Nope. Radio waves are oscillating EM radiation at a constant velocity of 3 x (10^8) meters / second in a vacuum. That is the speed limit. 300 000 000 m/s is actually a round-off figure. According to text books on the subject, the exact figure is 2,9978 x (10^8) m/s. However, this error factor is so small (less than 1/1000 percent) that 3 x (10^8) is normally used for general purpose.

Nope. Radio waves are oscillating EM radiation at a constant velocity of $3 \times 10^8 ms^{-1}$ in a vacuum. That is the speed limit.

$300 000 000 ms^{-1}$ is actually a round-off figure. 

According to text books on the subject, the exact figure is $2,9978 \times 10^8 ms^{-1}$.

However, this error factor is so small (less than $0.001$ percent) that $3 \times 10^8$ is normally used for general purpose.