Microwave propagation experiments, over a short range, demonstrated that the ratio b=c/v of the light velocity c to the observed one v resulted to be less than unity. The various results are here interpreted and compared with the theoretical predictions according to a classical electromagnetic model and to an alternative model based on the assumption of a broken local Lorentz invariance. In any case, the observed superluminal behavior is found to be peculiar to near field.
Agresti, A., Cacciari, I., Ranfagni, A., Mugnai, D., Mignani, R., & Petrucci, A. (2015). Two possible interpretations of the near-field anomaly in microwave propagation. Results in Physics, 5, 196–198. https://doi.org/10.1016/j.rinp.2015.08.002