As the term implies, a "random wire" is a wire antenna of random length. A random wire generally works well for signal reception, and is an improvement over the built-in whip antenna that is included with many portable radios.
An antenna tuner can be used with a random wire to make it resonant at a particular frequency.
This site is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Some links may be affiliate links. We may get paid if you buy something or take an action after clicking one of these.