A magnetic field pad location system is provided with dual elongated field generation pads with self-tracking. Each pad comprises magnetic coils operable to generate magnetic fields. The pads include a mechanism for securing the two pads in place on a patient table to prevent movement of the pads. A processor executes a process for installation of the two pads, comprising correlation of the magnetic fields generated by the coils to define a reference magnetic field for sensing. In one embodiment, each pad includes a same number of magnetic coils in each spatial direction. In one embodiment, the magnetic coils are tri-axial coils placed at corners of the pads. In another embodiment, each pad includes an array of six single coils.