Anomalous forerunners in wave propagation interpreted by a typical diffraction integral

By using radar techniques over distances of 16 and 80 m, microwave propagation experiments revealed the presence of anomalous forerunners situated in advanced positions with respect to the main (luminal) peak. These results can be interpreted by a typical diffraction integral, which accounts for the existence of (fast) complex waves, which are usually considered only in the near-field region, but are still surviving beyond this limit.