MISSILE, IN PARTICULAR GUIDED MISSILE, HAVING A RADAR SENSOR UNIT

Abstract

A missile, in particular a guided missile, has a missile body and a radar sensor unit for acquiring a target object. The radar sensor unit contains at least one radar antenna, strip-shaped in the longitudinal direction, that is mounted or integrated on a circumferential surface of the missile body such that the longitudinal direction of the at least one strip-shaped radar antenna is aligned in the direction of the missile longitudinal axis.

Claims

1. A missile, comprising: a missile body having a circumferential surface; and a radar sensor unit for acquiring a target object, said radar sensor unit having at least one strip-shaped radar antenna, strip-shaped in a longitudinal direction, and mounted or integrated on said circumferential surface of said missile body such that the longitudinal direction of the at least one strip-shaped radar antenna is aligned in a direction of a missile longitudinal axis.

2. The missile according to claim 1, wherein said strip-shaped radar antenna is mounted or integrated such that the longitudinal direction of said strip-shaped radar antenna and the missile longitudinal axis span a plane.

3. The missile according to claim 1, wherein said at least one strip-shaped radar antenna is configured for operation as a transmitting antenna for transmitting radar signals and/or for operation as a receiving antenna for receiving reflected radar signals.

4. The missile according to claim 1, wherein said at least one strip-shaped radar antenna is one of at least two strip-shaped radar antennas that are mounted or integrated on said circumferential surface of said missile body and are disposed so as to be aligned substantially parallel to one another, wherein said at least two strip-shaped radar antennas are configured for operation as transmitting and/or receiving antennas.

5. The missile according to claim 4, wherein said radar sensor unit has at least one radar antenna group having said at least two strip-shaped radar antennas, wherein said at least one radar antenna group includes a first radar antenna configured for operation as a transmitting antenna and at least one second radar antenna, assigned to said first radar antenna, and is configured for operation as a receiving antenna for receiving reflected radar signals.

6. The missile according to claim 5, wherein said at least one radar antenna group is one of a plurality of radar antenna groups disposed in a manner distributed over a circumference of said missile body, and said plurality of antenna groups are disposed in an evenly distributed manner and/or in a manner distributed according to a stipulated symmetry over the circumference of said missile body.

7. The missile according to claim 1, wherein: said at least one strip-shaped antenna is one of at least two directly adjacent strip-shaped antennas; and said radar sensor unit is configured to emit radar signals having at least one stipulated radar wavelength and has said at least two directly adjacent strip-shaped radar antennas that are configured at least for operation as receiving antennas, wherein a distance between said at least two directly adjacent strip-shaped radar antennas configured for operation as the receiving antennas transversely with respect to the longitudinal direction of said strip-shaped radar antennas is at most as great as a or a multiple of the stipulated radar wavelength.

8. The missile according to claim 1, wherein: said missile body has a missile tip; and said at least one strip-shaped radar antenna is configured and operable such that it has an antenna radiation pattern that is able to be directed over a polar angle, the polar angle is defined with respect to a spherical coordinate system whose polar axis runs in a direction of the missile longitudinal axis of said at least one strip-shaped radar antenna, and a positive polar axis faces said missile tip.

9. The missile according to claim 8, wherein the antenna radiation pattern of said at least one strip-shaped radar antenna has an antenna main lobe with a half-power beamwidth of 30 degrees or less than 30 degrees over the polar angle and a half-power beamwidth of 30 degrees or more than 30 degrees over an azimuth angle defined by the spherical coordinate system.

10. The missile according to claim 8, wherein said at least one strip-shaped radar antenna is in a form of a radar antenna that is alignable over the polar angle by means of frequency or phase.

11. The missile according to claim 8, wherein: said at least one strip-shaped radar antenna is configured as a leaky wave antenna; and/or said at least one strip-shaped radar antenna is one of a plurality of radar antennas configured as phase-controlled group antennas.

12. The missile according to claim 1, wherein said at least one strip-shaped radar antenna is one of a plurality of antennas; further comprising an electronics unit having reception electronics and transmission electronics for said radar sensor unit, said electronics unit is connectable or connected to said radar sensor unit for data transmission purposes in order to operate said radar sensor unit, said electronics unit having at least one electronic component configured such that during an operation of said electronics unit said electronics unit operates said at least one strip-shaped radar antenna as a transmitting antenna and/or a receiving antenna, wherein an operation of said electronics unit and/or of said at least one strip-shaped radar antenna includes at least one of the following steps being carried out: connecting a transmitting channel of said transmission electronics of said electronics unit to said at least one strip-shaped radar antenna operable as said transmitting antenna, and connecting a receiving channel of said reception electronics of said electronics unit to said at least one strip-shaped radar antenna operable as said receiving antenna, wherein said radar antennas operable as said transmitting antennas and said radar antennas operable as said receiving antennas are connected to the transmitting and receiving channels, and operated, such that said radar sensor unit is operable with an antenna main lobe that is alignable or directed in a direction of the target object; actuating said at least one strip-shaped radar antenna to align the antenna main lobe with a detected or detectable target object, wherein an alignment of the antenna main lobe for the detectable target object is varied on a basis of target object data; varying an alignment of the antenna main lobe in successive detection cycles and ascertaining position data pertaining to the target object, containing polar angle data of the target object with reference to an on-missile coordinate system, by means of amplitude comparison of reflected radar signals detected in the successive detection cycles; simultaneously detecting a reflected radar signal for a radar signal transmitted by one of said radar antennas operated as said transmitting antenna by means of adjacent ones of said radar antennas operated as said receiving antennas and ascertaining the position data pertaining to the target object, containing azimuth angle data of the target object in the on-missile coordinate system, by means of phase and/or amplitude comparison of simultaneously detected radar signal; and ascertaining distance and/or approach velocity of the target object on a basis of received radar signals.

13. The missile according to claim 12, wherein said electronics unit has at least one said transmitting channel, and wherein said electronics unit has at least one said receiving channel, wherein said electronics unit is configured to connect said at least one transmitting channel to one of said radar antennas operable as the transmitting antenna and operable with the antenna main lobe that is alignable in a direction of the target object and to connect said at least one receiving channel to a radar antenna operable as said receiving antenna in order to capture the radar signals reflected by the target object.

14. The missile according to claim 1, wherein said circumferential surface on which said at least one strip-shaped radar antenna is mounted or integrated is in substantially planar form in the longitudinal direction of said at least one strip-shaped radar antenna.

15. The missile according to claim 1, wherein said circumferential surface is in cylindrical or conical form with respect to the missile longitudinal axis.

16. The missile according to claim 1, wherein the missile is a guided missile.

17. The missile according to claim 13, wherein said at least one said receiving channel is one of at least two receiving channels.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0086] FIG. 1 is a diagrammatic, perspective view of a guided missile with a radar sensor unit according to the invention;

[0087] FIG. 2 is a side, perspective view of a section of the guided missile shown in FIG. 1;

[0088] FIG. 3 is a front profile view of the guided missile shown in FIG. 1, at right angles to the side view of FIG. 2;

[0089] FIG. 4 is an enlarged, perspective view of a section of the guided missile in the region of the radar sensor unit;

[0090] FIG. 5 is a perspective view of a radar antenna group from FIG. 4 shown in detail;

[0091] FIG. 6 is an illustration of an antenna radiation pattern of an individual radar antenna in a first mode of operation;

[0092] FIG. 7 is an illustration of an antenna radiation pattern of an individual radar antenna in a second mode of operation;

[0093] FIG. 8 is a schematic cross-sectional view of the missile in the region of the radar sensor unit;

[0094] FIG. 9 is a circuit arrangement of the radar sensor unit;

[0095] FIG. 10 is an illustration showing the operation of the radar sensor to ascertain the polar angle of a target object by way of illustration; and

[0096] FIG. 11 is an illustration showing the operation of the radar sensor unit to ascertain the azimuth angle of a target object by way of illustration.

DETAILED DESCRIPTION OF THE INVENTION

[0097] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:

[0098] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown an exemplary embodiment of a guided missile 1 configured according to the invention with a radar sensor unit 2.

[0099] The guided missile 1, subsequently also called missile 1 for short, has a drive 3 that defines a drive end AE of the missile 1. At an end remote therefrom in the direction of the missile longitudinal axis L, i.e at a missile tip, the missile 1 has a missile head 4 that defines a head end KE. At the drive end AE the missile 1 has multiple fins, not denoted in more detail, for guidance and/or for stabilizing flight.

[0100] On a segment that follows the missile head 4 the missile 1 has a guidance section 5 in the direction of the drive end AE, the guidance section being followed towards the drive 3 by a warhead 6 by way of illustration. The design in the direction of the missile longitudinal axis L can differ from the design actually shown.

[0101] The guidance section 5 contains one or more computer and control units (not explicitly shown) for guiding the missile 1. Furthermore, electronic components of the radar sensor unit are accommodated in the region of the guidance section 5.

[0102] The radar sensor unit 2 contains multiple radar antennas 7 that are mounted and integrated on a circumferential surface that is planar in the direction of the missile longitudinal axis L but cylindrically curved in the circumferential direction.

[0103] For aerodynamic reasons the radar sensors 7 are configured to be substantially flush with the circumferential surface.

[0104] The arrangement in the region of the guidance section 5 has the advantage in particular that short signal paths can be achieved between the radar antennas 7 and assigned electronic components of the radar sensor unit 2.

[0105] The radar antennas 7 are in strip-shaped form, wherein the longitudinal direction of the strip-shaped radar antennas 7 is aligned in the direction of the missile longitudinal axis L. In the present example the longitudinal direction of each of the radar antennas 7 is parallel to the missile longitudinal axis L.

[0106] During operation of the radar sensor unit 2 the strip-shaped radar antennas 7 aligned parallel to the missile longitudinal axis L can be used, given appropriately selected operating parameters, to produce antenna main lobes 8 that are focused in relatively narrow fashion over the polar angle 9 (theta), in particular over a defined polar angle range of the antenna main lobe 8. The defined polar angle range may be less than 30 degrees, for example.

[0107] The polar angle 9 in this case is defined with reference to an on-missile, right-handed spherical coordinate system whose origin lies e.g. in the center of the longitudinal direction of a radar antenna 7, and which has a polar axis P that is parallel to the longitudinal direction of the radar antenna 7. In the present example the polar axis P is also parallel to the missile longitudinal axis L. The positive polar axis direction is defined by the direction in which the radar antenna 7 runs from the drive end AE to the head end. The polar angle 9 is measured between the polar axis P and the center axis M of the antenna main lobe 8 of the radar antenna 7 in the polar angle direction. In the circumferential direction with respect to the polar axis P the azimuth angle 10 (phi) is accordingly defined as a rotation angle with respect to a plane E that runs parallel to the polar axis P and contains the polar axis P.

[0108] An accordingly aligned antenna main lobe 8 can therefore illuminate a spatial segment situated obliquely with respect to the missile longitudinal axis L in order to detect and acquire a target object 11.

[0109] FIG. 2 shows a side profile view of the guided missile 1 in the region of the head end KE with reference to the spherical coordinate system's polar main plane that runs through the polar axis P and the coordinate origin of the spherical coordinate system, in order to schematically clarify the alignment of the antenna main lobe 8. As can be seen from FIG. 2 the antenna main lobe 8 is rotated through a polar angle 9 relative to the polar axis P and is focused over a defined polar angle range in the polar main plane, i.e. over a defined polar vertex angle 12. The polar vertex angle 12 of the antenna main lobe 8 may be e.g. less than 30 degrees in the respective defined region of the antenna main lobe 8, for example depending on operating parameters of the radar sensor unit 2.

[0110] Depending on the operating parameters the polar angle 9 of the antenna main lobe 8 can be aligned with the front half-space H, the polar angle 9 being able to be adjusted for example between close to zero degrees and 90 degrees with respect to the front half-space H by means of appropriate operation of the radar antennas 7. In other words, appropriate operation of the radar antennas 7 can result in the antenna main lobe 8 being swivelled in the front half-space H in the cited angle range. Swivelling of the antenna main lobe 8 in the rear half-space can likewise be achieved given appropriate operation of the radar antennas 7, the illumination of the front half-space H principally being significant for the acquisition of a target object 11, for the tracking of a target object 11 and for the target navigation of the guided missile 1 to the target object

[0111] FIG. 3 shows a front profile view of the guided missile 1, at right angles to the side profile view of FIG. 2, with reference to the spherical coordinate system's azimuthal main plane that runs at right angles through the polar axis P and the coordinate origin. As can be seen from the schematic depiction of FIG. 3 the antenna main lobe 8 sweeps over an azimuth vertex angle 13 in the defined region of the antenna main lobe 8 in the azimuthal main plane, the azimuth vertex angle being able to be greater than 30 degrees, for example, depending on the operating parameters of the radar sensor unit 2.

[0112] Looking at FIG. 1 to FIG. 3 together reveals in particular that the antenna main lobe 8 is aligned to the side of the missile longitudinal axis L and can illuminate a corresponding lateral spatial region.

[0113] FIG. 4 shows an enlarged section of the guided missile 1 in the region of the radar sensor unit 2. Specifically, FIG. 4 shows the region of the guidance section 5 with a radar antenna group fitted to the perimeter thereof. The radar antenna group contains a transmitting antenna 14 and two receiving antennas 15 assigned to the transmitting antenna 14.

[0114] The radar sensor unit 2 shown in FIG. 1 contains multiple such radar antenna groups, FIG. 4 showing just one radar antenna group for reasons of clarity. There may therefore be multiple radar antennas 7 and radar antenna groups on the circumferential surface of the guidance section 5, e.g. according to an evenly distributed arrangement in the circumferential direction. By way of example a total of four such radar antenna groups may be arranged in a manner distributed over the perimeter of the guidance section 5, at approximately identical intervals in the circumferential direction.

[0115] The transmitting antenna 14 and receiving antennas 15 have an elongate shape as seen in the missile longitudinal axis L, i.e. they are each in strip-shaped form. A strip-shaped radar antenna 7 can have a ratio of length to width in the range from 30:1 to 40:1, for example.

[0116] The transmitting antenna 14 and the receiving antennas 15 are of substantially identical length with respect to the missile longitudinal axis L. The beginnings and ends are each situated in planes that run at right angles to the missile longitudinal axis L. In particular the transmitting antenna 14 and the receiving antennas 15 in the example shown have substantially no offset in the direction of the missile longitudinal axis L. As already discussed above, selected radar antennas 7 may be offset in the direction of the missile longitudinal axis L, for example in order to prevent crosstalk by radar signals.

[0117] The strip-shaped transmitting antenna 14 and the strip-shaped receiving antennas 15 are in the form of leaky wave antennas in the present example.

[0118] Other types of antenna that, like leaky wave antennas, allow the antenna main lobe 8 to be aligned in the polar angle direction are also possible, however. Phase-controlled group antennas, which allow alignment of the antenna main lobe by means of appropriate adjustment of the phases of the antenna elements of the group antenna, may be mentioned in this context by way of illustration.

[0119] Leaky wave antennas allow the alignment of the antenna main lobe 8 to be adapted by varying the frequency, for example. The leaky wave antennas may be implemented as substrate-integrated leaky wave antennas, for example.

[0120] The number of radar antennas in a radar antenna group may differ from the example shown. In particular a radar antenna group can comprise more than just one transmitting antenna. Furthermore, it is possible for just one receiving antenna or more than two receiving antennas to be assigned to a radar antenna group.

[0121] In some variants it is also possible for a radar antenna 7 to be configured for selective operation as a transmitting antenna 14 and a receiving antenna 15. By way of example a corresponding radar antenna 7 may be configured such that it is alternately connectable as a transmitting antenna 14 and a receiving antenna 15. Furthermore, it is possible for the selective operation of the radar antenna 7 as a transmitting antenna 14 and a receiving antenna 15 to be implemented using a radio-frequency transmission/reception selector, for example a circulator or a coupler.

[0122] In the case of such variants with selective operation of a radar antenna 7 it is possible for the number of radar antennas to be reduced and for the radar sensor unit to be changed over between transmission and reception mode by means of appropriate operation.

[0123] Furthermore, it is possible for different radar antenna groups to be arranged in the circumferential direction, for example containing just one—or else multiple—reciprocally operable radar antennas or containing one or more radar antennas configured explicitly as transmitting antennas and one or more radar antennas configured as receiving antennas. Moreover, it is possible for the relative arrangement of the radar antennas to differ from the arrangement shown in FIG. 4. Furthermore, multiple radar sensor units 2 may be present on the missile body, for example at different positions in the direction of the missile longitudinal axis L.

[0124] The transmitting antenna 14 is at a first distance D1 from the receiving antennas 15 in the circumferential direction, and the receiving antennas 15 of the radar antenna group are at a second distance D2 from one another measured in the circumferential direction. The second distance D2 may be for example shorter than, identical to or greater than a radar wavelength at which the radar sensor unit 2 is operated. The second distance D2 is preferably in the order of magnitude of the radar wavelength. The second distance D2 may be shorter than, identical to or greater than the first distance D1, depending on the variant of the radar antenna group. By way of example, the second distance D2 may be chosen to be greater than the first distance D1 if such spacing is required in order to reduce crosstalk between the radar antennas 7. The first and second distances D1 and D2 actually shown in the figures are therefore intended to be understood merely as non-limiting exemplary embodiments.

[0125] FIG. 5 shows the radar antenna group of FIG. 4 in detail. The transmitting antenna 14 and the two receiving antennas 15 are mounted or integrated on or atop a support plate 16. The support plate 16 may be configured such that it can be mounted on the outside of an outer wall of the guided missile such that the transmitting antenna 14 and the receiving antennas 15 are oriented towards the outside. The support plate 16 may also be configured such that it forms part of the outer cover, i.e. part of the outer skin, of the guided missile 1 after being mounted on the missile body.

[0126] On the side of the support plate 16 that is remote from the transmitting antenna 14 and the receiving antennas 15 there may be respective connection interfaces for the transmitting antenna 14 and the receiving antennas 15, by which the transmitting and receiving antennas 14, 15 can be connected for signal transmission and control purposes to an electronics unit configured for operating the radar sensor unit 2. The support plate 16 can in particular act as a cover for the electronics unit 17 arranged beneath it in the missile body (FIG. 3). The electronics unit 17 arranged inside the missile body schematically in FIG. 3 is connected to the radar antennas 7 via radio-frequency cables 23.

[0127] FIG. 6 shows an antenna radiation pattern of an individual radar antenna 7 in a first mode of operation, and FIG. 7 shows an antenna radiation pattern of an individual radar antenna 7 in a second mode of operation. The radar antennas 7 are in the form of strip-shaped leaky wave antennas.

[0128] In the first mode of operation of FIG. 6 the radar antenna 7 is operated at a first frequency and has an antenna main lobe 8 at a first polar angle 9.1.

[0129] In the second mode of operation of FIG. 7 the radar antenna 7 is operated at a second frequency and has an antenna main lobe 8 at a second polar angle 9.2.

[0130] The first polar angle 9.1 is smaller than the second polar angle 9.2, as can be seen by looking at FIG. 6 and FIG. 7 together. When using corresponding radar antennas 7 as transmitting antennas 14 it is therefore possible to swivel the antenna main lobe 8. On the basis of a swivel of the antenna main lobe 8 it is possible to ascertain in particular the polar angle of a target object 11 situated in the field of view of the radar sensor unit 2 from the respectively captured reflected radar signals.

[0131] In particular the polar angle of a target object 11 situated in the field of view can be ascertained by means of amplitude comparison of the reflected radar signals. By way of example that polar angle of a radiated radar signal whose reflected radar signals show an amplitude maximum in the amplitude comparison can be used as a polar angle of the target object 11.

[0132] FIG. 8 shows a schematic cross-sectional view of the guided missile 1 in the region of the guidance section 5, the transmitting antennas 14 and the receiving antennas 15.

[0133] In the example shown in FIG. 8 a total of four of the radar antenna groups shown in FIG. 4 and FIG. 5 are arranged on the perimeter of the guidance section 5, the radar antenna groups being distributed such that they can be converted into one another by means of a rotation through an angle of 90 degrees about the missile longitudinal axis L.

[0134] The arrangement of the transmitting and receiving antennas 14, 15 shown in FIG. 8 can be used in combination to achieve a field of view that allows almost complete spatial coverage over the azimuth angle. In FIG. 8 the plane of the drawing lies in or parallel to the azimuthal main plane of the spherical coordinate system described earlier on.

[0135] In some variants the number of radar antenna groups shown in FIG. 8 can also vary and match the respective dimensions of the guided missile cross-section. With a larger diameter it may be necessary e.g. to arrange more than four radar antenna groups in order to obtain substantially complete spatial coverage over the azimuth angle. The same applies if coverage with fewer radar antenna groups is possible. If there are fewer radar antenna groups present than are required for complete coverage of the full azimuth angle, the missing coverage can be compensated for by virtue of the roll angle of the guided missile 1 changing during flight, for example, and the field of view being rotated as a result. Rotation of the field of view on the basis of adaptation of the roll angle can take place on the basis of data pertaining to prior knowledge of an approximate position of the target object 11, for example.

[0136] The arrangement of the transmitting and receiving antennas 14, 15 shown in FIG. 8 allows in particular the polar angle and the azimuth angle of a target object 11 to be ascertained.

[0137] The polar angle of a target object 11 can be ascertained, or at least narrowed down, as already described above, for example by virtue of the antenna main lobe(s) 8 of one or more radar antenna groups being swivelled over the polar angle in successive operating cycles, and the reflected radar signals of successive operating cycles being compared with one another in respect of amplitude. The polar angle of the target object 11 can then be assumed to be that polar angle at which the amplitude of a reflected radar signal is greatest, in particular has a maximum or passes through a maximum. By way of illustration, reference is made in this instance to methods described in S. A. Hovanessian, 1982, Radar Detection & Tracking Systems, ISBN 0-89006-018-5, which can be applied accordingly.

[0138] The azimuth angle of a target object 11 can be ascertained for example by virtue of radar signals radiated by a transmitting antenna 14 in an operating cycle and reflected by the target object 11 being simultaneously detected by adjacent receiving antennas. Phase and amplitude comparison of the simultaneously detected reflected radar signals can then be used to ascertain the azimuth angle of the target object 11. By way of example, reference is made in this instance to methods described in David K. Barton, 1985, Radar System Analysis, ISBN 0-89006-043-6, which can be applied accordingly.

[0139] Suitable search strategies for operating the radar sensor unit 2 may be implemented in order to ascertain the polar angle and azimuth angle of the target object 11.

[0140] The distance of the target object 11 can be ascertained by means of time-of-flight measurements, for example.

[0141] In the example shown in FIG. 8 the azimuth angle of the schematically depicted target object 11 can be ascertained by virtue of the transmitting antenna 14 situated at the top left transmitting a radar signal and reflected radar signals being received, in particular simultaneously detected, by the receiving antennas 15 assigned to the radar antenna group, this being indicated schematically by dashed arrows in FIG. 8. The azimuth angle of the target object 11 can then be ascertained from amplitude and/or phase comparison of the simultaneously detected, reflected radar signals.

[0142] However, receiving antennas 15 of a different, adjacent radar antenna group can also be used to ascertain the azimuth angle of the target object 11. If the target object 11 in the example of FIG. 8 is located in the region above the transmitting antenna 14 situated at the top right, for example, the receiving antennas 15 and corresponding received signals of the radar antenna group situated adjacently anticlockwise in FIG. 8 can be used.

[0143] FIG. 9 shows a circuit arrangement, in particular an electronics unit 17, for operating the radar sensors 7 to acquire a target object 11 by way of illustration.

[0144] The electronics unit 17 contains a transmitting channel 18 and two receiving channels 19, the transmitting channel 18 and the two receiving channels 19 being depicted schematically by dashed rectangles in FIG. 9.

[0145] The transmitting channel 18 in the version shown can be connected to one or more of the four transmitting antennas 14 by means of a switching network 20, said transmitting antennas being connected to the electronics unit 17 via radio-frequency cables 23.

[0146] The electronics unit 17 also contains two receiving channels 19, each receiving channel being able to be connected to one or more of in each case four receiving antennas 15 by means of further switching networks 21. The receiving antennas 15 are connected to the electronics unit 17 via radio-frequency cables 23.

[0147] In order to acquire a target object 11, i.e. in order to detect and locate a target object 11, the transmitting antennas 14 and receiving antennas 15 can be activated in respective operating cycles in the manner described above. An evaluation unit 24, which is depicted schematically by a dashed rectangle in FIG. 9, of the electronics unit 17 can evaluate the radar signals captured by the receiving antennas 15 and can accordingly use them to ascertain target object data, for example to ascertain the distance, polar angle, azimuth angle, velocity and/or acceleration of the target object 11.

[0148] If it is not possible to detect a target object 11 in an operating cycle, for example, one or more other transmitting antennas and/or other receiving antennas can be activated in a subsequent operating cycle, and received radar signals can be evaluated to ascertain whether a target object 11 is located in the respective field of view. Accordingly, transmitting and receiving antennas can be activated to ascertain the polar angle and azimuth angle and other target object data.

[0149] FIG. 10 shows the operation of the radar sensor unit 2 to ascertain the polar angle of a target object 11 by way of illustration and schematically. Specifically, the radar sensor unit 2 is operated with antenna main lobes 8 aligned differently over the polar angle in successive operating cycles.

[0150] In a first operating cycle corresponding to a first antenna main lobe 8.1 a reflected radar signal having a first amplitude A1 is measured, the first amplitude Al corresponding to the point of intersection on the direct connecting line 22 between the radar sensor unit 2, i.e. the receiving antenna/s 15, and the target object 11 in the depiction in FIG. 10.

[0151] In a second operating cycle corresponding to a second antenna main lobe 8.2 a reflected radar signal having a second amplitude A2 is measured, the second amplitude A2 corresponding to the point of intersection on the direct connecting line 22 between the radar sensor unit 2, i.e. the receiving antenna(s) 15, and the target object 11 in the depiction in FIG. 10.

[0152] As can be seen from FIG. 10 in a schematic depiction, the first amplitude Al is smaller than the second amplitude A2, from which it is possible to conclude that the polar angle of the second antenna main lobe 8.2 in the second operating cycle is closer to the actual polar angle of the target object 11 than the polar angle of the first antenna main lobe 8.1 of the first operating cycle.

[0153] On the basis of multiple successive operating cycles with respective different alignments of the antenna main lobe 8 over the polar angle it is then possible to assign to the target object 11 that polar angle PX for which the amplitude of the reflected radar signal is greatest, e.g. has or passes through a maximum. FIG. 10 depicts just two operating cycles for the purposes of illustration.

[0154] FIG. 11 shows the operation of the radar sensor unit 2 to ascertain the azimuth angle AX of a target object 11 by way of illustration and schematically.

[0155] In this case, radar signals radiated in an operating cycle and reflected by the target object 11 are simultaneously detected by adjacent receiving antennas 15. At least one phase difference in the received reflected radar signals is obtained on the basis of the distance AD between the receiving antennas 15 that exists in the azimuth direction.

[0156] From geometric considerations, the azimuth angle AX of the target object is obtained for example for a measured phase difference PD with a given radar wavelength I and on the basis of the distance AD between the two receiving antennas 15 from the following equation:

AX=invsin (I*PD/(2Pi*AD)),

[0157] where invsin denotes the inverse sine function and Pi denotes pi.

[0158] In regard to FIG. 1, FIG. 8, FIG. 9 and FIG. 10 it should also be mentioned that these are not to scale at least insofar as the target object 11 is much further away from the radar sensor unit 2 and the missile 1 under real conditions than depicted.

[0159] When ascertaining the target object data it is possible for the electronics unit 17, in particular the evaluation unit 24, and the radar sensor unit 2 to be operated in the manner described earlier on. In particular at least some of the operating parameters of the radar sensor unit 2 can be tailored to prior knowledge pertaining to the target object 11, for example pertaining to the position of the target object 11. By way of example the operating parameters can be adjusted to ascertain the polar angle PX of the target object 11 and/or the azimuth angle AX of the target object 11 in an initial phase of target acquisition on the basis of position data that have been/are ascertained and provided to the electronics unit 17 and evaluation unit 24 via an external unit or via a target acquisition unit other than the radar sensor unit 2, which target acquisition unit may be optical or infrared-based, for example. As soon as the target object 11 is in the field of view of the radar sensor unit 2 and is acquired, the operating parameters can be adapted on the basis of the received signals of the radar sensor unit 2, for example in order to set a suitable polar angle for the antenna main lobe 8 and/or to activate suitable radar sensor groups to acquire the target object 11 in the azimuth direction, such that the target object 11 can be tracked on the basis of the radar sensor unit 2 and remains in the field of view of the radar sensor unit 2.

[0160] According to some variants the radar sensor unit 2 contains strip-shaped individual radar antennas 7 in a parallel arrangement that are disposed along the missile longitudinal axis L on the surface of the cylindrical housing of the guidance section 5 of the missile 1 or, in the more general case, along the missile longitudinal axis L on a relatively narrow and long planar surface. The second distance D2 between adjacent receiving antennas 15 and the first distance D1 between the transmitting antennas 14 and the receiving antennas can be in the ranges already described earlier on.

[0161] In some variants the radar sensor unit 2 can contain at least one transmitting antenna 14 and two receiving antennas 15, but a larger number of transmitting antennas 14 and receiving antennas 15 may also be present in each case, e.g. one transmitting antenna 14 and a series of three or more adjacent receiving antennas 15 within a radar antenna group.

[0162] When using circulators and suitable distribution networks, in particular transmission/reception selectors, the transmitting and receiving antennas 14, 15 may be identical in some variants.

[0163] In some variants the strip-shaped radar antennas 7 have an antenna radiation pattern able to be directed over the polar angle whose 3-dB antenna main lobe width over the polar angle measures only comparatively few degrees but stretches from the middle of the two-digit to the low three-digit range of degrees over the azimuth angle.

[0164] The polar angle range over which the antenna radiation pattern of a strip-shaped radar antenna 7 is able to be directed and the 3-dB antenna main lobe widths of the antenna radiation pattern for the different alignments determine the spatial segment that can be illuminated by the radar antenna 7 and in which target objects 11 can be acquired.

[0165] In general, an antenna arrangement containing a transmitting antenna 14 with two or more adjacent receiving antennas 15 cannot definitely cover the entire space. In order to be able to capture larger spatial segments there may be provision for further antenna arrangements that are of the same type but point in different azimuth directions, e.g. radar antenna groups. A sufficiently large number of antennas can therefore be used to cover the space for substantially all azimuth angles. Gaps in the spatial coverage may remain only as a result of the limits of the directability of the antenna radiation patterns over the polar angle.

[0166] In some variants the electronics unit 17 contains one or more transmitting channels 18 for generating radar signals that are radiated or transmitted via connected transmitting antennas 14, and two or more receiving channels 19 for detecting radar signals reflected by a target object 11 that are then received via the connected receiving antennas 15.

[0167] In some variants the electronics unit 17 contains at least one transmitting channel 18 and two receiving channels 19 that are connected or can be connected to a corresponding number of transmitting and receiving antennas 14, 15. For more extensive antenna arrangements one transmitting channel 18 may be distributed over or connectable to all transmitting antennas 14, or else there may be provision for one transmitting channel 18 per transmitting antenna 14.

[0168] In some variants there is provision for a separate receiving channel 19 for each receiving antenna 15 in a series of adjacent receiving antennas 15 so that in particular phase and amplitude differences in simultaneously received radar signals can be evaluated to ascertain the azimuth angle AX of the target object 11.

[0169] If, according to some variants, the antenna arrangement consists of multiple homogeneous series or groups of adjacent receiving antennas 15 that are e.g. aligned in different azimuth directions, some variants allow the number of receiving channels 19 to be reduced to the number of receiving antennas 15 in a series or group of adjacent receiving antennas 15, with the receiving channels 19 being connected to that series or group of adjacent receiving antennas 15 that is currently intended to be used to receive.

[0170] If corresponding variants require switching to be effected between a few transmitting and receiving channels 18, 19 and many transmitting and receiving antennas 14, 15 then it may be possible not to use all of the transmitting antennas 15 for transmission or all of the receiving antennas 14 for reception in parallel. Accordingly, the target object 11 can be acquired only in the spatial segment that is respectively covered by the activated transmitting and receiving antennas 14, 15.

[0171] Successful detection and location of target objects 11 in a spatial segment by the radar sensor unit 2 requires the antenna main lobes 8 of the transmitting and receiving antennas 14, 15 that cover this spatial segment to be aligned with the target object 11 over the polar angle, for example by using possibly available prior knowledge of the approximate position of the target object 11 or as part of a search strategy that involves a spatial segment being progressively searched or scanned for possible target objects 11.

[0172] If the target object 11 is within the antenna main lobes 8 then it can be detected in the different connected receiving channels 19. According to some variants its position in spherical coordinates can be measured as follows: [0173] a) The polar angle can already be obtained relatively accurately by virtue of the target object 11 being in the antenna main lobe 8 of the transmitting and receiving antennas 14, 15 that is comparatively narrow over the polar angle. For more accurate measurement the alignment of the antenna main lobe 8 is varied between chronologically successive detections, for example slightly or progressively iteratively. Amplitude comparison of the different detections allows comparatively accurate location of the target object 11 to be achieved. [0174] b) The azimuth angle can be estimated only very coarsely using the mere knowledge that the target object 11 is within the antenna main lobe 8 that is comparatively wide over the azimuth angle. It can be accurately measured and ascertained by means of phase and amplitude comparison of simultaneous detections by adjacent receiving antennas 15. [0175] c) The distance and approach velocity of the target object 11 can be obtained from the received radar signal when a suitable form of modulation for the transmitted radar signal is chosen, for example.

[0176] The explanations above reveal in particular that the proposed radar sensor unit on a missile allows comparatively precise ascertainment of target object data. Furthermore, it is possible to functionalize the missile tip usually fitted with seeker optical systems or other target acquisition units in another way.

REFERENCE SIGNS

[0177] 1. guided missile [0178] 2. radar sensor unit [0179] 3. drive [0180] 4. missile head [0181] 5. guidance section [0182] 6. warhead [0183] 7. radar antenna [0184] 8. antenna main lobe [0185] 8.1 first antenna main lobe [0186] 8.2 second antenna main lobe [0187] 9. polar angle [0188] 9.1 first polar angle [0189] 9.2 second polar angle [0190] 10. azimuth angle [0191] 11. target object [0192] 12. polar vertex angle [0193] 13. azimuth vertex angle [0194] 14. transmitting antenna [0195] 15. receiving antenna [0196] 16. support plate [0197] 17. electronics unit [0198] 18. transmitting channel [0199] 19. receiving channel [0200] 20. switching network [0201] 21. further switching network [0202] 22. connecting line [0203] 23. radio-frequency cable [0204] 24. evaluation unit [0205] 25. AE drive end [0206] A1 first amplitude [0207] A2 second amplitude [0208] D1 first distance [0209] D2 second distance [0210] E plane [0211] H front half-space [0212] KE head end [0213] L missile longitudinal axis [0214] I radar wavelength [0215] M centre axis [0216] P polar axis [0217] PX target object polar angle [0218] PD phase difference [0219] AX target object azimuth angle [0220] AD distance between the receiving antennas