27,047 research outputs found
Communication system for a tooth-mounted RF sensor used for continuous monitoring of nutrient intake
In this Thesis, the communication system of a wearable device that monitors the user’s diet is studied. Based in a novel RF metamaterial-based mouth sensor, different decisions have to be made concerning the system’s technologies, such as the power source options for the device, the wireless technology used for communications and the method to obtain data from the sensor. These issues, along with other safety rules and regulations, are reviewed, as the first stage of development of the Food-Intake Monitoring projectOutgoin
Tunable negative permeability in a three-dimensional superconducting metamaterial
We report on highly tunable radio frequency (rf) characteristics of a
low-loss and compact three dimensional (3D) metamaterial made of
superconducting thin film spiral resonators. The rf transmission spectrum of a
single element of the metamaterial shows a fundamental resonance peak at
24.95 MHz that shifts to a 25 smaller frequency and becomes
degenerate when a 3D array of such elements is created. The metamaterial shows
an \emph{in-situ} tunable narrow frequency band in which the real part of the
effective permeability is negative over a wide range of temperature, which
reverts to gradually near-zero and positive values as the superconducting
critical temperature is approached. This metamaterial can be used for
increasing power transfer efficiency and tunability of electrically small
rf-antennas.Comment: 6 pages, 4 figure
Strong group velocity dispersion compensation with phase-engineered sheet metamaterials
Resonant metamaterials usually exhibit substantial dispersion, which is
considered a shortcoming for many applications. Here we take advantage of the
ability to tailor the dispersive response of a metamaterial introducing a new
method of group-velocity dispersion compensation in telecommunication systems.
The method consists of stacking a number of highly dispersive sheet
metamaterials and is capable of compensating the dispersion of optical fibers
with either negative or positive group-velocity dispersion coefficients. We
demonstrate that the phase-engineered metamaterial can provide strong
group-velocity dispersion management without being adversely affected by large
transmission loss, while at the same time offering high customizability and
small footprint.Comment: 10 pages, 4 figure
- …