16 lines
431 B
Markdown
16 lines
431 B
Markdown
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title: 空间损耗
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updated: 2022-05-16 12:03:07Z
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created: 2022-01-10 03:35:59Z
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# 自由空间损耗
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$IL(dB)=10lg^{{c\over{4πLf}}^2}=20lg^{c\over{4π}}-20lg^L-20lg^f$
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$=-32.45-20lg^{L-m}-20lg^{f-GHz}=-32.45-20lg^{m*G}$
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$=-92.45-20lg^{L-km}-20lg^{f-GHz}=-92.45-20lg^{km*G}$
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可以看出，距离增加一倍，损耗多6dB
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> 32.4对应1e9，即km与MHz成组，m与GHz成组，总1e6
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92.45对应1e12，即km与GHz成组
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