In a 3-element Yagi antenna, what is the longest radiating element?

A 3-element Yagi antenna consists of three types of radiating elements: a driven element, a reflector, and a director. The reflector is placed behind the driven element to bounce RF energy forward, increasing the antenna's directional gain. To act effectively as an inductive reflector at the operating frequency, it must be physically longer than the resonant driven element. Typically, the reflector is cut to be about 5% longer than the driven element. The boom, while often physically the longest part of the assembly, is a structural support rather than a radiating element.