4.
在平面直角坐标系\(xOy\)中,曲线\(C_{1}\)的参数方程为\( \begin{cases} \overset{x=a\cos \phi }{y=b\sin \phi }\end{cases}(a > b > 0,φ\)为参数\()\),且曲线\(C_{1}\)上的点\(M(2, \sqrt {3})\)对应的参数\(φ= \dfrac {π}{3}.\)以\(O\)为极点,\(x\)轴的正半轴为极轴建立极坐标系,曲线\(C_{2}\)是圆心在极轴上且经过极点的圆\(.\)射线\(θ= \dfrac {π}{4}\)与曲线\(C_{2}\)交于点\(D( \sqrt {2}, \dfrac {π}{4}).\)
\((1)\)求曲线\(C_{1}\)的普通方程,曲线\(C_{2}\)的极坐标方程;
\((2)\)若\(A(ρ_{1},θ)\),\(B(ρ_{2},θ+ \dfrac {π}{2})\)是曲线\(C_{1}\)上的两点,求\( \dfrac {1}{\rho _{1}^{2}}+ \dfrac {1}{\rho _{2}^{2}}\)的值.