In this paper, we propose a multi-beam and multi-range (MBMR) radar with frequency modulated continuous wave (FMCW) waveform and digital beam forming (DBF) algorithm to cover a detection area of long range and narrow angle (150m, §10 - ) as well as short range and wide angle (60m, §30 - ) as a single 24GHz sensor. The developed radar is highly integrated with multiple phased-array antennas, a two-channel transmitter and a four-channel receiver using K-band GaAs RF ICs, and back-end processing board with subspace- based DBF algorithm. The proposed 24GHz MBMR radar can be used for an adaptive cruise control (ACC) stop-and-go system which typically consists of three radars, such as two 24GHz short-range radars for object detection in an adjacent lane and one 77GHz long- range radar for object detection in the center lane.

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A Multi-Beam and Multi-Range Radar with FMCW and Digital Beam Forming for Automotive Applications

The phase-sensitive radio-echo sounder (pRES) is a powerful new instrument that can measure the depth of internal layers and the glacier bed to millimetre accuracy. We use a stationary 16-antenna pRES array on Store Glacier in West Greenland to measure the three-dimensional orientation of dipping internal reflectors, extending the capabilities of pRES beyond conventional depth sounding. This novel technique portrays the effectiveness of pRES in deriving the orientation of dipping internal layers that may complement profiles obtained through other geophysical surveying methods. Deriving ice vertical strain rates from changes in layer depth as measured by a sequence of pRES observations assumes that the internal reflections come from vertically beneath the antenna. By revealing the orientation of internal reflectors and the potential deviation from nadir of their associated reflections, the use of an antenna array can correct this assumption. While the array configuration was able to resolve the geometry of englacial layers, the same configuration could not be used to accurately image the glacier bed. Here, we use simulations of the performance of different array geometries to identify configurations that can be tailored to study different types of basal geometry for future deployments.

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Resolving the internal and basal geometry of ice masses using imaging phase-sensitive radar

This paper proposes the addition of a frequency scanning antenna to a conventional frequency modulated continuous wave radar with possible application to an anti-collision system in a vehicle. It is shown possible to extract the target range and angular position by analyzing the target echo in both time and frequency domains. The proposed system is simple to implement, without requiring the sophisticated wide-band amplifiers and timing circuitry required in a conventional pulse radar. Initial measurements show the feasibility of the proposed system.

A beam scanning frequency modulated continuous wave radar

Presents the principle of synthetic aperture frequency modulated continuous wave (FM-CW) radar and demonstrates the detection results of several objects buried in natural snowpack using the radar system. First, the synthetic aperture technique is explained with emphasis placed on showing that the Fourier transformed beat signal obtained by the FM-CW radar is equivalent to one kind of Fresnel hologram, which leads the authors to use the SAR technique. Then a radar system operative in the microwave L-band is explored to detect objects buried in natural snowpack. Several detection results are presented demonstrating the potential capability of high resolution imaging in the azimuth direction, comparing with real aperture images. >

Synthetic aperture FM-CW radar applied to the detection of objects buried in snowpack

The authors present a principle of synthetic aperture FM-CW (frequency-modulation continuous wave) radar and show the detection results at several objects in natural snowpack by an FM-CW radar. By incorporating the synthetic aperture technique, it was possible for the FM-CW radar to obtain images with high resolution in the azimuth direction in the snowpack. An averaging and subtracting processing technique is employed to make the synthetic aperture image clear, suppressing the clutter which is characteristic of the natural snowpack structure. From the experiment, this imaging FM-CW radar seems to have a potential ability to map objects embedded in a lossy medium. >

The frequency-modulated continuous-wave (FM-CW) radar is suitable for detecting objects placed in the near range compared to the pulse radars. This paper considers the principle of the synthetic aperture technique for the conventional FM-CW radar and presents the fundamental detection results of objects placed in the free space. A laboratory measurement is carried out to detect a metallic plate and a pipe in an anechoic chamber using an explored radar system operative in the microwave X-band. This demonstrates the high resolution detection in azimuth direction in the Fresnel region. It is shown that the radar has a potential ability in imaging objects placed in the near range.

Masashi Mitsumoto

Papers

Detection of objects by synthetic aperture FM‐CW radar