The performance analysis of direct sampling microwave radiometer

L-band direct sampling digital total power microwave radiometer (DSDTPMR) is a novel radiometer, which trades analog complexity for digital ditto. This article considered the low noise amplifier (LNA) gain fluctuation, analog-to-digital converter (ADC) sampling rates and quantization resolution, to derive a general mathematical expression of sensitivity of the DSDTPMR; Analyzed the influence of sampling rate, quantization on sensitivity of DSDTPMR; The simulation result indicating, when the sampling frequency is bigger than two times of signal bandwidth, the multi-bit quantization resolution has very small effect on the sensitivity; when the gain fluctuation obeys the Gaussian distribution, the gain fluctuation may reduce to radicN times.