In this paper is proposed a methodology for measuring the electric field strength in two types of environments: rural and suburban campuses of the University of Quindío from the ITU-R P.1406-1 recommendation. This recommendation proposes approximately 36 measurements at equal intervals over a distance of about 40 wavelengths, to obtain a median accurate to within 1 dB with 90% probability in the measurement the electric field strength. With the development of this paper a coefficient of variation to reduce the number of measurements of the electric field strength in the bands 800 and 1500 MHz with variations of less than 10% is obtained, reducing two-thirds of the number of measurements and maintaining the precision and probability conditions given in the recommendation.