1,721,100 research outputs found
Performance evaluation of astigmatic beam tracing in the application to picocell scenarios
No full textRecent improvements in beam tracing
No full textRay tracing methods together with geometrical optics (GO) and uniform theory of diffraction (UTD) are usually exploited to model electromagnetic field propagation in complex environments, such as urban and indoor scenarios. Ray-optics models calculate the total field impinging on a receiver as ray field superposition. In particular, 3D ray-tracers require high-resolution, site-specific information, which hugely increase the computational cost. The overall accuracy depends on. the amount of detail in the scene that a ray tracer is able to handle, as well as on the algorithms in use for ray tracing, several of which have been proposed. The paper discusses some recently proposed ray tracing techniques
Verbal short-term memory in individuals with congenital articulatory disorders: new empirical data and review of the literature
No full textTo investigate the nature of the articulatory rehearsal mechanism of the Articulatory Loop in Baddeley's Working Memory model, it seems particularly important to study individuals who developed a deficit (dysarthria) or total abolition (anarthria) of the ability to articulate language following a cerebral lesion
Low-profile Dual-polarized Isoflux Antennas for Space Applications
No full textDesign, realization and measurements of a X-band antenna for data downlink (DDL) from low Earth orbit (LEO) satellites are presented. This antenna has an isoflux radiation pattern and operates in dual circular polarization with crosspolar discrimination (XPD) higher than 18dB on the operational bandwidth. Two solutions are first proposed: one realized by a metasurface with circular strips printed on a dielectric slab, and one realized by concentric metallic corrugations. Starting from a basic scattering mechanism of a self-complementary ring-type metasurface excited by a perfectly polarized source, both these antennas are designed by optimizing an equivalent anisotropic impedance surface excited by a short hat feed. The performance of the two designs are compared. The corrugated antenna is realized and measured, confirming that the performances are compliant with the requirements for next generation DDL antennas
- …
