| The radiometer functions by exploiting the characteristic of different objects having different brightness temperatures,thereby enabling it to distinguish between objects,especially in scenarios with low signal power detection.As the utilization of spectrum resources and the development of radiometers,researchers have begun to explore the application of radiometers in the terahertz frequency band.The D-band(110-170 GHz)is located at the lower end of the terahertz frequency range.Research on radiometers in this frequency range has reached the chip level in foreign countries,while in China it is relatively limited.Therefore,this thesis is of positive significance in enriching the research results of D-band radiometers and improving their relevant performance.The radiometer studied in this thesis,operating in the D-band,is composed of a low noise amplifier,a detector,and an operational amplifier,with a focus on the development of the detector.In cases where the SPICE parameters of the detection diode are insufficient,based on the knowledge of diode theory,a three-dimensional electromagnetic model was established in HFSS to simulate the parasitic effects caused by the diode packaging,taking into account the physical structure,material characteristics,and approximate dimensions of the diode layers.The impedance characteristics of the Schottky junction were characterized using lumped parameters.The detector circuit was then designed and processed for testing.By comparing the simulated results of the detector reflection coefficient with the test results,the lumped parameters at the Schottky junction were gradually adjusted.Based on the fitted values that were closer to the actual values,the D-band detector was optimized.Additionally,to verify the performance of the selected diode in the W-band,a W-band detector was also designed.The test results showed that the voltage sensitivity of the W-band detector was greater than 1200 m V/m W in the frequency range of 75GHz-110 GHz,with a peak sensitivity exceeding7100 m V/m W,and an overall tangent sensitivity of approximately-60 d Bm@1.2k Hz.The voltage sensitivity of the D-band detector was greater than 1000 m V/m W in the range of110GHz-155 GHz,reaching up to 5500 m V/m W at its highest point,and the mean voltage sensitivity in the range of 160GHz-170 GHz was 1000 m V/m W.The tangent sensitivity measured at 110 GHz was approximately-55 d Bm@1.2k Hz.Utilizing the D-band detector and other discrete components,a radiometer was constructed with a temperature sensitivity of 0.55 K for an integration time of 16.4ms. |
