Star Trek Starship Deflector Shields

Deflector Shields

Deflector shields (so called because they deflect energy and physical objects from the ship to save it from harm, not because they have anything to do with the navigational deflector) are a ship's primary form of defense. They (and related types of technology, such as multiphasic force fields) are fields of highly focused spatial distortion created by shield generators and focused by subspace field amplifiers, within which generators maintain an energetic graviton field. Shield grids on the exterior of the hull shape the shield to conform to the ship (collectively, the shield grids are referred to as the shield matrix). When energy or physical objects impact the shield, its field energy is concentrated at the point of impact to resist the intrusion. Impacts are accompanied by a quick flash of Cerenkov radiation which humanoids perceive as a flash of colored light (blue for Starfleet shields, sometimes different colors for other species' shields.)

Shields are activated, or "raised," whenever threats to the ship become apparent. This could be an enemy attack, potentially dangerous emissions from a nearby star, or the presence of some enormous spacefaring creature. Shield modulation frequencies shift at random to prevent an enemy from adjusting the frequency of its weapons to penetrate the shield without resistance (on the other hand, adjusting the shields to match the frequency of a weapon can strengthen them against it). Raised shields interfere with sensors, so shield frequency rotation creates electromagnetic "windows" to which sensors automatically recalibrate to minimize this effect. (In game terms, shields without such windows impose a -1D penalty on all Sensors Tests (minimum of 1D is still rolled); Tests made when windows exist are rolled normally.) Often, however, Silent Running mode (See Operations Systems) comes into effect when shields are raised, so only passive sensor use is allowed anyway. Shields completely block transporters; no one can transport onto or off of a ship whose shields are raised.

Shields also interfere with warp travel. Software which controls warp drive and shield operation compensates for this effect. Without such measures, use of shields reduces a ship's Standard, Sustainable, and Maximum warp speeds by one-third.

Shields would interfere with outgoing attacks, except that Starfleet has anticipated and corrected for these problems. Torpedoes are equipped with shield transponders which allow them to pass through the shields unimpeded. (It might be possible to interfere with the transponder's signal, causing it to explode, but no workable means has yet been developed to take advantage of this idea.) Beam weapons' frequencies are set by the tactical computers to match that of the shields, so they pass through unhindered. (Theoretically, a ship could gauge another ships' shield frequency and sensing the frequency of outgoing beam weapon attacks, but rapid shield frequency changes during combat generally eliminates any chance of making practical use of this theory.)

Buying and Using Shields

Every ship has four shields: Forward, Aft, Port, and Starboard. Each one is paid for separately in terms of Weight Cost; each shield must have the same characteristics (the Aft shield cannot be weaker than the Forward shield, for example). Each shield provides a certain amount of Protection. When Protection reaches 0, the shield collapses and the ship is vulnerable to attack on that side. Each shield has a Recharge rating which indicates how long it takes for it to return to full strength after collapsing or being turned off.

Optional Rule: Shield Threshold: Even while shields remain intact, some damage manages to "leak" through them from some attacks. This reflects the concussion damage to the ship from extremely strong attacks, sudden changes in inertia, and other factors. Each shield generator incorporates a subspace field distortion amplifier which provides the shield with a Threshold rating. Threshold indicates the point at which damage leaks through the shield. For example, if a shield has a Threshold of 1D+2, an attack which does 7D+2 will leak 6D through to the ship. Hull Resistance offers defense against "leaked" damage. A ship's Threshold cannot exceed one-third of its full normal Protection except in certain circumstances (for example, if a shield offers Protection 5D, its Threshold cannot be higher than 1D+2).

The accompanying table describes the various types of shield equipment, their Weight costs, and their effects. Each type of equipment - shield generator, shield grid, subspace field distortion amplifiers, and shield recharging system - must be purchased per shield (i.e., four times).

Size	Length Range	Beam Range	Height Range
16	5,000 - 5,999 m	2,500 - 2,999 m	1,500 - 1,799 m
15	4,000 - 4,999 m	2,000 - 2,499 m	1,200 - 1,499 m
14	3,000 - 3,999 m	1,500 - 1,999 m	1,000 - 1,199 m
13	2,000 - 2,999 m	1,200 - 1,499 m	800 - 999 m
12	1,500 - 1,999 m	1,000 - 1,199 m	600 - 799 m
11	1,000 - 1,499 m	800 - 999 m	400 - 599 m
10	800 - 999 m	700 - 799 m	300 - 399 m
9	700 - 799 m	550 - 699 m	200 - 299 m
8	600 - 699 m	400 - 549 m	100 - 199 m
7	400 - 599 m	200 - 399 m	80 - 99 m
6	300 - 399 m	100 - 199 m	50 - 79 m
5	150 - 299 m	50 - 99 m	31 - 49 m
4	100- 149 m	26 - 49 m	21 - 30 m
3	51 - 99 m	11 - 25 m	6 - 20 m
2	6 - 50 m	4 - 10 m	2 - 5 m
1	1 - 5 m	1 - 4 m	less than 2 m

Shield Generator	Weight Cost	Protection		Distortion Amplifiers	Weight Cost	Threshold
Class 1	10 x Size	1D+2		Class Alpha	10 x Size	0D+1
Class 2	20 x Size	3D+1		Class Beta	15 x Size	0D+2
Class 3	30 x Size	5D		Class Gamma	20 x Size	1D+1
Class 4	40 x Size	6D+2		Class Delta	25 x Size	1D+2
Class 5	50 x Size	8D+1		Class Epsilon	30 x Size	2D
Class 6	60 x Size	10D		Class Zeta	35 x Size	2D+1
Class 7	70 x Size	11D+2		Class Eta	40 x Size	2D+2
				Class Theta	45 x Size	3D+1
				Class Iota	50 x Size	3D+2
Shield Grid	Weight Cost	Increase		Recharging System	Weight Cost	Recharge Speed
Type O	0	0%		Class 1	5 x Size	9 rounds
Type A	5 x Size	25%		Class 2	10 x Size	8 rounds
Type B	10 x Size	33%		Class 3	15 x Size	7 rounds
Type C	20 x Size	50%		Class 4	20 x Size	6 rounds

Write up notes:

• All Four systems must be purchased for each Shield Arc, regardless of whether or not the optional Shield Threshold rule is used.
• All Shield Systems listed are capital scale.