In military terms, the radius of action or combat radius: the range within which a weapon system (e.g., fighter aircraft) can operate.
戦闘機の行動半径は燃料搭載量や積載により変わる。
A fighter's combat radius varies depending on fuel load and payload.
空母の護衛艦隊は、その行動半径を考慮して展開した。
The carrier escort fleet deployed taking its operational radius into account.
The sphere or range of activity: the area within which a person or organization usually acts or moves.
子どもが小さい間は行動半径が家の周りに限られることが多い。
While children are small, one's range of activity is often limited to the area around the home.
転職してから行動半径が広がり、新しい友人もできた。
After changing jobs my range of activities expanded and I made new friends.