Evaluate the solution of the following problem

Problem- Satellites have orbited the Moon and bounced radio off the lunar surface and thence towards Earth. After many orbits, one can reconstruct the reflection intensity versus reflection angle.

Part 1- For 140 MHz radio, the reflected intensity was observed to dip at reflection angle 60°. Estimate the permittivity of the lunar regolith. Does the frequency of the radio much matter? The dip didn't go to zero; explain why this is so.

I need assistance to find the permittivity of the lunar regolith.