Signal distortion on VHF/UHF transionospheric paths: First results from the Wideband Ionospheric Distortion Experiment

[1] To the best of our knowledge, we report the first determination of ionospheric distortion, comprising the simultaneous characterization of both multipath and Doppler, on wideband, transionospheric VHF ( 158 MHz) and UHF ( 422 MHz) signals. The measurements took place as part of the test phase of the United Kingdom - United States Wideband Ionospheric Distortion Experiment during the evening ( similar to 1000 UT) of 18 January 2005. This characterization has been achieved using the ALTAIR radar at the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll (9.395 degrees N, 167.469 degrees E (12.87 degrees N, 237.16 degrees E corrected geomagnetic)) in the Pacific, in conjunction with a low Earth orbiting, constant radar cross-section, passive satellite ( calibration sphere). During the period when the two-way S-4 index was above similar to 0.8 on both channels, the median coherency times were 43 and 96 ms at VHF and UHF, respectively ( at 1.5 sigma). The corresponding median coherency bandwidths were 0.8 and 2.1 MHz.