Huygens´ principle in electromagnetics

A simple way of deriving Huygens´ principle in electromagnetic and transmission-line theory is given without recourse to Green´s functions and Green´s formulas. Huygens´ principle is derived for the electromagnetic fields simply by truncating Maxwell´s equations. The same is done for the voltage and current in a transmission line by truncating the telegrapher´s equations. Some simple consequences are also discussed