Quantum beacon

From Memory Alpha, the free Star Trek reference

The quantum beacon was a device used by the Enterprise crew to reveal Suliban stealth-cruisers.

It was positron based, and had an output of 200 gigawatts. The subassembly tolerances were isolated from the emitter algorithms, which was made possible by generating a stable flux between the positronic conductors and renormalizing the tertiary wave functions.

The quantum engineering required to build it was beyond Starfleet's level; the necessary knowledge was provided by Crewman Daniels to Captain Jonathan Archer, who acquired the technical know-how to build them within a two hour span. The beacons were temporarily installed on the grappling arm, replacing the ship's usual clamps. (ENT: "Shockwave")

The beacons also proved useful against cloaked Romulan mines, but not birds-of-prey. (ENT: "Minefield")