This paper introduces two time-domain field-based optimization procedures for microwave engineering. The methods are built on the foundations of MATLAB's optimization and neural network toolboxes. The first procedure makes use of a direct connection linking MATLAB's optimization toolbox with MEFISTO-3D NOVA. In this approach the field simulator acts as an objective function server for the optimization toolbox; these two programs work cooperatively with each other to tune the structure parameters to obtain a target response. The second procedure is an indirect optimization approach that makes use of MATLAB's neural network toolbox in conjunction with MEFISTO-3D NOVA to create a neural network model to emulate the structure of interest; the resulting neural network model is then used an objective function server in a normal MATLAB optimization process. Copyright © 2006 John Wiley & Sons, Ltd.