Joseph Helszajn , (25 April 1934 — 11 October 2019) was a British engineer and academic, who was a Professor of Microwave Engineering at Heriot-Watt University. He was best known for his work on non-reciprocal microwave circuits and devices, such as yttrium iron garnet isolators and circulators. During his tenure, Helszajn has authored multiple engineering textbooks on non-reciprocal microwave devices. Helszajn was born in Belgium in 1934 and emigrated to England in 1946. After obtaining a full technological certificate from Northern Polytechnic Institute in 1955, he obtained his M.S. degree from Santa Clara University in 1964. Helszajn has completed his doctoral degree in Leeds University in 1969. He was awarded the J.J. Thomson Medal by the Institution of Electrical Engineers in 1995, and elected a Fellow of the Royal Academy of Engineering in 1996. He was made an Officer of the Order of the British Empire in the 1997 Queen's Birthday Honours for services to engineering. He died on 11 October 2019.