Evaluation of a simplified Doppler frequency shifter
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Mechanical Doppler frequency shifting of a millimeter or submillimeter wave signal provides a means to implement a sensitive and highly coherent heterodyne receiver in a laboratory system. The rotary shifter, which we have previously described, is a precision-machined device suitable for use down to submillimeter wavelengths. We found at 140GHz, however, that the coherence of such a system is not affected by mechanical imprecision of the frequency shifter, and that the system dynamic range is only moderately affected by mechanical imprecision and by certain design simplifications. We have therefore built several versions of simpler and less precise Doppler frequency shifters and report here on their performance at 140GHz.
Key wordsDoppler frequency shifter mechanical frequency translation single sideband modulator heterodyne receiver selfmixing system
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