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In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances.
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]
In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]
The quadruple space and polarisation diversity systems needed two separate dish antennas (spaced several metres apart) and two differently polarised feed horns – one using vertical polarisation, the other using horizontal polarisation. This ensured that at least one signal path was open at any one time.
In atmospheric science, an atmospheric model is a mathematical model constructed around the full set of primitive, dynamical equations which govern atmospheric motions. It can supplement these equations with parameterizations for turbulent diffusion, radiation , moist processes ( clouds and precipitation ), heat exchange , soil , vegetation ...
Friis' original idea behind his transmission formula was to dispense with the usage of directivity or gain when describing antenna performance. In their place is the descriptor of antenna capture area as one of two important parts of the transmission formula that characterizes the behavior of a free-space radio circuit.
One key activity in communication theory is the development of models and concepts used to describe communication. In the Linear Model, communication works in one direction: a sender encodes some message and sends it through a channel for a receiver to decode. In comparison, the Interactional Model of communication is bidirectional. People send ...
In a note at the end of his work "A Dynamical Theory of the Electromagnetic Field", Maxwell discussed a model for gravity based on a medium similar to the one he used for the electromagnetic field. He concluded that the medium would have "an enormous intrinsic energy" and would necessarily have to be diminished in areas of mass.