已知\(O\)为坐标原点,点\(E\),\(F\)的坐标分别为\(\left( -\sqrt{3},0 \right),\left( \sqrt{3},0 \right)\),点\(P\),\(N\)满足\(|\overrightarrow{PE}|=4,\overrightarrow{ON}=\dfrac{1}{2}\left( \overrightarrow{OP}+\overrightarrow{OF} \right)\),过点\(N\)且垂直于\(PF\)的直线交线段\(PE\)于点\(M\),设点\(M\)的轨迹为\(C\).
\((\)Ⅰ\()\)求轨迹\(C\)的方程;
\((\)Ⅱ\()\)若直线\(l\)与\(C\)相交于\(A\),\(B\)两点,原点\(O\)到直线\(l\)的距离为\(1.\)求\(\triangle AOB\)面积的取值范围.