Drone detection radar

Abstract

A drone detection radar can include a plurality of antenna systems, each antenna system being arranged to transmit a signal into an associated sector, and to receive signals reflected from targets in the sector, the sectors collectively forming a monitored volume, and wherein a sub-set of the antenna systems are active at any one time, with the active sub-set of antenna systems being arranged to monitor their respective volumes for a duration sufficient to measure Doppler signals associated with slow moving drones, with the radar being arranged to switch to a different sub-set of antenna systems after each duration, such that the whole volume is monitored within a predetermined period. Combining a staring array from an antenna system with a plurality of switched antenna system allows drones to be both detected and tracked, with appropriate selection of the predetermined period.

Claims

1. A drone detection radar comprising: a plurality of antenna panel systems, each antenna panel system being configured to transmit, using a transmitter, a signal into an associated sector, and to receive, using a receiver, signals reflected from targets in the sector, wherein the sectors associated with the antenna panel systems collectively form a monitored volume, wherein a sub-set of the antenna panel systems are active at any one time, with the active sub-set of antenna panel systems being configured to monitor their respective volumes for a duration sufficient to measure Doppler signals associated with slow moving drones, with the radar being configured to switch to a different sub-set of antenna pane systems after each duration, such that the whole volume is monitored within a predetermined period, wherein each antenna panel system is arranged to monitor a sector approximately 60 in azimuth and 45 in elevation, and wherein each sub-set is arranged to monitor its respective sector(s) for up to 0.2 seconds before a switch to another sub-set occurs.

2. The radar as claimed in claim 1 wherein the whole volume is monitored within a period of every two seconds, every second, or every half second.

3. The radar as claimed in claim 1 wherein each sub-set of the antenna panel systems includes a single antenna system.

4. The radar as claimed in claim 1 wherein the radar includes five antenna panel systems, arranged to monitor a volume of nominally 180 in azimuth, and 90 in elevation.

5. The radar as claimed in claim 1 wherein each antenna panel system is connected to a common processor that is arranged to process digitised signals from each antenna panel systems, and to provide an alert if the signals are characteristic of being reflected from a drone.

6. The radar as claimed in claim 1 wherein the radar is arranged to vary a dwell time spent in a given sector according to whether a target has been detected within that sector.

7. The radar as claimed in claim 1 wherein each of the antenna panel systems comprises an antenna including a transmit antenna and a receive antenna.

8. The radar as claimed in claim 7 wherein each receive antenna includes of a plurality of elemental receive antennas each having a beam pattern that is configured to be combinable, in the radar, with beam patterns from one or more respective elemental receive antennas, to produce one or more narrower beams in a given direction.

9. The radar as claimed in claim 8 wherein the radar is adapted to manipulate the phase and/or amplitude of to the elemental receive beams during the combination with other beams, so as to tailor the beam direction of the one or more narrower beams.

10. A plurality of radars each configured according to claim 1, wherein each of the plurality of radars are arranged within a neighborhood, and are synchronized such that no two radars may transmit radiation within the same frequency band into a sector visible to two or more radars within the neighbourhood at a given time.

11. A plurality of radars each according to claim 1 wherein each of the plurality of radars is arranged within a neighborhood, and are synchronized, using an interface, such that no two radars are permitted to transmit towards each other simultaneously in the same frequency band.

12. The plurality of radars each according to claim 1 wherein each of the radars is arranged in a neighborhood, and are synchronized such that a first radar is configured to receive and process returns from targets of signals transmitted by a second radar.

Description

(1) The disclosed subject matter will now be described in more detail and by way of example only, with reference to the following Figures, of which:

(2) FIG. 1 shows a block diagram of an embodiment of a radar according to the presently disclosed subject matter;

(3) FIG. 2 shows an enclosure design for an embodiment of the presently disclosed subject matter;

(4) FIG. 3 shows an arrangement of three radars of the presently disclosed subject matter arranged to view a neighbourhood; and

(5) FIG. 4 shows approximate transmit and receive coverage for a five panel radar.

(6) FIG. 1 shows a simplified block diagram of an embodiment of the presently disclosed subject matter. This embodiment has five panels 10, of which one is shown in detail. Each panel is substantially identical in nature, and has front end electronics and antennas, forming an antenna system, mounted thereon. Common to all panels is a processor 12, that also acts as an interface to a common waveform generator 14, as well as providing an interface to external systems, such as a display and controller, and to other radars.

(7) Each panel 1 includes a transmit antenna 16, and transmitter circuitry 18, including a transmit amplifier. A receive antenna 20 is located adjacent the transmit antenna 16, and is connected to receiver front end circuitry 22 which contains amplification and down-conversion circuitry. A digitiser 24 is connected to an output of the receiver 22, which digitises the output and provides its digitised outputs to processor 12.

(8) The processor also controls an enable function 26, that enables one (or, in some other embodiments, more than one) of the panels, while disabling the remaining ones.

(9) It will be apparent to a normally skilled person that there are various interconnections between the components shown, and functions (such as power supplies, switching and routing components etc), that have not been shown but may be necessary to produce a functional system.

(10) In operation, the processor 12 chooses a panel to activate, by suitable control of its enable line to each panel. With one panel having been enabled, the processor controls the waveform generator to generate appropriate waveforms for upconverting and transmission by the transmitter 18 and antenna 16 on that panel. The receiver antenna 20, and the receiver front end 22 receive signals such as any reflections of transmitted signals from objects in a volume to be monitored. The receive antenna 20 includes of nine sub-antennas, in a square 33 array, each of which has its own receiver circuitry The receiver circuitry 22 amplifies, filters, and downconverts, the received signals from each sub-antenna, ready for digitisation by the digitiser 24. The digitiser 24 passes the digitised information back to the processor for processing. This processing includes at least running filtering, beamforming, detecting, and target tracking, routines on the data from the panel.

(11) The processor controls the duration of activation of the currently active panel (i.e. the dwell time), and, after that duration has elapsed, it switches to another panel and repeats the above process, storing any detected targets in memory. It cycles through the panels in sequence until all five have been activated, and then proceeds to repeat the cycle. Targets detected from the data in one panel may be tracked as they move to a different sector, as observed by another panel.

(12) If a target of interest is found in one panel, then the processor may be arranged increase the dwell time for that panel, and may reduce the dwell time in another panel or panels where no targets have been detected.

(13) FIG. 2 shows two views of a layout of an enclosure 30 of an embodiment of the presently disclosed subject matter. FIG. 2a shows a perspective view, whilst FIG. 2b shows a face-on view. Five panels 31a-e are arranged around a quarter sphere. Each panel 31 includes transmit and receive antennas, as described above, and has a coverage of 60 in azimuth, and 45 in elevation. Three panels 31a-c are located in a lower row, whilst two panels 31d-e are located in an upper row. The enclosure is suitable for mounting on a wall, fence, or similar vertical surface, or a pole or mast.

(14) A further embodiment (not shown) includes an enclosure that includes a hemisphere, with ten panels mounted thereon, with six panels occupying a lower row, and four occupying an upper row. Thus, it effectively includes two of the enclosures of FIG. 2 mounted back to back. Such an embodiment is useful for when 360 azimuthal coverage is required.

(15) Other embodiments may have other configurations of panels, or may have panels (or antennas) having different angular coverage.

(16) FIG. 3 shows an arrangement of three radars, A, B and C, each including an embodiment of the presently disclosed subject matter, that are arranged to view respective volumes, that make up a neighbourhood. Each radar is networked to the others using an interface (not shown) on each radar. Thus, each radar has knowledge of various parameters, such as the frequency band, and active beam direction at a given time, of the others. Each radar has an azimuthal scan volume that covers the other two radars. Thus, without any ameliorating measures being taken, it will be possible for one radar to illuminate a sector containing the second radar whilst the second radar is also illuminating a sector containing the first. Under such circumstances, the radiation transmitted from one radar may interfere with wanted signals received at the second radar. This is particularly problematic when the first and second radars are using the same frequency band, but can also be problematic when the frequency bands used by the first and second radars differ by less than some frequency difference.

(17) Thus, each radar is arranged to select a given sector for activation based upon knowledge of where the other radars are transmitting at that instant. It will wait until any radars in a given sector are not directing radiation at it, before it transmits into the sector. Some embodiments may be arranged such that a given radar may also not transmit into a sector containing another radar if that other radar is illuminating its own sector that lies within or adjacent to the position of the given radar. This reduces the level of radiation that will be received by a given radar from transmit antenna sidebands of other radars.

(18) For example, radar A has switchable sectors A1, A2 and A3, and radar B has switchable sectors B1, B2 and B3, where each sector corresponds to an active panel e.g. as described in relation to FIG. 1. Radar A is present in sector B1, and radar B is present in sector A2. Thus, the radars are arranged such that radar A does not activate its panel corresponding to sector A2 at the same time that radar B activates its panel corresponding to sector B1. Likewise, radar C also has similarly configured sectors, which have not been shown (for simplification of the figure), but it would also not activate any sector that illuminates another radar when that other radar is activating its own sector that illuminates radar C.

(19) Further embodiments of networked radars may be arranged to operate on a bistatic, or multistatic arrangement, wherein transmissions from one radar are received by one or more other radars. This may have benefits including improved vulnerability to some forms of electronic attack, or can be used to provide improved radar coverage including dwell time within a given sector, or cycle time between sectors.

(20) The radars forming the network may be arranged, as described above, to each control their own transmissions to avoid or reduce interference. Alternatively the radars forming a network may be configured such that there is one master radar (or other controller separate from the radars) that has knowledge of the arrangement of the radars, and commands each radar in the network appropriately to avoid any of the conflicts described above.

(21) FIG. 4 shows approximately the coverage pattern for a five panel radar. The radar covers a span in azimuth of nominally 180, and in elevation of nominally 90, as indicated by ref. 40. Each panel has a transmit antenna, which has coverage indicated by the five smaller loops (drawn in a solid line) 42. Each panel has an array of 3 by 3 receive sub-antennas (not shown) in a square array, the outputs from each of which may be summed with those of another one or more sub-antennas to form one or more combined beams. The summation may also include changing the phase and/or amplitude of one or more of the signals from the elemental receive antennas to manipulate the width and/or direction of the combined beam(s) This allows narrower beams to be produced, and used for super-resolution techniques as previously mentioned. Receive beam 44 is produced by the vector sum of the signals from each of the nine elemental antennas, with appropriate phase steering being applied to achieve a desired direction of maximum sensitivity, Likewise, receive beam 46 is produced by similar vector summation, with different phase steering to direct the beam's maximum sensitivity in a different direction. Other beams e.g. 48, 50, may be made from other such summations and phase or amplitude adjustments being made, and used (such as with monopulse processing) to provide greater angular resolution of detected targets.

(22) The receive beams 44, 46, 48 50 are all formed simultaneously using a digital beamformer, and so act as staring beams for the duration of activation of the particular panel.

(23) As previously discussed, the coverage beam pattern of the radar is switched, so that only a sub-set (typically one) transmit beam 42, and its corresponding receive antennas and beams, are active at any given time, before switching to the next sub-set.