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On 1 December 2020, China's Chang'E-5 (CE-5) probe successfully landed in the northeastern Oceanus Procellarum. This work mainly presents the results of Lunar Regolith Penetrating Radar (LRPR) equipped on the CE-5 Lander. The lunar regolith structure of the landing site from the surface to 3-m depth is unveiled by LRPR, which found that abundant rock fragments are distributed in uniform lunar regolith. The imaging result proved that the drilling and sampling process was prevented by big rocks at about 100 cm depth. On the basis of the response of lunar soil to electromagnetic (EM) wave, the EM properties of the landing site estimate that the relative dielectric constant and the loss tangent are 2.520 ± 0.186 and 0.0133 ± 0.0020, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a specially designed guided wave radar device for measuring the liquid level in the nuclear industry is proposed. A split-type design is introduced to adapt to a strong radiation environment. An L-band frequency modulated interrupted continuous wave (FMICW) radar is designed to ensure the signal-to-noise ratio of echo signal after long-distance signal transmission, which provides the isolation between transmitter and receiver of more than 60 dB using the gating technology. To overcome the shortcomings of limited installation and maintenance space, a novel coaxial waveguide probe with a multi-segmental structure is proposed and simulated. An adaptive signal processing algorithm is developed to remove false echoes and eliminate measurement fluctuations. A prototype of the proposed measurement system is fabricated and evaluated. Static and dynamic liquid level experiments are performed in an outdoor environment to assess performance and verify the effectiveness of the proposed radar. The results show that the standard deviation measurement error of the proposed radar is within 0.4 cm. The proposed system is expected to have a high potential for applications in liquid level measurement under complex conditions. [ABSTRACT FROM AUTHOR]

Sampling return in Chang'E-5 (CE-5) mission is the third phase of three strategic steps of China's lunar program. The three strategic steps are orbiting, landing, and returning. The sampling and drilling device is mounted on the Lander. One task of the CE-5 Lunar Regolith Penetrating Radar (LRPR) is to provide information support for the drilling and sampling device. This article introduces the scientific objectives of CE-5 LRPR and the difference with Chang'E-3 lunar penetrating radar. The system design, working principle, imaging, and calibration methods of LRPR are the highlight. Considering that the Lander is stationary, and its bottom is about 90 cm from the lunar surface, an antenna array is adopted to probe the subsurface structure and the regolith thickness for supporting the drilling. The design uses a pre-amplifier circuit to increase the dynamic range of the whole system, which enhances the detection effect of shallow lunar soil structure. For verifying the probing ability of LRPR, the marble slabs, metal balls, and stones are buried in the volcanic ash pool in advance for detection and verification. The pre-stack Kirchhoff depth migration imaging method is adopted to identify the burial depth and thickness of the target. The verification results meet the task requirements. [ABSTRACT FROM AUTHOR]

This paper presents the ice thickness, fine resolution internal reflecting horizons (IRHs), and distinct bottom topography measurements of Chinese Kunlun Station and Grove Mountains, Antarctica, derived from sounding these glaciers with a high-resolution radar. To enable the development of next-generation ice-sheet models, we need information on IRHs, bottom topography, and basal conditions. To this end, we performed measurements with the progressively improved ice-sounding radar system, currently known as the high-resolution ice-sounding radar developed by the Key Laboratory of Electromagnetic Radiation and Sensing Technology of Institute of Electronics, Chinese Academy of Sciences, Beijing, China. We processed the collected data using focused synthetic aperture radar (SAR) algorithm named the modified range migration algorithm using curvelets and the modified nonlinear chirp scaling algorithm to improve radar sensitivity and reduce along-track surface clutter. Representative results from selected transects indicate that we successfully sounded 3-km-thick ice with a fine resolution of 0.75 m. In this paper, we provide a brief description of the radar system, discuss the focused SAR processing algorithms, and provide sample results to demonstrate the successful sounding of the ice sheet in Antarctica. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 20-year-old man with epigastralgia, pain in the epigastric region, wherein two long rods in his stomach revealed after abdominal imaging performed to him.

The Tianwen-1 of China is expected to land and explore on the planet Mars in May 2021, carrying a Mars Rover-mounted Subsurface Penetrating Radar (RoSPR) system. A VHF band ultra-wideband (UWB) monopole antenna integrated on the Mars Rover, and described in this paper, has been designed for the subsurface exploration of Mars tens of meters deep. Conventional antenna design methods usually prove difficult in taking into account several key parameters such as miniaturization, broadband characteristics and radiation efficiency. Moreover, there is almost no special research on the reliability of antennas. For this purpose, a miniaturized air-coupled monopole antenna integrated with the Mars Rover has been designed. The overall length of the antenna is 0.13 λ at the lowest operating frequency. In addition, the classical Wu–King profile is improved, which not only satisfies the operating bandwidth of the antenna, but also increases the gain by 3–4 dB. In the design, the innovative application of planar embedded resistance greatly enhances the reliability of the antenna and thereby ensures that the antenna can work on Mars for a long term. This is the first application of this antenna design method in the aerospace field. Because it is difficult to test the low-frequency antenna accurately, a 1:4 scale model of the antenna and Rover is fabricated to equivalently measure the radiation characteristics of the antenna. Furthermore, the performance and practicability of the antenna and radar system are verified on the glacier. [ABSTRACT FROM AUTHOR]

The Chang'e-5 lunar exploration mission of China is equipped with a Lunar Regolith Penetrating Radar (LRPR) for measuring the thickness and structures of the lunar regolith in the landing area. Since the LRPR is stationary, an ultra-wideband multiple-input multiple-output (MIMO) array is designed as a replacement for conventional mobile subsurface probing systems. The MIMO array, with 12 antenna elements and a switch matrix, operates in the frequency band from 1.0 to 4.75 GHz. In this work, the design and layout of the antenna elements were optimized with respect to the lander. To this end, the antenna elements were designed as miniaturized Vivaldi antennas with quarter elliptical slots (i.e., quarter elliptical slotted antenna, or QESA). QESAs are significantly small while being able to mitigate the impact of the lander on antenna electrical performances. QESAs also have a wide operating bandwidth, flat gain, and excellent time domain characteristics. In addition, a high-temperature resistant ultra-light radome with high transmissivity is designed to protect the external antenna array. After calibration, the MIMO array is used to detect targets embedded in volcanic ash. The detection depth reaches 2.5 m, and the detection effect is good. [ABSTRACT FROM AUTHOR]