Characterising borehole radio antenna performance using finite-difference time-domain modelling

Abstract

Research Article| December 01, 2006 Characterising borehole radio antenna performance using finite-difference time-domain modelling Declan Vogt; Declan Vogt CSIR Division of Mining Technology, PO Box 91230, Auckland Park, 2006, South Africa e-mail: dvogt@csir.co.za Search for other works by this author on: GSW Google Scholar Andy Marvin Andy Marvin Department of Electronics, University of York, Heslington, York, YO10 5DD, United Kingdom e-mail: acm@ohm.york.ac.uk Search for other works by this author on: GSW Google Scholar Author and Article Information Declan Vogt CSIR Division of Mining Technology, PO Box 91230, Auckland Park, 2006, South Africa e-mail: dvogt@csir.co.za Andy Marvin Department of Electronics, University of York, Heslington, York, YO10 5DD, United Kingdom e-mail: acm@ohm.york.ac.uk Publisher: Geological Society of South Africa First Online: 09 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2006 Geological Society of South Africa South African Journal of Geology (2006) 109 (4): 561–570. https://doi.org/10.2113/gssajg.109.4.561 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Declan Vogt, Andy Marvin; Characterising borehole radio antenna performance using finite-difference time-domain modelling. South African Journal of Geology 2006;; 109 (4): 561–570. doi: https://doi.org/10.2113/gssajg.109.4.561 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract Radio Tomography (RT) has proven itself as an imaging tool for base metal orebody delineation. To date, theoretical considerations of the imaging technique and inversion algorithms have concentrated on the propagation of energy from the transmit antenna to the receive antenna, while ignoring the antennas themselves.The Finite-Difference Time-Domain technique for modelling antennas has been extended to efficiently model antennas embedded in arbitrary media such as rock. The model is set up with body-of-rotation symmetry to produce models that have three dimensional accuracy, while only having two dimensional computational cost. Wire dipole antennas are efficiently modelled by the addition of a subcell extension for a thin wire coated with a thin layer of insulation.The extended code is used, both to aid in the design of an improved antenna, and to investigate how the performance of the antenna affects the imaging of RT data in particular circumstances. A completely insulated antenna is preferred because its performance is more independent of the surrounding rock. The numerical model aids in the design of an improved antenna, with the optimum combination of performance features in a physically realizable antenna. If the electronics package is placed at the end of the dipole, the electronics package can be housed in a bare metal pressure casing without significantly affecting antenna performance as a function of rock type.The model also shows how the use of RT can be influenced by the geometry of the system and particularly by the use of conductors to suspend the RT antenna: wire cable support is not recommended until full waveform inversion techniques can take into account the presence of the wire. Antenna arrays appear to be viable, but if antennas without insulation are used, the spacing between the antennas should be at least as great as the length of each antenna. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.