High performance 3D sound localization for surveillance applications

One of the key features of the human auditory system, is its nearly constant omni-directional sensitivity, e.g., the system reacts to alerting signals coming from a direction away from the sight of focused visual attention. In many surveillance situations where visual attention completely fails since the robot cameras have no direct line of sight with the sound sources, the ability to estimate the direction of the sources of danger relying on sound becomes extremely important. We present in this paper a novel method for sound localization in azimuth and elevation based on a humanoid head. The method was tested in simulations as well as in a real reverberant environment. Compared to state-of-the-art localization techniques the method is able to localize with high accuracy 3D sound sources even in the presence of reflections and high distortion

Far-field energy harvesting rectifier analysis

\u3cp\u3eAn accurate equivalent circuit model to predict the power conversion efficiency (PCE) of a Schottky Barrier Diode (SBD) is presented in this paper. By making use of good insight into the used SBD models and careful analysis of circuit behavior, more efficient rectifier circuits have been identified. An increase in circuit efficiency of 18-25% is shown compared to state of the art, resulting in 20-180% more available energy from the rectifying circuit. Also the accuracy of the simulation results has increased significantly. All the simulations in this paper are performed in a conjugately matched environment, which allows for an objective comparison of different Schottky diodes.\u3c/p\u3

Frequency selective surface for RF energy harvesting applications

A novel application for frequency selective surfaces (FSSs) is presented. The novel FSS design can harvest power from arbitrarily polarised incident waves. The design does not involve a matching network, which results in a simple, polarisationindependent power harvester. An accurate analytical procedure, to calculate the impedance of the commercially available Schottky rectifiers, is presented. The results are validated by full-wave simulations and by measurements. A simple equivalent circuit model to predict the transmission and reflection characteristics of the gridded-square-loop FSS is employed. The design method is validated for different polarisations and for different incident angles. The addition of lumped elements (R, L, C) in the metallic conductive grid of the FSS is investigated. The waveguide simulator method and full-wave simulations are employed to validate the derived analytical equations. A 3 x 3 and a 5 x 5 RF harvesting FSS have been designed, simulated, fabricated and validated. A radio frequency (RF) to DC conversion efficiency of 25% for the 3 x 3 RF harvester and 15.9% for the 5 x 5 RF harvester is measured at an RF input power level of -6 dBm

Optimized rectenna design

Design steps are outlined for maximizing the RF-to-dc power conversion efficiency (PCE) of a rectenna. It turns out that at a frequency of 868 MHz, a high-ohmic loaded rectifier will lead to a highly sensitive and power conversion efficient rectenna. It is demonstrated that a rectenna thus designed, using a 50 O antenna and lumped element matching network gives a superior PCE compared with state of the art also for lower resistive loading. By omitting the matching network and directly, conjugate impedance matching the antenna to the rectifier, the PCE may be further increased and the rectenna size reduced as it is demonstrated with a rectenna prototype measuring only 0.028 squared wavelengths at 868 MHz and demonstrating a PCE of 55% for a -10 dBm RF input power level