RADAR: The Radar System

RADAR

RADAR is a term is used to refer to electronic equipment that perceive the presence, course, altitude, and distance of objects by using reflected electromagnetic waves. The term radar is in fact an acronym made up of the words radio detection and ranging (RADAR = RAdio Detection And Ranging). The fundamental basics of RADAR is built upon electromagnetic radiation. RADAR utilises radio waves which is a type of electromagnetic wave on the electromagnetic spectrum. RADAR finds target objects by sending out radio waves that bounce off targets as a radio echo. These echoes are then measured to detect the distance between the target and the RADAR system. These radio waves are not affected by lack of visibility and also penetrates weather to

Because of this, the altitude of certain targets that are located by the radar system may be displayed inaccurately. For example in the figure below, the line of sight of the radar system is directly in line with the plane, thus the radar will register the plane to have an altitude similar to the height of the radar despite the fact that the aircraft is actually 3000 feet above the ground. Ground targets, such as a plane crash site that are also at a range greater than the radar horizon will not be detected unless it is high enough to be above the horizon, just as the ship in the diagram below is underneath the horizon and hidden from the radar

At the end of 1 second, the plane is now at position A1 and under these conditions the next radio wave of 60 hertz emitted is located between the radar and point A1. Notice that this distance is only 720m (1,080 - 360). The 60 hertz is spread over this has a wavelength of just 12m (720 divided by 60). Using the formula f=vλ, we can calculate the new frequency to be 90 Hz.

The original frequency of 60 Hz is now an apparent frequency of 90 Hz. This Doppler Effect variation is directly proportional to the velocity of the approaching Plane. The greater the velocity of the incoming plane, the greater the quantity of waves that will be packed into the space between the radar and the plane. This allows us to make detailed calculations to approximate the velocity of the plane. Therefore, the utilisation of the Doppler Effect is a major factor in the effective running of a radar system.

Features of an efficient SONAR