We present an automatic framework combined space-time signal processing with Time Reversal electromagnetic (EM) inversion for subsurface and through-wall multitarget imaging using electromagnetic waves. This framework is composed of a frequency-wavenumber (FK) filter to suppress direct wave and medium bounce, a FK migration algorithm to automatically estimate the number of targets and identify target regions, which can be used to reduce the computational complexity of the following imaging algorithm, and a EM inversion algorithm using Time Reversal Multiple Signal Classification (TR-MUSIC) to reconstruct hidden objects. The feasibility of the framework is demonstrated with simulated data generated by GPRMAX.