Which unit is used to measure frequency?

Hertz is the unit used to measure frequency, which quantifies the number of cycles of a periodic phenomenon that occur in one second. In the context of radio communications, frequency is essential because it determines the specific channel or bandwidth over which signals are transmitted. For instance, when tuning a radio to a specific station, the frequency in hertz corresponds to the electromagnetic wave frequency on which that station operates.

The other options represent different concepts: decibels are a unit of measurement for power levels or signal strength, ohms measure electrical resistance, and voltage refers to the electric potential difference between two points. Although all these measurements are vital in the field of electronics and telecommunications, none pertain specifically to frequency in the way hertz does.