Effect of cable length in vector measurements of very long millimeter-wave components

In millimeter-wave applications, it is sometimes required to measure waveguide components that are several hundred wavelengths long. Depending on the vector network analyzer calibration technique used, the distance between the generator and receiver can be much longer than the one used during calibration when the device-under-test is inserted. If the frequency is swept or drifting, a systematic error is known to appear. A simple way of correcting the result combining two measurements was found.