Explicit microwave rotary phase shifter calibration algorithm

A microwave rotary phase shifter calibration method described previously by P.I. Somlo et al. (ibid., vol.20, no.8, p.532-7, 1972) requires the device under test (DUT) to be connected in tandem with a two-state phase stepper (flap) of initially unknown phase shift F to form an arm of a phase bridge circuit. The measurement is carried out by setting the DUT sequentially to a series of cardinal points, α_oi, i=1, . . ., M, equally spaced around the dial. At each, the phase bridge is balanced, and after introducing the flap, the new setting α_fi of the DUT needed to return the phase bridge to balance is found. The advantages of the method are that no standard phase shifter is required, that since the method is not a buildup method, errors are not cumulative, and that the phase bridge need not have any long-term stability. The algorithms previously described for data reduction are both iterative. Here, an algorithm that provides an explicit solution for the M unknowns is presented