferably on the top and bottom sides of the carrier 11

31, 32, 33. The reflectors 31, 32, 33 cause the bundling of the transmission power takes place exclusively in the desired transmission direction X. Without reflectors 31, 32, 33, the directors 17 would cause bunching in the desired transmission direction X and in the opposite spatial direction -X. As a result, only half of the

Transmission power in the desired transmission direction X available and the reception

Antenna gain would be only half as big. In addition, contrary to

desired transmission direction X emitted microwave signals interference or

 Impairment of arranged in this direction behind the individual antenna

 Instrument components, esp. Of regularly high-frequency interference signals very sensitive high-frequency module 9 cause. In the variant shown in Figures 2 and 3, as an example, reflectors 31, are provided which, seen on the corresponding sides of the carrier 1 1 against the transmission direction behind the dipole 15 in a parallel to

Dipollängsachse Y extending row arranged electronic components exist. The components are preferably SMD components. Particularly suitable for this purpose are components which have a highly reflective, comparatively large dielectric core, such as e.g. Resistors and capacitors.

In the embodiment shown in Fig. 4 are as reflectors 32 on the

Top side of the carrier 1 1 applied electrically conductive or provided with an electrically conductive coating - here only schematically illustrated - wall segments, e.g. metallic or metallized wall segments, provided. These may alternatively or additionally also be arranged on the underside of the carrier 11, which is not shown here. The wall segments are for example on the top and / or bottom of the carrier 1 1 arranged sheets, or metallic or metallized

Housing wall areas of a housing surrounding the individual antenna.

Alternatively or additionally, reflectors 33 shown in FIGS. 5 and 6 can be used. These reflectors 33 are formed by feedthroughs 35 passing through the carrier 11, which are arranged distributed along wide line structures 37 running parallel to the dipole longitudinal axis Y on the upper side of the carrier 11, and arranged underneath on the underside of the carrier 11 connect wide line structures 39. The vias 35 can

For example, as shown here, in a row, or arranged in a plurality of staggered rows. The distances between the side walls of the plated-through holes 35 to the side walls of each closest thereto Through contact 35 as possible less than a quarter of the wavelength λ of

 Microwave signals in the free space, and preferably less than one-eighth of the

 Wavelength λ of the microwave signals in the carrier material. The carrier 1 1 preferably consist of a low dielectric conductivity having, preferably low-loss, carrier material. In connection with the above-mentioned signal levels in the gigahertz range which are typical for level measurement, in particular in the range from 5 to 80 GHz, carriers 11 are preferably made of one

Used carrier material that is as low loss, and preferably a low dielectric constant ε _Γ , esp. A dielectric constant ε _Γ of less than or equal to 3, 5 has. For this purpose, for example, polytetrafluoroethylene ceramic circuit boards, as sold by Rogers, for example, under the names RO3003 and RO4003 are suitable.

In conjunction with carriers 1 1 with a low dielectric constant ε _Γ , it is advantageous if the carriers 1 1, at least in the region of the directors 17, have the smallest possible thickness, in particular a thickness of 50 μm to 700 μm. However, carrier materials with a low dielectric constant ε _Γ are regularly mechanically sensitive, since they usually contain little or no reinforcing glass fiber fabric. In cases where a correspondingly thin carrier 1 1 would not have sufficient mechanical stability due to the selected carrier material, a carrier 1 1 'can alternatively be used, which has a mechanically stable base 41, for example a conventional printed circuit board, to which a thin Layer 43 is applied from a low dielectric conductivity having preferably low-loss material. Four denoted by a) to d)

Embodiments of such carriers 1 1 'are shown in Fig. 7. The directors 17 of the antenna 5 can now - as shown in the embodiments a) and d) - on the side remote from the base 41 top of the layer 43, or - as in the embodiments b) and c) shown - on the base 41st facing bottom of the layer 43 may be arranged.

To achieve a low support thickness in the region of the directors 17, the base 41 in the area over which the directors 17 are located preferably has one

Recess 45 on. If the mechanical stability of the layer 43 allows this, the recess 45 can reach up to the layer 43 above it and release it. This is in the

Exemplary embodiments a) and b) are shown. In this case, the base 41 may also be made of metal. Alternatively, the recess 45 is to be dimensioned such that between the layer 43 and the

Recess 45 remains a thin layer 47 of the base material remains. This is in the

Embodiments c) and d) shown. The layer 47 preferably has a thickness less than or equal to 250μιη.

In this case, the embodiment c) has the advantage that the directors 17 are enclosed between the layer 43 and the layer 47. The directors 17 are thus protected against oxidation. They can thus be made of a, in view of the skin effect advantageous, highly conductive metal, esp. Pure copper, that must be nickel-plated and gold-plated or tinned to avoid oxidation.

Alternatively, instead of a thin carrier 1 1 of a carrier material with low dielectric conductivity or coated with such a material carrier 1 1 'a thicker carrier 1 1 "are used from a more stable carrier material.

In this case, the support 1 1 "to increase the directivity of the antennas according to the invention 5 preferably the transmitting side, ie on the side facing away from the respective dipole 15, 19 side of the directors 17 in front of the directors 17, equipped with an end portion 49 whose width in the transmission direction X continuously decreases This variant is shown in the embodiment shown in FIG.

 The end region 49, which tapers in the transmission direction X, effectively acts like a

dielectric lens through which the outgoing microwave signals experience additional focusing in the transmission direction X. It is with regard to the lens effect of the end portion 49 of advantage, a carrier material with a comparatively high

Dielectric constant ε _Γ use. The dielectric constant ε _Γ is preferably between 4 and 10 with regard to the lens effect.

The dimensioning of the antenna 5, esp. Of the dipole 15 and the directors 17 takes place in principle according to the criteria applicable to conventional Yagi-Uda antennas. The dimensioning is based on the type of level measurement used

Adapted to microwave signals.

The dimensioning is based on the wavelengths λ, which form the microwave signals S along the carrier 1 1. This is determined by the in the

Microwave signals contained frequencies and the relative permittivity ε, - of the

Carrier material determined.

In the pulse radar level measurement method, short microwave pulses of predetermined duration and signal frequency f are periodically transmitted at a predetermined repetition frequency. Accordingly, the dimensioning of the used signal frequency f designed. For comparatively long pulse durations, eg pulse durations greater than or equal to 10 nsec, the microwave signal S to be transmitted as well as the associated one contain

Receive signal R substantially only a known signal frequency f _. In that case, the dipole 15, 19 or 21 preferably has a length of the order of half a wavelength λ / 2. The directors 17 are preferably all the same length and slightly shorter than the dipole 15, 19 and 21, respectively. The distance from the dipole 15 to the nearest director 17 is on the order of 0.15 wavelengths λ, and the distances between any two adjacent directors 17 are preferably all the same and on the order of about 0.1 to 0.2 wavelengths λ , These

 Lengths refer in each case to the wavelength λ, which form the microwave signals of the predetermined frequency f in the free space.

The FMCW radar level measurement method uses continuously transmitted periodically frequency-modulated microwave transmission signals. Consequently, significantly broadband individual antennas are advantageous here.

An increase in the broadband can be achieved by

At both ends of the directors 17, a through-hole D is provided in each case. These vias D are in that shown in Figs. 2 and 3

 Embodiment schematically indicated by punctiform terminations.

To further increase the bandwidth can additionally on the illustrated in Fig. 3 underside of the carrier 1 1 to the vias D subsequent, the directors 17 on the underside of the carrier 1 1 end perpendicular to the transmission direction X.

continuing, extensions F are provided. These preferably have a short length of less than one eighth of the free-space wavelengths of the ones to be transmitted

Microwave signals on. A further increase in the bandwidth can additionally be effected by slightly varying the lengths L of the directors and their distances from one another over the length of the antenna 5. To achieve even greater broadband the individual antennas are preferably formed as logarithmic periodic antennas. In this case, the distance between adjacent directors in the transmission direction increases in each case by a constant amount, for example according to: d _{n +} = ke ^to d _n , where d _n respectively the distance between the η + 1-th and the n-th in front of the dipole 15, 19 and 21 respectively, while the length L of the directors in the transmission direction decreases in each case by a constant factor θ with θ <1, eg according to: L _{n +} = L ₀ θ ^η . In order to ensure an undisturbed by the environment of the antenna 5 training the microwave signals to be transmitted, it is sufficient for antennas 5 with only one

Single antenna on both sides of the directors 17 each one reflectorless as possible

Provide area with dimensions on the order of a quarter of the wavelength λ of the microwave signals in the free space. This is preferably done by the

Carrier 1 1 is formed correspondingly wide. With a length of the directors 17 of half a wavelength λ / 2, the total width of the carrier 1 1 is therefore at least one wavelength λ. Accordingly, the antennas 5 designed according to the invention are not only extremely flat, but also have a very narrow width when using a single individual antenna.

For a single individual antenna having antenna 5 with 28 directors 17 and a substrate with a dielectric constant ε _Γ of 3 thus results in a

 Pulse radar with a frequency f of 6.3 GHz antenna width (perpendicular to the transmission direction X) in the order of 2 cm and an antenna length (parallel to the transmission direction X) in the order of 27 cm. At a frequency f of 10 GHz, the antenna width is of the order of 1.5 cm and the antenna length is 28 cm in the order of 17 cm for 28 directors 17. At a frequency f of 25.5 GHz, the antenna width is of the order of 5 mm and the antenna length of 28 directors 17 is of the order of 7 cm. At a frequency f of 78 GHz, the antenna width is on the order of 2 mm and the antenna length is on the order of 2 cm.

Antennas 5 with such small dimensions offer the advantage that they can be used on the container 3 in openings with a correspondingly small nominal diameter. To achieve the most compact level measuring device, the antenna 5 and the high-frequency module 9 to be connected thereto are preferably integrated in a single module. For this purpose, the high-frequency module 9 can be arranged directly on the carrier 11 or on or in a carrier 11 comprising the multilayer printed circuit board. This is shown in FIGS. 2 and 5.

Due to the two inputs of the dipole 15, 19 and 21, the antenna terminal 13 is a balanced terminal. If the high-frequency subassembly 9 also has a symmetrical connection, it can be placed directly on the carrier 11

symmetrical antenna connection 13 are connected. This embodiment is shown schematically in FIG. If, however, an asymmetrical connection to an asymmetrical line or an asymmetrical connection is required for the connection of the high-frequency module 9, a corresponding converter must be provided between the antenna connection 13 and the high-frequency module 9. For this purpose, a balun 51 is preferably used. This is shown by way of example in FIG. 5. There, the balun 51 transfers the balanced connection lines of the antenna terminal 13 to a

Microstrip line. This comprises a conductor 53 connected to the balun 51 on the upper side of the carrier 11, and a planar metallization 55 applied underneath the carrier 1 1 underneath.

In both variants, the arrangement of antenna 5 and high-frequency module 9 on the common carrier 1 1 has the advantage that for connecting the antenna 5 to the high-frequency module 9 no expensive and usually expensive

Plug connections are required.

Plug-in connections inevitably reflect some of the transmitted power, typically on the order of 0, 3% to 10.0%. This reflected portion is no longer regularly available for the actual measurement. Signal components attributable to reflections or multiple reflections between the antenna and the radio-frequency module are superimposed during level measurement

Close range of the antenna in front of the antenna reflected portions of the actual

 Measurement signals. This increases the signal-to-noise ratio in the near range. Depending on the embodiment, thereby the level measurement in a near range of 0 m up to

 2 meters in front of the antenna impaired.

Due to the almost non-reflection here compared to connectors

Connection of the antenna 5 according to the invention to the high-frequency subassembly 9 thus increases the available power for level measurement, and significantly improves the signal-to-noise ratio in the vicinity of the antenna 5. Thus, in the vicinity of the antenna 5 according to the invention, it is also possible to measure fill levels of products 1 which have a lower dielectric constant ε _Γ , and thus a lower reflectivity. Examples of such fillers 1 are oil, plastic granules, or wheat or grain bran. While for measuring a level of an oil with a dielectric constant ε _Γ of 1, 5 with a working at 25.5 GHz pulse radar level gauge with a

Horn antenna regularly a horn diameter of about 100 mm and a horn length of about 450 mm is required, an antenna according to the invention 5 with a comparable measurement accuracy can be achieved with 30 directors 17 a length of 5.5 mm only a total width of slightly more than 12 mm and a length of about 80 mm. Due to the small dimensions of the antennas 5 described above, very compact level gauges can be constructed.

In this case, the antenna 5 is preferably introduced into a compact housing 57, in whose transmission-side end face a dielectric window 59 is inserted. These

Embodiment is shown in Fig. 8. In the housing 57, the high frequency assembly 9 is preferably housed.

 The window 59 consists of a microwave-permeable insulator of

preferably gas-tight and preferably pressure-resistant inserted into the front page. Particularly suitable for this purpose are windows made of pressure-resistant glass, polypropylene (PP), polytetrafluoroethylene (PTFE) or ceramic.

 In this way, a gas-tight flameproof enclosure of antenna 5 and

High-frequency module 9 causes, as for example for use in

explosive areas is required.

In this case, additional bundling or parallelization of the transmitted from the antenna 5 microwave signals S can be achieved, in which the window 59 - as shown here - is formed as a dielectric lens. Alternatively or additionally, a separation of the antenna 5 from the running in the container 3 process can be effected by the otherwise exposed

Components of the antenna 5 are embedded in a potting compound.

However, the described antennas 5 can be mounted directly on, in or above a corresponding container opening, if safety requirements permit this at the place of use.

Alternatively, the described antennas 5 can be used to feed a horn 61 to be mounted on the container 3. Two examples of this are shown in FIGS. 8 and 9. In both examples, the horn 61 in each case has a waveguide segment 63, which merges in the transmission direction X into a funnel 65 which widens in the transmission direction X.

In the variant illustrated in FIG. 9, the antenna 5 is arranged outside the waveguide segment 63. In the variant shown in Fig. 10, the antenna 5 is in the

Waveguide segment 63 introduced.

Depending on the application and intended use of the antenna according to the invention, it may have two or more of the individual antennas described above. To increase the directivity and the transmission power, this antenna 67 comprises a plurality of side by side on a support 1 1 arranged parallel preferably identical individual antennas 69, each having a dipole 15 and a plurality of this upstream directors 17 have. In the illustrated embodiment, the antenna shown in Figure 2 were used as individual antennas 69. Alternatively, of course, other embodiments according to the invention

Single antennas are used. In addition, to further increase the directivity and the transmission power and several of these antennas 67, or even a plurality of individual antennas are arranged one above the other and operated in parallel.

Today's level measurements are made regularly using microwave signals of a single predetermined frequency or a single predetermined narrow

 Frequency band. However, there are also applications where it is advantageous

Perform level measurements at different frequencies.

Application examples for this are described in the German patent application DE 10 2008 048582 A1 of the applicant. The range of applications extends from plausibility checking, which compares measurement results from measurements taken at different frequencies, to measurement techniques that use measurements taken at different frequencies

Additional information derived. The latter can be determined, for example, on the basis of the frequency dependence of the reflection properties of the medium, which are reflected in the amplitudes of the received signals. A field of application here are level measurements of products that tend to form films. This occurs e.g. in applications in which the product contains different density media that separate with time. In these applications, preferably a level gauge with a

used according to the invention, which consists of a corresponding number of each designed for one of the different frequencies or the different frequency ranges initially described individual antennas. The individual antennas can also be arranged side by side on one and the same carrier 11 as in the antenna 67 shown in FIG. 11. However, unlike the embodiment shown in FIG. 11, they are then not operated in parallel, but independently of one another. Alternatively, the individual antennas can be arranged parallel to one another and at least partially overlapping. FIG. 12 shows an exemplary embodiment for this, in which two individual antennas designed for different frequencies are arranged so that they overlap each other in a completely overlapping manner. Here, the dipole 15a of the higher frequency single antenna within the dipole 15b is the lower one

Frequency-designed single antenna arranged. Each dipole 15a, 15b is in

 Transmission direction X each have a set of associated directors 17a, 17b upstream. The two

Dipoles 15a, 15b and the associated directors 17a, 17b are arranged along a common antenna longitudinal axis running in the matching transmission directions X of the two individual antennas. In this way, two nested individual antennas, but together do not need more space than the designed for the lower frequency single antenna.

Alternatively, the individual antennas can of course also be arranged offset parallel to one another in such a way that their directors only follow one another in a partially overlapping manner in the transmission direction X.

However, the use of the antennas according to the invention is not limited to the

Level measurement limited. Antennas according to the invention are also suitable, in particular, for the metrological detection of transmitting, receiving

Transmission and / or signal generation properties

microwaved units 71, such as

High-frequency assemblies 9 of working with microwaves on the transit time principle level gauges, or from to a transmitting and / or receiving unit

connected antennas of working with microwaves on the transit time principle level gauges.

FIG. 13 shows a schematic representation of a device for metrological detection of transmission, reception, transmission and / or transmission

Signal generating properties of microwave designed units 71. The apparatus comprises a receptacle 73 for receiving the unit to be examined 71, and at least one antenna 75 according to the invention. The receptacle 73 and the antennas 75 are arranged relative to each other such that the transmission directions X of the antennas 75 have to be examined in the receiving device 73 to be examined unit 71 in the direction of the unit 71. This is realized in the present case in that the receiving device 73 is arranged between two antennas 75 which are each aligned with the receiving device 73. Alternatively or additionally, at least one antenna according to the invention above the unit 71 can be arranged. The antennas 75 are optionally each to a transmitting unit 77 and / or to a

Receiving unit 79 connected, and the receiving units 79 are connected to a

 Evaluation unit 81 connected. Preferably, at least the transmitting units 77 and the receiving units 79 are arranged directly on the carrier 1 1 of the respective antenna 75.

The measurement-related detection of transmission or signal-generating properties of the unit 71 to be examined is carried out by the unit 71 is put into operation, and thereby received by her emitted microwaves with at least one of the connected thereto to the associated receiving unit 79 antennas 75, and by means of the evaluation unit 81st be evaluated. In this way, for example

Transmission characteristics of antennas, as well as signal generation properties of

High frequency oscillators, frequency converters, or amplifiers.

The metrological detection of reception properties of the unit 71 to be examined is carried out by at least one of the antennas 73 connected thereto to the associated transmission unit 77 via the transmission unit 77 to be transmitted

Microwave signals is fed to the microwave signals in the direction of

be sent to the unit 71 and the effects of the impinging on the unit 71 microwave signals are detected on the unit 71 by measurement.

In this case, preferably comparative measurements are carried out, in which the unit 71 is put into its intended operation, and the functionality of the unit 71 or the results obtained therewith are detected and compared in the presence and absence of the microwave signals emitted by the antenna (s) 75. As far as the unit 71 allows this, individual modules or

Subassemblies of the unit 71 are activated and measured individually.

The metrological detection of transmission properties of the unit to be examined 71 takes place on the basis of two mutually oppositely arranged antennas 75 of which one sends microwave signals in the direction of the unit 71, and the other receives the passing through the unit 71 portions of these microwave signals. I contents

 3 containers

5 antenna

7 product surface

9 high-frequency module

I I carrier

 13 balanced antenna connection 15 dipole

17 directors

19 stretched dipole

 21 dipole

 23 line segment

 25 line segment

 27 via

29 line segment

 31 reflector

 33 reflector

 35 via

 37 Management structure

39 Management structure

 41 base

 43 layer of carrier material

45 recess

 47 shift

49 end area

 51 Balun

 53 trace

 55 metallization

 57 housing

59 dielectric window

 61 horn

 63 waveguide segment

 65 funnels

 67 antenna

 69 single antenna

 71 unit

 73 recording device

 75 antenna

 77 transmitting unit

79 receiving unit 81 evaluation unit

Claims

claims Antenna for a microwave running on the transit time principle Level measuring device for measuring a filling level (L) of a filling material (1) in a container (3) or for a device for checking the transmission, reception, transmission and / or signal-generating properties of a microwave-designed unit (71)  - At least one on a planar dielectric support (1 1) provided  Single antenna,  - having a on the support (1 1) provided dipole (15, 19, 21),  - The at least 10, especially 20-40, the dipole (15, 19, 21) in a perpendicular to  Surface normal on the support (1 1) extending transmission direction (X) of the antenna (5, 57) upstream, in the transmission direction (X) behind the other and spaced from each other on the carrier (1 1) arranged, parallel to each other and perpendicular to the transmission direction (X) aligned , has line-shaped directors (17), and  - Which on one of the transmission direction (X) opposite side of the dipole (15, 19, 21) arranged reflectors (31, 32, 33). Antenna according to Claim 1, in which the reflectors (31, 32, 33)  - On an upper and / or underside of the carrier (1 1) arranged electronic components, and / or  - On the top and / or the underside of the carrier (1 1) arranged electrically conductive or provided with a conductive coating, wall segments, esp. Metallic or metallized wall segments, sheets or housing wall portions of the respective individual antenna surrounding housing, and / or  - on the top and the bottom of the carrier (1 1) arranged line structures (37) interconnecting vias (35) include. An antenna according to claim 1, wherein the carrier (1 1) consists of a carrier material having a dielectric constant (ε _Γ ) is less than or equal to 3.5, or  - The carrier (1 1 ') has a base (41),  - On which a layer (43) is arranged from a carrier material, the one Dielectric constant (ε _Γ ) is less than or equal to 3.5, and  - The base (41) in a region in which the directors (17) on the support (1 1 ') are arranged, a recess (45). An antenna according to claim 1, wherein - The carrier (1 1) consists of a carrier material having a dielectric constant (ε _Γ ) greater than or equal to 4 and less than 10, and  - The carrier (1 1) on its side facing away from the dipole (15, 19, 21) side of the directors (17) in front of the directors 17 has an end portion (49) whose width in the transmission direction (X) of the antenna (5) decreases continuously , 5. An antenna according to claim 1, wherein  - The dipole (15) is a closed Faltdipol, esp. On a top of the carrier (1 1) applied Faltdipol, or  - The dipole (19) is an open elongated dipole, esp. On an upper side of the support (1 1) applied open elongated dipole is. An antenna according to claim 1, wherein  - At least one of the individual antennas for transmitting microwave signals (S) and / or for receiving received signals (R) is used, the frequencies of a predetermined frequency range included, and  - At least one of these individual antennas is designed such that  - in the support (1 1) at the ends of the directors (17) with the directors (17) connected vias (D) are provided,  - In the carrier (1 1) at the ends of the top of the carrier (1 1)  directors (17) associated with the directors (17)  Vias (D) are provided and on the underside of the carrier (1 1) to the vias (D) adjoining the directors (17) on the underside of the carrier (1 1) end perpendicular to the transmission direction (X) continuing extensions (F), in particular extensions (F) are provided with a length of less than one-eighth of the free-space wavelengths of the microwave signals,  the lengths (L) of their directors (17) and their distances from one another vary along the direction of transmission (X) along the length of the antenna (5), or - It is designed as a logarithmic antenna. An antenna according to claim 1, wherein  - At least one of the individual antennas for transmitting microwave signals (S) of a predetermined frequency and / or for receiving received signals (R) of the predetermined frequency is used, and  - These individual antennas are designed such that  - whose directors (17) are the same length, and  - The distances between each directly adjacent directors (17) of these individual antennas are all the same size. 8. An antenna according to claim 1, wherein two or more individual antennas on a common support (1 1) are arranged side by side or completely or partially overlapping. An antenna according to claim 1 or 8, wherein  - The individual antennas juxtaposed parallel operated for the same frequency or the same frequency range designed individual antennas (69), or  - The individual antennas juxtaposed individually operated for  different frequencies or different frequency ranges designed individual antennas are, or  - The individual antennas are completely or partially overlapping arranged individually operated designed for different frequencies or different frequency ranges individual antennas. 10. Working with microwaves on the transit time principle level gauge with  Antenna according to one of claims 1 - 9. Level gauge according to claim 10, wherein  - The antenna (5) in a housing (57) is arranged, and  - The housing (57) in the transmission direction (X) of the antenna (5) to the outside through a dielectric window (59), esp. A constructed as a dielectric lens window (59) is closed. 12. Level gauge according to claim 10, wherein  on the support (1 1) of the antenna (5), a high frequency assembly (9), in particular a High-frequency assembly for receiving and / or processing of the antenna (5) received signals received (R) and / or for generating via the antenna (5) to be transmitted microwave signals (S), is arranged. Level gauge according to claim 10, wherein  - The antenna has a balanced antenna connection (13), and  - The symmetrical antenna connection (13) via a balun (51) to a  asymmetrical connection line or an asymmetrical connection of the high-frequency module (9) is connected. Level gauge according to claim 10, wherein the antenna (5) feeds a waveguide segment (63) which merges in the transmission direction (X) into funnels (65) which expand in the transmission direction (X). 15. An apparatus for the metrological detection of transmission, reception, transmission and / or signal generation properties of units designed for microwaves (71), esp. Of high-frequency assemblies (9) of microwaves after the  Runtime principle working level gauges or connected to a transmitting and / or receiving unit antennas with microwaves after the  Runtime principle working level gauges, with  - At least one antenna (75) according to one of claims 1-9, and  a receiving device (73) for receiving the unit (71),  - In which the receiving means (73) and the antennas (75) relative to each other are arranged such that the transmitting directions (X) of the antennas (75) in the Receiving device (73) inserted unit (71) in the direction of the unit (71) have.