Changes

\frac{ 4\pi \leftbig| \mathbf{E^{ff}}(\theta,\phi) \rightbig|^2 |_{max} }{ \int\limits_0^{2\pi} \int\limits_0^{\pi} \leftbig| \mathbf{E^{ff}}(\theta,\phi) \rightbig|^2 \sin\theta \,d\theta \,d\phi }