268 results about "Microwave imaging" patented technology

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.

A method and apparatus for enhanced microwave imaging of an object collects microwave responses for multiple combinations of transmit antennas, receive antennas, and object movement states. The responses are grouped into sets of responses corresponding to at least two object movement states. An image is reconstructed from the set of responses for each movement state, and a differential image representative of object movement is generated from the reconstructed image for each of the at least two object movement states. The differential image is overlaid on a reconstructed image to obtain an enhanced composite image of the object.

A microwave imaging system suppresses sidelobes in a microwave image captured using a sparse antenna array using an illumination system that operates in two different illumination modes. The antenna array including subarrays of antenna elements arranged in a sparse geometry to form complementary subarray patterns. The illumination system operates in a first mode to transmit microwave illumination to both of the complementary subarray patterns of the antenna array and receive reflected microwave illumination from both of the complementary subarray patterns of the antenna array to produce a first receive signal. The illumination system further operates in a second mode to transmit microwave illumination to a first one of the complementary subarray patterns of the antenna array and receive reflected microwave illumination from a second one of the complementary subarray patterns of the antenna array to produce a second receive signal. Sidelobes are suppressed using a linear combination of the first and second receive signals.

An inspection system uses microwave radiation to capture a microwave image of a transportable item. The system includes a transmit scanning panel including a transmit array of transmit antenna elements, each being programmable with a respective phase delay to direct a transmit beam of microwave radiation toward a target of the transportable item for transmission of the microwave radiation through the target. The system further includes a receive scanning panel including a receive array of receive antenna elements, each being programmable with a respective phase delay to receive a receive beam of microwave radiation from the target. A processor measures the amplitude and phase of the microwave radiation in the receive beam to determine a relative value of a pixel within the microwave image of the transportable item based on a reference value of the pixel.

The invention discloses a microwave three-dimensional imaging method based on a rotary antenna array, and relates to a microwave imaging technology. The method comprises the following steps of: generating an electromagnetic signal by a signal transmitting module; driving an antenna array module which is distributed in a straight line form or a curved line form to rate by a mechanical scanning module, meanwhile, controlling the antenna array module by a switch array module to transmit an electromagnetic signal at the same time, and receiving a signal which is reflected back from an observation target by a back wave receiving module; converting a reflecting signal into a digital signal by an analogue-digital conversion module; and using the digital signal as back wave data acquired by an array element position of the corresponding antenna array; imaging the back wave data by a data processing module to acquire a three-dimensional complex image of the observation target; and displaying the three-dimensional complex image of the observation target by a display module. The imaging method disclosed by the invention is used for application fields of human body surface microwave image acquisition and safe detection, three-dimensional data acquisition of a human body and action based on actual circumstances, nondestructive testing, radar target imaging diagnosis and the like.

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.

A microwave imaging system for performing standoff microwave imaging includes an antenna array with a plurality of antenna elements, each capable of being programmed with a respective direction coefficient to direct microwave illumination toward a target within a volume that includes a standoff region, and each capable of being programmed with a respective additional direction coefficient to receive reflected microwave illumination reflected from the target. A processor measures an intensity of the reflected microwave illumination to determine a value of a voxel within a microwave image of the volume. The processor constructs the microwave image with a resolution sufficient to identify objects within the standoff region.

Microwave imaging via space-time beamforming is carried out by transmitting microwave signals from multiple antenna locations into an individual to be examined and receiving the backscattered microwave signals at multiple antenna locations to provide received signals from the antennas. The received signals are processed in a computer to remove the skin interface reflection component of the signal at each antenna to provide corrected signal data. The corrected signal data is provided to a beamformer process that time shifts the received signals to align the returns from a scatterer at a candidate location, and then passes the time aligned signals through a bank of filters, the outputs of which are summed, time-gated and the power therein calculated to produce the beamformer output signal at a candidate location. The beamformer is then scanned to a plurality of different locations in the individual by changing the time shifts, filter weights and time-gating of the beamformer process. The output power may be displayed as a function of scan location, with regions of large output power corresponding to significant microwave scatterers such as malignant lesions.

The invention provides a compressed sensing synthetic aperture radar (SAR) imaging method based on fractional order fourier transformation, and belongs to the technical field of microwave imaging. For a sparse target scene, a system emits a linear frequency modulation pulse signal; by adopting a method for projecting an echo signal to a low-dimension measurement matrix, measurement data which are much smaller than those required by a Nyquist sampling principle are acquired; due to the echo signal, after a reconstruction matrix is constructed by a simplified fractional order fourier transformation domain sparse mode and a data acquisition mode, a calculated distance pulse pressure result is optimized by a compressed sensing signal reconstruction method and is subjected to distance migration correction and direction pulse pressure to obtain a target scene imaging result. By the imaging method, the measurement data amount of a target scene with a sparse characteristic can be greatly reduced; and pressure on data storage and data transmission can be effectively relieved.

The field of the invention is that of devices for detecting objects concealed on human subjects. These devices are more particularly dedicated to the surveillance and protection of airport areas and transport airplanes. Currently, the devices rely either on X-ray detection or on microwave imaging. In the former case, the system can prove hazardous to human beings, and in the other case, the device raises ethical problems. The invention proposes a device whose operation relies on the reflective properties of the microwave signals polarized by the suspect objects that we are seeking to detect. This device can be portable or installed on security gates. This technique is simple to design, inexpensive, does not require any great computing power and is very well suited to the objects to be detected. The complete measurement is extremely quick and requires no sophisticated measuring instrument.

A system and a method are provided for estimating the average dielectric properties of a plurality of regions in space. The application of this technique is illustrated for determining the average properties of breast tissue. The knowledge of average properties is important when UWB microwave radar signal processing algorithms are used for tumor detection and localization. The method is an extension of a time-domain inverse scattering algorithm based on the finite-difference time-domain method. A hybrid conjugate gradient optimization is used to minimize a cost function defined between a measured and a calculated total electromagnetic field at a series of antennas. The output of the method is an average set of electromagnetic material parameters that describe specific regions of interest in either a non-dispersive heterogeneous medium or a dispersive heterogeneous medium.

The invention discloses a signal processing method for a random noise radar applicable to sparse microwave imaging, and relates to microwave imaging technologies. For a target scene with sparse characteristics, a transmit signal of a system is band-limited Gaussian random white noise; and observation data with observed quantity less than that required by a nyquist sampling theorem is obtained by a low-speed uniform sampling method during reception. After an observation matrix is set up in combination of a transmit signal form and a data acquisition manner, a backscattering coefficient of a scene target is obtained by optimizing and resolving the compressed sensing of a sparse signal processing theory, and high-resolution target detection and imaging are achieved. In order to improve calculating efficiency, a block signal processing method of the random noise radar applicable to the sparse microwave imaging is adopted; and during block processing, a corresponding block observation matrix is set up in combination with a block form of the data. Compared with the conventional radar system, the invention has the advantages that: a little observation data is needed to achieve the same resolution; and higher resolution can be achieved when the same observation data quantity is adopted.

The invention discloses a circular synthetic aperture radar (CSAR) 3D microwave imaging method for an earth synchronous orbit. In the method, parameters of the earth synchronous orbit are designed to cause a synthetic aperture radar (SAR) satellite platform to make a flight with an annular track around a target zone and above the target zone, and an antenna beam is caused to irradiate the target zone all the time by a circular synthetic aperture radar mode, and a ground object target is subject to continuous large-area fixed point observation to acquire high-resolution 3D imaging information of the ground object target. A CSAR system of the earth synchronous orbit provided by the system can acquire high-resolution 3D images of the ground object, solves the problem that the existing space-borne SARs are hard to acquire the high-resolution 3D information of the ground object; and is applicable to areas with complex and steep terrains as elevation information does not interfere with phase ambiguity in the SAR. The CSAR system of the earth synchronous orbit can realize the fixed point continuous observation of large-area zones, and solve the problems that the existing space-borne SARs have small observation zones and long revisit period.

The invention discloses a model constructing method of sparse microwave imaging processing. The model constructing method comprises the following steps of: firstly, establishing a linear regression model of microwave imaging by using a linear operator characteristic of microwave imaging according to a radar system parameter and a geometrical relationship of a radar and a scene; secondly, establishing a linear regression model of sparse microwave imaging though construction of a sparse observation model and a sparse transformation matrix; and finally, establishing a reconstruction model of sparse microwave imaging by applying a sparse signal reconstruction theory in sparse signal processing. The model constructing method of the sparse microwave imaging processing provided by the invention provides a theoretical basis for the sparse microwave imaging.

The invention discloses a microwave imaging method based on scenario block sparsity, and relates to a radar imaging technology. The method includes the steps of carrying out sparse observation over a block sparsity scenario in a compression sampling mode by utilizing a fact that the geometry size of a target in an actual imaging scenario is greater than the spatial resolution of high resolution microwave imaging radar and the imaging scenario usually covers multiple radar resolution units, and carrying out an efficient image reconstruction based on the block sparsity of the scenario. The method is different from an imaging method based on matched filtering; a sparse microwave imaging radar is based on sparse signal processing, recovers observed scarsity or transforms a domain sparsity scenario by that the method solves an optimization problem. Under the same sampling condition, the reconstruction of the sparse imaging scenario is more accurate than that of a conventional sparse microwave imaging, and sparser observation over the sparse scenario also can be achieved under the same reconfiguration performance conditions, so that the data rate of sampling is further reduced.

An antenna array for use within a microwave imaging system to capture a microwave image of a target is selectively programmed to optimize one or more parameters of the microwave imaging system. The array includes a plurality of antenna elements, each capable of being programmable with a respective phase shift to direct a beam of microwave radiation toward the target such that the microwave radiation from each of the plurality of antenna elements arrives at the target substantially in-phase. To optimize a parameter of the microwave imaging system, the phase shifts of selective ones of the antenna elements are altered, while still maintaining the substantially in-phase microwave radiation at the target.

A scanning panel for use in a microwave imaging system captures a microwave image of a target using two complementary arrays of antenna elements. Each of the antenna elements in a first array is capable of being programmed with a respective phase delay to direct a transmit beam of microwave illumination toward the target in a transmit beam pattern, and each of the antenna elements in a second array is capable of receiving reflected microwave illumination reflected from the target in a receive beam in a receive beam pattern complementary to the transmit beam pattern. The microwave image of the target is formed at an intersection between the transmit beam and the receive beam.

A microwave imaging system uses microwave radiation provided by a microwave source to image targets. The system includes an array of antenna elements that are capable of being programmed with a respective transmission coefficient to direct the microwave illumination from the microwave source toward a position on the target. The antenna elements are further capable of being programmed with a respective additional transmission coefficient to receive reflected microwave illumination reflected from the position on the target and direct the reflected microwave illumination towards a microwave receiver. 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 target. Multiple beams can be directed towards the target to obtain corresponding pixel values for use by the processor in constructing the image.

The invention relates to a method for testing an RCS (radar cross section) of a low-scattering conformal antenna based on two-dimensional microwave imaging, which is characterized by comprising the following steps: carrying out an RCS test on a metal envelope and a low-scattering conformal antenna in an installed state so as to obtain a two-dimensional microwave image; carrying out two-dimensional Fourier transform on the obtained new two-dimensional microwave image so as to obtain the data of a target spectral domain; carrying out an RCS test on a metal ball (the RCS of the metal ball is known) so as to obtain a two-dimensional microwave image, then carrying out two-dimensional Fourier transform on the obtained two-dimensional microwave image so as to obtain the data G0 (f, theta) of a scattered field of the metal ball, wherein the data of the scattered field varies with frequency and angle; and finally, obtaining the RCS of the conformal antenna, wherein the RCS of the conformal antenna meets the following formula: RCS= G1 (f, theta) (of the conformal antenna) - G0 (f, theta) (of the metal ball) + RCS (of the metal ball). The method provided by the invention is a method for testing an RCS (radar cross section) of a low-scattering conformal antenna in an installed state based on the two-dimensional microwave imaging technology, and after practicing, the obtained effect is good, therefore, the method provided by the invention has great engineering popularization value.

The invention discloses a sparse microwave imaging method, relating to the information acquisition and processing technology. By utilizing sparsity of microwave imaging observation, through introducing sparse signal processing theory into microwave imaging technology, after signal processing and information extraction, the geometrical and physical characteristics of an observation object such as space position, scattering characteristic and motion characteristic and the like are obtained, wherein the sparse signal processing theory is through searching sparse representation field of the observation object, obtaining sparse microwave signal of the observation object in space, time, frequency spectrum or polarizing field sparse sampling. According to the sparse microwave imaging method in the invention, the bottleneck problems existed in the prior art such as difficult system realization, complex imaging processing method, redundant information and difficult feature extraction and the like based on Nyquist sampling theorem and classic digital signal processing theory are solved, thus microwave imaging system structure and imaging complexity is reduced.

A microwave imaging system for constructing a stereoscopic microwave image of an object includes an antenna array with a plurality of programmable antenna elements and a processor. Each of the antenna elements is capable of being programmed with a respective first direction coefficient to capture a first microwave image of the object from a first focal point on the array. In addition, each of the antenna elements is capable of being programmed with a respective second direction coefficient to capture a second microwave image of the object from a second focal point on the array. The processor constructs the stereoscopic microwave image from the first and second microwave images.

The invention discloses a three-dimensional microwave imaging method for correcting a multi-channel amplitude-phase error, and relates to the technology of microwave three-dimensional imaging. The three-dimensional microwave imaging method for correcting the multi-channel amplitude-phase error comprises the following steps of: obtaining a two-dimensional image for each two-dimensional receiving channel datum in original three-dimensional microwave echo data by using a two-dimensional imaging algorithm; taking a scaler target as a reference target in all the two-dimensional images, taking the maximum amplitude value of each channel reference target as a reference, and performing amplitude correction on all the channel data; obtaining an actual distance and a ideal distance between the reference target and each receiving antenna, and taking the actual distance and the ideal distance as a filter H1(f) for correcting multi-channel distance offset; transforming a signal to a distance-direction frequency domain via Fourier transformation, performing multiplication with the filter, and then transforming the signal after the multiplication back to the distance-direction time domain via Fourier inverse transformation; getting an unwrapping phase at the peak value of the reference target in each two-dimensional image, and performing subtraction with the ideal phase progress value calculated by the ideal distance to obtain a factor H2(i) for correcting the multi-channel phase error; performing the multiplication on the H2(i) and the data after the two-dimensional imaging to compensate the influence of the phase error; and obtaining a three-dimensional image which is focused well in a target area by using a back-projection algorithm along the row-crossing direction Y.

A handheld microwave imaging device provides screening of objects, such as persons and other items. The imaging device includes an antenna array of antenna elements, each capable of being programmed with a respective direction coefficient to direct microwave illumination toward a target associated with the object, and each capable of being programmed with a respective additional direction coefficient to receive reflected microwave illumination reflected from the target. The imaging device further includes a processor operable to measure an intensity of the reflected microwave illumination to determine a value of a voxel within a microwave image of the object. The antenna array is compliantly mounted in a first portion of a support structure, while a second portion of the support structure defines a handle for enabling a user to control movement of the device.