Patent Description:
<CIT> relates to a system and method for detecting and visualizing targets by airborne radar.

According to an aspect of the invention, there is provided a system for radar-scanning a field of view according to accompanying claim <NUM>.

According to another aspect of the invention, there is provided a method for radar-scanning a field of view according to accompanying claim <NUM>.

Apparatus and associated methods relate to a system for radar-scanning a field of view. The system includes a signal generator, a plurality of antennas, and an image processor. The signal generator generates electromagnetic signals. The plurality of antennas is radially distributed about a rotatable turret. Each of the plurality of antennas is electrically connected to the signal generator so as to receive an electromagnetic signal that causes the antenna to direct an electromagnetic beam along a principal direction characterized by a rotational position θ to which the antenna is rotated by the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis of the rotatable turret. The azimuthal beam angles of the plurality of antennas are different from one another. Each of the plurality of antennas senses a reflected portion of the electromagnetic beam reflected from objects within the field of view upon to which the electromagnetic beam has been directed. As the rotatable turret rotates about the rotational axis, the principal directions sweep conical figures about the rotational axis. At least a portion of the conical figures intersect the field of view. The image processor determines, based on the reflected portions of the electromagnetic beams sensed by the plurality of antennas, directions and/or ranges to and/or velocities of the objects within the field of view. The rotatable turret is a nose-cone of a projectile or a missile.

A further embodiment of the foregoing method for radar-scanning a field of view. the method includes generating, via a signal generator, electromagnetic signals. The method includes receiving, via a plurality of antennas radially distributed about a rotatable turret, the electromagnetic signals generated by the signal generator. The rotatable turret is a nose-cone of a projectile or missile. The method includes rotating the rotatable turret about a rotational axis. The method includes directing, via each of the plurality of antennas, an electromagnetic beam along a principal direction characterized by a rotational position θ to which the antenna is rotated by the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis of the rotatable turret. The azimuthal beam angles of the plurality of antennas are different from one another. As the rotatable turret rotates about the rotational axis, the principal directions sweep conical figures about the rotational axis. At least a portion of the conical figures intersect the field of view. The method includes sensing, via each of the plurality of antennas, a reflected portion of the electromagnetic beam reflected from objects within the field of view upon to which the electromagnetic beam has been directed. The method also includes determining, via an image processor and based on the reflected portions of the electromagnetic beams sensed by the plurality of antennas, directions and/or ranges to and/or velocities of the objects within the field of view.

Apparatus and associated methods relate to using a plurality of antennas radially distributed about a rotatable turret to sequentially scan a field of view. Each of the plurality of antennas directs an electromagnetic beam and senses its reflection along a principal direction characterized by a rotational position θ of the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis of the rotatable turret. The principal direction of each of the antennas having a different azimuthal beam angle (e.g., ϕA) from the azimuthal beam angles (e.g., ϕB-ϕG) of the other antennas. At first and second rotational positions, θ<NUM> and θ<NUM>, of the rotatable turret, each of these antennas sequentially turned on and turn off, respectively, as they are rotated to such rotational positions. This enables the electromagnetic beams directed by the antennas to pan a scene both in azimuth (e.g., for all azimuthal beam angles ϕA-ϕG) and rotational positions (e.g., for all rotational positions θ: θ<NUM><θ<θ<NUM>). An image processor then determines, based on the reflected electromagnetic signals detected by the plurality of antennas, directions to and/or velocities of objects within the scanned field of view.

<FIG> is a perspective view of a missile equipped with a rotating multi-beam antenna scanning a ground-surface field of view. In <FIG>, missile <NUM> is flying overhead of ground-surface field of view <NUM>, in which target <NUM> operates and building <NUM> resides. Missile <NUM> is equipped with radar scanning system <NUM>. Radar scanning system <NUM> includes antennas 18A-<NUM> (only 18A-18C visible in <FIG> and <FIG>) radially distributed about nose-cone <NUM> of missile <NUM>. Nose-cone <NUM> is configured to rotate about roll axis <NUM> (i.e., rotational axis) of nose-cone <NUM> and missile <NUM>. Each of the antennas 18A-<NUM> (which are several) produces a single beam (which is fixed by the antenna design) at an azimuthal beam angle ϕA-ϕG, respectively, relative to the roll axis <NUM> of the missile <NUM>. In some embodiments nose-cone <NUM> rotates with respect to a non-rotating missile, and in other embodiments, nose-cone <NUM> and the missile rotate together.

<FIG> is a depiction of radially distributed antennas and the azimuthal beam angles of their projected electromagnetic beams. Each of antennas 18A-<NUM> is configured to direct a corresponding one of electromagnetic beams 24A-<NUM> (only 24A-24C visible in <FIG>), respectively, outward from missile <NUM>. Each of antennas 18A-<NUM> is also configured to detect corresponding electromagnetic beams 24A-<NUM>, respectively, if reflected from objects that intersect their projected beam paths. Such a missile system, as described with reference to <FIG>, is a monostatic radar system. As shown in <FIG>, electromagnetic beams 24A-<NUM> are directed along principal directions that make azimuthal beam angles ϕA-ϕG with roll axis <NUM>, respectively. Each of azimuthal beam angles ϕA-ϕG (only ϕA-ϕC visible in <FIG>) corresponding to antennas 18A-<NUM>, respectively, is different from the other azimuthal beam angles ϕA-ϕG corresponding to others of antennas 18A-<NUM>, respectively. For example, in an exemplary embodiment, ϕA<ϕB<ϕC<ϕD<ϕE<ϕF<ϕG. Each of antennas 18A-<NUM> has a fixed principal direction 26A-<NUM> (only 26A-26C visible in <FIG>), respectively.

As nose-cone <NUM> of missile <NUM> rotates about roll axis <NUM> of nose-cone <NUM> and missile <NUM>, antennas 18A-<NUM> sequentially direct electromagnetic beams 24A-<NUM> along principal directions that sweep conical figures (or conical spiral figures if missile <NUM> is moving) 26A-<NUM>, respectively, about roll axis <NUM>. Essentially, radar scanning system <NUM> is "looking" at one conical slice of the field of view at any given point in time. Here, the term conical figures includes conical spiral figures, which can be scanned during missile flight. Each of these sweeping conical figures 26A-<NUM> intercepts ground-surface field of view <NUM> along a corresponding one of paths 28A-<NUM> (only 28A-28C visible in <FIG>), so as to generate a two-dimensional scan of ground-surface field of view <NUM>. Paths 28A-<NUM> represent the paths of the centers of electromagnetic beams 24A-<NUM> as they intercept ground-surface field of view <NUM>. In practice, electromagnetic beams 24A-<NUM> have a non-zero beam width, resulting in a band of detection about paths 28A-<NUM>. The image processor can construct a two-dimensional image of ground-surface field of view <NUM> based on electromagnetic beams 24A-<NUM> reflected thereby and sensed by antennas 18A-<NUM>, respectively. Although each antennas 18A-<NUM> has such a fixed principal direction, the combination of different principal directions permits such two-dimensional imaging of ground-surface field of view <NUM>.

The image processor can be further configured to determine, based on the electromagnetic beams 24A-<NUM> reflected by objects in the ground-surface field of view <NUM> and then received by antennas 18A-<NUM>, directions and/or ranges to objects within the ground-surface field of view <NUM>, such as, for example, target <NUM> and building <NUM>. Directions to objects can be determined, based on which of electromagnetic beams 24A-<NUM> was directed toward the object, and at what roll angle θ (i.e., rotational angle or position) was the electromagnetic beam directed at the time of detection. Range of objects can be determined based on an out-and-back time of flight measured for the particular electromagnetic beam 24A-<NUM> that was directed thereto. Object velocity can also be determined by the frequency shift (also known as the Doppler shift) of the reflected electromagnetic signal 24A-<NUM>.

Various types of antennas can be used as antennas 18A-<NUM>. For example, in one embodiment antennas 18A-<NUM> can be patch antennas. In another embodiment, antennas 18A-<NUM> can be slotted waveguides. In embodiments, such as the one described with reference to <FIG>, only a portion of the <NUM>° conical figures is directed toward the intended field of view In the <FIG> embodiment, that intended field of view is the ground-surface field of view. In such embodiments, radar scanning system <NUM> can further include a sequencer that sequentially activates each of the plurality of antennas 18A-<NUM> in sequence as the principal directions of the plurality of antenna are oriented so as to scan the ground-surface field of view. In some embodiments, only one antenna is turned on at any given point in time. Each antenna is sequentially turned on at a specific roll position or roll orientation θ<NUM> (i.e., rotational position) of missile <NUM> and again turned off at another specific roll position θ<NUM>. By enabling antennas 18A-<NUM> at different specific roll axes, data can be collected across a broad scene, thereby generating a radar "image" of the terrain below missile <NUM>. Additional image data is added to the image as each scan of the field of view is processed.

<FIG> is a two-dimensional image of a plan view of the ground-surface field of view scanned by the rotating multi-beam antenna. In <FIG>, two-dimensional image <NUM> depicts ground-surface field of view <NUM> depicted in <FIG>, as generated by the image processor. Target <NUM>' and building <NUM>' in <FIG> are imagery generated of target <NUM> and building <NUM> depicted in <FIG>. Two-dimensional image <NUM> is constructed by assembling image data obtained from reflected electromagnetic signal 24A-<NUM>, which have paths of their centers as indicated in the dotted lines 32A-<NUM>. The reflected electromagnetic signals are processed by the image processor as swaths of image data about such paths as indicated in these dotted lines 32A-<NUM>. These dotted lines 32A-<NUM> indicate centers of the intersection of ground-surface field of view <NUM> and electromagnetic beams 24A-<NUM>, respectively, as they are rotationally activated during rotation of missile <NUM>. After nose-cone <NUM> or missile <NUM> has complected a complete roll cycle, missile <NUM> has advanced forward in space, as missile <NUM> is flying toward target <NUM> and building <NUM> as depicted in <FIG>. To illustrate the impact of the flight trajectory of missile <NUM> of the collection of radar scene information, image <NUM> includes solid lines of image data 34A-<NUM>. These solid lines indicate the centers of the intersection of ground-surface field of view <NUM> and electromagnetic beams 24A-<NUM>, respectively, as they are rotationally activated during the next rotation of missile <NUM> after the rotation corresponding to dotted lines 32A-<NUM>. In this way, each rotation of missile <NUM> can generate additional image data depicting additional portions of ground-surface field of view <NUM>. The image processor determines where each of lines of image data 32A-<NUM> and 34A-<NUM> are to be depicted within two-dimensional image <NUM> based on which of antennas 24A-<NUM> obtained data pertaining thereto and further based on flight data (e.g., position data, attitude data, etc.) of missile <NUM>. Left-hand boundary of image <NUM> is defined by the rotational angle θ<NUM> at which location each of antennas 18A-18F are enabled, and right-hand boundary of image <NUM> is defined by the rotational angle θ<NUM> at which location each of antennas 18A-18F are disabled.

<FIG> is a graph depicting detection range vs. azimuthal resolution (number of antennas) tradeoff. Various embodiments of radar scanning system <NUM> can include more or fewer antennas than the seven depicted in <FIG> (of which only three can be seen in the perspective of the drawing). Increasing the number of antennas can improve the spatial imaging resolution of the two-dimensional image in the azimuthal direction. As nose-cone <NUM> is equipped with more antennas, however, the size of each of these antennas necessarily must decrease, because surface area of nose-cone <NUM> is finite. As the size of each of the antennas decreases, the power of the electromagnetic beam projected thereby also decreases. As the power of the electromagnetic beam decreases, so too does the detection range as signal-to-noise ratio of the electromagnetic beam reflected by objects in the ground-surface field of view and detected by the antenna aligned thereto also decreases. This reduction in the signal-to-noise ratio results in a reduction in overall detection range of the radar system. Thus, there is a tradeoff between the number of antennas and the resulting image quality (e.g., spatial resolution in azimuth vs. detection range).

In <FIG>, graph <NUM> illustrates design tradeoffs between number of antennas and detection range and/or spatial resolution. Graph <NUM> includes horizontal axis <NUM>, first and second vertical axes 40A and 40B, spatial-resolution/antenna-number relation 42A, and detection-range /antenna-number relation 42B. Horizontal axis <NUM> is indicative of the number of antennas distributed about a rotatable turret of a radar scanning system. First vertical axis 40A is indicative of the spatial resolution of imagery generated by the radar scanning system. Spatial-resolution/antenna-number relation 42A depicts the increasing spatial resolution in azimuth that can be obtained by increasing the number of antennas distributed about the rotatable turret. For example, more swaths of image data can be generated for each rotation as more antennas are distributed about the rotatable turret. Second vertical axis 40B is indicative of the detection range of imagery generated by the radar scanning system. Detection-range/antenna-number relation 42B depicts the decreasing detection range that results from increasing the number of antennas distributed about the rotatable turret.

Using additional antennas results in smaller antenna aperture area available for each antenna. Smaller available aperture area results in reduced antenna gain thereby reducing the detection range of each individual antenna. Consequently, there is a system tradeoff when it comes to choosing the number of antennas. A greater number of antennas will permit a greater number of electromagnetic beams available for scanning the scene during a missile roll cycle (i.e., rotation). Therefore, increasing the number X of antennas will result in an increase in the spatial resolution of the system within the span of azimuthal angles ϕA-ϕX. However, having more antennas means dividing up more of the available surface area along the missile's circumference amongst more antennas thereby reducing the amount of aperture area per antenna. Less available aperture area per antenna results in lower overall gain. A reduction in antenna gain reduces the detection range of each antenna via the radar range equation formula.

To illustrate these tradeoffs by way of example, suppose a series of flat Circuit Card Assemblies (CCAs) is used as patch antenna arrays inscribed in a section of the missile's body dedicated to a radar system. This section of the missile has a length L and the missile's radius is R. If we assume the CCAs form an inscribed polygon in a circle, then the maximum area available for each CCA will be A = 2RL sin(π/n) where n is the number of antennas. As the number of antennas n increases, the aperture area A is necessarily reduced. Since antenna gain is related to antenna aperture by the following formula, Eqn. (<NUM>): <MAT>.

Here in Eqn. (<NUM>), ε is antenna efficiency, G is antenna gain, and λ is the wavelength of the electromagnetic radiation). According to Eqn. (<NUM>), if antenna aperture is reduced, the antenna gain G will also be reduced. Reduced antenna gain G will adversely impact the detection range of the radar system. This reduction in detection range is illustrated by the radar range equation which describes the minimum detectable range for a radar system, Eqn. (<NUM>): <MAT>.

Here, Ps is the RF emitter source power, σ is the radar cross section of the target and Pmin is the minimum detection power). From the radar range equation (Eqn. (<NUM>)) as antenna gain G falls so does the minimum detection range Rmin. Therefore, choosing the number of antennas n for such a radar system architecture requires careful consideration based on applications and needs as there is a tradeoff between azimuthal scan resolution and the maximum detection range of such radar systems.

<FIG> is a perspective view of an alternative embodiment of the rotating antenna concept not used in a missile application. The purpose of <FIG> is to highlight how a rotating multi-beam antenna system can be applied in other applications. In this embodiment, a ground-based multi-beam antenna can be used for scanning an airspace field of view. In <FIG>, radar scanning system <NUM>' includes antennas 18A-<NUM> radially distributed about rotatable turret <NUM>' of radar scanning system <NUM>'. Radar scanning system <NUM>' includes rotator (e.g., a motor) <NUM> that rotates rotatable turret <NUM>' about rotational axis <NUM>'. Each of antennas 18A-<NUM> is configured to direct a corresponding one of electromagnetic beams 24A-<NUM> outward from rotatable turret <NUM>'. Each of antennas 18A-<NUM> is also configured to detect corresponding electromagnetic beams 24A-<NUM> reflected from objects that intersect their projected beam paths (i.e., system <NUM> is a monostatic radar system). Electromagnetic beams 24A-<NUM> are directed along principal directions that make azimuthal beam azimuthal beam angles ϕA-ϕG with rotational axis <NUM>', respectively. Each of azimuthal beam angles ϕA-ϕG corresponding to antennas 18A-<NUM>, respectively, is different from the other azimuthal beam angles ϕA-ϕG corresponding to others of antennas 18A-<NUM>, respectively. Each of antennas 18A-<NUM> has a fixed principal direction, respectively.

As rotatable turret <NUM>' of radar scanning system <NUM>' rotates about rotational axis <NUM>' of rotatable turret <NUM>', antennas 18A-<NUM> sequentially direct electromagnetic beams 24A-<NUM> along principal directions that sweep conical figures 26A-<NUM> about rotational axis <NUM>'. Each of these sweeping conical figures 26A-<NUM> intercept airspace field of view <NUM>' along a corresponding path so as to generate a <NUM>° scan (along the roll axis) of airspace field of view <NUM>'. The image processor can construct a two-dimensional image of <NUM>° field of view <NUM>' based on electromagnetic beams 24A-<NUM> reflected thereby and sensed by antennas 18A-<NUM>, respectively.

The image processor can be further configured to determine, based on the electromagnetic beams 24A-<NUM> reflected by objects in the airspace field of view <NUM>' and then received by antennas 18A-<NUM>, directions and/or ranges to objects within the airspace field of view <NUM>', such as, for example, target <NUM>'. Directions to objects can be determined, based on which of electromagnetic beams 24A-<NUM> was directed toward the object. Range and velocity of objects can be determined based on an out-and-back time of flight and Doppler shift, respectively, measured for the particular electromagnetic beam 24A-<NUM> that was directed thereto.

<FIG> is a block diagram of an embodiment of a system for radar-scanning a field of view. In <FIG>, radar scanning system <NUM>" or rotatable turret <NUM>" ground system includes controller <NUM> and rotatable turret <NUM>". Rotatable turret <NUM>" has antennas 18A-<NUM> mounted thereto. Each of antennas 18A-<NUM> is configured to direct electromagnetic beams 24A-<NUM> along principal directions that make azimuthal beam angles ϕA-ϕG with rotational axis <NUM>", respectively. Controller <NUM> includes rotator <NUM>' that rotates rotatable turret <NUM>" about rotational axis <NUM>" so as to cause electromagnetic beams 24A-<NUM> to scan a conical figure of space. In some embodiments, rotational axis <NUM>" can be changed so as to change the space which the conical figures scan.

As illustrated in <FIG>, controller <NUM> includes radar signal generator <NUM>, reflected signal detector <NUM>, sequencer <NUM>, image processor <NUM>, memory <NUM>, user interface <NUM> and positional data interface <NUM>. Image processor <NUM>, in one example, is configured to implement functionality and/or process instructions for execution within radar scanning system <NUM>". For instance, image processor <NUM> can be capable of receiving from and/or processing instructions stored in program memory 54P. Image processor <NUM> can then execute program instructions so as to cause radar signal generator <NUM> to generate electromagnetic signals that will cause electromagnetic beams to be projected from antennas 18A-<NUM>. Sequencer <NUM> can coordinate activities of each of antennas 18A-<NUM>, thereby controlling the field of view that is scanned thereby. Electromagnetic signals reflected by objects in the field of view are detected by reflected signal detector <NUM>. These signals can be processed by signal processor <NUM> and/or stored in data memory 54D, for example. Image processor <NUM> can generate a images of the field of view based on such signals generated by reflected signal detector <NUM>. Image processor <NUM> can also send control commands to the various other subsystems, such as, for example, radar signal generator <NUM>, reflected signal detector <NUM>, sequencer <NUM>.

In various embodiments, radar scanning system <NUM>" can be realized using the elements illustrated in <FIG> or various other elements. For example, image processor <NUM> can include any one or more of a microprocessor, a control circuit, a digital signal image processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry.

Memory <NUM> can be configured to store information within radar scanning system <NUM>" during operation. Memory <NUM>, in some examples, is described as computer-readable storage media. In some examples, a computer-readable storage media can include a non-transitory medium. The term "non-transitory" can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). In some examples, memory <NUM> is a temporary memory, meaning that a primary purpose of memory <NUM> is not long-term storage. Memory <NUM>, in some examples, is described as volatile memory, meaning that memory <NUM> does not maintain stored contents when power to radar scanning system <NUM>" is turned off or interrupted. Examples of volatile memories can include random-access memories (RAM), dynamic random-access memories (DRAM), static random-access memories (SRAM), and other forms of volatile memories. In some examples, memory <NUM> is used to store program instructions for execution by image processor <NUM>. Memory <NUM>, in one example, is used by software or applications running on radar scanning system <NUM>" (e.g., a software program implementing electrical control of radar signal generator <NUM>, reflected signal detector <NUM>, sequencer <NUM>, etc.) to temporarily store information during program execution, such as, for example, in data memory 54D.

In some examples, memory <NUM> can also include one or more computer-readable storage media. Memory <NUM> can be configured to store larger amounts of information than volatile memory. Memory <NUM> can further be configured for long-term storage of information. In some examples, memory <NUM> includes non-volatile storage elements. Examples of such non-volatile storage elements can include magnetic hard discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.

User interface <NUM> can be used to communicate information between radar scanning system <NUM>" and a user (e.g., an operator, a soldier, etc.). User interface <NUM> can include a communications module. User interface <NUM> can include various user input and output devices. For example, User interface can include various displays, audible signal generators, as well switches, buttons, touch screens, mice, keyboards, etc..

User interface <NUM>, in one example, utilizes the communications module to communicate with external devices via one or more networks, such as one or more wireless or wired networks or both. The communications module can include a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and receive information. Other examples of such network interfaces can include Bluetooth, <NUM>, <NUM>, and Wi-Fi radio computing devices as well as Universal Serial Bus (USB) devices.

Positional data interface <NUM> can be used to communicate information between radar scanning system <NUM>" and a vehicle positioning system (e.g., a flight control system). Positional data interface <NUM> can include a communications module. Positional data interface <NUM> can receive positional information of radar scanning system <NUM>", which can be used by image processor <NUM> to generate imagery of the field of view scanned by radar scanning system <NUM>". In a missile application, for example, the positional coordinates and attitude can be received by image processor <NUM> via positional data interface <NUM>. Such positional data can then be used to control sequencer <NUM> so as to scan a desired field of view. Such positional data can also be used by image processor <NUM> so as to accurately map the objects that reflect the projected electromagnetic signals into the imagery generated.

<FIG> is a graph depicting sequenced enablement of a plurality of antennas used to scan a field of view. In <FIG> graph <NUM> includes horizontal axis <NUM>, vertical axis <NUM> and antenna enablement signals ENA-ENH. Horizontal axis <NUM> is indicative of roll angle θ of missile <NUM> (depicted in <FIG>). Vertical axis <NUM> is indicative of enablement signals for a radar scanning system that has eight antennas distributed about nose-cone <NUM> of missile <NUM>, as indicated by subscript letters A-H. Enablement signals ENA-ENH indicate when each of antennas 18A-<NUM> of such an eight-antenna radar system are enabled. Each of antennas 18A-<NUM> is enabled when roll-oriented at an angle at which an initial boundary (e.g., a left-hand side boundary) of the field of view to be scanned is aligned with the electromagnetic beam projected thereby. Each of antennas 18A-<NUM> is then disabled when roll-oriented at an angle at which a final boundary (e.g., a right-hand side boundary) of the field of view to be scanned is aligned with the electromagnetic beam projected thereby. In some embodiments, adjacent enablement signals ENA-ENH are such that as the preceding enablement signal ENX indicates the preceding antenna being disabled coincides with the subsequent enablement signal ENX+<NUM> indicating that the subsequent antenna is being simultaneously enabled. In other embodiments, the enablement signals can overlap, permitting two or more antennas simultaneously operating.

The following are descriptions of the present invention and further embodiments.

Apparatus and associated methods relate to a system for radar-scanning a field of view. The system includes a signal generator, a plurality of antennas, and an image processor. The signal generator generates electromagnetic signals. The plurality of antennas is radially distributed about a rotatable turret. Each of the plurality of antennas is electrically connected to the signal generator so as to receive an electromagnetic signal that causes the antenna to direct an electromagnetic beam along a principal direction characterized by a rotational position θ to which the antenna is rotated by the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis of the rotatable turret. The azimuthal beam angles of the plurality of antennas are different from one another. Each of the plurality of antennas senses a reflected portion of the electromagnetic beam reflected from objects within the field of view upon to which the electromagnetic beam has been directed. As the rotatable turret rotates about the rotational axis, the principal directions sweep conical figures about the rotational axis. At least a portion of the conical figures intersect the field of view. The image processor determines, based on the reflected portions of the electromagnetic beams sensed by the plurality of antennas, directions and/or ranges to and/or velocities of the objects within the field of view. The rotatable turret is a nose-cone of a projectile or missile.

The system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing system can further include a sequencer that sequentially activates each of the plurality of antennas in sequence when the principal direction of the antenna is rotationally positioned so as to direct the electromagnetic beam toward the field of view.

A further embodiment of any of the foregoing systems can further include a sequencer that sequentially deactivates each of the plurality of antennas in sequence when the principal direction of the antenna is rotationally positioned so as to not direct the electromagnetic beam toward the field of view.

A further embodiment of any of the foregoing systems can further include a sequencer that sequentially activates each of the plurality of antennas when the antenna is at a first rotational position θ<NUM> and deactivates each of the plurality of antennas when the antenna is at a second rotational position θ<NUM>, wherein the first rotational position θ<NUM> and the second rotational position θ<NUM> determine boundaries of the field of view.

A further embodiment of any of the foregoing systems can further include a rotator that rotates the rotatable turret about the rotational axis.

A further embodiment of any of the foregoing systems, wherein each of the plurality of antennas can be a patch antenna.

A further embodiment of any of the foregoing systems, wherein each of the plurality of antennas can be a waveguide antenna.

Some embodiments relate to a method for radar-scanning a field of view. The method includes including generating, via a signal generator, electromagnetic signals. The electromagnetic signals generated by the signal generator are received via a plurality of antennas radially distributed about a rotatable turret. The rotatable turret is a nose-cone of a projectile or missile. The rotatable turret is rotated about a rotational axis. An electromagnetic beam is directed, via each of the plurality of antennas, along a principal direction characterized by a rotational position θ to which the antenna is rotated by the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis of the rotatable turret, the azimuthal beam angles of the plurality of antennas being different from one another. As the rotatable turret rotates about the rotational axis the principal directions sweep conical figures about the rotational axis, at least a portion of the conical figures intersects the field of view. A reflected portion of the electromagnetic beam reflected from objects within the field of view upon to which the electromagnetic beam has been directed is sensed via each of the plurality of antennas. Directions and/or ranges to and/or velocities of the objects within the field of view are determined via an image processor based on the reflected portions of the electromagnetic beams sensed by the plurality of antennas.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing method can further include sequentially activating, via a sequencer, each of the plurality of antennas in sequence when the principal direction of the antenna is rotationally positioned so as to direct the electromagnetic beam toward the field of view.

A further embodiment of any of the foregoing methods can further include sequentially deactivating, via a sequencer, each of the plurality of antennas in sequence when the principal direction of the antenna is rotationally positioned so as to not direct the electromagnetic beam toward the field of view.

A further embodiment of any of the foregoing methods can further include sequentially activating, via a sequencer, each of the plurality of antennas when the antenna is at a first rotational position θ<NUM>, and sequentially deactivating, via the sequencer, each of the plurality of antennas when the antenna is at a second rotational position θ<NUM>, wherein the first rotational position θ<NUM> and the second rotational position θ<NUM> determine boundaries of the field of view.

Claim 1:
A system (<NUM>) for radar-scanning a field of view (<NUM>), the system comprising:
a signal generator (<NUM>) that generates electromagnetic signals;
a plurality of antennas (18A-<NUM>) radially distributed about a rotatable turret (<NUM>'), each of the plurality of antennas electrically connected to the signal generator so as to receive an electromagnetic signal that causes the antenna to direct an electromagnetic beam (24A-<NUM>) along a principal direction (26A-<NUM>) characterized by a rotational position θ to which the antenna is rotated by the rotatable turret and an azimuthal beam angle ϕ with respect to a rotational axis (<NUM>) of the rotatable turret, the azimuthal beam angles (ϕA-ϕG) of the plurality of antennas being different from one another, each of the plurality of antennas sensing a reflected portion of the electromagnetic beam reflected from objects within the field of view upon to which the electromagnetic beam has been directed,
wherein as the rotatable turret rotates about the rotational axis the principal directions sweep conical figures about the rotational axis, at least a portion of the conical figures intersecting the field of view; and
an image processor (<NUM>) that determines, based on the reflected portions of the electromagnetic beams sensed by the plurality of antennas, directions and/or ranges to and/or velocities of the objects within the field of view,
wherein the rotatable turret is a nose-cone (<NUM>) of a projectile or missile (<NUM>).