DEFENSIVE SHIELDS

The term "shields" refers generally to the energy field generated to protect starships and other spacefaring vessels from harm, whether natural hazards or an attack by threat forces. The term includes deflectors (USS Voyager has a main deflector and an auxiliary deflector). This page describes defensive shields, as used to protect against enemy attack. Tuvok: "Aft shields are down, Captain. Re-routing auxiliary power to the shields." source CC

Voyager's shields in use. The purple-white "bubble" around the ship becomes visible whenever enemy fire hits them. Here Voyager flies over a Borg tactical cube. [Unimatrix Zero]

Shields are the primary defence system and, when raised, they encompass the entire vessel. Shields are generated through the grid that covers the uper port and starboard sides of the ship's engineering hull. They comprise a barrier of projected energy. The frequency of the energy barrier can be modulated or rotated on demand, as when the order is given to "rotate shield harmonics", in order to maximise effectiveness. The term "shield harmonics" actually refers to the interaction of different frequencies of forcefield energy present in a deflector shield. Shield harmonics vary with the modulation, geometry, frequency and nutation of the shields. This set of data can also be used in much the same way as a fingerprint in order to identify ships by their type, class and origin. [#38 Innocence]

Voyager's shields in use as a Kazon-Nistrim warship opens fire.
[#27 Maneuvers]

Example of the use of rotating shield harmonics:

In [#27 Maneuvers] Voyager is suddenly fired upon by a Kazon raider. Voyager tries hailing the Kazon ship but there is no response. A hit puts the warp engines offline so that Paris cannot implement Janeway's order to go to warp 3 and escape. Voyager returns the Kazon fire and implements evasive pattern omega 3. Tuvok reports that the Kazon are continuously matching their weapons frequency to Voyager's shield frequency. The Kazon phaser fire makes an opening in Voyager's starboard shields 72 centimetres in diameter. Chakotay tries to close it by rotating shield harmonics. The opening grows to 4 metres and Chakotay orders Tuvok to rotate shield harmonics continuously. This has no effect. The animated screenshot shows Voyager's shields being hit by Kazon phaser fire.

You need animated images enabled to see the above animated screenshot.

In [#136 Collective] Janeway resists attempts by a group of Borg children to seize Voyager's deflector. When the Borg children lock a Borg tractor pulse onto the deflector dish, it causes stress on Voyager's hull and hull breaches on decks 10 and 11, and Janeway orders, "Increase shield strength and randomise the harmonics."
Here is an animated screenshot showing the Borg tractor pulse trying to tear off Voyager's deflector dish.

Shields are raised on demand, but the ship's computer can automatically raise them whenever it identifies a threat.

USS Voyager's shields extended around USS Equinox. [#120 Equinox, Part One]

Modified shields around USS Voyager and USS Equinox [#120 Equinox, Part One]

Shields can also be extended. For instance, in [#120 Equinox, Part One] Voyager extended her shields around USS Equinox (above left). This was done by matching the frequency of the Equinox's shield emitter.

Shields are vulnerable to repeated attacks. Shield integrity is usually reported to the ship's captain expressed in percentage terms e.g. shields are down 20% or are at 80%.

Voyager's shields are also vulnerable to chroniton-based weapons such as chroniton torpedoes because they are in a state of temporal flux. In [#76 and #77 Year of Hell] Seven and Tuvok successfully developed shields against such weapons, the events in that story "unhappened", so that in the corrected timeline Voyager did not enter Krenim space, nor was attacked by chroniton-based weapons, and so did not develop a defence against them.

Transporters cannot be used while shields are raised as nothing and no one can be beamed through a shield. (This fact was first mentioned in [TOS: Arena].) For instance, in [#41 Resolutions] Tuvok orders the shields to be temporarily lowered during an attack by Vidiians in order to transport aboard an anti-viral serum, leaving Voyager vulnerable for those few seconds.

Transporters cannot penetrate multi-phasic shielding [#135 Tsunkatse].

Next page: WEAPONS including self-destruct system.