Design of Improved TEM Horn Antenna in Double Exponential Approach for Impulse GPR Applications
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Date
2021-05
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Addis Ababa University
Abstract
Ground Penetrating Radar (GPR) is a popular geophysical technique that is used to
investigate the ground using electromagnetic waves. Analogous to medical imaging GPR
is used for subsurface imaging and exploration.
Antenna is a key element of any GPR system. The design of GPR antennas differs
from the classical approach. Classical antennas are designed for operating in free space
but antennas for GPR must operate in the vicinity of the ground and this is a major
constraint in their design. The GPR antenna must couple the electromagnetic waves
directly in to the ground.
In this thesis, improved Transverse Electromagnetic (TEM) horn antennas are
designed for impulse GPR applications and improving the design of the TEM horn
antenna is focused on reducing the aperture reflections in double exponential approach.
Student version of FEKO software is used in the simulation and The simulation
results show that, TEM horn antennas, TEM60cm and TEM120cm each with aperture
impedance of 200 and 250 Ohm designed in double exponential approach have less
Voltage Standing Wave Ratio(VSWR) than TEM horn antenna with 377 Ohm aperture
impedance of similar size as the frequency of operation increase and the VSWR of
TEM60cm and TEM120cm each with aperture impedance of 200 and 250 Ohm is less than
2 over an ultra-wide frequency range within the frequency range of interest.
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Keywords
TEM, TEM Horn Antenna, Impulse GPR Applications