The subnucleonic beam was a Hirogen ship-mounted weapon.

A subnucleonic beam could perform rapid scans of an enemy ship and could also severely disable it. The subnucleonic beam worked by disrupting a ship's propulsion systems, communications systems, weapons, and its navigational sensors. Once a target ship was disabled, the Hirogen used their tractor beam technology to draw in their prey. (VOY: "Hunters")