After posting the previous blog entry, I was reminded of a new term I encountered last week. I was sure I had encountered this term before. I just looked it up and discovered why.
It turns out I had been introduced to the term 'Fresnel' previously, but in an entirely different context. When I researched the term Fresnel lens, I was immediately reminded of the Amateur Radio course I took last winter. Fresnel zones refer to elliptical radiation patterns of radio signals and the need to keep geographic obstacles outside this zone. Avoiding obstacles in your signal's Fresnel zone minimizes the distorted out-of-phase signals that commonly occur in mountainous areas.
As I discovered, the name Fresnel refers to Augustin-Jean Fresnel, a French physicist who invented a way of constructing refractive lenses with much lighter materials than were previously used in the early 19th century lighthouses. His discoveries about the behavior of light are not directly related to radio signals, but diffraction of radiation patterns are somewhat similar, hence the term Fresnel zone.
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