How far can radar waves travel?
Light waves have wavelengths of about 500 nanometers (500 billionths of a meter, which is about 100–200 times thinner than a human hair), whereas the radio waves used by radar typically range from about a few centimeters to a meter—the length of a finger to the length of your arm—or roughly a million times longer than …
How a radar can detect an object or shows something over-the-horizon?
How a skywave OTH radar works: A powerful shortwave signal from a large transmitting antenna (left) reaches a target beyond the horizon by refracting off the ionosphere, and the echo signal from the target (right) returns to the receiving antenna by the same route.
How does secondary surveillance radar work?
Secondary surveillance radar (SSR) is a radar system used in air traffic control (ATC), that unlike primary radar systems that measure the bearing and distance of targets using the detected reflections of radio signals, relies on targets equipped with a radar transponder, that reply to each interrogation signal by …
How does frequency affect radar?
Frequency is a fundamental property of any radar instrument since it directly affects measurement performance in various ways. When propagating through a medium, radar signals are absorbed and the signal strength decreases. High-frequency signals suffer more attenuation than low- and mid-frequency signals.
Do radar signals travel in a straight line?
RADAR HORIZON / LINE OF SIGHT There are limits to the reach of radar signals. At the frequencies normally used for radar, radio waves usually travel in a straight line. The waves may be obstructed by weather or shadowing, and interference may come from other aircraft or from reflections from ground objects (Figure 1).
How does radar bounce off the surface?
The radar signal bounces off a rough, flat surface and scatters in every direction with only a few data points bouncing back to the sensor. The orientation of each radar pulse results in various shades of grey pixels in the radar image. A very common return is the double-bounce.
What is the constant of line of sight for radar?
This is done to account for the effect of the atmosphere on radar propagation. For a true line of sight, such as used for optical search and rescue, the constant in the equations changes from 1.23 to 1.06. A nomograph for determining maximum target range is depicted in Figure 2.
Why do planes not show up on radar?
The waves may be obstructed by weather or shadowing, and interference may come from other aircraft or from reflections from ground objects (Figure 1). As also shown in Figure 1, an aircraft may not be detected because it is below the radar line which is tangent to the earths surface.