Radio Frequency Jammers are devices which broadcast signals on one or more radio frequencies, deliberately blocking, jamming, or interfering with radio transmissions on the same frequencies. Typically used as criminal means to prevent radio-based communication devices on the same frequency from working, RF Jammers are illegal for private use in several areas, usually with the penalty of heavy fines.
RF Jammers do, however, have various tactical uses in combat, such as preventing Improvised Explosive Devices from detonating and sabotaging enemy communications, and usually see legally authorized use at military sites and checkpoints.
The RF Jammer appears in Battlefield 3 during the singleplayer mission Comrades. At the start of the mission, Dima activates the Jammer to prevent Solomon from detonating the nuclear device that the PLR operatives attacking the EURONEXT exchange are carrying, which will work as long as he remains within range of the bomb. Dima attempts to track down the bomb courier in the stock exchange, eventually pursuing him out of the building and killing him at a downtown metro station. However, the courier had nothing in his bag; he was sent out merely to lure the GRU operatives out of jamming range of the bomb, which is then denoted back at the EURONEXT.
The RF Jammer is a gadget introduced in the Battlefield Hardline: Getaway expansion for the Mechanic kit. The gadget temporarily disables nearby deployed enemy gadgets, such as Breaching Charges, Laser Tripmines, Satellite Phones, Cameras, and more. The jammer has an effective jamming radius around the player, shown on the minimap as a green circle around the player, and will disable any enemy gadgets in the radius for a couple seconds when activated. It may also be used inside of a vehicle.
The RF Jammer has a limited charge, shown by the meter on the front of the device, which lasts for about four seconds before depleting. The jammer will recharge at a consistent rate as long as there is charge left, shown by the meter being green; if the jammer is fully depleted however, the device will shut off and have to fully charge before use, as shown when the meter is red.