Signal booster
A signal booster was a vital component of any communications system and was designed to strengthen the signal. 

When Lieutenant Uhura was picking up a faint distress call from an unidentified spacecraft, while the  was in orbit of Capella IV, Mr. Scott suggested she "put a booster on it" and "try to pull it in." ()

While crash landed on an unnamed planet in the Gamma Quadrant, Quark told Odo that the signal booster of the  was completely shot. ()

See also 
 Booster
 Subspace amplifier

Communications technology
Subspace