Subspace defense field
A subspace defense field was an advanced, subspace-based defense field technology utilized aboard Pralor vessels. 

Following the abduction and transport of B'Elanna Torres off , by Pralor Automated Personnel Unit 3947, to aboard one of these vessels, Harry Kim was unable to make a transporter lock on her to bring her back. Kim noted that they had "erected some sort of subspace defense field around their vessel" and that "our targeting scanners can't penetrate it." In further attempting to locate Torres aboard the vessel, Chakotay noted that "their shielding is making it tough to get clear readings." ()

Subspace
Shield technology