This article presents a new hybrid technique which combines two different numerical methods in the frequency domain, namely the Frequency Domain Transmission Line Matrix (FDTLM) and the Wave Concept Iterative Process, to analyse three-dimensional (3D) microwave structures. As a result, a considerable reduction of the computation time and required computer memory is achieved compared with the classic FDTLM. The good agreement between simulation results and experimental published data validates the present analysis approach.