Phase measurement, traceability, and verification theory and practice

Presently available technology allows the construction of phase calibration equipment with phase resolutions of at least one part in 2 ¹⁸, that is, a phase resolution of 0.00137°. The users and the manufacturers of such equipment are faced with the practical problem of verifying their phase accuracy-both relative and absolute-and their traceability to some more accurate source. The authors present measurement methods that allow both relative and absolute high-resolution phase determinations in the vicinity of 0°, 60°, 90°, and 180° angles. They also present practical methods of implementing all of these methods together with comparative experimental data for all of them