Nondirectional Beacons: Coverage Limitations Due to Night Effect.

摘要

Annex 10 of International Standards and Recommended Practices Aeronautical Telecommunications contains tables of the distances at which the groundwave and skywave from a non-directional beacon (NDB) are equal and the distances at which the groundwave exceeds the skywave by 10 dB. These tables were probably based upon the experience of users. In this report the modeling assumptions necessary to duplicate the tables using modern computer prediction methods are determined. A table of distances at which the groundwave exceeds the skywave by 10 dB is computed for frequencies from 190 kHz to 1000 kHz and for ground conductivities from 5 mho/m to 0.00025 mho/m. (Author)