Sensor system for fuze

Abstract

The invention relates to a sensor system, for arrangement in a fuze for a projectile, comprising at least two antenna structures, a transmitter antenna structure and a receiver antenna structure, wherein each antenna structure comprises a matrix of antenna elements.

Description

[0001] SENSOR SYSTEM FOR FUZE

[0002] TECHNICAL AREA

[0003] The present invention relates to a sensor system for arrangement in a fuze for a projectile comprising an antenna structure comprising a matrix of antenna elements, wherein the antenna elements are arranged in at least two positions distributed on the fuze in its longitudinal direction A and / or rotational direction B forming an antenna structure in the form of a matrix with at least 2 antenna elements and at least one feed network arranged to the antenna structure, and at least one transmitter device arranged to the feed network, and at least one receiver device arranged to the feed network, and at least one processor unit arranged to the receiver device for signal processing of the received signal. The invention further relates to a fuze and projectile.

[0004] BACKGROUND OF THE INVENTION, PROBLEM AREA AND PRIOR ART

[0005] Projectiles arranged to impact a target may utilize different systems or techniques to enhance their ability to impact the target. For example, the projectile may be arranged with different sensors to sense the target object and act with fragments to achieve a larger area of weapon effect. Further, the projectile may be arranged with various means for guiding the projectile, such as fins, which may cause the projectile to steer towards the target object. In order to improve the ability of the projectile to act on the target, the projectile may be arranged with a sensor system, such as a proximity fuze. Proximity fuzes can utilize sensors operating in optical wavelength ranges or sensors adapted for electromagnetic radiation in lower frequency ranges such as in the microwave range.

[0006] Patent document US 2006 0087 472 Al describes a proximity fuze comprising a radar device including UWB transmitter and UWB receiver. The patent document does not show an antenna array arranged in the proximity fuze.

[0007] Solution to the above problem and additional problems with solution are described below. THE INVENTION AND ITS PURPOSE

[0008] One object of the present invention is to solve the problems identified above.

[0009] The invention consists of a sensor system, for arrangement in a fuze for a projectile, comprising at least two antenna structures, a transmitter antenna structure and a receiver antenna structure, wherein each antenna structure comprises a matrix of antenna elements, wherein the antenna elements of the transmitter antenna structure are arranged in at least two positions distributed on the fuze in its longitudinal direction A and / or rotational direction B forming a transmitter antenna structure in the form of a matrix with at least 2 antenna elements and the antenna elements of the receiving antenna structure are arranged in at least two positions distributed on the fuze in its longitudinal direction A and / or rotational direction B forming a receiving antenna structure in the form of a matrix with at least 2 antenna elements, and at least one first feed network arranged to the transmitting antenna structure and at least one transmitter device arranged to the first feed network, and at least one second feed network arranged to the receiver antenna structure, and at least one receiver device arranged to the second feed network, and at least one processor unit arranged to the receiver device for signal processing of the received signal.

[0010] According to further aspects for a sensor system according to the invention applies; t h a t at least two antenna elements are arranged in series on a feed network. t h a t the feeding network is a microstrip. t h a t the antenna is of the patch antenna type. t h a t the antenna is of the dipole type. t h a t the antenna is of the slot antenna type. t h a t the antenna elements are of the waveguide antenna type. t h a t the antenna elements are of the gap waveguide antenna type. t h a t the antenna elements are arranged to transmit and receive electromagnetic signals in the frequency range between 55 GHz and 97 GHz. t h a t the transmitting antenna structure and / or the receiving antenna structure is arranged on a flex board. t h a t the first feeding network and / or the second feeding network is provided with at least one phase shifter to phase control the antenna structure. t h a t the first feeding network and / or the second feeding network is arranged with at least one splitter / combiner. t h a t the antenna elements for the transmitting antenna structure at least 5 positions in the longitudinal fuze A and at least 2 positions in the rotational fuze B forming an antenna structure in the form of a matrix with at least 10 antenna elements. t h a t the antenna elements for the receiver antenna structure are arranged in at least 5 positions in the longitudinal fuze A and at least 4 positions in the rotational fuze B forming an antenna structure in the form of a matrix with at least 20 antenna elements. t h a t the sensor system is arranged in fuzes and where the processor unit is arranged to a detonator where the detonator is initiated when a target object is detected by the sensor system.

[0011] The invention further comprises a fuze characterized in that a sensor system is arranged in the fuze and wherein the processor unit is arranged to a detonator where the detonator is initiated when a target object is detected by the sensor system.

[0012] According to further aspects for a fuze according to the invention applies; t h a t the fuze further includes an impact sensor.

[0013] The invention further comprises a projectile comprising a warhead and a fuze comprising a sensor system arranged to the projectile. LIST OF FIGURES

[0014] The invention will be described in more detail below with reference to the accompanying figures:

[0015] Fig. 1 shows an antenna of the patch antenna type.

[0016] Fig. 2 shows a feed network to an antenna structure according to an embodiment of the invention.

[0017] Fig. 3 shows a serially fed patch antenna structure according to an embodiment of the invention.

[0018] Fig. 4 shows a fuze in side view according to one embodiment of the invention.

[0019] Fig. 5 shows a block diagram of a sensor system according to one embodiment of the invention.

[0020] Fig. 6 shows a block diagram of a sensor system according to an alternative embodiment of the invention.

[0021] DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention discloses a new and alternative design of sensor system for proximity fuze, which is a type of fuze, for a projectile device, also referred to as a shell. A launching device, also called a cannon, howitzer, or gun, such as a medium caliber gun, is intended to launch a projectile by means of a propellant. Preferably, a propellant, such as gunpowder, is initiated in a part of the gun, often a sleeve or a chamber specially adapted for this purpose. Initiation is achieved by igniting the propellant, for example with a primer or igniter in an ammunition unit, which is initiated by impact. Other methods of igniting the propellant may be by laser or electrical energy igniting the propellant. The propellant bums with high velocity and high gas evolution, creating a gas pressure in the chamber that drives the projectile out of the barrel of the launcher. The propellant is adapted to generate, as far as possible, a constant pressure on the projectile throughout the barrel trajectory, as the projectile moves through the barrel, creating a high velocity of the projectile as the projectile leaves the barrel mouth. Projectiles, such as various types of grenades, usually include some form of warhead and some form of fuze that initiates the warhead. Fuzes can be of different types, where impact fuzes are commonly used for projectiles that are intended to explode on contact with an object, time fuzes where the projectile is intended to explode at a certain predetermined time, and proximity fuzes where the projectile is intended to explode when an object comes within a certain distance of the projectile. Proximity fuzes are preferably used when combating aircraft, while time fuzes and impact fuzes can be used when combating a large number of different objects. It is advantageous to combine different types of fuze functions in the same fuze, so that if a fuze with a zone tube function does not detect an object, the projectile will burst after a certain time, etc.

[0023] Proximity fuzes have traditionally used low-frequency electromagnetic radiation, but radar technology, which uses more high-frequency electromagnetic radiation, can also be used. Radar is equipment and technology for detecting and determining distances using radio waves. Radar mainly uses short-wave radio waves, i.e. electromagnetic radiation, to identify distances and possibly the position and direction of travel of various objects arranged at a distance from the radar transmitter. A signal is emitted, reflected towards the object and detected by the sender. Commonly the same antenna structure is used to transmit as to receive the radar signal.

[0024] In recent years, the automotive industry has developed technology for radar in cars to increase safety through automatic braking in queuing situations, for example. Developments in the automotive industry have led to the development of both technology and components, especially cheap semiconductor components. By applying components from the automotive industry for fuzes, the production costs of fuzes with radar functionality can be reduced.

[0025] The warhead preferably includes some form of explosive and some form of shrapnel casing enclosing the explosive. Furthermore, various forms of guidance means, such as fins, may be provided, either in the fuze or in a separate sub-component.

[0026] In order to stabilize the projectiles after the projectiles have left the barrel, the projectiles are preferably arranged with rotation or with fins. In the case that the projectiles are arranged with rotation, the projectiles are said to be rotationally stabilized and in the case that the projectiles are arranged with fins, the projectiles are said to be fin- stabilized. Fin-stabilized projectiles should have no rotation or very low rotation as they leave the barrel.

[0027] To achieve rotation of the projectiles, grooves are often arranged in the barrel to which the projectile connects during the ejection process. Grooving means that the barrel of a firearm, the barrel, is provided with spiral grooves. The opposite is smooth-bore barrel. When the grooves engage the projectile during firing, it rotates along its longitudinal axis. Through the rotation, minor irregularities or damage to the projectile will not cause a drift. Rotation is also necessary for an oblong (torpedo- shaped) projectile to maintain its direction after leaving the barrel and not start tumbling around, this is referred to as the projectile being rotationally stabilized. In smoothbore weapons, only round (spherical) projectiles or fin- stabilized projectiles can be fired. An oblong projectile without fins will tumble as it leaves the muzzle.

[0028] FUNCTION DESCRIPTION

[0029] An ejection device is arranged to fire, shoot, projectiles with a propelling charge. The propellant charge, which may be, for example, gunpowder, bums after initiation and generates a high pressure which propels the projectile out of a barrel. The projectile may be arranged in a case filled with a propellant charge, called an ammunition unit, in which the projectile arranged in the case is applied or loaded to the ejection device.

[0030] Alternatively, the projectile may be arranged in the barrel separately by a process known as seating, usually by deforming a rim around the projectile against a groove in the barrel which retains the projectile in the barrel. The propellant charge is arranged in what is often referred to as a chamber in which the propellant charge is combusted to produce gases, gunpowder gases, which cause the projectile to move in the barrel. Preferably, a continuous / constant pressure is created in the chamber which also fills up the barrel with pressurized gas behind the projectile as it moves towards the mouth of the barrel.

[0031] Preferably, projectiles with calibers in the range of 20 - 105 mm are arranged in the form of cased ammunition, while larger calibers, the projectile is not cased. However, it happens that even larger calibers are cased. Different forms of antennas / antenna elements can be arranged on the projectile, such as ceramic patch antennas, which are a variant of a microstrip antenna, which can be manufactured with a compact form factor. Since the patch antenna is relatively narrowband, the patch antenna also has a filtering function that filters signals outside the frequency range for which the antenna is adapted, which is important for filtering out broadband interference.

[0032] A patch antenna requires a ground plane which is a substantially flat conductive surface connected to electrical ground. Ideally, it should be large relative to the antenna element, the patch element.

[0033] Fig. 1 shows a perspective view of a conventional patch antenna 10 with a patch element

[0034] 11 having an approximately square surface, where the side of the square surface is preferably the wavelength / 2. An antenna for, for example, 1575.42 MHz, which is a frequency utilized in GPS receivers, provides a square surface of the patch element of 95x95 mm. A conductive base plate 12, which acts as a ground plane, is preferably arranged parallel to said patch element, which is necessary for the function. Printed circuit boards, shielding housings and metallic parts of the product on which the antenna is arranged can be used as conductive base plates when acting as ground planes. The space 13 between the patch element 11 and the conductive base plate 12 may be provided with a ceramic or plastic filling with a different dielectric constant which, in the case of a ceramic, may result in a reduction of the size of the antenna to 25x25 mm and 19x19 mm respectively for the patch element with a thickness of a couple of mm in the case that the frequency is that of a GPS receiver as indicated above. The shrinking of the physical size of the patch due to the ceramic filling will greatly degrade the bandwidth which is not necessarily negative unless an excessive information transmission rate is assumed.

[0035] The patch element 11 has a feed 16, wherein the antenna is manufactured with the plate

[0036] 12 as ground. Preferably, the antenna is fed with a signal arranged in a coaxial cable in which the center conductor is arranged to the patch element and the outer conductor to the plane 12. This type of feed is called probe feed, alternatively the antenna can be fed with a microstrip or aperture coupling. The thickness of the feed wire may be different compared to the central conductor of the coaxial cable or may have a modified design to improve matching. The feed is placed very close to the diagonal of the near square patch element 11 at a distance from the center hole 14 which will give a suitable match (50 ohms etc.). A ceramic patch antenna can be made from metallized ceramic, where the patch element 11 is slightly smaller than the ceramic.

[0037] The patch antenna 10 according to one embodiment of the invention has a hole 14 in the center of the antenna, within which hole 14 a conductive tube 15 is arranged for shorting the patch element 11 to the conductive base plate 12, i.e. said conductive tube is in electrical contact with the patch element and the conductive base plate. The conductive tube 15 can be created by metallizing the hole 14 if the antenna is manufactured with solid material as filling. The conductive tube 15 may also be made of a metal tube which is inserted into said hole and connected to said patch element 11 and said conductive base plate 12

[0038] In Fig. 2, an embodiment of a feed network 100 to a plurality of antenna elements is shown, in Fig. 2 illustrated by 8 antenna elements 110, 1102 110'2 110'", 110"", 110 , 110""", 110 where the antenna elements are arranged in pairs to a fourth, fifth, sixth and seventh splitter / combiner 120"2 120"", 120'"", 120""" in the third stage, the fourth and fifth splitter / combiners 120'", 120"" and the sixth and seventh splitter / combiners 120'"", 120""'" respectively are arranged in the third stage to a second and third splitter / combiners 120', 120" in a second stage of splitter / combiners. In the first stage of splitter / combiners, the second and third splitter / combiner 120', 120" are arranged to the first splitter / combiner 120 in the first stage. Feeding 130, to the first splitter / combiner 120 is preferably done by a coaxial cable or by microstrip if the feeding network is arranged on a printed circuit board. The feeding network can be adapted according to the number of antenna elements. A splitter / combiner works by splitting the signal from one port to two ports in one direction or combining from two ports to one port in the other direction. By combining a network of a number of splitters / combiner, in Figure 2 seven, eight antenna elements can be arranged to one output / input. Thus, one input signal can be transmitted to eight antenna elements and, conversely, eight received signals on each antenna can be coordinated to one output. If phase shifters are provided in the feed network, the antenna structure can function as a phase-controlled antenna. By arranging a phased array antenna, the antenna's radiation pattern can be customized, and the beam lobe can be directed in different directions to change the performance of the antenna structure. The feed network embodiment shown in Figure 2 can be applied to both a first feed network arranged to a transmitting antenna structure and a second feed network arranged to a receiving antenna structure. Fig. 3 shows a serially fed patch antenna structure 150 that is commonly used in vehicle radar systems. In the embodiment shown, there are two parallel serially fed structures, i.e. a matrix comprising 2 x 4 antenna elements, a total of 8 antennas. The number of antennas is adapted based on frequency range and size of the area that can be arranged with antennas and based on requirements for the functionality of the system. In the embodiment shown, there are 8 patch antennas, 161, 162, 163, 164, 165, 166, 167, 168, where four patch antennas, 161, 162, 163, 164, are arranged on a first feed network 171, and where four patch antennas, 165, 166, 167, 168, are arranged on a second feed network 172. The feed networks, 171, 172, are preferably a microstrip to which the patch antennas are arranged. The feed networks 171, 172 are coordinated in the shown embodiment to feed point 170. Depending on the technical structure, the respective feed networks can also be arranged separately to the appropriate microwave component. By designing the feed networks, components such as splitter / combiner and phase shifter can be eliminated as their function can be created as described for example in the literature, such as T. Metzler, Microstrip series arrays, IEEE Transactions on Antennas and Propagation (Volume: 29, Issue: 1, January 1981), hereby incorporated in the text of the application. The advantages of arranging the antennas in a matrix structure are that the antenna radiation pattern can be directed and that the antenna gain can be improved. Microstrip is a type of electrical transmission line that can be manufactured using several different manufacturing techniques where a conductor is separated from a ground plane by a dielectric layer called a substrate. A feed network consisting of microstrip structure is used to distribute microwave frequency signals. Typical realization techniques are printed circuit boards (PCB) or alumina or silicon coated with a dielectric layer. Microwave components such as antennas, couplers, filters, power dividers, etc. can be arranged using microstrip technology, with the entire device arranged as a metal pattern on the substrate. Microstrip technology is simpler and cheaper than traditional waveguide technology and is much lighter and more compact. The embodiment shown in Figure 3 can be applied to both a transmitting antenna structure and a receiving antenna structure.

[0039] In Fig. 4, a fuze 200 is shown comprising a nose cone 210 in which an antenna structure is arranged in the surface of the fuze or behind a protective layer arranged on the nose cone 210. The fuze is circularly symmetrical for connection, preferably with a threaded joint 220, in the nose of a projectile. The fuze shown in Fig. 4 is of the proximity fuze type and is arranged with a sensor system comprising an antenna structure. Proximity fuzes are preferably used for projectiles fired at air targets but can also be used against ground targets and can detect target objects in the vicinity of the projectile while the projectile is traveling in the trajectory of the projectile. The most common type of proximity fuze is the radar-based proximity fuze. These emit a continuous or pulsed radio signal after launch. When the proximity fuze projectile approaches the ground or a flying object, part of the transmitted signal is reflected and picked up by a receiver in the proximity fuze, the receiving antenna can be the same as the transmitting antenna. Due to the movement of the shell, the reflected signal has a slightly higher frequency than the transmitted one, which is called the Doppler effect. The difference between the transmitted signal and the received signal creates interference and the resulting signal is sensed and triggers the proximity fuze when it reaches a predetermined value. As the proximity fuze senses signal strength, and does not directly measure the distance, the height of the breeze is affected by whether the ground reflects poorly, for example in dry ground, or well, for example in wet ground. On some proximity fuzes, it is therefore possible to adjust the sensitivity before firing. When a target is detected, the proximity fuze can initiate an explosive charge in the projectile that creates a weapon effect, such as shrapnel, which can act on the target. The sensitivity of the proximity fuze is adapted to the ability of the warhead to generate damage in the target object. Fragments are preferably radially dispersed from the projectile but can be adapted according to the capabilities and performance of the proximity fuze, warhead, launching device and target. The antenna structure is arranged with a number of antenna elements in a matrixshaped structure arranged around the fuze 200 and in the axial direction of the fuze. The antenna matrix is arranged in the fuze axis A, which is the axial extent of the fuze, and in the fuze axis B, which is the circularly symmetrical tapered surface around the fuze. The antenna array thus includes antennas arranged in rotation B, on the surface formed by the circumference of the fuze, and in longitudinal A. The circumference of the fuze decreases in the longitudinal direction A, so that a smaller number of antennas can be arranged in the rotational direction B of the fuze closer to the tip of the fuze relative to the base of the fuze where the circumference in the rotational direction B of the fuze is larger. Preferably, the matrix forming the antenna structure is symmetrical but may also be asymmetrical as an adaptation to the conical shape of the fuze. Where appropriate, both a transmitting antenna structure and a receiving antenna structure are arranged in the nosecone.

[0040] In Fig. 5 shows a block diagram of a sensor system 1000 including a control unit 1010 that controls the functionality of the components included in the sensor system 1000. A waveform generator 1020 comprises, for example, an oscillator that generates the carrier frequency that the sensor system uses to transmit the signal from the proximity fuze to the sensor system 1000. The waveform generator 1020 may be arranged to generate a certain predetermined frequency but may, in an alternative embodiment, be controlled by the control unit 1010 to change the carrier frequency. However, the change in frequency must be within the bandwidth of the antenna structure 1060. A transmitter 1030 may amplify the carrier signal from the waveform generator 1020 and may modulate the signal or otherwise affect the signal to be transmitted from the antenna structure 1060. The signal from the transmitter 1030 may pass through a duplexer 1050. A duplexer is an electrical device that enables two-way communication over a single path, for example, by isolating a transmitter 1030 from a receiver 1040 and enabling the transmitter 1030 and receiver 1040 to utilize the same antenna structure 1060. After a pulse or continuous signal is transmitted from the antenna structure 1060 by the transmitter 1030, a reflected pulse, for example reflected from a target object, may be received by the antenna structure 1060 and relayed to the receiver 1040. The received signal to the receiver 1040 may, for example, be filtered in various ways before the signal is relayed, in signal processed form or as the originally received signal, to a processor unit 1070 which makes a calculation of the received signal and based on predetermined criteria, the processor unit 1070 may determine whether the received signal represents that a target object is within the proximity fuze, and thus the warhead, range of action. If the processor unit 1070 determines that a target object is within the range of action, the proximity fuze initiates a detonator that initiates the warhead, whereupon the action, for example in the form of shrapnel or preformed fragments, such as bullets, such as cemented carbide bullets, is dispersed from the warhead towards the target object.

[0041] In Fig. 6 shows a block diagram of a sensor system 1100 including a control unit 1010 that controls the functionality of the components included in the sensor system 1100. For example, a waveform generator 1020 comprises an oscillator that generates the carrier frequency that the sensor system uses to transmit the signal from the proximity fuze to the sensor system 1000. The waveform generator 1020 may be arranged to generate a certain predetermined frequency but may, in an alternative embodiment, be controlled by the control unit 1010 to change the carrier frequency. However, the change in frequency must be within the bandwidth of the transmitter antenna structure 1150. A transmitter 1030 may amplify the carrier signal from the waveform generator 1020 and may modulate the signal or otherwise affect the signal to be transmitted from the transmit antenna structure 1150. After a pulse or continuous signal is transmitted from the transmitter antenna structure 1150 by the transmitter 1030, a reflected pulse, for example reflected from a target object, may be received by the receiver antenna structure 1160 and relayed to the receiver 1040. The received signal to the receiver 1040 may, for example, be filtered in various ways before the signal is relayed, in signal processed form or as the originally received signal, to a processor unit 1070 which makes a calculation of the received signal and based on predetermined criteria, the processor unit 1070 may determine whether the received signal represents that a target object is within the proximity fuze, and thus the warhead, range of action. If the processor unit 1070 determines that a target object is within the range of action, the proximity fuze initiates a detonator that initiates the warhead, whereupon the action, for example in the form of shrapnel or preformed fragments, such as bullets, such as carbide bullets, is dispersed from the warhead towards the target object. The advantage of having a separate transmitter structure and receiver structure is that transmission and reception can take place simultaneously in that transmission can take place from the transmitter 1030 to the transmitter antenna structure 1150 while reception takes place with the receiver antenna structure 1160 to the receiver 1040

[0042] EXAMPLE OF EXECUTION

[0043] Examples of calibers are 20 - 155 mm. With a projectile arranged with a sabot or driving mirror it is possible, for a given barrel diameter, to shoot all calibers between the largest caliber the barrel allows and all calibers below this largest caliber.

[0044] The antenna structure is connected to the electronics of the projectile including a receiver, transmitter or transceiver. The antenna structure can also be used for communication. Examples of communications that may be exchanged to the projectile include guidance information to the projectile, position information from the projectile, method of action to the projectile, sensor information from the projectile, and other information relevant to improving the ability of the current, or other subsequent or preceding projectiles, to achieve effect on one or more targets. Appropriate adaptation in terms of antenna operating frequency is determined by antenna principle and size constraints related to the arrangement of the antenna structure on the projectile.

[0045] The antenna structure may be arranged embedded in a casting compound, for example of epoxy, resin or silicone. Where the molding compound has no or limited impact on the electromagnetic performance of the antenna structure. The casting compound protects the antenna from external influences, e.g. from gunpowder gases, which may act on the antenna during the launch phase.

[0046] The antenna elements can be patch-antennas, dipole antennas or of other antenna types.

[0047] ALTERNATIVE EMBODIMENTS

[0048] The invention is not limited to the particular embodiments shown but can be varied in different ways within the scope of the claims.

[0049] It is recognized, for example, that the number, size, material and shape of the elements and details of the projectiles are adapted to the barrel(s), projectile and projectile compositions and other design characteristics of the projectiles.

[0050] For example, projectiles may be arranged for blast action, fragmentation action, incendiary action, thermobaric action, firefighting, training projectiles, light kits, smoke kits, electromagnetic action, electromagnetic jamming or other loads and functions.

Claims

PATENT CLAIMS1. Sensor system, for arrangement in a fuze for a projectile, comprising at least two antenna structures, a transmitter antenna structure and a receiver antenna structure, each antenna structure comprising a matrix of antenna elements, characterized in that the antenna elements of the transmitter antenna structure are arranged in at least two positions distributed on the fuze in its longitudinal direction A and / or rotational direction B forming a transmitter antenna structure in the form of a matrix with at least 2 antenna elements and the antenna elements of the receiving antenna structure are arranged in at least two positions distributed on the fuze in its longitudinal direction A and / or rotational direction B forming a receiving antenna structure in the form of a matrix with at least 2 antenna elements, and at least one first feed network arranged to the transmitting antenna structure and at least one transmitter device arranged to the first feed network, and at least one second feed network arranged to the receiver antenna structure, and at least one receiver device arranged to the second feed network, and at least one processor unit arranged to the receiver device for signal processing of the received signal.

2. A sensor system according to claim Icharacterized in that at least two antenna elements are arranged in series on a feed network.

3. Sensor systems according to any of the above claims characterized in that the supply network is a microstrip.

4. Sensor systems according to any of the above claims characterized in that the antenna elements are of the patch antenna type.

5. A sensor system according to any of claims 1 - 3 characterized in that the antenna elements are of the dipole antenna type.

6. A sensor system according to any of claims 1 - 3 characterized in that the antenna elements are of the slot antenna type.

7. A sensor system according to any of claims 1 - 3 characterized in that the antenna elements are of the waveguide antenna type.

8. A sensor system according to claim 7characterized in that the antenna elements are of the gap waveguide antenna type.

9. Sensor systems according to any of the above claims characterized in that the antennas are arranged to transmit and receive electromagnetic signals in the frequency range between 55 GHz and 97 GHz.

10. Sensor system according to any of the above claims characterized in that the receiver antenna structure and the transmitter antenna structure are arranged on a flex board.

11. Sensor system according to any of the above claims characterized in that the first feed network is provided with at least one phase shifter to phase steer the transmitting antenna structure.

12. Sensor system according to any of the above claims characterized in that the first supply network and / or the second supply network is provided with at least one splitter / combiner.

13. A sensor system according to any of the above claims characterized in that the antenna elements of the transmitter antenna structure have at least 5 positions in the longitudinal direction of the fuze A and at least 2 positions in the rotational direction of the fuze B forming an antenna structure in the form of a matrix with at least 10 antenna elements.

14. A sensor system according to any of the above claims characterized in that the antenna elements of the receiverantenna structure are arranged in at least 5 positions in the longitudinal direction of the fuze A and at least 4 positions in the rotational direction of the fuze B forming an antenna structure in the form of a matrix with at least 20 antenna elements.

15. Fuze characterized in that the sensor system according to any of claims 1 - 14 is arranged in the fuze and wherein the processor unit is arranged to a detonator where the detonator is initiated when a target object is detected by the sensor system.

16. A fuze according to claim 15 characterized in that the fuze further comprises an impact sensor.

17. A projectile comprising a warhead characterized in that a fuze according to claim 16 is arranged to the projectile.

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