Fig. 2
From: Application of ground scatter returns for calibration of HF interferometry data
Transfer function between interferometer phase shift and elevation angle obtained for the boresight direction of the radar antenna. The black curve shows total phase shift for the given interferometer base of 100 m and a typical Hokkaido radar frequency of 11 MHz for the elevation range between 0° and 90° (for the remaining back-lobe range 90°–180°, the dependence should be mirrored around 90° elevation and zero phase). The blue line corresponds to the measured phase confined to the ±π interval and shows that a single measured phase value corresponds to multiple elevation angles. The conventional 2π range used for calculating SuperDARN elevation is highlighted by red