Cyclonic Barriers

Cyclonic Barriers, along with grav-plating are one of the few pretech technologies that's design was simple enough to be easily replicated today in the postech era. While commonly shortened to just "shields" the nomenclature does not translate perfectly. Shields like those seen on smaller planetary vehicles, starfighters and advanced suits of power armor are actually entirely different forms of technology.
Cyclonic Barriers are used on large scale starships (frigates and higher) as a purely defensive technology. Usually installed as part of the life support suite, cyclonic barriers draw massive quantities of power from a ship's reactor and funnel it through a dimensional converter. This newly converted meta-dimensional energy is then stored within the cyclonic barrier system until needed.
When the ship comes under fire, advanced automated systems (often aided by a combat VI) inject the energy into several of the thousands of barrier emitters spread across the hull of the ship. These emitters spin this energy in the cyclone shapes from which the system derives its name, creating a barrier of meta-dimensional energy that covers the threatened portion of the hull. This barrier can diffuse as much as 70% of the energy used by energy weapons, and warps the trajectories of projectile weapons so they either miss entirely or hit with only glancing blows.
The systems are not infallible however. More often than not they only reduce incoming damage instead of stopping it entirely, and they are susceptible to overload should too much fire target the same hull section at one time.