In recent years, arrays have been widely used in many applications, especially those applications that need high guidance, whether in military, medical, or other applications. Arrays are highly oriental, unlike single antennas. In this work, we analyze the effect of the insulating substrate insulation constant on the 2X2 microstrip patch antenna array at a frequency of 2.4 GHz, which is suitable for WLAN applications. CST Microwave Studio Version 2019 was used to design, simulate, and analyze the proposed model. The bar line feeding technique was used to feed the array. A set of mathematical relationships was used to calculate the dimensions of the array. We simulated and analyzed the array on three dielectric pillars: (FR-4) with a dielectric constant of 4.3, (Polycarbonate) with an isolation constant of 2.9, and (Porcelain) with an isolation constant of 6. The 2X2 array was manufactured and printed on the insulating substrate (FR-4) and the practical results were compared with the simulation results. There was a good agreement between the practical and theoretical results
