A Novel Near Field Image Reconstruction Method Based on Beamforming Technique for Real-Time Passive Millimeter Wave Imaging

Zhao, Yan; Si, Weikang; Han, Bingxin; Yang, Zihan; Hu, Anyong; Miao, Jungang

doi:10.1109/access.2022.3161532

Cited by 6 publications

(3 citation statements)

References 32 publications

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“…In addition, it is also necessary to solve the difficulty of phase shift control accuracy of the phase shifter in a six-port chip to improve the phase detection error of the correlator. On the premise of completing the above work, the correlator can be used in the existing passive millimeter-wave security imaging system [39,40] to eliminate local oscillator (LO) links in the original system and reduce the volume of the system. Furthermore, passive-millimeter-wave imaging technology and optical imaging technology [41,42] can be integrated to obtain millimeter-wave and optical information of the measured human body, which is conducive to improving the detection rate of dangerous things in the security imaging system.…”

Section: Discussionmentioning

confidence: 99%

Design of a Compact Analog Complex Correlator for Millimeter-Wave Radiation Temperature Measurement System

Dong

et al. 2023

Micromachines

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Human body temperature is a fundamental physiological sign that reflects the state of physical health. It is important to achieve high-accuracy detection for non-contact human body temperature measurement. In this article, a Ka band (32 to 36 GHz) analog complex correlator using the integrated six-port chip is proposed, and a millimeter-wave thermometer system based on the designed correlator is completed for human body temperature measurement. The designed correlator utilizes the six-port technique to achieve large bandwidth and high sensitivity, and miniaturization of the correlator is achieved through an integrated six-port chip. By performing the single-frequency test and the broadband noise measurement on the correlator, we can determine that the dynamic range of input power of the correlator is −70 dBm to −35 dBm, and the correlation efficiency and equivalent bandwidth are 92.5% and 3.42 GHz, respectively. Moreover, the output of the correlator varies linearly with the input noise power, which reveals that the designed correlator is suitable for the field of human body temperature measurement. Then, a handheld thermometer system, with a size of 140 mm × 47 mm × 20 mm, is proposed using the designed correlator, and the measurement results show that the temperature sensitivity of the thermometer is less than 0.2 K.

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Section: Discussionmentioning

confidence: 99%

Design of a Compact Analog Complex Correlator for Millimeter-Wave Radiation Temperature Measurement System

Dong

et al. 2023

Micromachines

Self Cite

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“…In one of these systems [18], a 22 GHz aperture synthesis imager having a 10 cm diameter antenna array, had its transverse and normal spatial resolutions measured to be λ and 7λ respectively, at a range of 10 cm from the array. In another hybrid imaging system with aperture synthesis in the vertical direction and phased array beam-forming in the horizontal direction, which was operated at 34 GHz and having an aperture of 35 mm(V ) × 40.8 mm(H) [32], the angular resolution in the vertical direction is around 1 • [33]. To be specific, the transverse spatial resolution was measured to be 2.15λ at a range of 1 m in front of the array and 6λ at a range of 3 m [33].…”

Section: Spatial Resolution Of Several Typical Locations On the Human...mentioning

confidence: 99%

The Effects of Obscuration in Passive 3-D Millimeter-wave Imaging for Human Security Screening

Sun¹,

Salmon²,

Zhuge³

et al. 2023

PIER

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The possibility of near-field passive 3-D imaging using the aperture synthesis technique is theoretically proven and highlights the opportunity for imaging the entire human body by an antenna receiving array that surrounds the body. In these scenarios there will be partial obscuration of some regions of the body, by other parts of the body. This results in some receivers in the array being able to measure emission from certain parts of the body, while others are obscured from a measurement. A model is presented which enables the effects of obscuration to be assessed for planar-like, cylindrical-like, and concave-like regions of the human body. The effect the obscuration has on the spatial resolution of the imager is evaluated by examining the 3-D point spread function, as determined by a near-field aperture synthesis imaging algorithm. It is shown that over many areas of the human body, the Abbe microscope resolution of λ/2 (5 mm@30 GHz) in a direction transverse to the human body surface is achievable, an attractive proposition for security screening. However, the spatial resolution in a direction normal to the human body surface is shown to be close to λ (10 mm@30 GHz). In regions of greater obscuration, such as in the armpits, the resolution may fall to λ (10 mm@30 GHz) and 5λ (50 mm@30 GHz) in the directions transverse and normal to the human body surface, respectively. It is also shown by simulation using a human body solid model and the 3-D aperture synthesis imaging algorithm how the image quality changes with the number of receiving antennas.

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“…The position of the source element must be close to the reference point source, otherwise the correction effect will be degraded. In [15], the near-field beamforming method is applied to determine the near-field imaging of ASR, and the imaging quality relies on the optimization of the weight vector. [16] adopts the angular spectrum method to ASR near-field imaging.…”

Section: Introductionmentioning

confidence: 99%

A Near-Field Imaging Method Based on the Near-Field Distance for an Aperture Synthesis Radiometer

Wu,

Li,

Song

et al. 2024

Remote Sensing

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For an aperture synthesis radiometer (ASR), the visibility and the modified brightness temperature (BT) are related to the Fourier transform when the distance between the system and the source is in the far-field region. BT reconstruction can be achieved using G-matrix imaging. However, for ASRs with large array sizes, the far-field condition is not satisfied when performing performance tests in an anechoic chamber due to size limitations. Using far-field imaging methods in near-field conditions can introduce errors in the images and fail to correctly reconstruct the BT. Most of the existing methods deal with visibilities, converting near-field visibilities to far-field visibilities, which are suitable for point sources but not good for extended source correction. In this paper, two near-field imaging methods are proposed based on the near-field distance. These methods enable BT reconstruction in near-field conditions by generating improved resolving matrices: the near-field G-matrix and the F-matrix. These methods do not change the visibility measurements and can effectively image both the point source and the extended source in the near field. Simulations of point sources and extended sources in near-field conditions demonstrate the effectiveness of both methods, with F-matrix imaging outperforming near-field G-matrix imaging. The feasibility of both near-field imaging methods is further validated by carrying out experiments on a 10-element Y-array system.

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A Novel Near Field Image Reconstruction Method Based on Beamforming Technique for Real-Time Passive Millimeter Wave Imaging

Cited by 6 publications

References 32 publications

Design of a Compact Analog Complex Correlator for Millimeter-Wave Radiation Temperature Measurement System

Design of a Compact Analog Complex Correlator for Millimeter-Wave Radiation Temperature Measurement System

The Effects of Obscuration in Passive 3-D Millimeter-wave Imaging for Human Security Screening

A Near-Field Imaging Method Based on the Near-Field Distance for an Aperture Synthesis Radiometer

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