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Radio: Difference between revisions
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→Random wire antenna for AM/MW reception
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In a disaster situation with no access to mobile data nor the Internet, and a handheld radio does not provide sufficient reception or is unavailable, AM/MW radio is a good first option. If you are wanting to listen for local shortwave (AM/MW) broadcasts and have little resources and/or poor reception with a little handheld, even a rough 6 meters length of wire should give you opportunity to listen to many stations within an AM/MW range (about 500 kHz to 13 MHz). | In a disaster situation with no access to mobile data nor the Internet, and a handheld radio does not provide sufficient reception or is unavailable, AM/MW radio is a good first option. If you are wanting to listen for local shortwave (AM/MW) broadcasts and have little resources and/or poor reception with a little handheld, even a rough 6 meters length of wire should give you opportunity to listen to many stations within an AM/MW range (about 500 kHz to 13 MHz). | ||
The most common configuration for random wire antennae is to suspend it between a home (or shelter) and a tree or adjacent structure. A loop can be made in the wire, twisted tight, and paracord or rope used to fasten it to each end. It is important that the wire is electrically insulated from the structures it is tethered to. If just using wire to affix to the structures, ceramic insulators can be added inline at each end, with the feedline to the receiver connected to the suspended antenna section. In the absence of insulators, a ceramic cup with a sturdy handle can be used, with each portion of wire twisted to each end of the handle and the cup horizontal. | The most common configuration for random wire antennae is to suspend it between a home (or shelter) and a tree or adjacent structure. A loop can be made in the wire, twisted tight, and paracord or rope used to fasten it to each end. It is important that the wire is electrically insulated from the structures it is tethered to. If just using wire to affix to the structures, ceramic insulators can be added inline at each end, with the feedline to the receiver connected to the suspended antenna section. In the absence of proper ceramic insulators, a ceramic cup with a sturdy handle can be used, with each portion of wire twisted to each end of the handle and the cup horizontal. Alternatively, a solid piece of polyethylene plastic (for instance a dog chew toy, holes put at each end) can be used. | ||
When the wire is short enough, it can alternatively be hung vertically from a roof or tree, and sometimes enjoy better reception as it will have closer polarity (electromagnetic orientation) to that of the broadcasting antenna. | When the wire is short enough, it can alternatively be hung vertically from a roof or tree, and sometimes enjoy better reception as it will have closer polarity (electromagnetic orientation) to that of the broadcasting antenna. | ||
Random wire antennas are ever at risk of electrical storms, and so such an antenna should be electrically grounded. For this exposed metal plumping pipe can be used, or a steel stake driven deep into the ground. | Random wire antennas are ever at risk of electrical storms, and so such an antenna should be electrically grounded. For this exposed metal plumping pipe can be used, or a steel stake driven deep into the ground. If you do not do this, you risk destroying your equipment. | ||
[[File:Homemade_balun.jpeg|thumb|Homemade 1:1 balun using a toroidal core and coaxial cable. This simple RF choke works as a balun by preventing signals passing along the outside of the braid]] | [[File:Homemade_balun.jpeg|thumb|Homemade 1:1 balun using a toroidal core and coaxial cable. This simple RF choke works as a balun by preventing signals passing along the outside of the braid]] | ||