@TechReport{	  it:2002-007,
  author	= {F. Edelvik and G. Ledfelt and P. L{\"o}tstedt and D. J.
		  Riley},
  title		= {An Unconditionally Stable Subcell Model for Arbitrarily
		  Oriented Thin Wires in the FETD Method},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Scientific Computing},
  year		= {2002},
  number	= {2002-007},
  month		= feb,
  abstract	= {A computational subcell model for thin wires is developed
		  for electromagnetic simulations. The Maxwell equations are
		  discretized by a finite element approximation on a
		  tetrahedral grid. The wires are described by a second-order
		  equation for the current. The geometry of the wires can be
		  chosen independent of the volume grid. A symmetric coupling
		  between field and wires yields a stable semi-discrete
		  field-wire system and an unconditionally stable fully
		  discrete field-wire system. The system of equations is in
		  each time step solved by a preconditioned conjugate
		  gradient method. The accuracy of the subcell model is
		  demonstrated for dipole and loop antenna with comparisons
		  with the Method of Moments and experimental data. }
}