THE NON-RADIATING COMPONENT OF THE FIELD GENERATED BY A FINITE MONOCHROMATIC SCALAR SOURCE DISTRIBUTION

We separate the field generated by a spherically symmetric bounded sca lar monochromatic source into a radiative and non-radiative part. The non-radiative part is obtained by projecting the total field on the sp ace spanned by the non-radiating inhomogeneous modes, i.e. the modes w hich satisfy the inhomogeneous wave equation. Using residue techniques , introduced by Cauchy, we obtain an explicit analytical expression fo r the non-radiating component. We also identify the part of the source distribution which corresponds to this non-radiating part. The analys is is based on the scalar wave equation.