Attenuation with distance and wind speed of HF surface waves over the ocean

Abstract

An HF monostatic experiment is performed in order to evaluate the relative attenuation with distance of radio waves propagating in the ground wave mode over the sea surface, at 7 and 14 MHz. Clear evidence of the wind speed (causing the sea roughness) influence arises from the data, particularly at 14 MHz. The results are compared to Barrick's theoretical calculations, and a good agreement is found for the values of attenuation rates (in decibels per kilometer) and their variation with the wind speed in the upwind/downwind case. Some discrepancies in the data are partially interpreted as due to a fetch influence upon the radar cross section.