Traveling-wave antenna

In radio and telecommunication, a traveling-wave antenna is a class of antenna that use a traveling wave on a guiding structure as the main radiating mechanism. Their distinguishing feature is that the radio-frequency current that generates the radio waves travels through the antenna in one direction. This is in contrast to a resonant antenna, such as the monopole or dipole, in which the antenna acts as a resonator, with radio currents traveling in both directions, bouncing back and forth between the ends of the antenna. An advantage of traveling wave antennas is that since they are nonresonant they often have a wider bandwidth than resonant antennas. Common types of traveling wave antenna are the Beverage antenna and the rhombic antenna.