In a half-circle path, the distance covered is the semicircle's length:
\[
\text{Distance covered} = \pi \times \text{radius} = \pi \times 1 = \pi \, \text{m}
\]
The displacement, a straight line, is the circle's diameter:
\[
\text{Displacement} = 2 \times \text{radius} = 2 \times 1 = 2 \, \text{m}
\]
The ratio of distance to displacement is:
\[
\frac{\pi}{2} = \pi : 1
\]
Hence, the answer is \( \pi : 1 \).