53. In spherical coordinates, let $\widehat a_\theta.\widehat a_\phi$ denote until vectors along the ,θ φ directions.

$E={100\over r}\sin\theta cos(\omega t-\beta r)\widehat a_\theta$ V/m  and

$E={0.265\over r}\sin\theta cos(\omega t-\beta r)\widehat a_\phi$  A/m

represent the electric and magnetic field components of the EM wave of large distances r from a dipole antenna, in free space. The average power (W) crossing the hemispherical shell located at r=1km,0≤θ≤π/2 is _______