The signature radius is, for all intents and purposes, how "big" a ship appears on sensors. While the signature radius does not describe how big the ship appears visually, most other aspects are governed by the signature size of the ship.
A ship's signature is generally related to its size (a frigate is smaller and has a smaller signature radius than a battleship), and while all ships of a certain size tend to have similar signature radii, there are three ship classes with notably smaller signature radii than their peers:
- Logistics cruisers (Tech 2)
- Attack battlecruisers (also called "tier 3 battlecruisers")
- Blockade Runners (Tech 2)
There are also two classes of ships with notably larger signature radii than similar ships:
As a rough guide:
|Ship class||Sig. radius|
Signature radius affects many things, notably:
- How quickly a ship can be targeted.
- How much damage the ship takes from most weapons.
- How easily a ship can be detected with combat probes.
- Main article: Targeting
The larger a ship's signature radius, the faster other ships can lock on. Locking speed also depends on the scan resolution of the targeting ship (the higher the scan resolution, the faster you can lock on). Generally speaking, small ships have small signature radii and high scan resolutions, whereas large ships have large signature radii and low scan resolutions. For details on how to improve your scan resolution (or reduce your enemy's), see targeting.
Signature radius and weapon damage
A smaller signature radius can help to reduce incoming damage from turrets, missiles and bombs (the only weapon system that is not affected by signature radius is the smartbomb). You can find more information about this effect and the equations in the dedicated articles about Turret Damage, Missile Damage and Bombs.
Modifying signature radius
Modules and Rigs
There are no skills that alter the signature radius of your ship. However, there are several modules that will increase either your or your opponent's signature radius, and one module that can decrease your signature radius:
- Microwarpdrives (MWDs): These propulsion modules increase your signature radius by 500% while active (less for faction modules) in exchange for a 500% increase in speed. This means that while the MWD is active, all turret-based ships have a much greater chance to hit you. This can be offset by your increased speed, as long as you do not fly directly at the attacker. Against missiles, the increase in signature radius has no real effect on incoming damage, as the increase in velocity counters it.
- Target Painters: These EWAR modules increase the target's signature radius by 25-30%. This increase in signature radius can greatly boost damage if the target is smaller than the missile/turret type used against it, or if it's moving too quickly for the explosion radius of the missile/tracking of the turret. If your turrets hit often or the missile's explosion velocity is much larger than the target's velocity, target painters will have very little effect.
- Shield Extenders: The small, medium, large, and x-large shield extenders add a flat 1, 2, 7, and 25 m to the ship's signature radius, respectively.
- Shield Rigs: Each increases the ship's signature radius by 10%. Note this penalty can be reduced (down to 5%) with the Shield Rigging skill.
- Inertial Stabilizer modules: These increase your signature radius by 10-11%.
Signature Radius Suppressor
The Signature Radius Suppressor is an electronic support module found in pirate data sites. This module can only be fitted in battleship-class vessels (including Marauders and Black Ops). Notably, it is the only module that can reduce a ship's Signature Radius.
- The module passively reduces your signature radius by 10%.
- The module can be activated at a 660 GJ cost to reduce your signature radius by 70% for 12 seconds. Duration of the activation period can be improved by the skill Signature Masking.
- The module has a reactivation delay of 150s after use.