Is RCS of a target dependent on Pulse Width used in a Radar System?

The RCS measurements are generally done with a bistatic arrangement with CW illuminations. But in Radar, the pulse widths can be as low as 1us. Does the RCS of a shape depend on the time of illumination of target, if it is a low illumination time case?

Case preview: We are working on a X-Band Radar with pulse width of 1us and are calibrating it with a corner reflector of measured RCS 22 dBsm. However, the received echo from Corner Reflector is lower by nearly 15 dB than what is expected. Is RCS dependent on Pulse Width?

Its a bandwidth thing, with CW you have a DC level, with a pulse, you have not, so if its a proper RMS detector then the output is down by the mark/space ratio. If its peak measuring (RMS calibrated) then it should be OK, providing the circuits have a wide enough bandwidth to handle the narrow pulse width.
Frank