Quad-slinky attic Dipole
A multi-band HF antenna for indoor/attic use built using four slinky toys obtainable from any toy or drug store. I bought mine for $3.99 each at Walgreens. They were $1 more each at Toys R Us, so your mileage may vary.
This dipole simply consists of two slinky toys soldered together per side. It is very simple to construct, simply remove the clip at the ends of two slinkys, and clip them together, followed by soldering. Repeat this process for the other side, and fashion some sort of center insulator. I used fiberglass with holes drilled so I could thread the end of the slinky through them. Finally, feed using ladder line or twin lead. I used RadioShack “low loss” type 300 ohm twin lead to feed this antenna. It loads up flat on all bands using my antenna tuner, and seems to perform fairly well for an indoor antenna everywhere I have tried it. It works especially well on 40 meters despite being only stretched to about 35 feet total.
As with any compromise antenna, you can't expect “full size” performance, especially indoors. I get well over S8 worth of line noise with the antenna indoors. Another thing to note is that the slinky is made of cheap steel, and will rust outdoors very quickly. Be sure to coat it with spray paint or something similar if you plan to use it outside.
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