Synchronization is an important feature in wireless sensor networks, often needed to enable correct operation. In this paper, the usage of magnetic field coupling is explored, to provide Time of Flight information, useful to develop a timestamp based clock distribution system. In particular, the proposed approach can be easily implemented using very low-cost hardware, despite the good performance that can be obtained. Experimental results show very good short-term stability; standard deviation of consecutive signal burst inter-arrival time is in the sub-nanosecond region. The results have been compared with a similar commercial solution using low frequency wakeup receiver; in this case, standard deviation of signal bursts inter-arrival times is on the order of few microseconds.