Time-domain Computations using Source Functions and Field-source Equilibrium Relations

D. Mitrovich (USA)


Time domain Green function; Equilibrium relations


An electric field dyadic Green function for free space is derived in a form, called a `source function', with an in tegrable singularity in the source region. It allows explicit time evolution of the modified electric field integral equa tion (EFIE) applied to surface scattering. The field-source equilibrium (FSE) relations are derived between the non local electric and magnetic fields on the one hand, and the surface sources (currents and charges) on the other. These `exact' relations include the interaction fields as well as the usual incident fields from distant sources. If the in teraction fields are neglected the magnetic field FSE re lation becomes the usual Physical Optics approximation. Source functions and the FSE relations were used in two three-dimensional, time domain numerical simulations to compute: radiation patterns from a conical helical antenna driven at a fixed frequency, and scattering of a cw plane wave by a perfectly conducting sphere. This surface scat tering simulation was explicit but remained stable. Excel lent agreement between the computed and known results validates the approach.

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