  We are concerned with increasing stability in the inverse source problems for
the time-dependent Maxwell equations in R^3 , where the source term is
compactly supported in both time and spatial variables. By using the Fourier
transform, sharp bounds of the analytic continuation and the Huygens principle,
increasing stability estimates of the L^2 -norm of the source function are
obtained. The main goal of this paper is to understand increasing stability for
the Maxwell equations in the time domain.
