Topology-Optimised Metamaterial Design for Electromagnetic Wave Control in Nigerian Tropical Climate Communication Systems

Background: Metamaterials with engineered electromagnetic properties offer transformative capabilities for antenna miniaturisation, frequency selective surfaces, and electromagnetic shielding in communication systems. Design methodologies optimised for Nigerian tropical communication environments represent an unaddressed research frontier. Aim: This study developed topology-optimised metamaterial structures for electromagnetic wave control in communication applications at frequencies relevant to Nigerian telecommunications, accounting for tropical climate degradation effects. Methods: A combined topology optimisation and full-wave simulation framework was developed using COMSOL Multiphysics and a genetic algorithm-driven optimiser. Target functionalities included negative refractive index operation at 2.6 GHz and 3.5 GHz, and wideband frequency selective surface performance from 1 to 6 GHz. Prototypes were fabricated by photolithography on FR4 and Rogers substrates and characterised in an anechoic chamber. Experimental results were validated against simulation. Results: The topology-optimised negative index metamaterial achieved a figure of merit of 8.4 at 2.6 GHz, superior to conventional split-ring resonator designs. The frequency selective surface achieved a 3 dB bandwidth of 2.8 GHz centred at 3.5 GHz. Humidity accelerated aging tests showed less than 5% performance change after 1,000 hours at 85% RH. Conclusion: Topology-optimised metamaterials are viable for Nigerian telecommunications applications with adequate environmental stability. The design methodology is transferable to emerging 5G NR band requirements. Keywords: metamaterials, topology optimisation, electromagnetic wave control, Nigerian telecommunications, frequency selective surface.