A compact sensor system integrates electric and/or magnetic field sensors to accurately measure, with a high level of sensitivity, one or more electric and magnetic vector components of fields. The electric and magnetic field data can be utilized separately or combined. The sensor system is self-contained so as to include a built-in power source, as well as data storage and/or transmission capability. The integrated sensor system also preferably includes a global positioning system (GPS) to provide timing and position information, a sensor unit which can determine the orientation and tilt of the sensor system, and self-calibrating structure which produces local electric and/or magnetic fields used to calibrate the sensor system following deployment.