What is a mechanical device used in RADAR that produces free oscillation called?

In RADAR systems, a mechanical device that produces free oscillation is referred to as a tuning fork. Tuning forks are designed to vibrate at a specific frequency when struck, allowing them to generate a stable oscillation. This characteristic makes them useful in applications where precise frequency control is required.

Other options, while related to oscillatory behavior or signal generation, do not specifically represent a mechanical device dedicated to producing free oscillation in the same way. For example, an oscillator is an electronic circuit that can produce a continuous waveform, but it does not involve mechanical components in the same manner as a tuning fork. A resonant chamber is designed to enhance the oscillation of sound or electromagnetic waves, and an amplitude modulator is used to vary the amplitude of a signal, but neither serves the precise function of generating a free oscillation like a tuning fork does.