The Sensor Jammer is a special weapon of the game Star Trek: Armada which temporarily deactivates the sensor system of opposing ships within the radius of its effect. This is the same effect a Mutara Nebula has on sensors. It cannot be countered. It will wear off by itself. It is researched at the Covert-Ops Facility. The Sensor Jammer looks like this, when used:

The Sensor Jammer can be used while under cloak, provided the special energy is still enough for use. The using unit will then decloak. Cloaked ships affected by this weapon will decloak as well. An active Corbomite Reflector has no effect on this special weapon. Neither does the Shield Remodulation. The Phase Cloak, however does protect from it.