Abstract
Maxwell’s partial differential equations of electrodynamics formulated in the late
nineteenth century represent a fundamental unification of electric and magnetic fields,
predicting electromagnetic propagation phenomena. Up to now researchers worldwide
use  computers  ranging  from  simple  desktop  machines  to  massively  parallel
supercomputing  arrays  to  obtain  solutions of  these  equations  for  the  purpose  of
investigating electromagnetic wave guiding, radiation and scattering.
Analytic solutions were, first, introduced. However, they are limited to specified
geometrical  structures.  Numerical  solutions  were, afterwards, developed  to  obtain
more  accurate  solutions  to  any type  of structure. Finite  difference  time  domain
(FDTD) technique is  a  direct  numerical  solution  method  for  Maxwell’s  time
dependent curl equations. This method employs no potentials. Rather, it is based upon
volumetric  sampling  of  the  unknown  near-field  distribution  of  fields  within  and
surrounding  the  structure  of  interest. The FDTD technique is  a  marching  in  time
procedure that  simulates the  continuous  actual  electromagnetic  waves  in  a  finite
spatial region by sampled data of numerical analogs propagating in a computer data
space. As the numerical wave propagates, the time is incremented taking into account
the  characteristics  of  the  modelled  different  regions. For  simulation, where  the
modelled region must extend to infinity, absorbing boundary conditions are employed
at the outer grid truncation planes which ideally permit all outgoing wave analogs to
exit the region with negligible reflection.
In  this  thesis,  a  lightning  return  stroke  model  is  chosen  to  illustrate  an
electrodynamic phenomenon. The lightning channel current is modelled  by analytic
approximation  in  the  form  of  Heidler  function  taking  into  account  the speed  of
propagation  and  the decreasing amplitude  giving  an  accurate  representation  of  the
phenomenon. Fields  radiated  by  the  channel  are, then, simulated  and  calculated
through  an  FDTD  domain  code.  Hybrid  method  is  used  to  show  the  simplicity  in
which the FDTD method can be implemented and manipulated with other methods.
Key  words: Electrodynamics, Maxwell’s equations, FDTD, lightning  strike, hybrid
solution.