Frequency Steerable Two Dimensional Focusing Using Rectilinear Leaky-Wave Lenses

The concept of frequency steerable two-dimensional electromagnetic focusing by using a tapered leaky-wave line source embedded in a parallel-plate medium is presented. Accurate expressions for analyzing the focusing pattern of a rectilinear leaky-wave lens (LWL) from its constituent leaky-mode tapered propagation constant are described. The influence of the main LWL structural parameters on the synthesis of the focusing pattern is discussed. The ability to generate frequency steerable focusing patterns has been demonstrated by means of an example involving a LWL in hybrid waveguide printed-circuit technology and the results are validated by a commercial full-wave solver.

Enhancing Frequency-Scanning Response of Leaky-Wave Antennas Using High-Impedance Surfaces

The use of high-impedance surfaces (HISs) to increase the frequency-scanning sensitivity of hollow leaky-wave antennas (LWAs) is presented. The LWA consists of a hollow rectangular waveguide with one of its narrow walls replaced by a partially reflective surface, and it is loaded with a metallodielectric HIS to increase its beam-scanning response. Theoretical results based on a simple transverse equivalent network illustrate the physical mechanism responsible for the improvement, and they are verified by experiments on a prototype working in the 11-16 GHz band.

A comparison of nonstaggered compact FDTD schemes for the 3D wave equation

This paper aims at providing a better insight into the 3D approximations of the wave equation using compact finite-difference time-domain (FDTD) schemes in the context of room acoustic simulations. A general family of 3D compact explicit and implicit schemes based on a nonstaggered rectilinear grid is analyzed in terms of stability, numerical error, and accuracy. Various special cases are compared and the most accurate explicit and implicit schemes are identified. Further considerations presented in the paper include the direct relationship with other numerical approaches found in the literature on room acoustic modeling such as the 3D digital waveguide mesh and Yee's staggered grid technique.

A Frequency Domain Algorithm for Wave Separation

We propose a frequency domain adaptive algorithm for
wave separation in wind instruments. Forward and backward travelling waves are obtained from the signals acquired by two microphones placed along the tube, while the
separation ?lter is adapted from the information given by a
third microphone. Working in the frequency domain has a
series of advantages, among which are the ease of design of
the propagation ?lter and its differentiation with respect to
its parameters.
Although the adaptive algorithm was developed as a ?rst
step for the estimation of playing parameters in wind instruments it can also be used, without any modi?cations, for
other applications such as in-air direction of arrival (DOA)
estimation. Preliminary results on these applications will
also be presented.