Which material has the second lowest radar reflectivity in the given order?

• A. Wood
• B. Earth
• C. Concrete
• D. Masonry

Answer: (A)

Radar reflectivity is about how strongly a material reflects radar waves, which depends mainly on its dielectric properties and how the material is structured. Materials with higher dielectric constants and more internal interfaces scatter more energy back to the radar, producing stronger backscatter.

Wood tends to have a low effective dielectric constant because it’s porous and contains a lot of air. This porosity means less contrast at the radar interface and more energy is absorbed or scattered within the wood rather than reflected back. The result is weaker, or lower, backscatter compared with dense, high-permittivity materials.

Earth (soil) can reflect more than wood when moisture, roughness, and surface features are present, and concrete and masonry are dense, strongly scattering solids with higher permittivity. So, in many typical rankings, wood emerges toward the lower end of radar reflectivity, and in the given order it sits as the second lowest because the remaining materials generally produce stronger reflections.