noun
modulator
MAH-juh-lay-ter/mˈɑdʒʌlˌeɪtɝ/
A device or substance that controls or adjusts how something operates.
The modulator adjusts the signal before it reaches the antenna.

Etymology
A modulator was literally one who measured by rule—a regulator, including a musical director. That regulating role extends to a person or device that adjusts a quality or controls a wave.
In context
So you can give a frequency to this particular modulator and you can modulate the light intensity output of the modulator.
More examples
- This drug acts as a modulator of the immune response.
- A faulty modulator distorts the radio signal.
- The technician tests both modulators before installing them.
Forms
modulator · modulators
modulate verb — To control or adjust how something operates.
modulation noun — The adjustment of a signal, process, or activity.
Similar words
- regulator
- Often maintains a steady level rather than varying a pattern.
- controller
- Usually directs an entire system rather than adjusting one activity.