Physics and War: Radar

Radar Physics

RADAR stands for Radio Detection And Ranging. After the war has turned aerial, it has become essential to scour the air spaces off the enemy planes or other flying objects. Due to the humongous nature of the space that needs to searched any brute force search operation like using planes or other ground or sea means, manually, is next to impossible. To automate and make the surveillance process efficient RADAR is used. RADAR was developed during world war-II separately by various nations and played a pivotal role in the war. Let’s discuss the science behind RADAR, its history and its role in the current times.

RADAR uses radio waves to search the air and sea spaces to detect objects. Heinrich Hertz has shown that radio waves are reflected off solid surfaces. Alexander Popov noticed that the radio messages sent across two vessels are affected by a third vessel passing in between. He stated that this interference, usually ignored as noise, can be used to detect the third ship. These were the early findings of the behaviour of radio waves echoed back. With time, RADAR was developed independently by several nations. The science behind each of these is the same.

A radio wave, just like a sound wave, is reflected back from a solid object. And hence the name radio-echo. Just as what we have learnt during our Physics tuition classes on Sound, the logic behind the working of RADAR is simple; if you shout out at a hill you hear an echo, conversely if you hear an echo it tells that there is a hill. This is exactly how RADAR works like. Depending on the time taken for the echo to reach back one can calculate the distance between the hill and the source of the sound. Similarly one can calculate the distance at which the solid object is based on the time taken by the radio waves to reach back to the source (after being reflected off the solid objects).

In order to scour the entire air space or sea space one has to send signals in all the directions and receive the reflected signals. Reflected signals essentially tell the presence of an object, a further analysis of the time taken for the signal to travel the round trip can be used to estimate the distance at which the object is placed, a constant exchange of signal between the object and the source gives the speed of the object. This is how one can sweep the the skies sitting at a desk. RADAR is no longer an acronym as it has lately made a dictionary entry as radar. RADAR is now largely used for tracking and guiding civilian aircraft and its military usage hasn’t entered the obsolete category yet.