Commercial HF Radio
canopic jug writes:
Computer consultant J B Crawford, author of the Computers Are Bad newsletter, has posted an overview of commercial HF radio with a bit of background into the technology and some of its advantages and disadvantages:
According to a traditional system of classification, "high frequency" or HF refers to the radio spectrum between 3 and 30 MHz. The label now seems anachronistic, as HF is among the lowest ranges of radio frequencies that see regular use. This setting of the goalposts in the early days of radio technology means that modern communications standards like 5G are pushing major applications into the EHF or "extremely high frequency" band. The frontiers of basic radio technology now lie in the terahertz range, where the demarcation between radio waves and light is blurred and the known techniques for both only partially apply. HF, by contrast, is ancient technology. HF emissions can be generated by simple, brute-force means. Ironically, this makes HF a bit difficult: the incredible miniaturization and energy efficiency of modern electronics makes HF radio hard to receive and transmit in a reasonable footprint, one of several reasons that HF radio sees little consumer use.
HF still has a variety of interesting uses, including some new, surprising ones. The signals go beyond the horizon and around the curvature of the Earth due to their interaction with parts of the atmosphere.
Previously:
(2021) The $50 Ham: a Cheap Antenna for the HF Bands
(2020) ARRL Requests Expanded HF Privileges for Technician Licensees
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