(Georgia Institute of Technology, 2011-05)
Morys, Marcin M.; Durgin, Gregory D.
The formation of corona discharges at high
potentials was studied. Glow coronas were found to be generated
when the electric field magnitude is in excess of 3MV/m in
general for air at atmospheric pressure. The number density of
electrons in the glow corona can only be approximated, but the
results obtained from the Boltzmann transport equation promise
to be accurate enough to give meaningful wave attenuation
results, so long as the number density is below 1019 m-3 electrons.
Above this density, the attenuation increases dramatically and
approximations for density may no longer be valid. Wave
propagation and antenna parameters in a corona plasma can be
computed through simulation using dielectric slabs of complex
impedance to simulate a plasma sheath.
(Georgia Institute of Technology, 2010-11)
Griffin, Joshua D.; Durgin, Gregory D.
Multipath fading can be heavy for ultra-high frequency
(UHF) and microwave backscatter radio systems used in
applications such as radio frequency identification (RFID). This
paper presents measurements of fading on the modulated signal
backscattered from a transponder for backscatter radio systems
that use multiple antennas at the interrogator and transponder.
Measurements were performed at 5.8 GHz and estimates of the
backscatter channel envelope distributions and fade margins
were calculated. Results show that multipath fading can be reduced
using multiple transponder antennas, bistatic interrogators
with widely separated transmitter and receiver antennas, and
conventional diversity combining at the interrogator receiver.
The measured envelope distribution estimates are compared to
previously derived distributions and show good agreement.