Leia uma explicação para esta série de 30 posts clicando aqui
"The amplitude of a radio wave expanding outward through space varies inversely with distance, weakening with increased distance. The decrease of strength with distance is called attenuation. Under certain conditions the attenuation is greater than in free space.
A wave traveling along the surface of the Earth loses a certain amount of energy to the Earth. The wave is diffracted downward and absorbed by the Earth. As a result of this absorption, the remainder of the wave front tilts downward, resulting in further absorption by the Earth.
Attenuation is greater over a surface which is a poor conductor. Relatively little absorption occurs over SEA water, which is an excellent conductor at low frequencies, and low frequency groundwaves travel great distances over water."
CHAPTER 10. RADIO WAVES
BOWDITCH
THE AMERICAN PRACTICAL NAVIGATOR
A wave traveling along the surface of the Earth loses a certain amount of energy to the Earth. The wave is diffracted downward and absorbed by the Earth. As a result of this absorption, the remainder of the wave front tilts downward, resulting in further absorption by the Earth.
Attenuation is greater over a surface which is a poor conductor. Relatively little absorption occurs over SEA water, which is an excellent conductor at low frequencies, and low frequency groundwaves travel great distances over water."
CHAPTER 10. RADIO WAVES
BOWDITCH
THE AMERICAN PRACTICAL NAVIGATOR
Leia uma explicação para esta série de 30 posts clicando aqui
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