  The kinetic transport of electrons through graphene magnetic barriers is
studied theoretically in presence of an external time harmonic scalar
potential. The transmission coefficients are calculated in the framework of the
non-perturbative Floquet theory using transfer matrix method. The time
dependent scalar potential is found to suppress the usual Fabry-Perot
oscillations occurring in the transmission through a constant vector potential
barrier (corresponding to two oppositely directed delta-function magnetic
barriers). Two types of asymmetric Fano resonances (FR) are noted and are
discussed for the narrow barrier structure. One of them arises due to the
oscillatory mode while the other due to the evanescent mode of the electron
wave inside the barrier. In contrast, the oscillating field favors the
transmission for rectangular magnetic barrier structure and also exhibits the
FR due to the presence of bound state inside the barrier. The characteristic
Fano line shape can be tuned by varying the amplitude of the oscillating
potential. The detection of such FR offers an efficient tool for the
identification of the quasi-bound and evanescent extended states inside the
barrier not reported in the literature so far, for the case of graphene
magnetic barrier structures.
