The paper describes a 31.25 MHz bandwidth wideband channel sounder used to characterize a transhorizon path over the English Channel (La Manche) at 11.64 GHz. The measurements were done continuously for a period of 8 months (June 5, 1996, to January 5, 1997), capturing 515 Mb of data each day. A nonlinear regression technique, singular value decomposition prony (SVD-P), was used to estimate the channel impulse response from the measured transfer function. The received signal levels obtained together with their dynamic signatures were used to categorize the mechanisms into three broad groups: ducting, strong enhancements, and troposcatter. The statistical analysis carried out gave strong correlation between signal levels, delay spread, coherence bandwidth, and Doppler spread. The results also help to highlight the limitation of traditional channel characterization parameters such as delay spread. The investigation has also revealed the potential and propagation conditions of an over the sea transhorizon path as a high-data-rate communication channel. The research has qualified and quantified the interference potential in spectrum reuse and the frequency decorrelation probabilities to combat it. ¿ 2001 American Geophysical Union