This paper presents microstrip patch antenna array for RF energy harvesting system. The goal of proposed and fabricated antenna is to harness energy from surrounding environment consisting of mobile phone towers. The antenna has as: η=((PDC)/(Preceived))* 100(2) been designed to work in GSM1800 band. Initially a two patch antenna array has been designed and was later modified to four patch antenna array. Antenna simulation, analysis, computation of return losses, 3D polar plot and gain of the antenna has been done using High Frequency Simulator Software (HFSS). The simulated results show that the antenna array provides good performance in terms of return loss of-25 dB and a high gain of 9.2 dB resonating at 1.78 GHz frequency.