ELF Propagation in a Non-Stratified Earth-Ionosphere Waveguide.
Abstract
This report analyzes extremely low-frequency (ELF) propagation under conditions where the properties of the earth-ionosphere waveguide change markedly over transverse distances comparable with the width of a Fresnel zone. An integral equation formulation is presented that can be used to obtain numerical results for most types of daytime ionospheric disturbances. Approximate solutions are given for ionospheric disturbances of the type that would occur in single-burst nuclear environments. These fullwave results are compared with results calculated from the widely used two-dimensional WKB approximation, which neglects transverse ionospheric gradients. It is shown that this WKB approximation gives good results for burst-heights above about 100 km, but that fullwave theory that accounts for transverse gradients must be used for lower burst altitudes. For these lower burst-heights, the WKB method seriously overstates the propagation anomaly caused by an on-path burst and understates the anomaly caused by an off-path burst. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1978
- Accession Number
- ADA056143
Entities
People
- E. C. Field Jr.