Two directional UWB monopole antennas are proposed. It is shown that a design methodology for omnidirectional UWB rectangular planar monopole antennas can be applied for directional ones. The directional features are taken by introducing a slanting angle between the radiator and the ground plane. The slanting angle also plays a role in the low cutoff frequency, and it is considered in a propose...

The problem of how a wave propagates in an infinite medium filled with scatterers has revealed the notion of an effective medium: the mean wave propagates as in an homogeneous medium with complex index. Is this notion of an effective medium still valid when the scatterers are bounded in space? The problem is treated here for isotropic point scatterers. It is shown that (i) the waves propagate i...

We design a perfectly matched layer for the advection-diffusion equation. We show that the reflection coefficient is exponentially small with respect to the damping parameter and the width of the PML and this independently of the advection and of the viscosity. Numerical tests assess the efficiency of the approach.

Except in the deep ocean, the seabed has a major influence on low-frequency acoustic propagation. The formulation of an adequate geoacoustic model of the seabed is therefore one of the most important tasks facing anyone carrying out acoustic propagation modelling to predict underwater sound levels in coastal and continental shelf waters. It is often assumed that seabed layering on scales signif...

Orthogonal polynomials on the unit circle are completely determined by their reflection coefficients through the Szegő recurrences. We assume that the reflection coefficients converge to some complex number a with 0 < |a| < 1. The polynomials then live essentially on the arc { e : α ≤ θ ≤ 2π−α } where cos α 2 def = √ 1− |a|2 with α ∈ (0, π). We analyze the orthogonal polynomials by comparing th...

The invariant imbedding evolution equations for the amplitude reflection and transmission coefficients of a disordered 1D chain are shown to follow from the continuum limit, for weak disorder, of recursion relations between reflection (transmission) coefficients of Anderson chains of N andN−1 atoms embedded in infinite non-disordered chains. We show that various available analytical and numeric...

The inverse scattering problem on the line is studied for the generalized Schrodinger equation (d* f/V&*) + @H(X)* fi= Q(X) $, where H(x) is a positive, piecewise continuous function with positive limits H, as x --+ 2~. This equation, in the frequency domain, describes the wave propagation in a nonhomogeneous medium, where Q(X) is the restoring force and l/H(x) is the variable wave speed changi...

A method is given for finding the shifts in position of the solitons for the case of nonzero reflection coefficient. Expressions for boost generators in terms of scattering data play a prominent role in the analysis. Phase-shift formulas which show the effect of the radiation component on the soliton motion are deduced for the nonlinear Schrodinger equation, the Korteweg —de Vries equation, and...

Exact reflection and transmission coefficients for supersymmetric shapeinvariant potentials barriers are calculated by an analytical continuation of the asymptotic wave functions obtained via the introduction of new generalized ladder operators. The general form of the wave function is obtained by the use of the F(−∞,+∞)-matrix formalism of Fröman and Fröman which is related to the evolution of...

Using complex plane analysis we show that left-handed slab may support either leaky slab waves, which are backward because of negative refraction, or leaky surface waves, which are backward or forward depending on the propagation direction of the surface wave itself. Moreover, there is a general connection between the reflection coefficient of the left-handed slab and the one of the correspondi...