radiograph
发表于 2025-3-30 08:43:04
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Frenetic
发表于 2025-3-30 12:44:34
Historical Overview,tions. Note that for convenience, here ELF is used as shorthand for the combination of the ELF, SLF, and ULF ranges (3–30 Hz, 30–300 Hz, and 0.3–3 kHz, respectively), for which EM wavelengths range from . km in the air. This chapter provides a historical overview of wireless communications at such l