  During recent years interest has been rising for applications of vector light
beams towards magnetic field sensing. In particular, a series of experiments
were performed to extract information about properties of static magnetic
fields from absorption profiles of light passing through an atomic gas target.
In the present work, we propose an extension to this method for oscillating
magnetic fields. To investigate this scenario, we carried out theoretical
analysis based on the time-dependent density matrix theory. We found that
absorption profiles, even when averaged over typical observation times, are
indeed sensitive to both strength and frequency of the time-dependent field,
thus opening the prospect for a powerful diagnostic technique. To illustrate
this sensitivity, we performed detailed calculations for the $5s \;\,
{}^2S_{1/2}$ ($F=1$) $-$ $5p \;\, {}^2 P_{3/2}$ ($F=0$) transition in rubidium
atoms, subject to a superposition of an oscillating (test) and a static
(reference) magnetic field.
