Attenuation Standard in the Frequency Range of 50–75 GHz

An accurate primary standard has been constructed for RF attenuation measurements in the frequency range of 50-75 GHz. Based on the IF substitution method, it employs an inductive voltage divider (IVD) working at 10 kHz as a reference standard. A highly stable IF signal is obtained for precision measurement using phase-lock technology on the frequency-converted local signal. The IVD component is a sequence of six-decade IVDs that are combined to realize an attenuation of 80 dB. They are particularly and independently fabricated to realize the improved performance in uncertainty at 10 kHz. Each IVD has independent input and output terminals; therefore, it can be individually calibrated and precisely evaluated. Measuring RF signals, including several subharmonics, is generated by a frequency quadrupler. The influence that is associated with the subharmonics is theoretically analyzed. Sources of uncertainties in the system are discussed, and the overall expanded uncertainty is found to be 0.004-0.13 dB corresponding to a measured attenuation range up to 80 dB.