This paper presents a novel, low-cost, and portable RF power measurement system, operating in GSM 900 and GSM 1800 frequency bands. This measurement model consists of four basic circuits; microstrip folded dipole antenna (MFDA) that received the ambient RF signals, a power meter that generates DC output voltage according to received RF signal power level, a microprocessor that converts the data's analog to digital, and a computer to record and screen the time-varying data. Seventeen measurements, each for six hours, were performed in nine locations in Isparta for the indoor-to-outdoor scenario. The range between the minimum and maximum power values of the average RF power levels obtained in time-dependent measurements was calculated as approximately 15 dB, 18 dB, and 33 dB for indoor, semi-indoor, and outdoor ambients, respectively. The indoor/semi-indoor/outdoor ambient RF power levels were respectively varied between −55.1 dBm to −4.13 dBm, −43.92 dBm to −6.12 dBm, −44.89 dBm to 0.1 dBm in all measurements.