Metallic mesh coatings are used on visible and infrared windows and domes widely to provide shielding from EMI (Electromagnetic Interference). In this paper, different EMI mesh geometries are compared with each other regarding various performance parameters. But to decide the best fitting EMI mesh geometry to particular optic system is a little bit complicated issue. Therefore, we try to find a simple optimization methodology to decide best EMI mesh geometry design that fits our particular high performance ISR (Intelligence, Surveillance and Reconnaissance) systems.