Deflector shield (Stargate)

Deflector shields are seen many times throughout the Stargate universe, most notably the variety used by the Goa'uld

Goa'uld/Tok'ra shielding

The Goa'uld were the first race seen to possess shielding technology, although one of the weakest varieties. The Goa'uld use oscillating frequency principles for their shields, meaning that at the right velocity they can be penetrated by something moving sufficiently slowly or quickly.

Personal defense shields

These types of shields are GeneRally used by system lords to defend themselves and use the same oscillating frequency principle as their larger shield counterparts. These forms of shields have also been used to perform as an iris stopping matter from reintegrating unless the user is fitted in Kull warrior armor. It has also been used to create a one-way doorway to hold prisoners who are of extreme danger to the SGC.

Ship shields

Using the same oscillating frequency principle that all Goa'uld shields use they can also be penetrated by objects traveling at the right velocity, be it a dart or an energy weapon. When struck by a weapon the shields glows orange with the weapon either exploding or bouncing off. The SGC have developed missiles that have a frequency modulator chip that theoretically allows them to pass through shields, also Drone weapons can penetrate the most advanced Goa'uld shielding. The most advanced shields ever to be used by a Goa'uld have been the shields used on Anubis's mothership with Ancient technology so it is unknown if these forms of shields are just copies of the ancient shielding or if they have been modified by Anubis enough to be classified as original technology. Shields currently used by the Jaffa and Tok'Ra are incapable of fully stopping The Primary energy weapons of Ori warships, either.

Asgard shielding

Asgard shielding is of the most sophisticated shielding available possibly capable of rivaling the Ancients, one of the most profound shield makers to ever have existed. Asgard shielding uses a front and aft shielding generator to create a round elliptical barrier when struck. When struck the shield becomes apparent in its shape as stated above but also color. The colors seem to depend on the ship but it is unknown why or if it serves a purpose as to why the colors are different. This form of shield is the primary defense for all Beliskner-class cruisers as well as the BC-303 Prometheus and BC-304 Daedalus. The shield will succumb to continuous fire and eventually allow damage to bleed through to the hull of the ship if it is not removed from fire to allow itself time to recharge. A shield equipped with a ZPM gains a significant boost in power.

While in hyperspace, Asgard shields will not function, and the vessel will succumb to an external explosion if one occurs. Samantha Carter used this vulnerability against a fleet of Replicators invading an Asgard world. The Asgard used the first of the O'Neill class battleships as a decoy, fleeing into hyperspace. The Replicators followed it, and were destroyed when the ship self destructed.

Ancient shielding

The Ancients were arguably the most advanced shield makers in the universe. They were successful in creating almost impenetrable shields used as prison cells, on ships, and on their city Atlantis. The Ancient shields on a damaged (and presumably power-depleted) Ancient ship were capable of surviving in the midst of a huge volcanic eruption for at least 4.1 seconds.

References

de:Energieschild