For the next six years, Harvard was his home. He received his M.S. in communication engineering in 1944 and the doctor of science degree in 1947; his thesis was entitled “Theory of Coupled Antennas and Its Application.” He was the second doctoral student of Professor R.W.P. King, with whom he remained close friends throughout his life. He continued at the Cruft Laboratory at Harvard as a research fellow until 1949, when he moved west to take a position as research physicist at the Stanford Research Institute in Palo Alto. Some of the technical reports he wrote during this period are still important reference documents.
In 1954, he was appointed associate professor of electrical engineering at Ohio State University (OSU) in Columbus. Two years later, he left to take a faculty position at the Technical Institute of Aeronautics in São José dos Campos, Brazil, where he became proficient in Portuguese. He returned to OSU in 1961 and then, in 1964, joined the faculty of UM as professor of electrical and computer engineering; he also became a member of the Radiation Laboratory at UM. Except for a few years (1967–1969) when he took a reduced appointment to work part time for KMS Industries, he remained at Michigan for the rest of his career. He was made emeritus professor in 1986 and was honored by his colleagues and former Ph.D. students in a special session at the 1985 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting held in Vancouver, Canada.
Professor Tai is recognized throughout the world for his research on antenna theory, electromagnetic theory, and applied mathematics. His extension of Hallén’s pioneering work on antennas to coupled cylindrical antennas established the foundation of multielement array antennas, which are used extensively in a variety of radio systems. His refinement of Schelkunoff’s biconical antenna theory provided a much-needed understanding of how antennas can be designed to operate over a wide band of frequencies. His book, Dyadic Green’s Functions in Electromagnetic Theory, published in 1971, popularized the use of Green’s functions for the solution of diffraction-dependent antenna problems.