A report on Japanese developments of antennas from Yagi-Uda antenna to self-complementary antennas

In this paper, first, studies on the design method of Yagi-Uda antennas performed in Japan during the period of several years since the mid 1940s are briefly reviewed, and their connection to the slot antennas is mentioned. Then, the state of the theoretical researches on slot antennas in Japan around the later 1940s is explained. Under those circumstances, the self-complementary antennas were originated and their constant-impedance property was discovered by the author in 1948. The extensions of the principle of this antenna to various other types of the structures, and the results of the extensive developmental investigations in Japan for this type of antenna are succinctly described.