I guess, we all have heard about RADARS, at least once in our life. Radars are used all around us & we know where they are used but don't know much about how they actually work. In this post, I will just try to give a small summary about the RADARS & their applications. In case you want to get the mathematical or engineering details, you can visit wikipedia or other e-books that are available over internet. I will try to find out such books & in case I get any I will share them in my subsequent posts.
Radars are used in wide variety of applications like from weather/storm monitoring (meteorological applications), in Air Traffic Controlling, military operations- identifying hostile targets & guiding weapons, in space programs- to map earth or lunar surfaces, etc. There are variety of radars available depending upon their intended use like Doppler radars, Synthetic Aperture Radars (SAR), Active/Passive Electronic Scanned Array(AESA/PESA) radars, etc.
Basic function of radars:-
1) To find out whether an object is present at a distance or not.
2) In case an object is there, what is its speed?
3) To map a surface (like lunar or earth's surface).
So how radar actually works? It's quite simple! At least in principle. It works on the principle of echoes & Doppler shifts. In every radar there are two parts- transmission & receiving unit. Transmission unit consist of a radio wave emitter which emits radio waves in particular direction. The receiving unit consist of a receiver that detects the signal bounced off from targets (echoes). In this way radar detects if an object is present at a particular distance or not.
To find out, whether the object is approaching or leaving & the speed of the object, the effect of Doppler shift is used. Doppler shift is the apparent change in frequency (of sound/light) caused by an object which is approaching/moving away at some speed.
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