AbstractMicrowave reflectometry is a diagnostic well suited to measure the plasma density profile in large fusion devices. The possibility to make reflectometry measurements with unfavourable propagation of the incident microwaves is especially important in devices where significant modifications of the flux surfaces are expected, as will be the case of ITER. The sensitivity of reflectometry to D-shaped and circular plasma configurations was studied in ASDEX Upgrade. Ray tracing was used to model the experiments and to determine the limits for reflectometry measurements.