what is radar reflection?

Question

GCSE science

Answer 1

Reflection

Brightness can indicate reflectivity as in this 1960 weather radar image. The radar's frequency, pulse form, and antenna largely determine what it can observe.Electromagnetic waves reflect (scatter) from any large change in the dielectric or diamagnetic constants. This means that a solid object in air or vacuum, or other significant change in atomic density between the object and what's surrounding it, will usually scatter radar (radio) waves. This is particularly true for electrically conductive materials, such as metal and carbon fibre, making radar particularly well suited to the detection of aircraft and ships. Radar absorbing material, containing resistive and sometimes magnetic substances, is used on military vehicles to reduce radar reflection. This is the radio equivalent of painting something a dark colour.

Radar waves scatter in a variety of ways depending on the size (wavelength) of the radio wave and the shape of the target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a mirror. If the wavelength is much longer than the size of the target, the target is polarized (positive and negative charges are separated), like a dipole antenna. This is described by Rayleigh scattering, an effect that creates the Earth's blue sky and red sunsets. When the two length scales are comparable, there may be resonances. Early radars used very long wavelengths that were larger than the targets and received a vague signal, whereas some modern systems use shorter wavelengths (a few centimetres or shorter) that can image objects as small as a loaf of bread or smaller.

Short radio waves reflect from curves and corners, in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between the reflective surfaces. A structure consisting of three flat surfaces meeting at a single corner, like the corner on a box, will always reflect waves entering its opening directly back at the source. These so-called corner reflectors are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect, and are often found on boats in order to improve their detection in a rescue situation and to reduce collisions. For similar reasons, objects attempting to avoid detection will angle their surfaces in a way to eliminate inside corners and avoid surfaces and edges perpendicular to likely detection directions, which leads to "odd" looking stealth aircraft. These precautions do not completely eliminate reflection because of diffraction, especially at longer wavelengths. Half wavelength long wires or strips of conducting material, such as chaff, are very reflective but do not direct the scattered energy back toward the source. The extent to which an object reflects or scatters radio waves is called its radar cross section.

Answer 2

When the radio wave sent by the transmitter section of a radar hit an object and bounces back to the receiver section of the radar. The radar feflection is the waves bouncing off the object back to the radar's receiver section

Answer 3

If you shine a flashlight out in your yard at night, you see the stuff in the yard because your light hits the stuff and some light comes back to your eyes. Pretty much the same with radar.

Answer 4

All electromagnetic waves reflect to any metal surface.
Radar is such a wave with wavelength of about an inch and will be reflected as well. It is used in weather balloons and to find flying or floating objects.

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