Computational Time Reversal—A Frontier in Electromagnetic Structure Synthesis and Design

Microwave component design by electromagnetic structure synthesis is attractive because the electromagnetic field has the inherent property to minimize loss, sensitivity to tolerances, and vulnerability to field breakdown. However, it is conceptually and computationally challenging, and its technical possibilities have thus been explored only tentatively so far. This paper introduces a first, but critical new step towards systematic electromagnetic structure synthesis, based on computational time reversal, and employing the time and space discrete transmission line matrix (TLM) method. The novelty of this paper resides in the exploitation of the scattering nature of the TLM model, which allows the near-field of a source or a scatterer to propagate into the far-field and back. By ignoring the conventional restriction that spatial wavelengths must always be much larger than the space discretization step, one can reconstruct multiple impulsive sources with the spatial and temporal resolution of the TLM algorithm. This crucial insight promises to be the key to a successful synthesis strategy. This paper describes the reconstruction of electromagnetic sources through computational time reversal, demonstrates the self-consistency of this procedure by means of a validation example, and outlines the next steps towards a full electromagnetic synthesis capability.