This paper is devoted to the study of the electromagnetic Field measurement system at ELF and VLF band of frequencies. This system will be applied to detect the Electromagnetic Precursors, in a site near Cordillera de los Andes. The Magnetic Field Meassurement System, consist of a loop antenna of 252 turns, to induce a Voltage, conected to the Analog to Digital card, in a Personal Computer, running with a software to obtain the Fourier Transform of the input signal. The Antenna Factor is very usefull to link the Induction on the Loop antenna and the Magnetic field.
The Antenna Factor of the Loop Antenna, has been obtained by mean of the Helmholtz Coils, that have a Uniform Magnetic Field in the center. The magnetic field measured have been tested in the Laboratory