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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/4171

Title: Experimentally achieving borehole antenna radar directivity in the time domain in the presence of strong mutual coupling
Authors: Vogt, D
Nyareli, T
Keywords: Borehole radar
Directional antennas
Time domain
70th EAGE
Issue Date: Jun-2008
Publisher: European Association of Geoscientists and Engineers
Citation: Vogt, D and Nyareli, T. 2008. Experimentally achieving borehole antenna radar directivity in the time domain in the presence of strong mutual coupling. 70th EAGE (European Association of Geoscientists and Engineers) Conference. Rome, italy, 9 - 12 June 2008, pp 7
Abstract: It is difficult to achieve significant directivity in the radial direction of a borehole radar antenna, because the spacing of antenna elements is typically constrained by the borehole diameter to be considerably less than a wavelength. Previously published borehole radar antennas have achieved directivity by post processing data received in the frequency domain, or by constructing an aperture antenna, where borehole dimensions allowed this. In this paper, a time-domain technique is investigated for determining the radial direction of reflectors detected in borehole radar images. The antenna itself is an array of four elements and the delay in arrival of the signal between elements is used to determine its direction. We show here that a relatively slow sampling rate is adequate to resolve the small time intervals between signals received on different antenna elements. Mutual coupling between the antenna elements does affect the relative timing, but does not prevent the extraction of usable directional data. Experimental data from a test tank confirms that estimates of reflector direction can be made to within avout +15 degrees /-5 degrees of the true direction for antenna elements 20 mm apart in water, excited with a pulse that has a centre frequency of 250 MHz
Description: 70th EAGE (European Association of Geoscientists and Engineers) Conference. Rome, Italy, June 2008
URI: http://hdl.handle.net/10204/4171
ISBN: 9789073781535
Appears in Collections:Mining and geoscience
General science, engineering & technology

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