"Radar underwater" is a "dumbing down" of how sonar works
but it is effective because the concepts as to how sonar and radar work are similar when reduced to the lowest denominator.
In RADAR you have a transmitter and a receiver... the transmitter sends out a broad beam of radio energy which strikes an object. A portion of that energy is reflected in what is called an "echo" which is received by the receiver antenna.
one could argue that active sonar works similarly to RADAR- in that it sends a sound pulse which is reflected by an underwater object.
when explaining to laymen, wives and girlfriends how sonar works, this comparison is not at all inappropriate in my opinion, as they likely dont give a damn to hear about the differences between active and passive sonars and the effects of water temperature and thermal layers, aspect ratios etc.
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