Design of Yagi Aerials

An account is given of work carried out at the Telecommunications Research Establishment on the design and use of Yagi aerial arrays during the period 1938¿42. An attempt is made to give sufficient information in tabular form for an aerial of given characteristics to be designed approximately. Final adjustment by experiment will be required unless a previous design is copied exactly. The advantages and limitations of multiple Yagi arrays are considered and a simple theoretical explanation of the mode of operation of a Yagi aerial is given. The types of polar diagram obtained when the design parameters are changed are deduced from vector diagrams. Only aerials of length greater than one wavelength are considered. These normally consist of three or more directors in addition to an exciter and a reflector.