Comparison of observed and predicted phase-front distortion in line-of-sight microwave signals

Two experiments are reported which were designed to demonstrate the theoretical relationship between the phase-front distortion of line-of-sight microwave signals and the refractive index structure along the propagation path. Measurements were made on a slanted 64-km path in Hawaii with an elevation angle of
2.5\deg
, using a horizontal array of 4 antennas at the upper terminal to observe the phase structure function, and an airborne refractometer to measure the refractive index structure. The predicted phase structure function computed from the refractometer data is compared with the observed structure function, and shows best agreement in the periods 0100-0700 hour and 1300-1900 hour.