A portable model of heavy weaponry, the Radiation Cannon fired radiation at organic enemies to wear them down. The weapon had no adverse effects for droids, so those equipped with the cannon felt as though they had little to fear from the radiation it would fire; as such, battle droids could be outfitted with the cannon to fire upon enemy defenses and slowly but surely erode away otherwise effective positions.
Instead of their standard E-5 blaster rifles, some B1 battle droids (pictured) were deployed into combat with more powerful weaponry, such as Radiation Cannons.
During the Clone Wars between the Confederacy of Independent Systems and the Galactic Republic, the Confederacy armed some of its B1-series battle droids with Radiation Cannons. Serving in the Separatist Droid Army, the droid troopers armed with those weapons were useful for wearing down defenses built by Republic clone troopers. Equipped with a much more powerful weapon than other B1 units, thus giving them unique capabilities that enchanced their unit formations, Radiation Cannon–equipped B1s became an example of how the normally standardized Droid Army sometimes rearranged its weaponry to provide its droids with new ways to achieve victory in battles.
When equipped with a Radiation Cannon, a B1 would need to look past the army's standard issue E-5 blaster rifle to instead fully capitalize on the new gear. During one engagement between 20 BBY and 19 BBY, one such B1 fought against Republic clones in a forested environment. Radiation Cannon–armed B1s were also fielded in conjunction with E-5s sniper rifle–equipped B1s; the Radiation Cannon–equipped units attacked defenses on the frontline, while the droids armed with the sniper rifles targeted enemies who were hiding behind cover.
The miniature of what Star Wars: Legion calls a "Radiation Cannon B1 Trooper" was included with other B1 models in the B1 Battle Droids Upgrade Expansion.
The Radiation Cannon was introduced to the new Star Wars canon in an August 6, 2019 article on Fantasy Flight Games' website advertising the B1 Battle Droids Upgrade Expansion for their Star Wars: Legion tabletop game. Along with other B1 models and cards, the B1 Upgrade Expansion came with a finely sculpted hard plastic miniature—which players can paint in any way they chose and can be assembled to represent a B1 unit that the game calls a "Radiation Cannon B1 Trooper"—and a card of the droid trooper.
Within the Star Wars Legends continuity, the cannon originated in the LucasArts video game Star Wars: Battlefront, which was released on September 21, 2004. It was used by pilot battle droids during ground combat. Named the "radiation launcher" in the game itself, the weapon was identified as the RD-4 grenade launcher in the game's official guide, which was written by David Knight and published by Prima Games on September 28 of that year.