Design and implementation of an integrated switched-oscillator impulse generator
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Date
2019-08-26
Authors
Mohammadzamani, Samira
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Abstract
In this thesis, an integrated impulse generator has been designed,
simulated, fabricated and tested. The switched-oscillator topology has been
used
as the impulse generator. A switched oscillator consists of a low impedance
transmission line, which charges through a DC source with a large input impedance. The
transmission line is connected to a high speed switch at one end and a high
feed point
impedance antenna at the other end. After charging the transmission line,
closing the fast switch short circuits the transmission line, resulting a
transient wave propagating toward the antenna. The high mismatch between
transmission line characteristic impedance and antenna feed point impedance
causes a big reflection at the antenna terminal. Due to the short circuit at
switch terminal, the reflected signal will
reflect back at the switch terminal as well. These back and forth reflections
generates a series of pulses at the antenna terminal which will transmit by the
antenna. Switched oscillators are used to generate high power electromagnetic
signals in high power microwave applications.
A time domain simulation as well as the sensitivity analysis have been done in
this thesis to find the most important design parameters. Three prototype
switched oscillator has been designed and fabricated. The first prototype
consists of a gas discharge tube as switch, a coaxial cable, and a monopole
antenna. In the
second prototype, a gas discharge tube as switch, a microstrip transmission line, and a
printed circuit board monopole antenna is used. In the third prototype, a conductor-backed
coplanar waveguide is used
instead of microstrip transmission line.
The
switched oscillator impulse generator is
designed to operate in the industrial, scientific and medical (ISM) radio
frequency band with purpose
of being part of the interrogation system of a passive, wireless electric field
sensor. An impulse generator with the resonance frequency of 915 MHz and
bandwidth of 10 MHz has been designed and fabricated in this project.
Description
Keywords
Switched Oscillator, Impulse generator