Electromagnetic probing of salt with high frequency radar
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Date
1978
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Abstract
The major thrust of this dissertation is the development, field testing, and theoretical evaluation of a high frequency (HF) radar system for use in probing rock salt where very-high frequency (VHF) radars have failed. The failure of the VHF radars is attributed to high electromagnetic attenuation due to the presence of water in the salt. Due to the conflicting conditions of a decrease in attenuation and a decrease in resolution as the radar frequency decreases, the optimum frequency range for probing wet salt is in the HF region. The Alpha II radar system is a portable, pulsed HF radar system designed to probe in wet salt. It operates at a frequency of 30 MHz with up to 10kW of peak output power, a pulse width of 1 μs, and a repetition frequency of 1 kHz. The travel times of received radar reflections are measured on an oscilloscope and converted to ranges using the radar speed in salt, which is measured in situ by probing through pillars of known thickness. Analog signal processing using a boxcar integrator may be performed to increase the signal-to-noise ratio of the received radar reflections. The Alpha II radar system was successfully field tested within two salt mines: Morton Salt Company's Kleer mine at Grand Saline, Texas, where the salt is dry, and Canadian Salt Company's Ojibway mine near Windsor, Ontario, where the salt is wet..
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Vita.
Keywords
Electromagnetic measurements, Radar, Antennas, Vibration, Rock salt, Testing, Geophysics