Sure it could be a "field" that might as well be described as magic. But where's the craft's interaction with the atmosphere? Normally an object traveling thousands of miles an hour hits a fair amount of atmosphere. An object traveling fast enough actually turns atmospheric gases into a plasma. Plasma is not only hot but will reflect radio waves.
Now you need to invent a second magic technology that explains the lack of plasma trails following the path of this supposedly hypersonic object.
Now you need to invent a second magic technology that explains the lack of plasma trails following the path of this supposedly hypersonic object.