An iterative algorithm incorporating aperture-domain management and an appropriate measurement strategy are employed to recover the aperture phase of a reflector antenna from a single scan of the radiated field amplitude and a simulated approximation of the aperture amplitude. Simulated and experimental results are presented which validate this reflector antenna metrology technique at millimetre wavelengths. Accelerated convergence is obtained and a new sensitive error metric is introduced to assess convergence to the solution. Measurement conditions are identified for modest signal-to-noise requirements and the prevention of algorithm stagnation.