Subject(s)
Aging , Deglutition Disorders/etiology , Deglutition Disorders/therapy , Enteral Nutrition , Gastrostomy , Stroke/complications , Aged , Humans , Quality of Life , Stroke/therapyABSTRACT
Attenuation and near-and far-field measurements, which were made with different launch spot sizes and numerical apertures on sub-1.0-dB/km optical waveguides, have shown that an equilibrium mode distribution is not established in the 1.1-km length. It was experimentally found that the source launch conditions could be described by an effective mode volume (EMV) that was found to be correlated with the measured attenuation rate. By using an EMV transfer model, the insertion loss of a 3.3-km concatenated section was predicted within 0.21 dB of that measured for a variety of launch conditions.
ABSTRACT
This article describes a two-dimensional Luneburg lens, fabricated from steps of foam glass of different refractive index as an approximation to a continuous index gradient. This is an improvement over lenses fabricated by assembly of machined parts, which unavoidably contain some air gaps, resulting in different path lengths through the lens. The foam glass lens is superior to a plastic lens since it is able to withstand higher temperatures and hence higher powers, in addition to having superior aging characteristics. Measurements have been made throughout the microwave band, and the results clearly establish the feasibility of this fabrication technique for the construction of a microwave Luneburg lens.
