What materials allow most of a RADAR beam to pass through without reflection?

The reason glass and plastic are highlighted as the correct materials that allow most of a radar beam to pass through without significant reflection lies in their physical properties. Radar waves are a form of electromagnetic radiation, and their behavior when encountering different materials is influenced by factors such as the material's density, electrical conductivity, and dielectric properties.

Glass, for instance, has low electrical conductivity and is often used in applications where transparency to radar waves is desired, such as in certain types of sensor enclosures. Similarly, plastic, depending on its type and formulation, can exhibit low reflection and absorption of radar waves, allowing for effective transmission through the material.

In contrast, materials like wood and concrete can pose challenges for radar transmissions due to their denser composition, which can lead to scattering or partial reflection of the radar waves. Metal and stone tend to reflect radar waves effectively due to their high density and conductivity, which is why they are not suitable for allowing radar waves to pass through. Lastly, fabric and paper are not typically considered in radar applications due to their varying thickness and density, which can also lead to distortion or scattering of radar signals.

Overall, glass and plastic's ability to permit radar beams to pass with minimal interference makes them the best choice among the materials listed.