As it turns out, a cheap expandable metal coil just so happens to make ... There are a few other write-ups online about people using a Slinky as a cheap antenna, such as this detailed analysis ...

It’s just a metal spring, not even meant to be a toy ... 80 feet of steel wire coiled into a two-inch spring: the Slinky. He and his wife, Betty James, took out a $500 loan to start James ...

If not, you can buy the original Slinky for about $2.99. Just hook the metal spring around the pole of your bird feeder and attach it to the very top. Gravity should pull the spring down ...