How Antennas Transmit
To begin with, all radio transmissions are electromagnetic (EM) waves. To transmit a radio wave, a moving magnetic field induces a current and a voltage in a length of wire. You can test this yourself by connecting a sensitive voltmeter to a loop of wire and wiggling a strong magnet back and forth within the confines of the loop. You’ll see a small voltage and current appear on the voltmeter. It’s a small current—on the order of several microamps—but that’s because you’re not wiggling the magnet fast enough. If you increase the frequency of your magnet-wiggling, the voltage and current will increase in the wire, which in turn will increase the power of the transmission (remember your electrical equations—, or power equals ...
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