A Magnetic Frill Source Model for Time-Domain Integral-Equation Based Solvers

A magnetic frill source model developed for time-domain integral-equation-based solvers for accurate characterization of coaxially driven structures is presented. The MFS model is developed by representing the coax as a magnetic frill current, and the evaluation of the expressions for fields radiated by this current does not call for numerical differentiation of any kind. Also, the expression for the axial component of the electric field only calls for one-dimensional numerical integration. For model validation and demonstration of efficacy, the developed source model is incorporated into a marching-on-in-time (MOT) scheme for broadband characterization of coaxially-driven antenna structures comprised of arbitrarily shaped perfect electrically conducting surfaces and thin wires. The numerical results obtained from the MOT scheme incorporated with the developed source model are compared with values obtained by measurement, and with the traditionally used delta gap source model. Compared to the delta gap source model, the magnetic frill source model provides a relatively accurate characterization of the antenna structures over a wide band of frequency.