Two high-order accurate Calderón preconditioned time domain electric field integral equation (TDEFIE) solvers are presented. In contrast to existing Calderón preconditioned time domain solvers, the proposed preconditioner allows for high-order surface representations and current expansions by using a novel set of fully-localized high-order div- and quasi curl-conforming (DQCC) basis functions. Numerical results demonstrate that the linear systems of equations obtained using the proposed basis functions converge rapidly, regardless of the mesh density and of the order of the current expansion.

All known integral equation techniques for simulating scattering and radiation from arbitrarily shaped, perfect electrically conducting objects suffer from one or more of the following shortcomings: (i) they give rise to ill-conditioned systems when the frequency is low (ii) and/or when the discretization density is high, (iii) their applicability is limited to the quasi-static regime, (iv) they require a search for global topological loops, (v) they suffer from numerical cancelations in the solution when the frequency is very low. This work presents an equation that does not suffer from any of the above drawbacks when applied to smooth and closed objects. The new formulation is obtained starting from a Helmholtz decomposition of two discretizations of the electric field integral operator obtained by using RWGs and dual bases respectively. The new decomposition does not leverage Loop and Star/Tree basis functions, but projectors that derive from them. Following the decomposition, the two discretizations are combined in a Calderon-like fashion resulting in a new overall equation that is shown to exhibit self-regularizing properties without suffering from the limitations of existing formulations. Numerical results show the usefulness of the proposed method both for closed and open structures.

Single source time-domain electric and magnetic field integral equations for analyzing scattering from homogeneous penetrable objects are presented. Their temporal discretization is effected by using shifted piecewise polynomial temporal basis functions and a collocation testing procedure, thus allowing for a marching on in time (MOT) solution scheme. Unlike dual source formulations, single source equations involve space-time domain operator products, for which spatial discretization techniques developed for standalone operators do not apply. Here, the spatial discretization of the single source time domain integral equations is achieved by using the highorder divergence-conforming basis functions developed by Graglia et al. alongside the high-order divergence- and quasi curl-conforming (DQCC) basis functions of Valdés et al. The combination of these two sets allows for a well-conditioned mapping from div- to curl-conforming function spaces that fully respects the space mapping properties of the space-time operators involved. Numerical results corroborate the fact that the proposed procedure guarantees accuracy and stability of the MOT scheme.

An innovative LDS 4G antenna solution operating in the 698-960 MHz band is presented. It is composed of two radiating elements recombined in a broadband single feed antenna system using a multiband matching circuit design. Matching interfaces are synthesized thanks to lumped components placed on the FR4 PCB supporting the LDS antenna. Measurement shows a reflection coefficient better than -6 dB over the 698-960 MHz band, with a 30% peak total efficiency. Measurement using a realistic phone casing showed the same performances. The proposed approach can be extended to additional bands, offering an innovative antenna solution able to address the multi band challenge related to 4G applications.