Disclosed herein is a system and method for determining a thickness of ice on Radio Frequency (RF) systems The system includes a sensor unit for use in determining the thickness of ice on a surface of a RADAR system having a RADAR antenna, the sensor unit including a sensor unit antenna tunable to a harmonic of a RADAR antenna signal, the harmonic having a frequency within an ice absorption band, wherein the sensor unit antenna emits the harmonic at a first signal strength; and, a sensor unit receiver communicatively coupled to the sensor unit antenna and configured to detect a second signal strength of the harmonic received by the sensor unit antenna.