CZ32968U1 - Cross bundle antenna system for detecting small flying objects - Google Patents

Description

Technical field

The present invention relates to a cross-beam antenna system intended for the detection of small flying objects (eg drones), which simultaneously allows rapid repetition of information about the entire monitored area, while providing sufficient time for reliable classification and detection of the drone with high accuracy.

BACKGROUND OF THE INVENTION

Unmanned aerial vehicles (UAVs, or drones) have experienced an unprecedented boom in recent years. Thanks to the rapid development of technology, higher battery capacity and the development of small sensors for collecting information, UAVs become very affordable and inexpensive. The current generation of UAVs has a number of unique features such as autonomous flight over a defined trajectory, high-definition audio / video recording even under poor conditions (weather, visibility), greater operating range, relatively high carrying capacity and excellent maneuverability. At the same time, these unique features present a serious security risk. Not only at airports where a potential UAV encounter with landing or taking off aircraft could lead to a serious accident, but also in all areas of interest such as nuclear power plants, industrial operations, government buildings and institutions, stadiums and generally places where moving many people, national borders, etc. Although the operation of unmanned systems in the Czech Republic is governed by law, especially Supplement X - unmanned systems, L 2 - rules of flying issued by the Civil Aviation Authority, there has recently been a number of cases where unmanned operations are grossly violated. Installing cameras and flight in protective zones, transporting or dropping dangerous or prohibited substances, or disrupting the work of emergency services in critical situations are just some examples that have so far only been in the field of anti-social behavior. The possibility of programming an unmanned flight without the presence of an unregistered pilot and not marking the system with a fireproof label are typical situations where an unmanned system cannot be identified by public authorities and the pilot - the offender may at best misuse this means of committing serious crime; attacks.

The Council of Worldwide Manufacturers of Security Technology is therefore striving to create a system for early detection of these devices. The cheapest are systems that detect the radio communication of the drone, or those that are able to take over its control. At present, however, drones can move completely autonomously (for example based on GPS) without communicating with the control site. Recently, the optical control of space has improved a lot in the world with cameras with automatic search and target classification, but this is ineffective in conditions of reduced visibility. For this reason, security systems cannot do without active radar sensors, specializing in this kind of object: targets with a very small reflective surface and low Doppler characteristics, moving near terrain, buildings, structures and other obstacles. Many manufacturers of radar systems used their radars to guard the battlefield or perimeter protection and after making adjustments to their SW or HW, they offer these devices as radars for UAV detection. If we confine ourselves to fixed ground-based space surveillance equipment, virtually all world radar manufacturers are involved in this category (Prime Cons. And Technol: Spotter RF family, https://anti-drone.eu/; Blighter Surv. System: A-400, https://www.blighter.com; Electronic Industry COUNCIL: RHS sensor fam., Https://www.rada.com; Airbus Defense and Space: SPEXER 1000/500, https: // Kelair Hughes: SharpEye SxV; https://www.kelvinhughes.com; Thales: SQUIRE; https: //www.thalesgroup.com; Harrier: DSR- 200; https: //www.detect- inc.com; Advance Radar Technology: Drone Sentinel, https://www.advanceradartechnologies.com; SRC Inc, USA: SR Hawk,

- 1 CZ 32968 U1 https://www.srinc.com; ELTA: ELM2026, https://www.spacedaily.com/reports/NewIsraeliantidro necounter-measure).

The different types of UAVs are usually categorized according to the size of the effective radar cross section (RCS):

• UAS (Unmanned Aerial System): RCS = 1 sqm (large unmanned aircraft eg Euro Hawk) • Mini UAV: RCS = 0.1 sqm (eg AGM-86B) • Micro UAV: RCS <0 , 05 m2 (commercial copter types eg DJI-Phantom)

Depending on the categories and environments in which the UAVs operate, the radar range for drones is between 1 km and 10 km. The resolution of these systems in azimuth is 2 ° to 4 ° in elevation 4 ° to 45 ° at a distance of 1 to 45 m. The range of the monitored sector in azimuth ranges from 60 ° to 360 °, but most often 90 °, in elevation 10 ° to 45 °. The most commonly used frequency band is X or Ku, exceptionally band S (Electronic Industry Council: RHS sensor fam., Https://www.rada.com). Transmitted power ranges from 6 to 200 W (Thales: SQUIRE, https://www.thalesgroup.com), modulation predominantly FMCW or FMiCW, exceptionally FM pulse. Antenna systems are mostly electronically scanned antennas (ESA), exceptionally a combination of mechanical and electronic scanning (Kelvin Hughes: SharpEye SxV, https://www.kelvinhughes.com). It can be seen that this is a relatively diverse group of devices.

The big problem of all drone radar monitoring is to achieve fast and reliable detection of this object in the prescribed area and to accurately determine its position or its path parameters. High accuracy requires very narrow beam antennas, which, with the need for reliability of classification, necessarily leads to an increase in the repetition time of the entire monitored area or to a reduction in the search space. These problems are usually solved by sophisticated space search scenarios, which always worsen the equipment's readiness to record a new object of interest. Although the manufacturer's data on these radar parameters is often sensational, practical demonstrations confirm the advertised range only in an unobstructed environment (eg above sea level, above flat terrain, etc.) but near obstacles (eg between or above buildings or structures), drone detection is usually not reliable.

The entire designated area shall be searched within the maximum allowable recovery time T _o b specified by the system user. In drone detection systems, T ₀ b is in the range of 1 to 2 s. Products with a higher T _o b value will usually not find use in drone detection.

This maximum allowable recovery time is given by the product of the collection time Td of each partial sector and the number of beams needed to cover the entire defined angular space. Thus, if the entire space is searched sequentially (for example, using a prior art pencil-beam antenna system), the number of beams required to cover the entire defined angular space is equal to the product of the number of horizontal and vertical beams, reducing the maximum possible collection time Td. from each partial sector.

In a system with alternating coverage of the sector of interest with a height and side antenna, both antennas work as both transmit and receive antennas. First, the entire sector of interest is covered by the beams of one antenna and then the beams of the other antenna. The number of beams required to cover the entire defined angular space is then equal to the sum of the horizontal and vertical beams, which, compared to the pencil beam system, shortens the maximum possible collection time Td for each partial sector, is not optimal in this case either.

-2GB 32968 U1

The essence of the technical solution

The present invention relates to an antenna system with cross beams to provide rapid repetition of information about the entire monitored area, while providing sufficient time for reliable classification and detection of the drone with high accuracy of position determination. An antenna system for detecting small flying objects according to the present invention is designed for detecting small flying objects in the defined angular sector Ω with azimuthal width ΔΦ and elevation width ΔΘ (Ω = ΔΦ χΔΘ). This antenna system includes two antennas: transmit and receive. The transmitting antenna gradually covers the desired sector with narrow beams in elevation and with the full azimuthal width of the monitored sector. The receiving antenna is multi-beam and the monitored sector simultaneously covers azimuth-narrow beams having a typical cosecant waveform in elevation and covering the entire elevation range. Both antennas are linear antenna arrays, consisting of antenna elements spaced along a vertical axis at a height antenna and a horizontal axis at a side antenna. The high-altitude antenna is powered by the transmitter and works as a transmit antenna. The signal from the transmitter is divided in the altitude antenna into parallel paths by a power divider and is routed to all antenna elements of the altitude antenna via phasers. The elevation of the height antenna beam axis is controlled by phasers by adjusting the phases of the transmitted signal on individual elements of the antenna. The high-altitude antenna creates at any moment a beam with a small width at 0v3ds and with a width at azimuth ΔΦ that covers the entire defined sector in the azimuth. The signals captured by the side antenna elements are processed in parallel receivers, which together form the receiver of the system. The side antenna is multi-beam (ie, in the beam shaping circuit behind the receiver, as an integral part of the receiver or as an integral part of the processor, several receiving beams are simultaneously formed, whose signals are then further processed in the beam signal processor). The individual beams of the side antenna have a small width in the azimuth Φ83 <ιβ, and in elevation each beam of this antenna covers the entire range of elevation ΔΘ of the specified sector. By this arrangement of the system, the whole space is divided into partial sectors Ωι = Φ83 <ιβ x 0v3 <ib with small widths in the azimuth Φ83 <ιβ i at 0v3ds elevation.

For drone detection equipment, all of the designated area shall be searched within a certain maximum recovery time T _o b, as determined by the user of the system. Information collection time: Td from each partial sector Ωι = Φββηβ x 0v3 <ib is therefore limited in the case of a cross-beam system by the condition: Td <T ₀ b / Nv.

If classical prior art antenna systems were used, for example with a pencil beam, it would be necessary to search the whole sector sequentially M _T = Nv.Ns beams, so that for the collection of information from one partial sector only the time T _{DT would be} :

T _DT <T _ob / M _T = T _ob /(Nv.Ns) = To / Ns, which for example typically Φ83 <ιβ = 2 °, ΔΦ = 90 ° means T _dt <Td / 45; and in the case of a system with alternating coverage of the interest sector with a height and a side antenna, it would be necessary to gradually apply M _s = Nv + Ns beams, so that the time devoted to one partial sector Tds can be at most:

T _DS <Tob / Ms = T ₀ b / (N v + N _s ) = T _d. N v / (N v + N _s ), which for example at 0 v 3dB = 4 ° and ΔΘ = 44 ° will be Tds <T _D / 5;

At the same time required T ₀ b restoration information and the same size partial sectors may therefore be in the present technical solution time Td collecting information from one partial sector significantly longer, which allows to increase the quality and reliability of the detection and identification of small, slow-moving objects in a complex environment (ie in the presence of obstacles and other moving objects).

The times of Tds and T _DT could be shortened only at the expense of increasing the partial sector Ωι.

U1 and in complicated environments with many obstacles will reduce the reliability of its detection.

In a cross-beam system, all beams of the side (receiving) antenna are processed in parallel (simultaneously), so that only the time needed to irradiate the space successively with the Nv beams of the height antenna is needed to search the entire space. Therefore, information can be obtained from a certain direction for Td = T _O b / Nv, while for AC systems only T ₀ b / (Nv + Ns) and T ₀ b / (Nv.Ns) can be used. .

The object of the present invention is an antenna system for detecting small flying objects in a defined angular sector, wherein the angular sector A is the product of the azimuthal width A0 and the elevation width A0, wherein the antenna system comprises:

- a transmitter connected to a height antenna, the height antenna comprising a linear antenna array of at least two phased antenna elements (phaser located at each antenna element) spaced along a vertical axis, and a power divider (one power divider for the overall antenna) to divide the signal from the transmitter to parallel paths to individual antenna elements;

a multi-beam side antenna composed of a linear antenna array of at least two antenna elements distributed along a horizontal axis;

a system receiver composed of parallel signal receivers captured by individual elements of a side antenna;

a side antenna beam shaping circuit connected to the receiver of the system;

a processor for processing the signals of the individual bundles of signals captured by the side antenna; wherein the height antenna is adapted to generate a beam of 0s3dB in elevation and azimuthal width svaz and wherein the side antenna signal beams have a width of 0s3dB in azimuth and each beam of that antenna covers the entire elevation width ΔΘ of the defined angular sector Ω;

and wherein the number of Nv beams of the height antenna signal and the number Ns of the beams of the side antenna signal needed to cover the entire defined angular sector Ω are equal to:

Nv = ΔΘ / 0V3dB; Ns = AO / Os3 dB

In one embodiment, the side antenna beam shaping circuit is an integral part of the receiver.

In another embodiment, the side antenna beam shaping circuit is an integral part of the signal processing processor.

Up to the beam shaping circuit, the signals from all N _e elements of the receiving antenna are processed in parallel in separate receivers of the individual elements, so that these parallel receivers are also N _e . In the beam shaping circuit, these N _e signals are linearly transformed, and the Ns signals (Ns < N _e ) are output from the circuit, each corresponding to one of the receiving (side) antenna beams. Further, the signals of the individual beams are processed in parallel (simultaneously) in Ns of the same processors.

-4GB 32968 U1

Clarification of drawings

Giant. 1: An antenna system for detecting small flying objects comprising a height antenna 1, a side antenna 2, antenna elements 3 and 4, a vertical axis 5, a horizontal axis 6, a transmitter 7, a power divider 8, a phaser 9, a receiver 10 the beam signals processor 12, the signal receivers 13 of the individual antenna elements of the side antenna 2.

Giant. 2: Individual beams 14, 15 of height and side antennas in the defined sector 16.

Example of technical solution implementation

Example 1: An antenna system for detecting small flying objects

An antenna system for detecting small flying objects in a defined angular sector Ω where the angular sector ω is the product of the azimuthal width ΔΦ and the elevation width ΔΘ is shown in Fig. 1. 1 and 2, and comprises a transmitter 7 connected to a height antenna 1, wherein the height antenna 1 comprises a linear antenna array of at least two antenna elements 3 with phasers 9 distributed along a vertical axis 5, a power divider 8 to divide the signal from the transmitter 7 into parallel paths to individual antenna elements 3 with phasers 9;

a multi-beam side antenna 2 composed of a linear antenna array of at least two antenna elements 4 distributed along a horizontal axis 6;

a system receiver 10 comprising signal receivers 13 of individual antenna elements; beam forming circuit 11;

a processor 12 for processing individual bundles;

wherein the altitude antenna 1 is adapted to generate elevation and azimuthal width 6 signal beams 6> v3dB and wherein the side antenna signal beams 15 have a width of 0smb in azimuth, and each antenna beam 15 covers the entire elevation width ΔΘ of the defined angular sector Ω and wherein the number N _{in the} beams 14 of the height antenna 1 and the number Ns of the beams 15 of the side antenna 2 needed to cover the entire defined angular sector Ω are equal to:

Nv = ΔΘ / Θ V3dB; NS - A <ø / <øs3dB

Since all side antenna beams are processed in parallel, the time to collect information Td from each partial sector Ωι = <I> s3dB x 0v3dB is limited by the condition: Td <T ₀ b / Nv.

During the detection of small flying objects by the cross-beam antenna system according to the present invention, the transmitter 7 sends a signal to the height (vertical) antenna 7. This signal is divided by the power divider 8 and the phasers 9 into individual antenna elements 3 transmitting the signal in the Nv beams 14, covering the entire elevation width A0 of the delimited angular sector Q. If the detected object is in the delimited angular space, the signal beam 14 is reflected. The receiving side antenna 2 (horizontal) detects the reflected signal by the individual antenna elements 4 and processes it in parallel with the individual antenna element signal receivers 13, the beam shaping circuit 11 and the single beam processor 12.

-5 GB 32968 U1

Signal processing description:

The number of elements of the receiving (side) antenna is denoted N _e . The signals from the individual elements of the side antenna are processed simultaneously in N _e parallel receivers (antenna elements).

In each of these receivers, the signal is filtered, amplified, and transformed into a complex envelope (i.e., mixed into a baseband). The method of this transformation depends on the type of modulation of the transmitted signal used. During these operations, the signal is digitized.

In the beam shaping circuit, a linear transformation of the set of Ne signals of the individual elements into a set of Ns (Ns <N _e ) of the signals of the individual beams is performed. These are further processed in the beam processor, and the process of this processing can be very varied. It usually includes the following operations (in different order): Doppler filtering, integration, detection, data extraction, tracking and target classification. The result of this processing is to determine the distances and partial beams in which the objects are located and the moments of their detection.

PROTECTION REQUIREMENTS

Claims (3)

Antenna system designed to detect small flying objects in a defined angular sector (Ω), where the angular sector (Ω) is the product of azimuthal width (ΔΦ) and elevation width ((), characterized in that it contains: - a transmitter (7) connected to a height antenna (1), the height antenna (1) comprising a linear antenna array of at least two antenna elements (3) with phasers (9) distributed along a vertical axis (5) and a power divider (8) for splitting the signal from the transmitter (7) into parallel paths to individual antenna elements (3); - a multi-beam side antenna (2) composed of a linear antenna array of at least two antenna elements (4) distributed along a horizontal axis (6); - a system receiver (10) comprising signal receivers (13) of individual antenna elements (4) connected to the beam shaping circuit (11) of the side antenna (2); - a processor (12) for processing the signals of the individual signal bundles (14) captured by the side antenna (2); wherein the height antenna (1) is adapted to generate beams (14) of a signal having a width (0v3 <ib) of elevation and an azimuthal width (ΔΦ); and wherein the side antenna signal beams (15) have azimuth width (Φββ, ιβ) and each antenna beam (15) covers the entire elevation width (ΔΘ) of the defined angular sector (Ω); and wherein the number (Nv) of the height antenna signal beams (14) and the number (Ns) of the side antenna signal (2) beams (15) required to cover the entire defined angular sector (Ω) are equal to: Nv = ΔΘ / Θ V3dBI Ns = ΔΦ / ΦβΒ, ΙΒ Antenna system according to claim 1, characterized in that the beam shaping circuit (11) of the side antenna (2) is an integral part of the system receiver (10). -6GB 32968 U1 Antenna system according to claim 1, characterized in that the beam shaping circuit (11) of the side antenna (2) is an integral part of the processor (12). 2 drawings