VHF sporadic E-a significant factor for EMI

摘要

Sporadic E, or Es, is an ionospheric propagation mode which is useless for service but is crucial in estimating interference at VHF. It is particularly important in Asia where temperate latitude sporadic E has its summer and yearly peak. Examples are given of the reduction in broadcast service area and year-to-year variability at the 99% of the time service level.