Past studies show that non-ionizing radiation (NIR) exposure may affect living things. Thus, this kind of exposure needs to be monitored to provide sustainable public health. The proper measurement technique and the high gain antenna are required to obtain an optimum reading. The main purpose of this paper is to provide the performance analysis results of a circular patch (CP) antenna which operates up to 4 GHz. The antenna is designed and simulated using CST Studio Suite® software which has a simple circular radiation patch structure with half grounded plane with defected ground structure (DGS) design. The comparison between the performance of the proposed CP antenna characteristics and the simulation results were presented in terms of the radiation pattern, bandwidth, S-parameter, gain and efficiency for validation. Based on the actual measurement results, the CP antenna performance is acceptable since it successfully operates within the targeted frequency band (S-parameter: 0.89 GHz to 4 GHz) with the percentage of frequency bandwidth (FBW) that is equal to 127.2%. Besides, the highest gain of simulated and measured obtain are 2.099 dBi and 5.17 dBi respectively with the omnidirectional radiation patterns for both measurements. The developed antenna is suggested to be used in the ambient reading of frequency signals for NIR exposure measurement purpose. © Penerbit UMT.