Reducing Effects of LO Cable Movement in Antenna and Long Distance VNA Measurements

We evaluate a method for estimating and removing local oscillator cable drift in transmission measurements using a network analyzer. The geometric mean of the measured forward and reverse transmission, including drift, can be used to estimate the actual transmission without drift. This requires the measurement of passive, symmetrical transmission measured with a bi-directional two-port remote-mixing down-converting measurement system. This method is being used in antenna measurements where cable movement is unavoidable. It is viable for other calibrations and measurements using remote-mixing systems and frequency extenders at higher frequencies.