A wideband receiver-module for passive MM wave imaging array: Optimization and test results
Results of noise and impedance optimization of a W-band receiver-module are given. A wideband compact receiver-module for MM wave passive imaging array has been developed on the basis of InP MMIC LNA and a highly sensitive impedance matched low-barrier detector diode. Achieved bandwidth is 85–100 GHz, the gain factor is 30 dB that was sufficient to provide 15 mK/Hz1 temperature sensitivity of the receiver-module. Tests results of the receiver-module are presented.
A High Sensitivity Full W-Band Radiometer with Temperature-Compensation Function
In this paper, a high sensitivity full W-band radiometer is demonstrated. The radiometer consists of a full W-band low-noise amplifier, a zero bias detector, a video amplifier and so on. To achieve high sensitivity, the minimum noise figure of the LNA is 2.8dB. And the gain is better than 20dB in full W-band. Meanwhile, a temperature-sensitive gate voltage compensation circuit is designed to fulfill the temperature-compensation function. Finally, the measurement results show the temperature sensitivity of all radiometers is better than 0.33K. And the thermal drift ratio is better than 15% between high and low temperature.
In search of optimum chest radiography techniques.
A nation-wide study of chest radiography in Sweden had previously revealed a large variation in the physical and technical factors involved, in particular the radiation dose. In this study the image quality could not be assessed unambiguously. The aim of the present study was to try to establish a correlation between visual grading of radiographs and physical and technical factors in order to find the optimum chest X-ray system. The physical and technical performance of 24 chest units was evaluated. Radiographs were taken of an anthropomorphic chest phantom supplied with test structures simulating various pathologies. Image quality was assessed by visual grading analysis of the radiographs. The physical and technical parameters of the units rated best were used to exemplify good radiographic practice. The results were in agreement with the recommendations issued by the Commission of the European Communities (CEC). It was also shown that low radiation dose is compatible with high-quality radiographic imaging of the chest.