via HACKADAY: Identify That Antenna By Sight

It’s a skill that radio amateurs pick up over years but which it sometimes comes as a surprise to find that is not shared by everyone, the ability to casually glance at an antenna on a mast or a rooftop and guess what it might be used for. By which of course I mean not some intuitive ability to mentally decode radio signals from thin air, but most of us can look at a given antenna and immediately glean a lot of information about its frequency and performance. Is this privileged knowledge handed down from the Elmers at the secret ceremony of conferring a radio amateur’s licence upon a baby ham? Not at all, in fact stick around, and I’ll share some of the tricks.