Spectral-Domain Computation of Fields Radiated by Sources in Non-Birefringent Anisotropic Media

We derive the key expressions to robustly address the eigenfunction expansion-based analysis of electromagnetic (EM) fields produced by current sources within planar non-birefringent anisotropic medium (NBAM) layers. In NBAM, the highly symmetric permeability and permittivity tensors can induce directionally-dependent, but polarization independent, propagation properties supporting "degenerate" characteristic polarizations, i.e. four linearly-independent eigenvectors associated with only two (rather than four) unique, non-defective eigenvalues. We first explain problems that can arise when the source(s) specifically reside within NBAM planar layers when using canonical field expressions. To remedy these problems, we exhibit alternative spectral-domain field expressions, immune to such problems, that form the foundation for a robust eigenfunction expansion-based analysis of time-harmonic EM radiation and scattering within such type of planar-layered media. Numerical results demonstrate the high accuracy and stability achievable using this algorithm.Comment: The official (preliminary) published version of this manuscript, along with copyright information, can be found using the provided DOI. IEEE Antennas Wireless Propag. Lett., 201

Interference-Nulling time-reversal beamforming for mm-wave massive MIMO systems

We present a novel beamforming technique for multi-user frequency-selective indoor channels called interference-nulling time-reversal (INTR). The beamformer is implemented with a pre-filter designed to minimize the inter-user interference present in conventional time-reversal (TR). Moreover, our technique relies on a large number of antennas at the transmitter to mitigate inter-symbol interference, enabling low computational complexity receivers. We demonstrate that INTR outperforms previous TR techniques with respect to average bit error rate per user and achievable sum rate. Thus, INTR can be used for space division multiple access in no-line-of-sight mm-wave massive MIMO, providing remarkable diversity and multiplexing gains

Electromagnetic horizons and convex-spherical reflectionless absorber coatings

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