An 8 mm-band two-dimensional Synthetic Aperture Interferometric Radiometer (SAIR) called BHU-2D has been developed by Electromagnetics Engineering Laboratory of Beihang University. The radiometer could obtain images in realtime benefiting from the adoption of a 1bit/2level FPGA-based correlator array. The correlator array requires a group of Power Measurement Units (PMUs) to denormalize the correlation coefficients into visibility function samples. The design and implementation of the PMU in BHU-2D is presented in this paper. The PMU adopts a novel method based on probability statistics. The principle and quantitative error analysis of this power measurement method is presented. In order to verify the principle of the design, a sample board is manufactured and a series of validation experiments have been conducted. Measurement results have proved that the performance of the PMU could meet the requirements of SAIR systems. The PMU has been applied to BHU-2D and the result is satisfactory.
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