实验探讨了在群速超光速的情况下信号传播速度的特点。正弦调幅信号通过失配的传输导线组时在特定的频率下能够出现群速超光速现象。验证了群速超光速在光子晶体中的速度随着导线的延长是起伏变化的，所获得的信号包络传输速度分别为1倍多光速到2倍多光速。当失配线足够长时(实验中为179．8m)，甚至出现负群速。实验结果表明群速超光速与通常以光速传递情况的差异不但表现在大小方面，而且还表现在速度值的起伏方面。实验结果揭示了群速超光速传输速度特点与光和电的正常传输情况有明显的区别。

The characteristics of signal transmission speed in the condition of superluminal group velocity are discussed. When an amplitude modulated sinusoid signal is sent into mismatched transmission line groups at some special carrier frequencies,its group velocity of envelope is superluminal. The speed fluctuation according to the length changes of the line is verified. The group velocity of the signal envelope in the forbidden band is one to two times faster than the speed of light(c)in vacuum. Even negative group velocity occurs when the total length of the mismatched line group is long enough such as 179.8 m. According to the experiment,differences between superluminal group velocity in certain condition and the light speed in general propagation exist in not only the speed values but also the speed fluctuations. The experimental result reveals that the characteristic of superluminal group velocity propagation speed is obviously different from that of electricity and light in normal propagation.