Sonar is a method of sound based ranging. Therefore as an object it is not subject to an antonym. There is the principal of radar which can also range, but it uses radio waves instead.
sonar(sound navigation and ranging)
A sonar is Fitted into a ship to detect how deep the water is
the Challenger
sonar,is used to map mid-ocean ridges:]
sonar - by bouncing sound signals off the bottom of the ocean, they were able to map the depth of the ocean. Deep sea diving would take too long. Satellites were not in orbit until the 1970's and submarines were not necessary since sonar could be done from the surface on a boat.
Sound detector
sonar sonar sonar sonar SONAR
sonar sonar sonar sonar SONAR
sattelite with sonar
sonar
Sonar
Sonar
No, the Arctic fox does not use sonar. It is not equipped with sonar.
Sonar is measured in sound
In the mountains i detect a rock with my SONAR.
sonar means '...of, or relating to sound'
SONAR=Sound Navigation And Ranging