We are performing a multi-frequency radio analysis of a well-known deep field: the Lockman Hole, which is one of the best studied sky regions in different wavebands. This will provide us with important complementary data (for example redshifts) to the radio data, allowing us to characterize the physical and evolutionary properties of the various classes of sources composing the faint radio population. LOFAR imaging of the Lockman Hole can play an important role in this project, allowing, for the very first time, to observe the sub-mJy source population at very low frequencies (30-200 MHz), where self-absorption phenomena are expected to be very important. Here we present some preliminary results.