EP0450191A2 - Transducer arrangement - Google Patents

Abstract

2.1 Directional characteristics of transducer arrangements having a multiplicity of transducer elements, which are arranged at equidistant intervals greater than half the wavelength, have so-called grating lobes of equal sensitivity in addition to the main lobe. If the transducer elements are distributed randomly, the grating lobes are attenuated such that incorrect bearings are prevented. However, to generate a plurality of directional characteristics or a directional characteristic which can be pivoted, individual propagation time compensation or phase compensation must be provided for each direction and each transducer element. 2.2 In order to simplify the circuit complexity for directivity formation, the multiplicity of transducer elements is split, according to the invention, into groups, the transducer elements within the group being arranged at the same intervals and being arranged from group to group at 1.5 times the value of the interval. The groups have identical or different numbers of transducers which reduce from the centre outwards, as a result of which the received energy from the grating lobe direction is greatly attenuated. 2.3 The transducer arrangement can be used advantageously in underwater sound technology for broadband or narrowband passive or active systems, especially for reception. <IMAGE>

Description

The invention relates to a transducer arrangement with a plurality of transducer elements for a pivotable directional characteristic of the type mentioned in the preamble.

In radar and sonar technology, transducer arrangements or antennas are required to form directional characteristics in order to determine the direction and distance of wave-emitting or reflecting targets. The opening angle of a directional characteristic determines the accuracy of the direction determination or bearing to the target and is determined by the length dimension of the transducer arrangement. A clear determination of the direction is only possible, however, if a plurality of transducer elements are arranged equidistantly over the length of the transducer arrangement at a distance from the smallest half wavelength to be received. Then the directional characteristic consists of a main lobe of maximum sensitivity and damped side lobes. However, if the distances between the transducer elements are greater than half the wavelength, be it for cost reasons or because of the geometrical dimensions of the transducer elements themselves or because of heat problems that occur during active operation, a direction determination is only possible under certain conditions, since the directional characteristic is not the desired one Main lobe has other lobes of the same sensitivity, so-called grating praise. Wave incidence from one or more of the directions in which the grating lobes point would simulate a bearing from the direction in which the main lobe is pointing. In order to rule out such incorrect bearing, in an actively working location system, for example, only a narrow sector is irradiated with waves, so that the grating lobe directions lie outside the sector. If it is not possible to limit the sector, the grating praise is suppressed or damped, for example, by constructing the transducer arrangement from transducer elements arranged statistically with respect to one another, as described, for example, in US Pat. No. 3,553,703.

PCT application WO 88/10523 corresponding to EP application 0315689 discloses a flat transducer arrangement for transmitting electromagnetic waves, which is composed of transducer elements arranged on concentric circles. Transducer elements of different sizes are used per circle, so that the distances of the transducer elements in the radial direction are different due to the different transducer element sizes. The number of identical transducer elements per circle is determined by the transducer element size. The length of the radii of the concentric circles does not increase periodically. The transducer element size increases from the center and decreases towards the edge of the transducer arrangement, the smallest transducer elements are in the middle. Due to the non-periodic structure of the transducer arrangement, grating praise, due to the amplitude evaluation of the emitted wave due to the different sizes of the transducer elements, is attenuated, the antenna gain being the same as for a Transducer arrangement with transducer elements of the same size.

For localization tasks, a plurality of directional characteristics pointing in different directions or a pivotable directional characteristic can be formed by phase control of the transducer arrangement. A special phase control of the irregularly arranged transducer elements is necessary for each spatial direction, so that the expenditure on phase rotating elements for direction formation is considerably greater, especially in the case of a continuously monitored spatial area, than in the case of a regularly configured antenna configuration.

It is an object of the present invention to provide a transducer arrangement of the type mentioned in the preamble of claim 1, in which a plurality of directional characteristics pointing in different directions or a swiveling directional characteristic can be formed by avoiding incorrect bearing by grating praise without great additional effort. This object is achieved by the features mentioned in the characterizing part of claim 1.

The advantage of a transducer arrangement according to claim 1 is that the manufacture is particularly simple, since the transducer arrangement is based on a halftone spacing of the transducer elements from one another and thus a periodicity. This rasterization is also advantageous for the dimensioning of the directional element, so that when a directional characteristic is swiveled or a plurality of directional characteristics pointing in different directions are formed simultaneously Converter elements can be assigned multiples of phase rotation or transit time increments and a special delay or phase value for time compensation of their received signals does not have to be calculated and provided for each converter element.

The transducer elements within a group have the same distance and from group to group 1.5 times the value of this distance. This measure ensures that at a distance greater than half the wavelength of the associated operating frequency, an incident of waves from the grating-lobe direction does not lead to incorrect bearing, since transducer elements of adjacent groups do not use the distance d, but 1.5 · d and waves received at the grating-lobe angle are shifted from group to group by half a wavelength and their received signals are thus extinguished. The energy received with an equidistant arrangement of the converter elements from the grating lobe direction is split and distributed into adjacent angular ranges in the converter arrangement according to the invention. For groups with the same number of transducers, this results in a directional characteristic with a main lobe and a zero at the associated grating lobe angle for each swivel angle.

The grating-lobe angle is, apart from the swivel angle into which the directional characteristic points, dependent on the frequency and the spacing of equidistant transducer elements. The offset of the groups by 1.5 times the distance gives the advantage that the suppression of the grating praise is guaranteed for each swivel angle of the directional characteristic and each frequency. Thus, the converter arrangement according to the invention is not only for Narrow-band, but also particularly useful for broadband reception, for example in waterborne sound technology for trailing antennas for direction finding of watercraft in the low-frequency range, because the configuration of the transducer arrangement saves transducer elements and thus a price reduction without reducing the bearing accuracy.

When used in the high-frequency, narrow-band range, in which, for example, the size of the transducer elements cannot be arranged at a distance smaller than half the wavelength of the received sound waves, good bundling can be achieved in a particularly cost-saving and advantageous manner in terms of production technology, since the large number of transducer elements is also possible large dimensions of the transducer arrangement can be reduced and costs and weight can be saved with the same output. The transducer arrangement according to claim 1 can thus advantageously be used in mine hunting and mine avoidance systems in which incorrect direction finding would be particularly harmful.

Both in narrowband and in broadband operation, it is equally advantageous that the directional generator is realized by multiples of phase or transit time increments, which means that the outlay on circuit technology can be kept low.

The large number of transducer elements can, however, not only be arranged along a straight line, but also along a curved line which follows, for example, a vehicle wall, one then speaks of a so-called conformed array. When used in water-borne noise technology, the follows Transducer arrangement of the contour of a ship, submarine or torpedo. The converter arrangement according to the invention can also be implemented for a cylinder base. In all of these converter arrangements, the directional characteristics are formed by compensating the transit time or phases of the received signals from the installation location to a straight line perpendicular to the direction of incidence of the wave and summation. Starting from this straight line, the dimensioning of the transducer arrangement is to be carried out according to claim 1. The individual transducer element locations are obtained by vertically shifting from the virtual location on the straight line to the geometric location on the installation line, which is canceled again by the direction generator.

For a flat transducer arrangement with a bundling of its directional characteristics in azimuth and elevation, the surface is divided by lines crossing each other in the middle and the transducer elements arranged in groups along the lines.

The plurality of transducer elements is arranged along a straight line according to the advantageous development of the transducer arrangement according to the invention and its number of groups along the straight line is selected according to the advantageous further development according to claim 3 so that a required damping distance between the main lobe and fragmented grating praise in The area around the grating lobe angle is maintained. Receiving energy that would be received from the grating-lobe direction in an equidistantly arranged transducer arrangement is distributed by the transducer arrangement according to the invention into adjacent angular ranges between the grating-lobe angle and the swivel angle. The angular ranges are from the Number of groups dependent. This also means that with the same bundling, the individual transducer elements per group move closer together, since the group spacings are equal to 1.5 times the value of the transducer spacings within the group. If the groups of transducer elements are of the same size, the directional characteristic results in lobes that are significantly less sensitive than the main lobe. In the angular range around the grating-lobe angle, the lobes are fragmented grating lobes that are symmetrical to the grating-lobe angle, in the remaining angular range up to the main lobe periodically occurring lobes that can be understood as pseudo-grating lobes. Their sensitivity decreases towards the main club.

In order to obtain a directional characteristic that is similar to a directional characteristic that can be achieved with a transducer arrangement with noisy spacings of the transducer elements that are not periodic but statistical, according to an advantageous development of the transducer arrangement according to claim 4, the groups have different numbers of transducers, wherein the groups are arranged symmetrically to the center of the transducer arrangement. A converter arrangement is particularly advantageous in which the number of converters of the groups closest to the center is greatest and decreases towards the edge of the converter arrangement. This measure also splinters the pseudo-grating praise and, apart from the main lobe, the directional characteristic is continuously attenuated over all angular ranges to approximately the same level, which is lower the larger the number of groups. An additional influence on the directional characteristic by an amplitude evaluation of the received signals of the Transducer arrangement according to the invention is possible and has the known advantages with regard to its side lobes. Simulation calculations of the directional characteristic can be used to easily optimize the number of groups and their number of transducers.

It is particularly advantageous to select the number of transducers in the groups such that the transducer arrangement, as stated in claim 5, consists of two identical sub-bases which are arranged nested one inside the other and are mirror-inverted side-to-side. Each of the two sub-bases has a grid that is equal to the distance between the transducers. However, the two sub-bases are shifted from each other by 1.5 times the distance. By this measure, the position and level of all lobes, except for the main lobe, are distributed such that when the main lobe is pivoted, incident wave energy from other angular ranges is uniformly damped, the damping in the angular range around the associated grating lobe angle all the more the greater the number of groups. The reduction in the angular range between the grating lobe angle and the direction in which the main lobe points is the same if the number of converters in the groups is not the same. The fragmented grating lobes symmetrically around the grating lobe angle level off in particular to the same low level when the number of transducers decreases from the center to the outside.

It is particularly advantageous to dimension the number of converters of the groups according to claim 6. The specified regulation is comparable to the Leverage Act. It will the distance between the center of the transducer arrangement and each individual transducer element of the groups belonging to a sub-base added up to the right and left of the center of the transducer arrangement. A directional characteristic with maximum sensitivity in the main lobe at maximum swivel angle and uniform damping in the other angular range is ensured in that the sum of the distances to the right of the center is equal to the sum of the distances to the left of the center. As a result, the focus of each sub-base is almost on the middle of the transducer arrangement. With this dimensioning, it is assumed that the received signals of the transducer elements are added in the directional generator after an amplitude evaluation of "1".

However, if a non-uniform amplitude evaluation is carried out to further improve the directional characteristic, according to the advantageous development according to claim 7, the product is formed from the respective distance and the amplitude evaluation factor and the sum of the products for each sub-base taking into account the position of the transducer with respect to the center "Zero". With such a transducer arrangement, the damping by the grating-lobe angle in an angular range of approximately 10 ° is more than 35 dB compared to the sensitivity of the main lobe. The fragmented grating praise that limits this angular range has an attenuation of a good 10 dB. The attenuation in the angular range up to the swivel angle of the main lobe increases continuously up to values of 30 dB.

The dimensioning of the number of transducers in the groups depends on the application of the transducer arrangement and is different, for example, in the case of a broadband operation, as is necessary for monitoring a sea area in a trailing antenna, than in the case of narrowband operation, as is e.g. is common in actively working sonar systems, where a high degree of selectivity with regard to echoes from a wide-range, irradiated sector is necessary.

In active systems, it is particularly advantageous to dimension the transducer arrangement for reception according to claim 7, in which the average number of transducers in the groups is selected so that echoes from directions other than the direction of the main lobe are received with significantly less sensitivity. In the case of pulsed sound from the grating-lobe direction, the measure according to claim 8 ensures that the same number of transducer elements always have received signals that cancel each other out while the pulse sweeps across the transducer arrangement.

The transducer arrangements described for the reception case are also suitable for transmission.

Fig. 1

eine Wandleranordnung mit Gruppen von Wandlerelementen, deren Wandlerzahlen gleich sind,

Fig. 2

eine Richtcharakteristik der Wandleranordnung gemäß Fig. 1,

Fig. 3

eine Richtcharakteristik für eine Wandleranordnung mit statistisch angeordneten Wandlerelementen,

Fig. 4

eine Wandleranordnung aus zwei Teilbasen, deren Gruppen unterschiedliche Wandlerzahlen aufweisen,

Fig. 5

eine Richtcharakteristik der Wandleranordnung gemäß Fig. 4,

Fig. 6

ein Diagramm für Richtmaße über dem Winkel, parametriert mit der Anzahl der Gruppen.

The invention is described in more detail below on the basis of exemplary embodiments shown in the drawing for a transducer arrangement with a multiplicity of transducer elements for transmitting and / or receiving sound waves, which is part of a sonar system. Show it:

Fig. 1

a transducer arrangement with groups of transducer elements whose number of transducers are the same,

Fig. 2

1 shows a directional characteristic of the converter arrangement according to FIG. 1,

Fig. 3

a directional characteristic for a transducer arrangement with statistically arranged transducer elements,

Fig. 4

a converter arrangement consisting of two sub-bases, the groups of which have different converter numbers,

Fig. 5

4 shows a directional characteristic of the converter arrangement according to FIG. 4,

Fig. 6

a diagram for standard dimensions over the angle, parameterized with the number of groups.

1 shows a transducer arrangement for a waterborne sound system with a large number N of transducer elements which are arranged along a straight line 10. The transducer elements are followed by a direction generator (not shown here), which consists of phase shifters with monochromatic reception or from delay elements with broadband reception. The received signals of the transducer elements are added instantaneously when sound waves are received from the vertical to the center 11 of the transducer arrangement and form a directional characteristic with a main lobe in the direction of the perpendicular and secondary lobes. The larger the extension L of the transducer arrangement, the smaller its opening angle. With the transducer arrangement and the direction generator, the directional characteristic can be swiveled from the perpendicular to the center by angle ζ by running time or phase control, whereby the maximum swivel angle is the drawn angle ζ _max . Likewise, several directional characteristics can be formed, the main lobes of which point at different swivel angles.

N = 32 transducer elements are arranged on the straight line 10, each forming groups 21, 22, 23, 24 with eight transducer elements, q = 4 being the number of groups. Within each group 21 to 24, the transducer elements are at a distance d from one another, between groups 21 and 22 or 22 and 23 or 23 and 24 1.5 times the value of the distance d. The distance d between the transducer elements is greater than λ / 2, where λ is the smallest wavelength of the received sound wave. With a swivel angle ζ _{max of} the directional characteristic, in addition to side lobes, another lobe with the same sensitivity as the main lobe, the so-called grating lobe, occurs at a grating lobe angle β, as for example in "Microwave Scanning Antennas" from RC Hansen, Academic Press, New York and London, 1964, shown on page 203. The relationship sin β = sin ζ - n λ / d applies. The number of grating-lobe angles β and their size depend on the distance d of the transducer elements with respect to the wavelength λ of the received wave and on the swivel angle ζ. For each swivel angle ζ and each frequency f, different grating lobe angles β are set.

Für die Richtungsbildung einer Richtcharakteristik unter einem Schwenkwinkel ζ = ζ_max = 45° gemäß Fig. 1 ist die Verzögerungszeit τ_m zwischen den äußeren Wandlerelementen jeder Gruppe 21, 22, 23, 24, z.B. zwischen den Wandlerelementen an den Positionen von B und A

nötig, wobei m die um eins verminderte Wandlerzahl z jeder Gruppe ist.The distance d between the transducer elements is calculated from the dimension L of the entire transducer arrangement, the plurality N of transducer elements and the number q of groups according to the rule (N-1) * d + (q-1) * 1.5 d = L for example d = 3 λ / 4. If there is sound from the swivel angle ζ, the result is Grating lobe angle β as follows for n = 1:

$\text{sin β = sin ζ- 4/3.}$

For the direction formation of a directional characteristic at a swivel angle ζ = ζ _max = 45 ° according to FIG. 1, the delay time τ _m between the outer transducer elements of each group 21, 22, 23, 24, for example between the transducer elements at the positions of B and A

necessary, where m is the number of converters z of each group reduced by one.

Fällt eine Schallwelle aus der Richtung ζ=ζ_max ein, so werden das Empfangssignal ${\text{U·e}}^{\text{jω (t+τ}}{\text{0}}^{\text{)}}$

des Wandlerelements an der Position B mit der Anfangsphase ωτ₀ und der Kreisfrequenz ω um die Verzögerungszeit τ_m+1+τ_m, das Empfangssignal ${\text{U·e}}^{\text{jω (t+τ}}{\text{0}}^{\text{+τ}}{\text{m}}^{\text{)}}$

des Wandlerelements an der Positions A um (τ_m+τ_m+1-τ_m) verzögert und das Empfangssignal

${\text{U·e}}^{\text{jω(t+τ}}{\text{0}}^{\text{+τ}}{\text{m+1}}^{\text{)}}$

des Wandlerelements an der Position D um τ_m und das Empfangssignal an der Position E

${\text{U·e}}^{\text{jω(t+τ}}{\text{0}}^{\text{+τ}}{\text{m+1}}^{\text{+τ}}{\text{m}}^{\text{)}}$

nicht verzögert. Die konphasen Signale werden addiert:

Fällt bei dieser Richtungsbildung eine Schallwelle aus dem Grating-Lobe-Winkel β ein, so weist die empfangene Schallwelle an dem Wandlerelement an der Position D gegenüber dem Wandlerelement an der Position E, die jeweils die äußeren Wandlerelemente der Gruppe 23 bilden, einen Laufzeitunterschied t_m auf, dessen Vorzeichen gegenüber den Verzögerungszeiten τ negativ ist.

For the transducer element to the adjacent group 23, for example between the transducer elements at positions B and D, there is a delay time of

If a sound wave comes in from the direction ζ = ζ _max , the received signal ${\text{U · e}}^{\text{jω (t + τ}}{\text{0}}^{\text{)}}$

of the transducer element at position B with the initial phase ωτ₀ and the angular frequency ω by the delay time τ _{m + 1} + τ _m , the received signal ${\text{U · e}}^{\text{jω (t + <figure-callout id="0" label="τ" filenames="imgf0002.png" state="{{state}}">τ</figure-callout>}}{\text{0}}^{\text{+ τ}}{\text{m}}^{\text{)}}$

of the transducer element at position A is delayed by (τ _m + τ _{m + 1} -τ _m ) and the received signal

${\text{U · e}}^{\text{jω (t + <figure-callout id="0" label="τ" filenames="imgf0002.png" state="{{state}}">τ</figure-callout>}}{\text{0}}^{\text{+ τ}}{\text{m + 1}}^{\text{)}}$

of the transducer element at position D by τ _m and that Receive signal at position E

${\text{U · e}}^{\text{jω (t + <figure-callout id="0" label="τ" filenames="imgf0002.png" state="{{state}}">τ</figure-callout>}}{\text{0}}^{\text{+ τ}}{\text{m + 1}}^{\text{+ τ}}{\text{m}}^{\text{)}}$

not delayed. The phase signals are added:

If a sound wave occurs from the grating-lobe angle β during this direction formation, the received sound wave has a transit time difference t _m at the transducer element at position D compared to the transducer element at position E, which each form the outer transducer elements of group 23 whose sign is negative compared to the delay times τ.

Diese Laufzeitunterschiede t_m und t_m+1 ergeben sich stets zwischen den Wandlerelementen an den Grenzen benachbarter Gruppen 24/23 bzw. 23/22 bzw. 22/21. Es entsprechen also die Positionen F, E, D den Positionen D, A, B usw.The transit time difference t _{m + 1} between the converter element at position E and the converter element at position A is calculated as follows:

These runtime differences t _m and t _{m + 1} always arise between the transducer elements at the borders of neighboring groups 24/23, 23/22 and 22/21. Positions F, E, D correspond to positions D, A, B etc.

wobei ω·τ_β eine beliebige Anfangsphase ist. Dieses Empfangssignal bei der Position E wird nicht verzögert,
an der Position D das Empfangssignal ${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+t}}{\text{m}}^{\text{)}}\text{,}$

das un τ_m verzögert wird, und nach Einsetzen von (1) und (3) das verzögerte Signal

${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+m· λ/c)}}\text{,}$

bei der Position A das Empfangssignal ${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+t}}{\text{m+1}}^{\text{)}}\text{,}$

das um die Verzögerungszeit τ_m+1 verzögert wird, und nach Einsetzen von (2) und (4) das verzögerte Signal

${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+m λ/c + 3 λ/2c)}}\text{,}$

bei der Position B das Empfangssignal
${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+t}}{\text{m+1}}^{\text{+t}}\text{m),}$

das um τ_m+1+τ_m verzögert wird, und nach Einsetzen von (1), (2), (3) und (4) das verzögerte Signal

${\text{U·e}}^{\text{jω(t+τ}}{\text{β}}^{\text{+m·2·λ/c+3 λ/2c).}}$

Nach Addition erhält man

Man erkennt, daß der 1,5fache Abstand d eine Phasenverschiebung zwischen den Empfangssignalen bei D und A um 180° oder λ/2 bewirkt. Innerhalb der Gruppen 21, 22, 23, 24, werden die verzögerten Signale konphas addiert, von Gruppe 21/22 bzw. 22/23 bzw. 23/34 jedoch gegeneinander um eine halbe Wellenlänge verschoben, so daß eine Summierung der verzögerten Empfangssignale bei gerader Anzahl der Gruppen 22, ..., 24, Null ergibt. Im Gegensatz dazu wird durch die Kompensation im Richtungsbildner bei Schalleinfall aus dem Schwenkwinkel ζ eine konphase Addition der Empfangssignale erreicht.If one adds the delay time τ in the direction generator to the transit time difference t, the result at reception under the grating-lobe angle β is:
at position E the received signal ${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{)}}\text{,}$

where ω · τ _{β is} any initial phase. This reception signal at position E is not delayed,
at position D the received signal ${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ t}}{\text{m}}^{\text{)}}\text{,}$

the un τ _{m is} delayed, and after the onset of (1) and (3) the delayed signal

${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ mλ / c)}}\text{,}$

at position A the receive signal ${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ t}}{\text{m + 1}}^{\text{)}}\text{,}$

which is delayed by the delay time τ _{m + 1} , and after the onset of (2) and (4) the delayed signal

${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ m λ / c + 3 λ / 2c)}}\text{,}$

at position B the receive signal
${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ t}}{\text{m + 1}}^{\text{+ t}}\text{m),}$

which is delayed by τ _{m + 1} + τ _m , and after the onset of (1), (2), (3) and (4) the delayed signal

${\text{U · e}}^{\text{jω (t + τ}}{\text{β}}^{\text{+ m · 2 · λ / c + 3 λ / 2c).}}$

After addition you get

It can be seen that the 1.5 times the distance d causes a phase shift between the received signals at D and A by 180 ° or λ / 2. Within groups 21, 22, 23, 24, the delayed signals are added in phase, but shifted by half a wavelength from group 21/22 or 22/23 or 23/34, so that the delayed received signals add up even number of groups 22, ..., 24, zero results. In contrast to this, a compensation of the received signals is achieved by compensation in the directional generator when sound is incident from the swivel angle ζ.

FIG. 2 shows a diagram in which directional sensitivity R / dB is plotted against the angle ϑ for a directional characteristic of a converter arrangement according to FIG. 1, which consists of q = 20 groups, each group having, for example, a number of converters z = 5. The direction generator is set so that its main lobe 30 points to the maximum swivel angle ζ _max . The grating-lobe angle β is located in an angular range 31, which is limited by the two highest fragmented grating praise 32, 33, which have an attenuation of R1 in relation to the directional sensitivity R of the main lobe 30. In the angular range 31 around the grating-lobe angle β, the damping is substantially greater, approximately three times as large as R1. In addition, so-called pseudo-grating praise 34, 35, 36, 37 and 38 can be recorded in the directional characteristic, which have almost the same angular distances from one another and whose damping is greatest in the vicinity of the main lobe.

FIG. 3 shows the course of a directional characteristic over the angle ϑ at which the same number N = 100 of converter elements are accommodated with the same extension of the converter arrangement as in FIG. 2. However, their distances from one another are stochastic or noisy. The secondary level attenuation is almost constant over the entire angular range and is somewhat less than the fragmented grating praise 32 and 33 in FIG Grating lobe angle β itself is not as high a damping R2 as achieved with the converter arrangement according to the invention. The damping is comparable over the entire angular range.

$\text{L = 108,5 d.}$

Bei einer maximalen Frequenz von 100 kHz ist der Abstand d = 0,75·λ. Die einzelnen Wandlerelemente in jeder Gruppe haben einen Abstand von 0,75 λ zueinander, die Gruppen untereinander einen Abstand von 1,5.0,75 λ.In order to level the so-called pseudo-grating praise 33 to 38 according to FIG. 2, the number of converters z of the q groups is varied. 4 shows such a transducer arrangement with N = 100 transducer elements, which are arranged over an extension L of, for example, 1.20 m. 100 converter elements are divided into q = 20 groups 110, 111, ..., 129. The distance d is calculated from the dimension L:

$\text{L = (N-1) d + (q-1) x 0.5 x d}$

$\text{L = 108.5 d.}$

At a maximum frequency of 100 kHz, the distance d = 0.75 · λ. The individual transducer elements in each group are spaced 0.75 λ apart, the groups are spaced 1.5.0.75 λ apart.

The first group 110 located on the left outer edge has only one transducer element, the adjacent group 111 has two, the group 112 three transducer elements, the group 113 four transducer elements, the group 114 five transducer elements, the groups 115 and 116 six transducer elements, the group 117 seven transducer elements and groups 118 and 119 each have eight transducer elements. The number of transducers z in the following groups have the same size symmetrically with respect to the center 11. The groups with the even numbers 110, 112, ..., 128 form a sub-base 200, the groups 111, 113, ..., 129 with odd numbers form a second sub-base 300. The sub-bases 200, 300 are nested one inside the other and reversed mirror-symmetrically. Each sub-base 200, 300 has a grid of d, which is shifted from one another by d / 2.

The number of transducers z of the q groups are selected such that a directional characteristic according to FIG. 5 is achieved with a corresponding directional element when swiveling by the maximum swivel angle _max . This directional characteristic is characterized by the fact that a maximum attenuation is achieved around the grating-lobe angle β and that no further periodic components are recorded in the directional characteristic. The secondary levels in the area of the main lobe 30 are also particularly strongly damped. In order to obtain such a pattern of the directional characteristic, the following dimensioning instructions have been observed:
Starting from the center 11, with an amplitude shading of the transducer elements of "1", the product is formed from the distance from the perpendicular to the transducer element multiplied by the amplitude evaluation factor "1". All products for sub-base 200 are added with the correct sign and divided by the sum of the amplitude evaluation factors - here half of the plurality N of converter elements. If possible, this value must be zero. Then the focus of each sub-base 200 and 300 is on the middle 11. With this dimensioning rule it is achieved in particular that no pseudo-grating praise arises.

Der Schwerpunkt der Teilgruppe 200 liegt somit in der Mitte 11 der Wandleranordnung. Für die Teilbasis 300 gilt das gleiche.For subgroup 200, ie for groups 110, 112, ....., 128 must apply:

The focus of subgroup 200 is thus in the middle 11 of the transducer arrangement. The same applies to the sub-base 300.

wobei c=1500 m/s die Schallgeschwindigkeit ist. Die Länge 1 ist somit etwas größer als die mittlere Länge zweier Gruppen auf der Wandleranordnung gemäß Fig.4. Dämpfungsabstand und Dämpfung der zersplitterten Grating-Lobes 31, 32 gegenüber der Hauptkeule 30 bei Impulsbetrieb ist in Fig. 5 gestrichelt eingezeichnet und wesentlich besser als bei monochromatischem Dauerschallbetrieb mit f=100 kHz. Ähnlich günstige Dämpfungsverläufe sind bei breitbandigem Empfang um eine Mittenfrequenz von 100 kHz zu verzeichnen.The arrangement shown in FIG. 4 can be used particularly advantageously in a waterborne sound system in which the pulse mode is used, the pulse duration being, for example, Δ t = 0.1 ms. 4, q = 20 groups are distributed over the entire extent L = 1.2 m, so that the average length of two groups corresponds to approximately 12 cm. With a swivel of ζ _max = 45 ° and an incidence of sound waves below the grating-lobe angle β = 39 °, on average at least two groups are simultaneously swept by sound waves, which corresponds to a length 1 on the straight line of the transducer arrangement from

where c = 1500 m / s is the speed of sound. Length 1 is thus somewhat greater than the average length of two groups on the converter arrangement according to FIG. 4. Damping distance and damping of the fragmented grating praise 31, 32 with respect to the main lobe 30 Pulse operation is shown in dashed lines in Fig. 5 and much better than monochromatic continuous sound operation with f = 100 kHz. Similarly favorable attenuation curves can be seen with broadband reception around a center frequency of 100 kHz.

Fig. 6 shows a diagram in which the standard dimension R in dB for a different number q of groups is entered over the angle ϑ. The sensitivity of the main lobe 30 is entered under the angle ϑ = ζ _max and the sensitivity of the grating praise is entered under the grating lobe angle β. The sensitivities are the same if the transducer arrangement has equidistantly distributed transducer elements whose spacing is greater than half the wavelength. The incident energy over the grating-lobe angle β is distributed through the group-wise arrangement of the transducer elements to adjacent angular ranges, whereby an attenuation in the entire angular range is achieved which is greater than the attenuation specified for q = 20, which is equal to the reduction R 1 of the Reference measure is. For q = 20, two points are entered on two curves r and s, which limit the angular range 31 according to FIG. 2 and correspond to the fragmented grating praise 32, 33 in FIG. 2. The curves r and s indicate limit values for the damping of the fragmented grating praise for the different number q of groups. For increasing number q of groups, the two curves r and s asymptotically approach a limit value R₀ which corresponds to the damping if the transducer distances are statistically distributed. 6, the number q of groups is to be dimensioned depending on the task of the entire sonar system.

Claims (8)

Transducer arrangement with a large number of transducer elements for transmitting and / or receiving waves in a predeterminable frequency range, the distance from one another of which is greater than half the wavelength of the highest frequency in the frequency range, for several or a pivotable directional characteristic with a predetermined opening angle and damped grating praise, thereby characterized in that the transducer elements are the same and are arranged in groups (21, 22, 23, 24 or 110, 111, ..., 129) along a line and symmetrically to the center (11) of the transducer arrangement, that distances (d) of the transducer elements in each group (21, ..., 24 or 110, ..., 129) are identical to one another and from group to group (21/22, ..., or 110/111, 111/112, ...) are equal to 1.5 times the value (1.5d). Transducer arrangement according to claim 1, characterized in that the line is a straight line (10). Transducer arrangement according to Claim 1 or 2, characterized in that the number (q) of groups (21, 22, 23, 24 or 110, 111, ..., 129) for the multiplicity (N) of transducer elements depends on the required damping distance between main lobe (30) and fragmented grating praise (31, 32) can be selected. Converter arrangement according to Claim 2 or 3, characterized in that the groups (22/23, 21/24 or 110/129; 111/128; ..., 119/120) which are arranged symmetrically to the center (11), have the same number of converters (z) that the number of converters (z) of neighboring groups (21/22, ..., 23/24 or 110/111, ..., 119/120, ..., 128/129) are the same or different and are chosen decreasing from the center to the edge of the transducer arrangement. Converter arrangement according to Claim 4, characterized in that the number of converters (z) per group (110, ..., 129) are selected such that the groups (110, 112, 114, ..., 128 or 111, 113, ..., 129) along the straight line (10) starting from the edge over the middle (11) to the other edge, one group (111, 113, ... or 112, 114, ...) overlapping two into each other form nested subbases (200, 300) with the same structure from the edge and each subbase (200, 300) has a grid of the spacing (d) of the transducer elements and their multiples and the grid of the two subbases (200, 300) against each other half the distance (d) of the transducer elements is shifted. Transducer arrangement according to Claim 5, characterized in that the number of transducers z in the groups (110, ..., 128 or 111, ..., 129) are selected such that the sum of the distances between each sub-base (200, 300) the middle (11) of the transducer arrangement and each transducer element on each side are the same. Transducer arrangement according to Claim 5, characterized in that the number of transducers (z) in the groups (110, ..., 128 or 111, ..., 129) are selected such that the sums of the. For each sub-base (200, 300) Products from the distances between the center (11) of the transducer arrangement and each transducer element multiplied by an amplitude evaluation factor with which a received signal of the respective transducer element is evaluated are the same on each side. Transducer arrangement according to one of Claims 1 to 7, characterized in that the number (q) of groups (110, ..., 129) and the average number of transducers (z) are selected as a function of the pulse duration (Δ t) during pulse operation, that the mean length (1) of two adjacent groups (119/120) is approximately equal to the pulse duration (Δ t) multiplied by the speed of sound (c) and divided by the sine of a maximum swivel angle (ζ _max ) plus the grating-lobe angle ( β) is.

Images