Two compact single-chip 94-GHz frequency-modulated continuous-wave (FMCW) radar modules have been developed for high-resolution sensing under adverse conditions and environments. The first module contains a monolithic microwave integrated circuit (MMIC) consisting of a mechanically and electrically tunable voltage-controlled oscillator (VCO) with a buffer amplifier, 10-dB coupler, medium-power and a low-noise amplifier, balanced rat-race high electron-mobility transistor (HEMT) diode mixer, and a driver amplifier to increase the local-oscillator signal level. The overall chip-size of the FMCW radar MMIC is 2 x 3.5 mm2. For use with a single transmit-receive antenna, a 94-GHz microstrip hexaferrite circulator was implemented in the module. The radar sensor achieved a tuning range of 1 GHz, an output signal power of 1.5 mW, and a conversion loss of 2 dB. The second FMCW radar sensor uses an MMIC consisting of a varactor-tuned VCO with injection port, very compact transmit and receive amplifiers, and a single-ended resistive mixer. To enable single-antenna operation, the external circulator was replaced by a combination of a Wilkinson divider and a Lange coupler integrated on the MMIC. The circuit features coplanar technology and cascode HEMTs for compact size and low cost. These techniques result in a particularly small overall chip-size of only 2 x 3 mm2. The packaged 94-GHz FMCW radar module achieved a tuning range of 6 GHz, an output signal power of 1 mW, and a conversion loss of 5 dB. The RF performance of the radar module was successfully verified by real-time monitoring the time flow of a gas-assisted injection molding process
A single-chip 94 GHz frequency modulated continuous wave (FMCW) radar module has been developed for high resolution sensoring under adverse conditions and environments. The monolithic microwave integrated circuit (MMIC) includes a varactor tuned VCO with injection port, very compact transmit and receive amplifiers and a single-ended resistive mixer. To enable bidirectional operation of a single transmit-receive antenna a combination of a Wilkinson divider and a Lange coupler was integrated. The circuit features coplanar technology and cascode HEMTs for compact size and low cost. These techniques result in a particularly small over-all chip-size of only 2 x 3 mm2. The packaged 94 GHz FMCW radar sensor achieved a tuning range of 6 GHz, an output power of 1mW and a conversion loss of 5 dB. The RF performance of the radar module was successfully verified by real-time monitoring the time flow of a gas-assisted injection molding process
Deformation and failure of fiber-reinforced materials (FRM) can cause electric charge displacements. This, consequently, leads to variations in the external electric field. These can be observed and recorded during the loading process without any contact to the sample. Analyzing, these signals named electric emission (EE) can be done individually and also statistically when an acoustic emission equipment is used. Fracture of carbon and glass fibers yields EE signals of large amplitudes, whereas the polycarbonate matrix material exhibits smaller ones. The signals obtained in a tensile test with the composite materials exceed the ones of the matrix material but do not attain those of the fiber material. From the shape of the EE signals conclusions can be made on the elementary fracture process. From these experiments it can be concluded that the EE method is a valuable tool with respect to the detection of failure occurence of composite materials as is the acousti emission technique. The EE Technique is a field method and does, therefore, not require any sample preparation. This makes it a low cost technique which can be possibly applied in the field as well as in the laboratory
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