Field coil
The field coil was a form of technology designed to transmit subspace emissions, which functioned as key components in starship and space station operations, including the sensors, warp drive and communications systems. ()

After entering V'ger, Spock discovered what he described as "a kind of plasma-energy conduit – possibly a field coil for a gigantic imaging system," where he discovered a series of images depicting objects encountered by V'ger. ()

In the mid-24th century, the  starships were built with both primary and secondary field coils. Engineers aboard these starships had access to technical manuals for these monitors, which were stored in the Engineering Systems Database. For the Galaxy-class , Doctor Leah Brahms wrote the operating protocols for both types of coils. ( okudagram)

Twenty-three field coils, working in concert from the surface of Bilana III, were the source behind the creation of a soliton wave, the first step towards "warp without warp drive." ()

A verteron pulse was capable of overloading the field coils aboard a starship. This method was used by the Hekarans to disable several ships that traversed the Hekaras Corridor in mid-2370. ()

In order to keep a transporter signal lock on an individual, and counteract the effects of a subspace transporter system, it was necessary to tie a ship's subspace field coils into the transporter system. This tie in could be used for implementing a subspace transport, by means of using the transporter system to shunt something through subspace. ()

Clogged plasma injectors could cause both the inertial dampers and field coils to go off line. ()

Field coils were utilized in Cardassian space stations, such as Terok Nor and Empok Nor. () While stranded on Empok Nor in 2373, Chief Miles O'Brien suggested the modification of the field coils to emit a series of covariant pulses through the deflector grid, and "use the station like an old-fashioned telegraph and tap out an SOS," but in order for the signal to be strong enough, it was necessary to boost power to the station's induction grid. ()

See also 
 Chambers coil
 Driver coil
 Plasma coil

de:Subraumfeldspule
nl:Veldspoel
Subspace
Spacecraft components