FR2783316A1 - Air/sea de fence munition has electromagnetic proximity fuse circuit with tube couple antenna and commanded explosive magnetic field trigger - Google Patents

Abstract

The circuit for a de fence munition has a high frequency antenna (13) coupled to a high frequency tube (11) which is fed by a compressor magnetic field (10). An explosive is set off by a base command when the munition is near the target to be neutralized.

Description

The present invention relates to an electromagnetic ammunition

  of self-protection likely to be launched remotely by a carrier in the direction of vectors or objects, aircraft or missiles, likely to constitute a threat to the integrity of combatants or materials of which they are the target provided that the threatening objects or vectors are equipped with electronic devices sensitive to radiation

electromagnetic waves.

  It applies in particular to the protection of infantrymen, planes, helicopters, ships, or land vehicles equipped with launchers for the implementation of ammunition. It can also be used as an offensive weapon for the creation of equipment malfunctions

  electronics installed on land sites.

  To protect weapons systems or combatants such as infantrymen against an air threat, it is known to use a scrambling technique consisting in illuminating the threatening object with the aid of electromagnetic waves in order to disrupt its system. control. The jammers emit either in the infrared when it is a question, for example, of blinding optronic missile directors or infrared cameras carried by aircraft or land vehicles, or microwave radio waves

  when the seeker of the missile is a radar for example.

  In addition to the electromagnetic self-protection techniques currently known for the jamming of auto directors of missiles or of radar, deception or deception techniques are also used. The decoy techniques use for example, electromagnetic decoys with glitter clouds, whose radar equivalent surfaces (SER) are larger than the object to be protected, or infrared decoys with smoke or explosion-proof compositions, the use of smoke n being limited to date only to the

  millimeter electromagnetic band.

  Other types of protection aim more specifically to create a gene for pilots of aircraft by blinding them with ammunition

  dazzling optics or deafening acoustics.

  All of these techniques when taken in isolation are only effective for a specific type of aggression. This requires to have effective protection, to implement several different systems which is not always possible on a battlefield in particular

  for the protection of infantrymen or military aircraft for example.

  A solution to this problem could be provided by the use of electromagnetic wave radiation devices with microwave characteristics similar to those used for radars or battlefield jammers with a sufficiently strong radiated wave power to disturb the operation or cause damage to electronic control systems for missiles or aircraft. This solution could be all the more interesting as the increasingly large share of electronics in the devices and subsets of weapons and armaments increases their

  susceptibility to intense and impulse electromagnetic fields.

  Unfortunately self-protection systems with radio waves or microwave currently known do not allow to illuminate the threatening targets with sufficient levels to

  saturate and disturb the electronics of these targets.

  The object of the invention is to overcome the aforementioned drawbacks. To this end, the invention relates to an electromagnetic self-protection munition characterized in that it comprises a transmitting antenna coupled to a microwave tube supplied by a compressor. explosive-based magnetic field controlled when the ammunition is near a target to be neutralized. Other characteristics and advantages of the invention will appear

  in the description which follows, made with reference to the appended drawings which

  represent: FIGS. 1a, 1b of the configurations of the munition according to the invention in its launching tube and in flight.

  Figure 2 an embodiment of a munition according to the invention.

  Figure 3 an equivalent electrical diagram of the electrical device

  of the ammunition shown in Figure 2.

  Figure 4 a diagram illustrating the operation of the compressor

  field shown in Figure 2.

  FIGS. 5a to 5d of examples of the use of ammunition according to the invention. The ammunition according to the invention which is shown in Figures 1 and 2 is intended to be launched towards a target to be scrambled by a tube

  launch 1 as shown in figure la.

  It comprises a tube 2 closed at one of its ends by a

bottom plate 3.

  Foldable fins 4 are fixed to the bottom plate 3. These are folded back into the launch tube 1 before launching the ammunition and open during the flight. A powder cartridge 5 used for ejecting the ammunition from the launch tube 1 is also fixed on the plate.

bottom 3 outside the tube 2.

  A firing device 6 comprising one or more detonators 7 and a device 8 for controlling the emission of electromagnetic waves arranged around the firing device 6 are

  placed inside the tube 2, above the bottom plate 3.

  Above the control device 8 and the firing device 6 rests an electromagnetic wave generator device 9. The generator device 9 includes a magnetic field compressor by explosive 10 coupled to a microwave tube 1 1 of magnetron or klystron type for example, through a

switching 12.

  An antenna 13 of the horn, rectangular or cylindrical type placed at the second end of the tube is supplied by the microwave tube 11. According to another alternative embodiment of the invention not shown, the antenna 13 can also be a conforming antenna , formed by wire elements engraved or deposited on

  the outer shell of the ammunition to match its shape.

  A supply battery 14 is housed at the second end of the cartridge between the microwave tube 11 and the antenna 13. The battery 14 stores the energy necessary for the operation of the

compressor 10.

  The magnetic field compressor 10 comprises, in the manner shown in FIGS. 2 and 3 o the homologous elements bear the same references, a toroidal capacitor 15, a step-up transformer 16 and a solenoid 17. The primary winding of the transformer 16 is connected in series with the solenoid 17. As shown in FIG. 3, a first end of the capacitor 15 is connected on the one hand, to a first pole of the supply battery 14 by means of a current switch 18 and on the other hand, at a first free end of the solenoid 17 not common with the primary winding of the transformer 16 by means of a current switch 19. A device 20 for trapping a magnetic field having the role of both current and rheostat switch for the solenoid 17 connects when the switch part is closed, the first free end of the solenoid 17 to a first extremi free tee of the primary winding of the transformer 16 not common with the second end of the solenoid 17. The second pole of the battery 14 is connected by a ground circuit M to the second end of the capacitor 15 and to the first end of the primary of the

transformer 1 6.

  The secondary winding of the transformer 16 supplies the tube

  microwave 1 1 via a switching device 12.

  As shown in FIG. 2, the elements composing the magnetic field compressor are arranged concentrically around the longitudinal axis of the tube 2. The solenoid 17 completely surrounds the field trap device 20 while the toroidal capacitor 15 only partially covers the solenoid 17. The elements, 17, 20 rest against the control device 8. The part of the solenoid 17 not covered by the toroidal capacitor 15 is covered by the primary and secondary windings of the transformer 16. The magnetic field trapping device 20 has the shape of an electrically conductive copper tube by

  example of wall thickness 1 to 1.5 mm, filled with an explosive 21.

  The explosive 21 is intended to produce, as shown diagrammatically in FIG. 4, an expansion of the conductive tube along the axis XX ′ in order to gradually bring it into contact with the turns of the solenoid 17 while ensuring a short- cicuit between the first free end of the solenoid 17 and the mass M in order to trap the primary electrical energy in the solenoid 17, while progressively decreasing its inductance. The magnetic field compressor 10 is controlled by the control device 8 which controls the opening and closing of the switches 18 and 19 and the firing of the explosive 21, when the

  minition is close to its target.

  At initialization, the switch 18 is closed to charge the capacitor 1 5 by the battery 14. At the end of charging the switch 18 is open and the switch 19 is closed to transfer the energy contained in the capacitor 15 and magnetize before the explosion of the explosive 21 the primary of the transformer 16 in series with the solenoid 17. The primary current Io obtained creates a magnetic field Bo. This magnetic field then remains trapped after the explosion of the explosive 21 by the device 20 which closes on itself the circuit formed by the primary of the transformer 16 in series with the solenoid 17. The explosion produces an expansion of the copper tube forming the device 20 which reduces

  gradually like a rheostat the inductance of the solenoid 17.

  The current I1 (t) flowing in the solenoid 17 then increases from its initial value Io to a final value If. This variation of current produces at constant flux an increase in the magnetic field which passes from the initial value Bo to a final value Bf defined by the relation óo = Of = BoSo = BfSf So

= Bf = Bo-

  Sf At the end of the expansion of the copper tube, the final surface Sf intercepted by the field Bf becomes very small of the order of 5 10 2 to 10'2 times the initial surface So intercepted by the initial field Bo which

  produces a Bf field between 20 and 100 times the value of the Bo field.

  The current Io passing through the solenoid 17 and the primary of the transformer 1 6 can reach a value between 1 and 3 kA, and the primary current If final flowing in the primary winding of the transformer 16 can reach 100 OkA to give a current of 1 kA at the secondary output of the transformer 16 and a secondary voltage of several tens of kV. The corresponding rise times are

  around ten Lis, or around 10 kV / gs.

  The switching device 12 makes it possible to stiffen the rising edge of the signal obtained between the secondary output of the transformer 16 and the microwave tube 1 1. As a guide, a rising edge of i OOkV / gs can be obtained by placing in parallel on the impedance of the tube a copper multi-wire fuse exploding during the flow of current and a spark gap in series with the impedance of the tube intended to reinforce the

  stiffening of the rising edge when the fuse explodes.

  To resist the forces generated by the magnetic field during the compression phase, the ammunition furthermore comprises a first dielectric casing 22 of high mechanical strength made of Kevlar, glass or carbon fiber for example, placed in the space separating the capacitor 15 and the transformer 16 of the solenoid 17, and a second dielectric envelope 23 external to the winding of the voltage transformer 16 also of high mechanical strength and

  of material similar to those which may constitute the first envelope 22.

  As shown in Figures 5a and 5d, the ammunition according to the invention can be launched from several carriers. When, for example, a weapons, transport or helicopter plane detects the arrival of a threat, a self-protection ammunition according to the invention is launched in the direction of the threat, in order to jam, deceive or disturb the organs of detection or guidance of the threatening object. In the context of the applications shown diagrammatically in FIGS. 5a and 5b which show the firing of ammunition on missiles from a weapons plane or a ship, each ammunition can produce when it is for example at a distance of 1000 meters from the missile a signal of -28 dB on the detector of the missile seeker while the maximum signal receivable by the auto director of the missile before saturation is around -40 dB. This signal is more than enough to saturate the receiver as well as the missile's electrical circuits, each time that ammunition of the same type is used. A shot for example from a series of 10 ammunitions ejected every 100 ms can under these conditions very quickly put the auto director in a saturated mode and maintain it throughout the self-protection phase as far as the target distance threat decreases, the received power increases very

  quickly based on the square of the distance.

  In the context of infantryman self-protection, the ammunition according to the invention allows an infantryman to attack a threatening target from a distance by emitting an electromagnetic pulse in front of the target a few tens of meters from it with a large angular opening. In the example of FIG. 5c which represents an infantryman under the threat of a helicopter, the power of the microwave waves received by the helicopter can reach a few watt / cm2 for a pulse of several MW emitted by the munition at a distance of a few tens of meters. This power density is sufficient to significantly disturb the electronic circuits of the helicopter and even cancel its

mission.

  The angular aperture of the main lobe of the radiation emitted by the antenna being so great that it is not necessary to use a weapon with very high precision or trajectory correction ammunition. The advantage of this type of operation is that it does not require the use of a launching weapon with very high precision or trajectory correction ammunition, while

  significantly increasing the probability of hitting the target.

  Finally, in the context of FIG. 5d, the ammunition according to the invention

  can be remotely controlled from a launcher on the ground.

  In this context it can not only neutralize a threat like a helicopter but also it can be used to degrade the functioning of terrestrial electronic installations such as

  example of radio communication stations.

Claims (9)

Claims   1. Self-protection electromagnetic ammunition characterized in that it comprises a transmitting antenna (13) coupled to a microwave tube (1 1) supplied by a magnetic field compressor (10) based on an explosive controlled when the ammunition is nearby of a target to be neutralized.   2. Ammunition according to claim 1 characterized in that the magnetic field compressor (10) comprises a toroidal capacitor (15) coupled in parallel on the primary winding of a transformer (16) step-up voltage via a current switch (19) connected in series to a solenoid 7) to magnetize the primary winding of the transformer (16) and a magnetic field trapping device (20) ensuring the closure on itself of the circuit formed by the primary of the transformer (16) in series with the solenoid (17) and a progressive short-circuiting of the turns of the solenoid (17).   3. Ammunition according to claim 3 characterized in that the magnetic field trapping device (20) is formed by an electrically conductive tube filled with explosive (21) of longitudinal axis coincident with the longitudinal axis (XX ' ) of the solenoid (17) and disposed inside of it, and in that the outer wall of the tube is brought into contact with the turns of the solenoid to ensure their short-circuiting by the expansion of the tube during the explosion of the explosive in the copper tube.   4. Ammunition according to claim 3 characterized in that the elements making up the magnetic field compressor (10) are arranged concentrically around the longitudinal axis (XX ') of the ammunition, the solenoid (17) completely surrounding the tube copper and the toroidal capacitor (15) only partially covering the solenoid, the remaining solenoid portion (17) not covered by the toroidal capacitor (15) being covered by the primary and secondary windings of the step-up transformer (16).   5. Ammunition according to any one of the preceding claims   characterized in that the ammunition comprises a cylindrical body (2) closed at one of its ends by a bottom plate (3), folding fins (4) fixed to the bottom plate (3), a powder tablet (5 ) fixed to the outside of the cylindrical body (2) on the bottom plate (3) to eject the ammunition when it is launched, a firing device (6) and a control device (8) of the magnetic field compressor   (10) disposed on the bottom plate (3).   6. Ammunition according to any one of the preceding claims   characterized in that the microwave tube (11) is a magnetron.   7 Ammunition according to any one of claims 1 to 5   characterized in that the microwave tube (11) is a klystron.   8. Ammunition according to any one of the preceding claims   characterized in that the transmitting antenna (13) is a horn.   9 Ammunition according to any one of claims 1 to 7,   characterized in that the transmitting antenna (13) is a conforming antenna conforming to the shape of the ammunition.