Whispering gallery effects in the troposphere

Abstract

Experimental data that recorded higher-than-expected signals at 3087.7 MHz far beyond the horizon in the presence of an elevated duct are examined and compared to results from the radio physical optics (RPO) propagation model. RPO is a range-dependent hybrid model that combines ray optics and parabolic equation methods. Previous modeling of this same case study using waveguide methods for both the measured elevated d:•ct and hypothetical evaporation ducts has been disappointing. However, when the elevated duct is allowed to rise slowly with increasing range, the RPO results closely match the observed signal levels, indicating that weakly attenuated Earthdetached, or whispering gallery, modes were the dominant propagation mechanism. HITNEY:WHISPERING GALLERY EFFECTS IN THE TROPOSPHERE