Abstract: An airborne weather radar system that detects potentially hazardous weather conditions associated with storms and includes a radar display featuring visual indications of these conditions. The radar display includes a vertical situation display having iconal representations and symbolic icons indicative hazardous weather conditions and aviation hazards along the aircraft's flight path not otherwise immediately apparent or shown on standard weather radar displays. The system includes processes for detecting and predicting hazardous weather conditions such as overshooting thunderstorm tops and vaulted thunderstorm energy and serious hazards such as turbulence and hail.

Abstract: A radar receiver on a moving platform images a moving target and non-moving clutter using a single SAR array. The radar receiver converts the radar returns into digital radar returns and motion compensates the digital radar returns with respect to a reference, then applies further phase compensation to obtain an autofocused synthetic aperture image. A plurality of moving target pixels descriptive of the moving target are detected within the autofocused synthetic aperture image. The plurality of moving target pixels are transformed from the autofocused image to the time domain. The time domain moving target data is focused by iteratively applying a phase compensation to the time domain moving target data.

Abstract: A method and apparatus comprising four co-planar metallic plates, two for transmission and two for reception, in which each pair of co-planer metallic plates of overall length L are disposed either in direct contact with the earth or are elevated a distance Z above the earth to form a capacitor comprising the metallic plates and the earth if Z=0 or if Z>0, the metallic plates, the air space and the earth. A short voltage or current pulse is applied to this capacitor via a transformer in which the magnetic flux current is adjusted to provide a pulse of the desired frequency composition in the air-earth propagation medium. This results in a frequency controlled pulse of electromagnetic radiation into the targeted subterranean geology at frequencies <500 KHZ.

Abstract: Embodiments of the invention provide a method and apparatus for indicating aircraft height relative to an obstruction in a terrain awareness warning system. The method includes receiving data indicative of geographic features of an obstruction, lateral distance of the geographic feature from an aircraft, height and flight path of the aircraft, calculating a projected height of the aircraft at the location of the obstruction using the data, generating a result signal, and displaying a colored indication on a display screen based on the result signal. The apparatus includes inputs for signals from instruments measuring height, flight path, and location of an aircraft, as well as an input for an instrument providing information about geographic features of terrain surrounding the aircraft. The apparatus includes a means for employing the signals to calculate an effective height of the aircraft relative to the terrain, and a screen display for graphically displaying the results of the calculation.

Abstract: Generating an image matrix includes accessing a round-trip time matrix for a space having points. The round-trip time matrix describes an estimated round-trip time for a signal to travel from a transmit antenna, to a point, and to a receive antenna. Signals reflected from an object of the space are received at the receive antennas. The following are repeated for at least a subset of the points to generate an image matrix: select a point of the subset of points; for each receive antenna, establish a waveform of a signal received by a receive antenna and identify a waveform value of the established waveform that corresponds to the selected point according to the round-trip time matrix; and combine the waveform values for the selected point to yield an image value for the selected point. The image matrix is generated from the image values.

Abstract: A system, according to various aspects of the present invention, provides a presentation to a hazard display. The system includes a memory having surveillance data and a processor. The processor updates an image in accordance with the surveillance data to provide an updated image. The processor also prepares a presentation in accordance with the updated image. The processor further provides the presentation to the hazard display. At least one of updating, preparing, and providing utilize a first scan mode for a hazardous region of the presentation and a second scan mode for a nonhazardous region of the presentation.

Abstract: A method and apparatus to remove human features utilizing at least one transmitter transmitting a signal between 200 MHz and 1 THz, the signal having at least one characteristic of elliptical polarization, and at least one receiver receiving the reflection of the signal from the transmitter. A plurality of such receivers and transmitters are arranged together in an array which is in turn mounted to a scanner, allowing the array to be passed adjacent to the surface of the item being imaged while the transmitter is transmitting electromagnetic radiation. The array is passed adjacent to the surface of the item, such as a human being, that is being imaged. The portions of the received signals wherein the polarity of the characteristic has been reversed and those portions of the received signal wherein the polarity of the characteristic has not been reversed are identified. An image of the item from those portions of the received signal wherein the polarity of the characteristic was not reversed is then created.

Abstract: An apparatus for identifying a buried object using ground penetrating radar (GPR) in a system containing at least one GPR sensor, comprises a data processor for detecting spatial correlations in data received from a GPR sensor in the apparatus and an image processor capable of building a data structure corresponding to an image of the buried object from data processed by the data processor. A method for identifying a buried object using GPR in a system containing a GPR sensor comprising detecting spatial correlations in data received from the GPR sensor in the system and building a data structure corresponding to an image of the buried object from the received data.

Abstract: A radar system for active obstacle warning and imaging of the surface of the earth, working in the pulse frequency or FH-CW range, which can be used in on-line operation in real time, includes a plurality of antenna elements for sending and receiving radar signals, which are arranged on the fuselage of an aircraft, and which may be turned on and scanned sequentially, whereby a synthetic aperture can be generated by means of periodic sending and receiving of the antenna elements. Antenna elements are arranged along the curved surface of the aircraft contour, whereby a SAR processor is present, which analyzes the data obtained from the antenna elements and displays them as processed radar images on board the aircraft, in a virtual cockpit.

Abstract: An exemplary embodiment of the invention relates to a computer-based program and system for displaying visually realistic raw radar signals. The computer program includes a RADAR display fade algorithm. The algorithm includes alpha blending and texture mapping for producing a slow fade. Use of two buffers and transfer of data between the buffers to produce a smooth update of the visual display while the sweep of the RADAR ray advances and new or updated RADAR contacts are displayed.

Abstract: Embodiments of the invention provide a method and apparatus for indicating aircraft height relative to an obstruction in a terrain awareness warning system. The method includes receiving data indicative of geographic features of an obstruction, lateral distance of the geographic feature from an aircraft, height and flight path of the aircraft, calculating a projected height of the aircraft at the location of the obstruction using the data, generating a result signal, and displaying a colored indication on a display screen based on the result signal. The apparatus includes inputs for signals from instruments measuring height, flight path, and location of an aircraft, as well as an input for an instrument providing information about geographic features of terrain surrounding the aircraft. The apparatus includes a means for employing the signals to calculate an effective height of the aircraft relative to the terrain, and a screen display for graphically displaying the results of the calculation.

Abstract: Active millimeter-wave imaging systems can include an antenna apparatus configured to transmit toward and receive from a subject in a subject position, electromagnetic radiation. A controller can include a transceiver configured to operate the antenna apparatus and produce an output representative of the received radiation, and a processor adapted to convert the transceiver output into image data representative of an image of the subject. The antenna apparatus may move in a partial or continuous loop around the subject, toward or away from the subject, or in an opposite direction to an associated antenna apparatus. Antenna units in the antenna apparatus may be oriented at different angular positions along an array. Antenna arrays may also be formed of a plurality of array segments, and a group of arrays may be combined to form an antenna apparatus.

Abstract: Motion compensation for coherent combination of pulses facilitates a SAR image of a scene on earth's surface. A great circle (406) is centered with respect to the earth's center, The great circle (406) has an axis (412) perpendicular to a first plane. Axis (412) passes through the earth's center. The first plane contains great circle (406) and includes the earth's center. Great circle (406) has a first center defined by an intersection of the first plane and axis (412). The scene has one or more radar scatterers and is located on a surface (402). The radar system is mounted on a moving platform (400) moving with a component of motion in a direction along great circle (406). The radar comprises a radar receiver for digitizing the radar returns having a phase from scatterers on surface (402), and a computer for focusing the phase of said radar returns from the scatterers on surface (402).

Abstract: A radar system for generating a three-dimensional image includes a radar transmitter which is operable to produce a radar signal of a frequency of at least three gigahertz. A plurality of radar receiving antennas from an antenna array. The antenna array is aerially translatable. For example, in one embodiment, the antenna array is disposed along the wings of an aircraft which, in operation, flies over the intended target area. A three-dimensional image is generated from a reflected radar signal returned from the surface of an object in response to the transmitted radar signal. The radar system may be incorporated into an aircraft and adapted to detect subsurface objects such as mines buried beneath the surface of the ground as the aircraft traverses over a target area.

Abstract: An imaging system includes an optical (visible-light or near IR) imaging system and a microwave imaging system. The optical imaging system captures an optical image of the object, produces optical image data representing the optical image and extracts optical image information from the optical image data. The microwave imaging system produces microwave image data representing a microwave image of the object in response to the optical image information.

Abstract: A see-through-the-wall (STTW) imaging system uses a plurality of geographically separated positioning transmitters to transmit non-interfering positioning signals. An imaging unit generates a synthetic aperture image of a target by compensating for complex movement of the imaging unit using the positioning signals. The imaging unit includes forward and aft positioning antennas to receive at least three of the positioning signals, an imaging antenna to receive radar return signals from the target, and a signal processor to compensate the return signals for position and orientation of the imaging antenna using the positioning signals. The signal processor may construct the synthetic aperture image of a target from the compensated return signals as the imaging unit is moved with respect to the target. The signal processor may determine the position and the orientation of the imaging unit by measuring a relative phase of the positioning signals.

Abstract: The system and method for standoff detection of human carried explosives (HCE) is a portable system that automatically detects HCE up to a range of 200 meters and within seconds alerts an operator to HCE threats. The system has radar only, or both radar and video sensors, a multi-sensor processor, an operator console, handheld displays, and a wideband wireless communications link. The processor receives radar and video feeds and automatically tracks and detects all humans in the field of view. Track data continuously cues the narrow beam radar to a subject of interest, the radar repeatedly interrogating cued objects, producing a multi-polarity radar range profile for each interrogation event. Range profiles and associated features are automatically fused over time until sufficient evidence is accrued to support a threat/non-threat declaration hypothesis. Once a determination is made, the system alerts operators through a handheld display and mitigates the threat if desired.

Abstract: A security inspection system uses microwave radiation to image targets on a human subject or other item. The system includes an array of antenna elements that are programmable with a respective phase delay to direct a beam of microwave illumination toward a target on the human subject or item. The antenna elements are further capable of receiving reflected microwave illumination reflected from the target. A processor is operable to measure an intensity of the reflected microwave illumination to determine a value of a pixel within an image of the human subject or item. Multiple beams can be directed towards the human subject or item to obtain corresponding pixel values for use by the processor in constructing the image.

Abstract: A millimeter wave imaging system that includes at least one millimeter wave frequency scanning antenna for collecting frequency dependent beams of millimeter wave radiation from a narrow one-dimensional field of view. The collected radiation is amplified at the collected frequencies and the amplified signals are separated into frequency dependent bins with a tapped-delay beam-former. These bins are then sampled to produce a one-dimensional image of the antenna field of view. A two dimensional image of a target may be obtained by moving the target across the field of view of the scanning antenna. In a preferred embodiment the antenna is only 4.5 inches in length and constructed from WR-10 waveguide with inclined slots cut in one of the narrow walls at 79 mil spacings. This geometry creates a frequency-scanned antenna spanning a 20 degree vertical field of view over a 75.5-93.5 GHz operational band of the sensor, starting at approximately 1 degree below horizontal at 93.

Abstract: The present invention includes an application of a dynamic logic algorithm to detect slow moving targets. Show moving targets are going to be moving in the range from 0-5 mph. This could encompass troop movements and vehicles or convoys under rough terrain.

Abstract: A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

Abstract: An image sensor section and a millimeter-wave sensor section separately detect objects. A sensor matching section determines whether the objects detected by the image sensor section and the millimeter-wave sensor section are one and the same object. If the objects are one and the same object, the sensor matching section estimates a position of the obstacle after a certain period. A collision prediction section determined whether there is going to be a collision between the vehicle and the object 50 from the position estimated by the sensor matching section.

Abstract: A plurality of image chips (202) (over 100), each of the chips containing the same, known target of interest, such as, for example an M109 tank are presented to the system for training. Each image chip of the known target is slightly different than the next, showing the known target at different aspect angles and rotation with respect to the moving platform acquiring the image chip. The system extract multiple features of the known target from the plurality of image chips (202) presented for storage and analysis, or training. These features distinguish a known target of interest from the nearest similar target to the M109 tank, for example a Caterpillar D7 bulldozer. These features are stored for use during unknown target identification. When an unknown target chip is presented, the recognition algorithm relies on the features stored during training to attempt to identify the target.

Abstract: A system for imaging the contents of containers includes an imager arranged to receive millimetre wave radiation from a reception volume through a receive antenna wherein, in use, the container is moving relative to the receive antenna, the reception volume is positioned such that the relative movement causes the reception volume to move through the container; data from the antenna is recorded as the reception volume moves through the container, and an image of the contents of the container is built up from the recorded data. The system is particularly suitable for imaging containers mounted on vehicles. The imager may advantageously be mounted in a portal, allowing convenient and controllable relative positioning of the container, and allowing the relative speed to be controlled or measured easily. The invention allows 3D or pseudo 3D images to be produced to aid identification of container contents. The invention also includes a method for imaging.

Abstract: A weather radar display system is disclosed. The weather radar display system comprises a weather radar antenna, processing electronics, coupled to the weather radar antenna, enhancing weather radar returns based on a reflectivity model which differentiates lower level activity from higher level activity when the weather activity is detected from weather systems at long range and the reflectivity using short range thresholds would display only higher level activity. A weather radar display displays multiple colors representative of the different levels of weather activity based on the enhanced returns.

Abstract: Disclosed are systems, methods, devices, and apparatus to interrogate a clothed individual with electromagnetic radiation to determine if a concealed weapon is being carried. This determination includes establishing data corresponding to an image of the individual and processing data sets corresponding to a number of spatial frequency representations of different image portions to evaluate if the concealed weapon is present.

Abstract: A system-of-systems avionics architecture that is compatible with futuristic multi-function multi-platform sensor applications. The method and device of the invention is based on localized “adaptive” waveform and spectrum allocation for ultra-wideband radio frequency and microwave signals. The invention includes a plurality of system platforms with each platform comprising a common radio frequency front end for receiving ultra-wideband signals, a common radio frequency back end for transmitting ultra-wideband signals and a plurality of sensors for exchanging data between platforms.

Abstract: A transceiver or transponder particularly for synthetic aperture radar, or SAR, systems, operating in a frequency band having a central frequency, the transponder comprising a receiver (1) and a transmitter (2) both thermally stable and made by microstrip technology, the receiver (1) and the transmitter (2) being adapted to receive and to transmit, respectively, an electromagnetic wave provided with at least one linear polarisation, the receiver (1) being connected to the transmitter (2) by amplifier means comprising an amplifier unit (5) for each linear polarisation of the wave received by the receiver (1), each amplifier unit (5) including at least two amplifier stages (7, 9, 11) cascade arranged along a single microstrip and interconnected to one another and to an input and to an output of the corresponding amplifier unit (5) by means of coupling or matching stages (6, 8, 10, 12), the output signal of each amplifier unit (5) having substantially the same frequency as the input signal thereto, the amplifier

Abstract: A radar system derives a correction for an actual boresight (311) of a radar monopulse antenna mounted on a moving platform from ? data and ? data generated with respect to an a priori known, calibrated boresight (309). The monopulse antenna (602) is coupled to a ground position measuring system (616) while acquiring data. The radar receiver acquires a ? and ? synthetic aperture map of the same radar scattering location with respect to the calibrated boresight. ? SAR data and the ? SAR data are motion compensated using the position and velocity supplied by the ground positioning system. A computer forms a ratio of the aligned ? pixels to the aligned ? pixels for each of a plurality of aligned ? pixels located near the calibrated boresight. The correction for the location of the actual boresight of the monopulse antenna is computed by an analysis of the ratio of aligned ? pixels and corresponding aligned ? pixels over the radar scattering location.

Abstract: A slope monitoring system having a radar and a video camera recording images sequences of the slope. A data processing unit performs coordinate registration to align the radar images and the video images. Interferometry is used to detect movement in the slope by generating interference maps between the images. These are suitably phase maps showing the phase change between a radar image and a reference image. An alarm occurs if a significant movement is detected.

Abstract: A system and method to build a radar reflectivity forecast mosaic from a collection of radar sites. The radar data from multiple radar sites is processed to create movement information for all of the precipitation areas. The movement information and precipitation areas are then mosaicked in a common geographical framework to create forecasted radar reflectivity mosaics. By using the reflectivity information and movement information from multiple radars, a wider scale, more coherent radar forecast can be generated.

Abstract: A system for allowing pilots to quickly determine weather hazard-free flight paths and weather hazards that exist along the aircraft flight plan. The system includes a memory, a processor, and a display device. The memory stores weather radar return information in a three-dimensional buffer. The processor is coupled to the memory. The processor receives a display distance value signal, retrieves weather radar return information stored in a plane of voxels in the three-dimensional buffer based on the selected display distance value and aircraft position information, and generates an image based on the retrieved weather radar return information. The display device is coupled to the processor for displaying the generated image.

Abstract: A radar device mounted to a vehicle includes a camera for obtaining images including the road surface in front of or behind the vehicle on which it is mounted, a sensor having for obtaining at least positional information on a target object of detection such as another vehicle in front or behind and a control unit for correcting the direction of the center axis of the sensor based on the image obtained by the camera. The control unit detects a line segment along a lane in which the vehicle is traveling, detects a vector indicative of the direction on a road-fixed coordinate system of the obtained line segment, and controls correction of horizontal and vertical directions of the center axis of the sensor so as to coincide with the direction of the detected vector.

Abstract: A method for short-term prediction of storm cells in aircraft using a modified weather radar system, and a modified weather radar system embodying the method.

Abstract: A method, apparatus, and computer readable medium are provided for creating a quantitative, three-dimensional representation of a surface of a human subject. Data representing a physical appearance of a human subject is gathered using inverse synthetic aperture radar. A source signal is directed toward the human subject as the target rotates through a range of motion and a return signal is collected. The returned signal is transformed into a quantitative representation of the surface data. The quantitative representation can be added to an archive or can be checked against an archive to determine if the human target is indexed in the archive.

Abstract: A method for displaying horizontally aligned characters on a radial display is disclosed. Each range bin for each scan line is associated with a rectangular grid location to determine the character located in the grid location and the background color and foreground color for the grid location. A font matrix corresponding to the appropriate character is then used to determine if the range bin corresponds to one of the pixels that make up the character or if the range bin corresponds to a background pixel. This determines if the range bin is assigned the foreground color or background color. The method is done for each range bin value and for each scan line. The range bin and scan line information is sent to a display.

Abstract: A system for processing radar data from two or more areas of interest is provided, such as for simultaneously processing vehicle speeds in the opposite lane in front of the patrol vehicle and in the opposite lane behind the patrol vehicle. The system includes an antenna signal processor that receives radar data from one or more radar antennae and generates speed data for a first vehicle travelling in a first direction relative to a radar observation point and a second vehicle travelling in a second direction relative to the radar observation point. A display generator system receives the speed data and user-entered display control data, and generates user-readable display data based on the speed data and the user-entered display control data.

Abstract: Described herein are frequency-domain back-projection processes for forming spotlight synthetic aperture radar (“SAR”) images that are not corrupted by the effects of multiple-bounce ghosting artifacts. These processes give an approximately exact reconstruction of the multiple bounce reflectivity function (MBRF) ƒ(x,y,&ggr;). Specifically, the evaluation of ƒ(x,y,&ggr;) in the &ggr;=0 plane gives an approximately exact reconstruction of the true object scattering centers which is uncorrupted by multiple-bounce contributions to the phase history data G(&xgr;, &thgr;). In addition, the non-zero dependence of ƒ(x,y,&ggr;) upon the MB coordinate &ggr; can be used to facilitate the identification of features-interest within the imaged region.

Abstract: A radar scan conversion protocol is defined to communicate radar data from application servers to thin clients with reduced network bandwidth requirements. The radar scan conversion protocol may be implemented as an extension to existing thin client protocols. The system is also capable of transmitting audio and video data through the application servers to the thin clients using appropriate compressed formats in order to minimize network bandwidth requirements.

Abstract: A new differential technique for forming optical images using a synthetic aperture is introduced. This differential technique utilizes a single aperture to obtain unique (N) phases that can be processed to produce a synthetic aperture image at points along a trajectory. This is accomplished by dividing the aperture into two equal “subapertures”, each having a width that is less than the actual aperture, along the direction of flight. As the platform flies along a given trajectory, a source illuminates objects and the two subapertures are configured to collect return signals. The techniques of the invention is designed to cancel common-mode errors, trajectory deviations from a straight line, and laser phase noise to provide the set of resultant (N) phases that can produce an image having a spatial resolution corresponding to a synthetic aperture.

Abstract: The invention relates to a radar system for active obstacle warning and imaging of the surface of the earth, working in the pulse frequency or FM-CW range, which can be used in on-line operation in real time, comprising a plurality of antenna elements for sending and receiving radar signals, which are arranged on the fuselage of an aircraft, and which may be turned on and scanned sequentially, whereby a synthetic aperture can be generated by means of periodic sending and receiving of the antenna elements. According to the invention, the antenna elements are arranged along the curved surface of the aircraft contour, whereby a SAR processor is present, which analyzes the data obtained from the antenna elements and displays them as processed radar images on board the aircraft, in a virtual cockpit.

Abstract: Imaging methods and systems for concealed weapon detection are disclosed. In an active mode, a target can be illuminated by a wide-band RF source. A mechanically scanned antenna, together with a highly sensitive wide-band receiver can then collect and process the signals reflected from the target. In a passive mode, the wide-band receiver detects back-body radiation emanating from the target and possesses sufficient resolution to separate different objects. The received signals can then be processed via a computer and displayed on a display unit thereof for further analysis by security personnel.

Abstract: In one aspect, the present invention provides an apparatus 10 for imaging. At least one source 12 (or 12/14) of composite radiation illuminates a field of view 16. The radiation includes a set of multiple phase-independent partials that are independently controllable and exhibit distinct physical features. A quasi-optical element 21 is disposed between the field of view 16 and a multi-element receiver 18. The multi-element receiver 18 is disposed to receive image radiation 28 from the quasi-optical element 21. Particular ones of the receiver elements transform the image radiation 28 into a set of electrical signals that include information relating to features of the partials.

Abstract: An apparatus for identifying a buried object using ground penetrating radar (GPR) in a system containing at least one GPR sensor, comprises a data processor for detecting spatial correlations in data received from a GPR sensor in the apparatus and an image processor capable of building a data structure corresponding to an image of the buried object from data processed by the data processor. A method for identifying a buried object using GPR in a system containing a GPR sensor comprising detecting spatial correlations in data received from the GPR sensor in the system and building a data structure corresponding to an image of the buried object from the received data.

Abstract: Disclosed are systems, methods, devices, and apparatus to determine if a clothed individual is carrying a suspicious, concealed object. This determination includes establishing data corresponding to an image of the individual through interrogation with electromagnetic radiation in the 200 MHz to 1 THz range. In one form, image data corresponding to intensity of reflected radiation and differential depth of the reflecting surface is received and processed to detect the suspicious, concealed object.

Abstract: A plurality of sub-antennas in a two-dimensional plane antenna 11 or the like receive milliwaves from concerned object 20. An A/D converter 12 converts the received signal to digital data. A signal processor 13 executes signal processing on the digital data for displaying images on a monitor 15. Prior to the measurement, a calibration signal source 14 generates a calibration signal. A phase compensator 133 in the signal processor 13 obtains phase compensation data, and compensates measurement data.

Abstract: A method and system for suppression of ground returns in a vertical profile radar display. The method includes receiving radar returns each comprising a plurality of range bins collated to a vertical profile radar display. The received range bins are analyzed to locate ground returns. A plurality of range bins are selected based upon the located ground returns. The radar returns are modified based upon the selected range bins.

Abstract: A millimeter wave imaging system that includes at least one millimeter wave frequency scanning antenna for collecting frequency dependent beams of millimeter wave radiation from a narrow one-dimensional field of view. The collected radiation is amplified at the collected frequencies and the amplified signals are separated into frequency dependent bins with a tapped-delay beam-former. These bins are then sampled to produce a one-dimensional image of the antenna field of view. A two dimensional image of a target may be obtained by moving the target across the field of view of the scanning antenna. In a preferred embodiment the antenna is only 4.5 inches in length and constructed from WR-10 waveguide with inclined slots cut in one of the narrow walls at 79 mil spacings. This geometry creates a frequency-scanned antenna spanning a 20 degree vertical field of view over a 75.5-93.5 GHz operational band of the sensor, starting at approximately 1 degree below horizontal at 93.

Abstract: Methods and Apparatus for early detection and identification of a threat, and alerting against detected threats, such as individuals wearing or carrying explosive materials and/or weapons, e.g., suicide bombers and other terrorists, at a great enough distance to limit loss of life and destruction of property are disclosed. The methods comprise transmitting a signal in the direction of a potential threat, measuring the detected reflected signal, and comparing the signal level with a threshold indicative of a threat. A monitor is employed to display the threat and attributes of the detected signals. The invention further illuminates the suspicious individual(s) with a Laser illuminator/designator and provides information about the distance to the suspicious individual(s).

Abstract: THz waves 4 on two different wavelengths are generated within a frequency range of about 0.5 to 3 THz, and a subject matter 10 is irradiated with the THz waves on two wavelengths to measure their transmittances, and thus the presence of a target having wavelength dependence on the absorption of the THz wave is detected from a difference of their transmittances. Furthermore, a surface of the subject. matter is scanned two-dimensionally with each of the THz waves on two different wavelengths, and an image of a position where the transmittances of the two wavelengths differ is displayed two-dimensionally.