You may also be looking for field emitters, or force field emitters.

Subspace field emitters are typically integrated into the warp nacelles on Federation starships.

Modifications to a starship's engine's power emissions, in conjunction with the installation of field buffers around the emitter coil, can cause a distortion of a ship's power signature to resemble malfunctioning phase modulators in the ship's subspace field emitters. (DS9: "The Homecoming")