Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract This paper proposes a partition of unity enrichment scheme for the solution of the electromagnetic wave equation in the time domain. A discretization scheme in time is implemented to render implicit solutions of systems of equations possible. The scheme allows for calculation of the field values at different time steps in an iterative fashion. The spatial grid is partitioned into a finite number of elements with intrinsic shape functions to form the bases of solution. Furthermore, each finite element degree of freedom is expanded into a sum of a slowly varying term and a combination of highly oscillatory functions. The combination consists of plane waves propagating in multiple directions, with a fixed frequency. This significantly reduces the number of degrees of freedom required to discretize the unknown field, without compromising on the accuracy or allowed tolerance in the errors, as compared to that of other enriched FEM approaches. Also, this considerably reduces the computational costs in terms of memory and processing time. Parametric studies, presented herein, confirm the robustness and efficiency of the proposed method and the advantages compared to another enrichment method.

, A. (2020) 'Explicit time integration with lumped mass matrix for enriched nite elements solution of time domain wave problems.', Applied mathematical modelling., 77 (2). pp. 1273-1293.

At the network access layer, optical fibre deployment continues at pace but copper cables containing twisted pairs will remain for some time and face an increasing bandwidth and data rate demand. Surface waves have been proposed to address these requirements. This paper reports and investigates the existence of stop bands reaching over 50 dB insertion loss on 1 metre long, typical final drop cables under surface wave excitation at a few GHz. Coupled mode analysis shows that lack of helical symmetry enables the formation of a stop band in systems containing twisted pairs. A representative core model containing a single twisted pair alongside a straight wire is thoroughly studied. Numerical simulations and measurements confirm the crucial dependence of the stop band frequency on the twist rate of the twisted pair. Further investigation into the role of the dielectric coating and the distance of the straight wire are performed as well. Finally, in systems with multiple twisted pairs, we find that the twist rate associated with any pair can create a stop band effectively limiting surface wave propagation. Thus, careful design and deployment strategies are required for use of surface waves on legacy copper networks.