Look at any ham tower and you will know it instantly: the long boom, the row of elements getting shorter toward the front. The Yagi-Uda antenna turns 100 in 2026, and it remains the most recognizable antenna on Earth — the rooftop TV antenna of the 1960s, the contest station's beam, the direction-finder's pointer. A century after its invention, we still have not found a better way to aim radio waves.
The story starts at Tohoku Imperial University in Sendai, Japan. Assistant Professor Shintaro Uda, working with his mentor Professor Hidetsugu Yagi, presented the theory in a Japanese journal in 1926 after systematic experiments showing that parasitic elements — a reflector behind a driven dipole and directors in front — could shape a sharp beam. The pair published the first English description the same year in the Proceedings of the Imperial Academy of Japan, describing what they called a "wave canal" to illustrate how the directors steer energy forward. When Yagi published a 1928 English survey of Japanese short-wave research, his name became attached to the invention worldwide — though he always acknowledged Uda's principal contribution, and the proper name is Yagi-Uda.
Then comes the wartime irony. The antenna's first great application was World War II radar, and Allied airborne radar sets used Yagis extensively — while many Japanese radar engineers were unaware of the design, partly due to army-navy rivalry. Japanese military authorities reportedly first learned of it after the Battle of Singapore, when captured British technician's notes mentioned a "yagi antenna," and the intelligence officers did not even recognize Yagi as a Japanese name.
After the war, the design conquered suburbia. By the 1960s Yagi-Udas sprouted on rooftops everywhere to pull in VHF television, and hams adopted the beam as their standard tool for DXing, contesting, and satellite work. The physics never changed: parasitic elements at precise spacings, roughly 8 to 10 dB of forward gain, and a clean front-to-back ratio from a few dollars of aluminum. Happy hundredth, Yagi-Uda — and remember to give Uda his half of the credit.