Step 1: Formula for Antenna Length.
The length \( L \) of an antenna required to transmit a signal of frequency \( f \) is given by the formula:
\[
L = \frac{c}{2f}
\]
where \( c \) is the velocity of light and \( f \) is the frequency. Substituting the values:
\[
L = \frac{3 \times 10^8}{2 \times 1.5 \times 10^8} = 1 \, \text{m} = 50 \, \text{cm}
\]
Step 2: Final Answer.
Thus, the length of the antenna required is 50 cm.