ANOMALOUS PULSE DELAY IN MICROWAVE PROPAGATION - A PLAUSIBLE CONNECTION TO THE TUNNELING TIME

Measures of pulse delay in microwave propagation, in open air and for short distances (not much greater than 1 m), were made by using launch er and receiver horns. When these are facing each other we observe a d elay time corresponding to a speed equal to c while, if the receiver h orn is shifted or tilted with respect to the launcher horn, the delay time decreases showing a superluminal behavior. In other words the mod ulation phase shift, interpreted as a propagation time, turns out to b e surprisingly smaller than the one relative to the light speed. This effect, which disappears for longer distances, is here interpreted on the basis of the existence of a special kind of evanescent waves (leak y waves). Just the presence of evanescent waves allows one to make a c omparison with the tunneling processes where superluminal transport pr operties have been theoretically predicted.