Direct sequence and time hopping ultra wideband over IEEE.802.15.3a channel model

In this paper, performance of two kinds of ultra wide band systems, namely Direct Sequence (DS) and Time Hopping (TH) over IEEE.802.15.3a channel model is compared by simulation. Simulation results show that DS-UWB performance is better than TH-UWB in multi-user environment. Also, it is indicated that performance in TH-UWB becomes worse with increasing the number of frames. Moreover, simulation is done for several number of fingers by S-Rake and P-Rake for Direct Sequence and Time hopping. Also, performance of Ultra Wide Band (UWB) system over IEEE 802.15.3a channel model is simulated, and their results are compared to upper bound of Bit Error Rate (BER) for UWB in log-normal fading channel.Zahra Shaterian, Mehrdad Ardebilipou

Rotation sensing based on the symmetry properties of an open-ended microstrip line loaded with a split ring resonator

This paper proposes the principle for rotation sensing based on an open-ended microstrip line loaded with a split ring resonator (SRR). It is shown that the variations in the depth of the resonance notch in the reflection coefficient of the structure can be used to sense the rotation angle of the SRR. This effect arises from the rotation-induced break of symmetry for the geometry. The proposed sensor benefits from a compact size and a higher dynamic range compared to previously published rotation sensors based on depth of notch. The sensor also benefits from immunity to the environmental changes such as temperature variations.Zahra Shaterian, Ali K. Horestani, and Christophe Fumeau

Hybrid staggered perfectly matched layers in non-staggered meshless time-domain vector potential technique

In this paper a hybrid algorithm for the implementation of Perfectly Matched Layers (PMLs) in the meshless magnetic vector potential technique is proposed. Solving the wave equation in time-domain, the magnetic vector potential technique avoids using staggered node distributions which are needed for calculating the E and H fields when directly solving Maxwell's equations. However, implementing PMLs with stretched coordinate formulation requires auxiliary variables on a staggered (dual) node distribution. To avoid defining staggered nodes in the whole computational domain, a hybrid algorithm is proposed in this paper: The algorithm keeps a single set of nodes for the magnetic vector potential A inside the free space while it uses staggered nodes for A and auxiliary variables inside the PML. The hybrid algorithm is validated in a 2D rectangular waveguide and numerical reflection coefficients are compared for different thicknesses of the PML and for different orders of a polynomial conductivity profile inside the PML. A good agreement between theoretical results and converged solutions validates the approach, with best performance using a polynomial order m = 3.Zahra Shaterian, Thomas Kaufmann, and Christophe Fumeau

First- and second-order meshless radial point interpolation methods in electromagnetics

This paper compares two different approaches for the time-domain meshless Radial Point Interpolation Method (RPIM) in electromagnetic simulations. These two algorithms are classified based on the order of partial differential equations which are needed for solving EM problems. Then the advantages and issues related to those two types of formulations are discussed.Zahra Shaterian, Thomas Kaufmann, and Christophe Fumeau

Time-domain vector potential technique for the meshless radial point interpolation method

Published online 9 January 2015 in Wiley Online Library (wileyonlinelibrary.com).Abstract not availableZahra Shaterian, Thomas Kaufmann and Christophe Fumeau

On the choice of basis functions for the meshless Radial Point Interpolation Method with small local support domains

The behavior of two different types of basis functions for the meshless Radial Point Interpolation Method (RPIM) is investigated in this paper. A 2D test function is interpolated through Gaussian and Wendland basis functions and the approximation errors on the low-order derivatives of the test function are calculated. It is shown that the Gaussian basis function is more appropriate for the interpolation in small support domains where as Wendland basis function is more accurate for larger support domains.Zahra Shaterian, Thomas Kaufmann and Christophe Fumeau

On the late-time instability of perfectly matched layers in the meshless radial point interpolation method

The time-domain behavior of the Uniaxial Perfectly Matched Layer (UPML) in the 3D meshless Radial Point Interpolation Method (RPIM) is investigated in this paper. It is theoretically shown that the UPML will become unstable after a very long time when the energy in the computational domain almost completely vanishes. A timed introduction of loss terms in the equations inside the UPMLs, i.e. at a time after absorption of most of the energy, can significantly delay or even remove the occurrence of this instability without compromising the accuracy of the solution.Zahra Shaterian, Thomas Kaufmann and Christophe Fumeau

Impact of different node distributions on the meshless Radial Point Interpolation Method in time-domain electromagnetic simulations

This paper investigates the effect of different node distributions on the accuracy of electromagnetic simulations performed with meshless methods. As a test case, a rectangular waveguide truncated with perfectly-matched layers is simulated using the three-dimensional meshless Radial Point Interpolation Method (RPIM) in the time domain. For the discretization of the geometry, different strategies of node distribution are utilized, namely a uniform grid distribution, a cylindrical distribution, and disturbed grid distributions with random displacements amounting to 5% and 10% of the grid average node distance. All distributions are generated with a similar node density, and the results are compared in terms of phase and amplitude of the propagating wave. The application of RPIM in all cases demonstrates similar levels of error, which indicates the robustness of this meshless algorithm with respect to different node distribution strategies.Zahra Shaterian, Thomas Kaufmann and Christophe Fumeau

Metamaterial-inspired displacement sensor with high dynamic range

Proceedings of the 4th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2013, United Arab Emirates, 18 Mar - 22 Mar 201: pp.274-276http://www.ieee.org/conferences_events/conferences/conferencedetails/index.html?Conf_ID=3070