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About RF Cafe
1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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February 1935 Short Wave Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Short Wave Craft was published from 1930 through 1936. All copyrights are hereby acknowledged. See all articles from Short Wave Craft.
Burying any antenna in the ground seems like a bad idea from radiated field pattern and efficiency perspectives. As determined in a 1974 paper published by the National Bureau of Standards, most of the energy from a buried dipole antenna that is not absorbed by the ground is radiated nearly straight up(many studies of underground antennas can be found). Motivating the NBS's burial study was a desire to conceal radio communications antennas in covert operations. This short piece in a 1935 edition of Short Wave Craft reports on a case Hams were experimenting with buried antennas in order to avoid the expense and trouble of an overhead installation. These days, Hams want to bury antennas for those same reasons AND to get around restrictive neighborhood and town restrictions prohibiting certain antenna installations.
Put Your Aerial Underground
Here's a clever way to try out an underground aerial for short-wave reception, the wire being placed inside a length of garden hose and buried 2 feet underground.
A well-known English radio writer, in a regular column in Amateur Wireless, recently pointed out the possibilities of the underground aerial for short-wave reception.
It appears that the writer was told about this type of collector, and tried it by burying a 30-ft. length of garden hose through which a wire had been threaded, 2 feet deep.
The results were a somewhat lower signal strength, as compared to a good overhead aerial, as might be expected. But, the noise-to-signal ratio was much improved, especially with regard to such noises as passing automobiles and street cars.
Different lengths of buried wires were tried, but the original 30-ft. length seemed to be the best length, as shorter wires reduced the pick-up too much, while longer wires damped the set and prevented correct operation.
Posted February 24, 2015