Abstract: A wireless communication method and apparatus using adaptive transmission polarization control are provided. The wireless communication apparatus includes an orthogonal polarization antenna, a channel state estimator, and a transmission polarization state (TPS) selector. The orthogonal polarization antenna receives at least one reference signal. The channel state estimator estimates a wireless polarization channel on the basis of the reference signal. The TPS selector selects a TPS corresponding to the estimated wireless polarization channel from among a plurality of predefined TPSs, and feeds back the selected TPS information. Accordingly, the wireless communication apparatus feeds back information for polarization control using minimum uplink wireless resources, and maximizes a transmission capacity on the basis of the feedback information.

Abstract: A polarimetric transceiver front-end includes two receive paths configured to receive signals from an antenna, each receive path corresponding to a respective polarization. Each front-end includes a variable amplifier and a variable phase shifter; a first transmit path configured to send signals to the antenna, where the transmit path is connected to the variable phase shifter of one of the two receive paths and includes a variable amplifier; and a transmit/receive switch configured to select between the first transmit path and the two receive paths for signals, where the transmit/receive switch includes a quarter-wavelength transmission line that adds a high impedance to the transmit path when the transmit/receive switch is in a receiving state.

Abstract: Provided are a device and method for estimating carrier frequency offset of OFDM signals transmitted and received through a plurality of polarized antennas that may accurately estimate carrier frequency offset used for carrier frequency synchronization acquisition when there is interference between polarized waves.

Abstract: Methods are described for radar detection of persons wearing wires using radar spectra data including the vertical polarization (VV) radar cross section and the horizontal polarization (HH) radar cross section for a person. In one embodiment, the ratio of the vertical polarization (VV) radar cross section to the horizontal polarization (HH) radar cross section for a person is compared to a detection threshold to determine whether the person is wearing wires. In another embodiment, the absolute difference of the vertical polarization (VV) radar cross section and the horizontal polarization (HH) radar cross section for a person is compared to a detection threshold to determine whether the person is wearing wires. To reduce false positives, other additional indicators, such as speed of movement, and or visual features of the person, can be used to further narrow a person suspected of wearing wires.

Abstract: The invention relates to a locating device, in particular a hand-guided locating device, with a locating unit (36) for detecting the presence of an object (16, 18) arranged in an examination object (14) by means of an examination signal (38), which has a polarization unit (50) provided for a procedure with the examination signal (38), and with a housing (20) for taking up the locating unit (36), which has a longitudinal axis (24). It is proposed that in at least one operating mode the polarization unit (50) specifies at least one first polarization plane (52, 54) aligned obliquely to the longitudinal axis (24).

Abstract: The invention provides a security scanner that produces a radar profile of a clothed person or another object such as a bag carried by a person at a distance and does not require close proximity of the person or object to the scanner itself. The scanner includes a millimeter wave antenna system optimised for short-range active imaging and arranged to provide rapid high-resolution images of an object or person of interest and processing means for resolving the images so as to detect the presence of predetermined objects. The processing means preferably includes means for comparing contrasts in reflectivity in the scanned images with predetermined expected values from skin and light clothing. The processing means may also include means for detecting predetermined behavioral or physical traits such as the effect on gait on carried weighty objects or stiff structures strapped to the person from the images of a scanned object or person. The scanner may be incorporated within a turnstile access arrangement.

Abstract: A vehicle obstacle detection device comprises: a radar unit provided between a back surface of a bumper and a wheel and configured to detect an obstacle by transmitting a radio wave through the bumper; and a misdetection prevention member for preventing misdetection in the radar unit by suppressing the occurrence of an own-vehicle's wheel reaching wave which is a part of a transmission wave and which passes between a transmitter section of the radar unit and the back surface of the bumper and reaches the wheel of the own vehicle.

Abstract: Embodiments of the present invention provide for improved estimation of environmental parameters in a dual-polarization radar system. In some embodiments, environmental parameters can be estimated using a linear combination of data received in two orthogonal polarization states. In particular, embodiments of the invention improve ground clutter and noise mitigation in dual polarization radar systems. Moreover, embodiments of the invention also provide for systems to determine the differential reflectivity and/or the magnitude of the co-polar correlation coefficient and the differential phase in a dual polarization radar system.

Abstract: A radar system for recording the environment of a motor vehicle includes at least two transmitter antennas for emitting transmission signals, one or more receiver antennas for receiving transmission signals that have been reflected by objects, and signal processing equipment for processing the received signals. The antennas are arranged so that a phase center of at least one receiver antenna, with regard to a spatial direction R, does not lie outside of phase centers of two transmitter antennas that are offset in this spatial direction. The signals received by this receiver antenna are separated according to the two signal portions respectively originating from these two transmitter antennas.

Abstract: A multi-polarization radio frequency (RF) antenna includes an array of impulse sensors that are capable of detecting RF signals within a surrounding environment. In some embodiments, antennas are provided for use within the high frequency (HF) band. The array of impulse sensors may include, for example, one or more B-dot sensors and/or one or more D-dot sensors. Various different antenna configurations are provided that are capable of operation with multiple different polarizations.

Abstract: A positioning system for radio frequency devices includes a two-way radio antenna, for vehicles, having a transmitting and a receiving element. Reference antennas have retro-directive arrays which can shape the signal beams in elevation; polarize transmission and reception signals according to a circular or a linear polarization, the polarized transmission retro-directively reflecting signals having the same polarization as the incident ones in the case of circular polarization, or retro-directively reflecting signals having orthogonal polarization in the case of linear polarization. An encoder is included for transmitting an identification code of the reference antenna. A controller processes the spatial and temporal data resulting from communication through the radio waves transmitted and received by the vehicle antennas and reflected by the reference antennas. The controller calculates the distance of the vehicle from the reference antennas that have reflected the signal transmitted by the antennas.

Abstract: A sensor system uses ground emitters to illuminate a projectile in flight with a polarized RF beam. By monitoring the polarization modulation of RF signals received from antenna elements mounted on the projectile, both angular orientation and angular rate signals can be derived and used in the inertial solution in place of the gyroscope. Depending on the spacing and positional accuracies of the RF ground emitters, position information of the projectile may also be derived, which eliminates the need for accelerometers. When RF signals of ground emitter/s are blocked from the guided projectile, the sensor deploys another plurality of RF antennas mounted on the projectile nose to determine position and velocity vectors and orientation of incoming targets.

Abstract: A method for onboard determination of a roll angle of a projectile. The method including: transmitting a polarized RF signal from a reference source, with a predetermined polarization plane; receiving the signal at a pair of polarized RF sensor cavities positioned symmetrical on the projectile with respect to a reference roll position on the projectile; measuring a difference between an output of the pair of polarized RF sensor cavities resulting from the received signal to determine zero output roll positions of the projectile; and comparing an output of the pair of polarized RF sensor cavities at each of the zero output positions to determine when the projectile is parallel to the predetermined polarization plane. The method can also include analyzing an output of at least one third sensor positioned on the projectile to determine whether the roll angle position of the projectile is up as compared to the horizon.

Abstract: In embodiments a system to generate a dual frequency, circularly polarized beam of rotating electromagnetic radiation comprises a first radiation source to generate a first radiation beam at a first frequency, a second radiation source to generate a second radiation beam at a second frequency, different from the first frequency, and a tee. In some embodiments the tee receives the first radiation beam and the second radiation beam, outputs a third radiation beam which represents a sum of the first radiation beam and the second radiation beam, and outputs a fourth radiation beam which represents a difference between the first radiation beam and the second radiation beam, wherein the third radiation beam and the fourth radiation beam are separated by a ninety-degree phase shift. The system further comprises a combiner to combine the third and fourth beams to produce an output beam. Other embodiments may be described.

Abstract: A method of operating a multi-function phased array radar system having an antenna array populated with dual-pol antenna elements is described. The method includes selectively controlling individual dipoles of each dual-pol antenna element in order to operate the array in either a polarimetric mode with improved cross-pol isolation, or in a multi-mission mode, wherein a plurality of singularly-polarized signals are produced.

Abstract: Differential polarization imaging systems include an axicon configured to provide a displacement of ray bundles associated with different image patches. The displaced ray bundles are directed to antenna horns and orthomode transducers so as to provide outputs correspond to orthogonal linear states of polarization (SOPs). The outputs are directed to a differential radiometer so that Stokes parameter differences between image patches can be obtained. The ray bundle displacements can be selected to correspond to a mechanical spacing of antenna horns. In some examples, ray bundle displacement corresponds to a displacement less than the diffraction limit.

Abstract: A phased antenna array includes an array of antenna elements, and an electro-optic (EO) readout circuit coupled to the array of antenna elements. The EO readout circuit includes an optical source having a first wavelength division multiplexer (WDM) configured to generate an optical carrier signal including beam carrier wavelengths, a first EO modulator configured to modulate a signal from an antenna element based upon the optical carrier signal, a second WDM coupled downstream from the first EO modulator, and optical-to-electrical converters coupled downstream from the second WDM. The second WDM is configured to multiplex each modulated beam carrier wavelength to a respective optical-to-electrical converter.

Abstract: A phased antenna array includes an array of antenna elements, and an electro-optic (EO) readout circuit coupled to the array of antenna elements. The EO readout circuit includes an optical source configured to generate an optical carrier signal, a first EO modulator configured to modulate a signal from an antenna element based upon the optical carrier signal, and an optical-to-electrical converter coupled downstream from the first EO modulator.

Abstract: A spacecraft has a high efficiency multi-beam antenna (MBA) system that serves a coverage region on the Earth. The coverage region subtends an angle, when viewed from the spacecraft, of at least ten degrees. The antenna system provides, within the coverage region, at least sixteen spot beams. A signal provided by the MBA system to each spot beam has a carrier to interference ratio (C/I) of no less than 20 dB. The system enables use of a three color frequency reuse scheme without recourse to signal encoding.

Abstract: Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Abstract: A missile radar system includes a tapered radome covering a front face of a main antenna. A calibration antenna is the combination of a metal tip and an attached one or more radiating or excitation elements (monopole) on the tip. A narrow end (wedge) of the radome may aid in directing planar calibration waves toward the main antenna. The metal tip has a curved inner surface that acts, with the attached radiating element(s), as an aperture antenna. Signals are emitted from the calibration antenna back toward the front face of the main antenna. The signals pass from the tip/reflector to the front face of the main antenna through a substantially-metal-free and substantially-dielectric-free volume defined by the inner surface of the radome. The radar system allows for calibration of the antenna prior to launch and/or during flight of the missile.

Abstract: A radar device has a transmitter having a field of view for transmitting a transmit signal and a receiver for receiving a received signal from the field of view of the transmitter. The transmit signal comprising first and second polarization components and multiple frequencies. There is a signal processor programmed to: detect received signal components comprising first and second polarization components and fundamental and harmonic frequencies corresponding to the first and second polarization components and multiple frequencies in the received signal; compare the received signal components to characterize the received signal and identify a remote device as a linear conductor or a non-linear conductor based on predetermined criteria; and generate a notification signal corresponding to the remote device when the remote device is identified.

Abstract: A synthetic-aperture radar system, and related operating method, for the monitoring of ground and structure movements, particularly suitable for emergency conditions, characterized by a ground based platform with polarimetric capabilities, that able to quickly acquire, embeddedly process and post-process data by a novel data acquisition “On the Fly” mode of operation, reducing by at least an order of magnitude the data acquisition time. The inventive system characteristics allows to achieve on-field measurement results on three-dimensional maps georeferenced to absolute coordinate systems (WGS84, Gauss-Boaga, and so on).

Abstract: A system includes a multi-system approach to detecting concealed weapons and person borne improvised explosive devices (PBIED). A first and second radar system operate at different center frequencies to provide, respectively, isolation of a target of interest from clutter and fine detail information on the target, such as whether the target is a living person, whether a concealed object may be present, material composition of the object, and shape, size, and position of the target relative to the system. Circular polarized radar beam may be used to distinguish a suspect object from within a crowd of people. Radar image of the object may be overlaid on visual image of a person carrying the object. Radar tracking of the object is coordinated with visual tracking of the target provided by a camera system, with visual display and tracking of the target overlaid with the radar information.

Abstract: A wireless sensor apparatus includes first and second polarization antennas whose polarization surfaces of radiation waves are mutually orthogonal, a first mixer circuit connected to the first polarization antenna and configured to input a first reception signal received by the first polarization antenna, a second mixer circuit connected to the second polarization antenna and configured to input a second reception signal received by the second polarization antenna, a signal generation circuit configured to generate pulse signals fed to the first and second polarization antennas and also supplied to the first and second mixer circuits, and a differential amplification circuit configured to perform a differential amplification on a mixed output obtained by mixing the first reception signal and the pulse signal by the first mixer circuit and a mixed output obtained by mixing the second reception signal and the pulse signal by the second mixer circuit.

Abstract: A wireless sensor apparatus controls, in a case where wireless waves are radiated by feeding pulse signals generated by a signal generation circuit to antennas, an operation timing of the signal generation circuit and a path from the signal generation circuit to the antennas in such a manner that after a prior pulse signal is fed to the antenna and simultaneously supplied to a mixer circuit, at a proximate timing which does not overlap with a pulse width of the prior pulse signal supplied to the antenna and the mixer circuit, a next pulse signal is fed to the antenna and simultaneously supplied to a mixer circuit.

Abstract: A calibration system for a dual polarization radar system with built in test couplers has been developed. The system includes a dual polarization radar transmitter antenna that generates a transmission pulse. A test coupler is located behind the antenna that reads a sample of the transmission pulse a test signal. A calibration circuit receives the sample of the transmission pulse and generates a test signal that simulates a desired atmospheric condition. Finally, a test antenna transmits the test signal to the dual polarization radar transmitter antenna for calibration of the system.

Abstract: The radar includes a PCB having a top surface and a bottom surface, and a processor mounted on the bottom surface of the PCB. The radar includes a second liquid crystal polymer layer formed on the top surface of the printed circuit board, a second microstrip array printed on the second liquid crystal polymer layer, the second microstrip array having a patch, a first liquid crystal polymer layer formed on the second liquid crystal polymer layer, a first microstrip array printed on the first liquid crystal polymer layer, the first microstrip array having a perforated patch, an antenna positioned underneath the patch and connected to the second microstrip array, and a transmit/receive module connected to a bottom surface of the second liquid crystal polymer layer and configured to transmit a first frequency signal to the first microstrip array and a second frequency signal to the second microstrip array.

Abstract: The radar includes a PCB having a top surface and a bottom surface, and a processor mounted on the bottom surface of the PCB. The radar includes a second liquid crystal polymer layer formed on the top surface of the printed circuit board, a second microstrip array printed on the second liquid crystal polymer layer, the second microstrip array having a patch, a first liquid crystal polymer layer formed on the second liquid crystal polymer layer, a first microstrip array printed on the first liquid crystal polymer layer, the first microstrip array having a perforated patch, an antenna positioned underneath the patch and connected to the second microstrip array, and a transmit/receive module connected to a bottom surface of the second liquid crystal polymer layer and configured to transmit a first frequency signal to the first microstrip array and a second frequency signal to the second microstrip array.

Abstract: A detection method comprising directing radiation such that it is incident upon a target, the radiation containing a component having a first polarisation and a component having a second orthogonal polarisation, detecting radiation which is scattered from the target, and analysing the polarisation state of the detected scattered radiation to determine whether the target includes an object.

Abstract: A method for estimating a radar cross-section (RES) of a given object by using a diffraction model of this object. With the model, it is possible to determine a basis adapted to said object on which is projected a vector of measurement. With the projected vector, it is possible to obtain a more complete reconstructed vector than the measurement vector in terms of incident wave and diffracted wave observation directions/polarizations and the components of which have a better signal/noise ratio than the measurements. The reconstructed vector is then used for calculating the RCS.

Abstract: An onboard radar apparatus includes a transmission wave generating unit configured to generate a transmission wave, a vertically polarized wave transmitting antenna configured to vertically polarize and transmit the transmission wave, a horizontally polarized wave transmitting antenna configured to horizontally polarize and transmit the transmission wave, a receiving antenna configured to receive a reflection wave, a switch control unit configured to perform a switching between the vertically polarized wave transmitting antenna and the horizontally polarized wave transmitting antenna, and a receiving unit configured to receive one of the reflection waves based on receiving levels of the reflection waves, which have been received by the receiving antenna before and after the switching is performed by the switch control unit.

Abstract: A synthetic aperture radar hybrid-quadrature-polarity method and architecture comprising transmitting both left and right circular polarizations (by alternately driving, at the minimum (Nyquist) sampling rate, orthogonal linear feeds simultaneously by two identical waveforms, +/?90° out of phase), and receiving two orthogonal linear polarizations, coherently. Once calibrated, the single-look complex amplitude data are sufficient to form all Stokes parameters, which fully characterize the radar backscatter.

Abstract: A method for onboard determination of a roll angle of a projectile.

Abstract: A radar system having orthogonal antenna apertures is disclosed. The invention further relates to an antenna system wherein the orthogonal apertures comprise at least one transmit aperture and at least one receive aperture. The cross-product of the transmit and receive apertures provides a narrow spot beam and resulting high resolution image. An embodiment of the invention discloses orthogonal linear arrays, comprising at least one electronically scanned transmit linear array and at least one electronically scanned receive linear array. The design of this orthogonal linear array system produces comparable performance, clutter and sidelobe structure at a fraction of the cost of conventional 2D filled array antenna systems.

Abstract: A method of providing a polarized radio frequency scanning source is provided. The method including amplitude modulating at least two synchronized polarized radio frequency (RF) carrier signals with a predetermined relationship between their amplitude modulation of their electric field components and their polarization states to provide a scanning polarized RF reference source with a desired scanning range, pattern and frequency. The two or more synchronized polarized RF carrier signals with the predetermined relationship between their amplitude modulation can obtain a periodic or non-periodic scanning range, rate and frequency.

Abstract: Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Abstract: A three-dimensional imaging radar operating at high frequency e.g., 670 GHz radar using low phase-noise synthesizers and a fast chirper to generate a frequency-modulated continuous-wave (FMCW) waveform, is disclosed that operates with a multiplexed beam to obtain range information simultaneously on multiple pixels of a target. A source transmit beam may be divided by a hybrid coupler into multiple transmit beams multiplexed together and directed to be reflected off a target and return as a single receive beam which is demultiplexed and processed to reveal range information of separate pixels of the target associated with each transmit beam simultaneously. The multiple transmit beams may be developed with appropriate optics to be temporally and spatially differentiated before being directed to the target. Temporal differentiation corresponds to a different intermediate frequencies separating the range information of the multiple pixels.

Abstract: A method of operating a multi-function phased array radar system having an antenna array populated with dual-pol antenna elements is described. The method includes selectively controlling individual dipoles of each dual-pol antenna element in order to operate the array in either a polarimetric mode with improved cross-pol isolation, or in a multi-mission mode, wherein a plurality of singularly-polarized signals are produced.

Abstract: An object candidate position detecting apparatus which detects a position of an object candidate includes a unifying mechanism which unifies a plurality of object candidates detected within a predetermined unified range into a single group. Where the relative positions of the object candidates stored in a unified information storage device changes such that the single group splits into a plurality of groups, a tracking mechanism judges whether any object candidate forming the group before the split continuously remains to be detected in a running lane in which a subject vehicle runs and which is estimated by a running lane estimator. Where any object candidate forming the group before the split is determined as continuously remaining to be detected in the running lane, the tracking mechanism determines that there is continuity between a group after the split including the thus-determined object candidate and the group before the split.

Abstract: An antenna system for a weather radar system includes a first transceiver and a second transceiver. The polarization of the first transceiver is orthogonal to the polarization of the second transceiver. The first transceiver and the second transceiver are interlaced to occupy the same volume.

Abstract: Polarization modulated transmitter, in particular for a weather radar, with at least two signal paths (3, 4) to which a radio frequency signal can be fed, and which are connected to a coupler (8), and with a phase modulation of the signal to be emitted via the antenna (1), it being possible to feed the same radio frequency signal to the at least two signal paths (3, 4) respectively having at least one transmit amplifier (5, 6), and a polarization modulator (7) is arranged for the phase modulation in one of the at least two signal paths (3, 4) in such a way that a radio frequency signal can first be phase modulated and then amplified.

Abstract: In an antenna radar system including a short-range function and a long-range function which is situated separately from the short-range function, the short-range function and the long-range function having different antenna apertures, means are provided for mutual cross-polarization of the signals emitted and received using the short-range function and the long-range function, through which the most efficient possible signal-technology decoupling between the short-range function and the long-range function is achieved.

Abstract: A system and method for communication that could be used in an identification friend or foe system. The method comprises generating a first message by a processor and controlling a beam steerer to deflect transmitted waves toward a first angle. The method further comprises transmitting the first message through an antenna in communication with the beam steerer toward the spatial angle. The method further comprises controlling the beam steerer to deflect waves received from the spatial angle. The method further comprises receiving a responsive wave at the antenna through the beam steerer at the spatial angle, the responsive wave including a second message responsive to the first message.

Abstract: In an antenna radar system including a short-range function and a long-range function which is situated separately from the short-range function, the short-range function and the long-range function having different antenna apertures, means are provided for mutual cross-polarization of the signals emitted and received using the short-range function and the long-range function, through which the most efficient possible signal-technology decoupling between the short-range function and the long-range function is achieved.

Abstract: The radar includes a PCB having a top surface and a bottom surface, and a processor mounted on the bottom surface of the PCB. The radar includes a second liquid crystal polymer layer formed on the top surface of the printed circuit board, a second microstrip array printed on the second liquid crystal polymer layer, the second microstrip array having a patch, a first liquid crystal polymer layer formed on the second liquid crystal polymer layer, a first microstrip array printed on the first liquid crystal polymer layer, the first microstrip array having a perforated patch, an antenna positioned underneath the patch and connected to the second microstrip array, and a transmit/receive module connected to a bottom surface of the second liquid crystal polymer layer and configured to transmit a first frequency signal to the first microstrip array and a second frequency signal to the second microstrip array.

Abstract: A calibration system for the receiver of a dual polarization radar system has been developed. The system includes a radar transmitter that transmits signals in horizontal and vertical polarizations and a radar receiver that receives the horizontal and vertical polarization signals. The system also includes a test signal generator that generates a continuous wave test signal. A calibration circuit for the radar receiver modifies the test signal to simulate weather conditions by adjusting the attenuation and Doppler phase shift of a continuous wave test signal.

Abstract: A guidance system for actively guiding a projectile, such as a bullet after it has been fired from a gun. The guidance system includes a radar unit that includes a plurality of receiver arrays. An optical scope is also mounted to the gun for optically sighting a target. An inertial measurement unit provided on the gun locks onto the target after it has been sighted by the scope, and provides a reference location at the center of the receiver arrays from which the bullet can be directed. The receiver arrays receive radar monopulse beacon signals from the bullet. The signals from the bullet are used to identify the position of the bullet and the roll of the bullet. The signals sent to the bullet provide flight correction information that is processed on the bullet, and used to control actuators that move steering devices on the bullet.

Abstract: A surveillance apparatus (100) is provided, said apparatus including a linear sub-array (101) of N omnidirectional transmitter elements (103) and a planar sub-array (102) of M receiver elements (104). A plurality of the transient elements (105) are generated by separating out at each of the receivers (104) the signals transmitted from the antenna elements (103) of the transmitter sub-array (101). This allows the geometry of each path (from each transmitter antenna element, to the point being imaged and back to the receiver antenna elements) to be converted to a delay or phase shift to focus on the particular point being imaged. The transient elements (105) form a cylindrical array (106) at the mid points between transmitter and receiver sub-arrays. Such a configuration enables a full 360 degrees of cover in azimuth and typically +/?60 degrees in elevation.

Abstract: Circularly-polarized antennas and their methods of use for active holographic imaging through barriers. The antennas are dielectrically loaded to optimally match the dielectric constant of the barrier through which images are to be produced. The dielectric loading helps to remove barrier-front surface reflections and to couple electromagnetic energy into the barrier.