Radar Energy Cone of Transmission and Footprint

Radar energy spreads out in a conical projection as it travels into the ground. The approximate size of the radiation footprint at a depth in the ground can be estimated from the antenna frequency and the RDP of the ground through which the energy passes.

The radar energy cone of transmission will often become focused as energy travels in successive layers in the ground of increasing RDP, which is common for most field conditions.

The cone of transmission is much broader with depth when the RDP of the material is low. In high RDP material the transmission cone is narrower, and its footprint radius at any one depth is much smaller.