Oceanic propagation measurements for beyond line-of-sight links at Q band

Abstract

This paper presents results from two experiments that were conducted to characterize propagation over the ocean at upper Q-band frequencies. Measurements of propagation loss versus path length were made off the Mid-Atlantic coast of the United States in February and November 2005. The results show that the propagation loss can be more than 100 dB less than the loss due to diffraction and refractive effects caused by a standard atmosphere. Comparison of the measurements with theoretical predictions suggests that the observed propagation enhancement at high Q-band frequencies is primarily due to tropospheric ducting; however, troposcatter may also play a role at Q band and above. An attempt was made to find simple regression rules that fit the measured propagation loss dependency on path length. It was discovered that the measured path loss in dB depends linearly on the logarithm of the path length and that the slopes and intercept values of the linear regressions are dependent on receiver height and environmental conditions. The results in this paper address a frequency band that is underrepresented in the open literature.

The Impact of Evaporative Ducting on Covert Communications

“…TEMPER predicts electromagnetic wave propagation in the troposphere using a parabolic approximation to the Helmholtz wave equation and solves the resulting parabolic wave equation directly using a stable numerical technique known as the Fourier split-step algorithm [6]. TEMPER has been validated for frequencies up to Q band [7], [8]. Execution of TEMPER is performed by specifying the values of pertinent system parameters and by providing the program with a vertical profile of the modified index of refraction, M(h).…”