A 3-phase, 500 kV horizontal line has minimum height of 13 m, sag at mid span = 13 m, phase spacing, S =16 m. conductors are 4*0.035 m with bundle spacing of B = 0.4572 m, calculate the matrix of Maxwell's potential coefficient for an untransposed configuration per kilometer. for calculation take Hav = Hmin + sag/3.