Greek heliographs

In the 5th century B.C., the Greeks used heliographs, which involved reflecting sunlight with polished shields or mirrors to send coded messages over distances. This early optical communication method laid the foundation for modern light-based signaling in amateur radio, such as Morse code via light signals. Heliographs emphasized the importance of line-of-sight and clear weather for effective communication, concepts still relevant in radio wave propagation and antenna placement in amateur radio. The Greeks’ innovative use of natural elements for communication mirrors the creative problem-solving that amateur radio operators employ today.