| > how can the conductor conduct when one of the ends is just hanging in the air? AC magic I suppose I struggled with these matters too. I wouldn't call it "AC magic", but "RF magic". Notice that you need a different mental model to understand those circuits. In DC and low-freq AC, it's enough to think that voltages and currents manifest themselves instantaneously in a conductor. But that is a (useful) simplification. Roughly speaking, the energy supplied by the power source takes time to propagate over the wire [0]. Having that in mind, take a look at the animated gif in this page: https://en.wikipedia.org/wiki/Dipole_antenna. I believe it's gonna make more sense now. This mental model also helps to understand why a magnetic loop isn't simply a piece of short-circuited wire -- for a DC or low freq AC circuit, it is indeed a short-circuit; for an RF circuit, it is not. [1] [0] https://en.wikipedia.org/wiki/Velocity_factor [1] this mental model is not enough to fully understand any antenna. Many designs also depend on other phenomena, like the electromagnetic interactions between its components, and interactions with its surroundings. But I think that, equipped with this mental model, you'll be able to research further in case you feel interested. |