File Download
There are no files associated with this item.
Supplementary

Citations:
 Scopus: 0
 Appears in Collections:
Article: Electromagnetic field of a dipole on a twolayer earth.
Title  Electromagnetic field of a dipole on a twolayer earth. 

Authors  
Issue Date  1981 
Publisher  Society of Exploration Geophysicists. The Journal's web site is located at http://scitation.aip.org/geophysics 
Citation  Geophysics, 1981, v. 46 n. 3, p. 309315 How to Cite? 
Abstract  The electromagnetic field due to a horizontal electric dipole placed on top of a twolayer earth is represented in terms of fields due to a dipole over a halfspace earth and its image source fields. Integral representations of image source fields are evaluated with uniform asymptotic approximations. Leading order ordinary saddlepoint approximation, giving rise to the geometrical optics approximation (GOA), is shown to be inaccurate especially when the angle of observation is close to the critical angle, which corresponds to the presence of a branchpoint singularity near the saddle point. In the uniform asymptotic approximation, the integrand of the image source integral is split into a branchpoint free part and another part containing the branchpoint singularity. The branchpoint free part can be approximated with a spherical wave function, while the part containing the branch point can be approximated with parabolic cylinder functions. Vertical magnetic field components and the horizontal electric field component near the surface are illustrated and compared with the geometrical optics approximation, giving the direct numerical result as well as experimental measurement. It is shown that the uniform asymptotic approximation yields excellent agreement with numerical and experimental results compared to the geometrical optics approximation. Authors 
Persistent Identifier  http://hdl.handle.net/10722/182459 
ISSN  2015 Impact Factor: 2.017 2015 SCImago Journal Rankings: 1.646 
DC Field  Value  Language 

dc.contributor.author  Chew, WC  en_US 
dc.contributor.author  Kong, JA  en_US 
dc.date.accessioned  20130502T05:15:27Z   
dc.date.available  20130502T05:15:27Z   
dc.date.issued  1981  en_US 
dc.identifier.citation  Geophysics, 1981, v. 46 n. 3, p. 309315  en_US 
dc.identifier.issn  00168033  en_US 
dc.identifier.uri  http://hdl.handle.net/10722/182459   
dc.description.abstract  The electromagnetic field due to a horizontal electric dipole placed on top of a twolayer earth is represented in terms of fields due to a dipole over a halfspace earth and its image source fields. Integral representations of image source fields are evaluated with uniform asymptotic approximations. Leading order ordinary saddlepoint approximation, giving rise to the geometrical optics approximation (GOA), is shown to be inaccurate especially when the angle of observation is close to the critical angle, which corresponds to the presence of a branchpoint singularity near the saddle point. In the uniform asymptotic approximation, the integrand of the image source integral is split into a branchpoint free part and another part containing the branchpoint singularity. The branchpoint free part can be approximated with a spherical wave function, while the part containing the branch point can be approximated with parabolic cylinder functions. Vertical magnetic field components and the horizontal electric field component near the surface are illustrated and compared with the geometrical optics approximation, giving the direct numerical result as well as experimental measurement. It is shown that the uniform asymptotic approximation yields excellent agreement with numerical and experimental results compared to the geometrical optics approximation. Authors  en_US 
dc.language  eng  en_US 
dc.publisher  Society of Exploration Geophysicists. The Journal's web site is located at http://scitation.aip.org/geophysics  en_US 
dc.relation.ispartof  Geophysics  en_US 
dc.title  Electromagnetic field of a dipole on a twolayer earth.  en_US 
dc.type  Article  en_US 
dc.identifier.email  Chew, WC: wcchew@hku.hk  en_US 
dc.identifier.authority  Chew, WC=rp00656  en_US 
dc.description.nature  link_to_subscribed_fulltext  en_US 
dc.identifier.scopus  eid_2s2.00019728597  en_US 
dc.identifier.volume  46  en_US 
dc.identifier.issue  3  en_US 
dc.identifier.spage  309  en_US 
dc.identifier.epage  315  en_US 
dc.publisher.place  United States  en_US 
dc.identifier.scopusauthorid  Chew, WC=36014436300  en_US 
dc.identifier.scopusauthorid  Kong, JA=7202290923  en_US 