A GSM1800 band antenna using inverted suspended circular patch is presented in this work. The proposed antenna is suitable for some specific used such as energy harvesting systems. The main objective of simulation is to increase the gain of patch antenna. A circular patch antenna of 32 mm radius has been optimized using Ansotf HFSS.v.15. The simulation results of antenna shows the return loss is -21 dB at 1.8 GHz for VSWR≤ 2. The maximum gain of antenna is obtained at 7.5 dB. The gain of antenna is increased by inverted suspended circular patch with same dimension of radiating patch from 7.5 dB to 8.5 dB. The gain of the antenna is increased with increasing the gap between top and bottom patch because of coupling between them. The gain of antenna is increased from 8.2 dB to 8.5 dB when gap is increased from 1 mm to 4 mm.