The Effect of Atmospheric Duct on Modern OFDM-Based Digital Broadcasting Systems

The aim of this paper is to investigate the effect of atmospheric ducts on modern OFDM-based broadcasting systems in VHF, UHF and L bands. Full-wave parabolic equation method will be used for calculation of electromagnetic field strength in time domain. It will be shown that the effect of atmospheric duct on the delay of electromagnetic field is negligible in comparison with the guard interval of OFDM signal. However, the duct amplifies the strength of EM signal which causes interference effects on adjacent services and because of brick-wall properties of OFDM-based signals, it may cause harmful effects on adjacent services and reduce the frequency reuse distance. Finally, it will be shown that the duct affects the field at far distances. Consequently, the usages of low distributed power transmitters are recommended for radio coverage in the presence of ducts.