How electromagnetic fields travel through vacuum? How electromagnetic fields travel through vacuum is it right to say that they propagate or travel? do they alternately form each other by charged particles?
 A: 
from a, b and c:
An electromagnetic field is propagating by changing the field that's
  generated by electrically charged particles pass through the air and
  the space that is devoid of particles of space.

An electromagnetic wave propagates, not an electromagnetic field.  An EM wave is a propagating disturbance in the existing electromagnetic field.
Consider the field of an isolated charged point particle - the field extends over all space.
Should the particle abruptly accelerate for some short time, the disturbance in the electromagnetic field of the particle will propagate 'to infinity' at the speed $c$.
From the classic textbook "Gravitation":

For an animated visualization, try the Java applet here.
A: The electromagnetic field is mediated by the exchange of virtual photons. This is described by Quantum electrodynamics. It's this exchange that bridges the gap of empty space.
I think the answer to this question has a pretty good representation of how an electromagnetic field propagates (at the speed of light) in vacuum.
