Recycling RF energy in the GSM-1800 band

In this paper, we present a study about the recuperation and the wireless transfer of the RF micro-energy in the waveband 1800 MHz -1900MHz. Actually, a series of measurements of the power RF available in the ambient surrounding using a spectrumanalyzer has enabled to us to determine the level of this power which is nearly constant in time and of order 14.5dBm/m2 (33.4μW/m2). Meanwhile, two types of antenna were studied to recover the power RF. The first is a spiral antenna which represents a quasi-unidirectional radiation with a circular polarization and a measured gain equal to 2.24dBi, the second is a array of circular patch antenna with a rectilinear polarization and a measured gain equal to 5.24dBi. Additionally, a rectifier RF/DC with low power of input based on Schottky diodes (voltage double) was characterized. Two systems (rectenna) were also tested in the ambient surrounding where the maximum measured power is about 0.33μW. What is more, some energy transfer tests were carried out inside the anechoic room whose the efficiency of conversion RF/DC could reach 20%. The maximum transferred power DC is equal to 5.6μW, with an 18KΩ of load.