Ham Radio General Class Practice Test

Which statement about a three-element, single-band Yagi antenna is true?

1. The reflector is normally the longest parasitic element

2. The director is normally the longest parasitic element

3. The reflector is normally the shortest parasitic element

4. All of the elements must be the same length

The correct answer is: The reflector is normally the longest parasitic element

In a three-element Yagi antenna, the arrangement typically includes a driven element, a reflector, and a director. The reflector plays a crucial role in directing the signal toward the director, which helps improve gain and directivity in the desired direction of reception or transmission. The reflector is designed to be longer than the driven element and the director, which contributes to its function in the antenna design. This increased length allows the reflector to create a phase difference that improves the overall performance of the antenna by reinforcing the signal radiated by the driven element and enhancing the forward gain. In contrast, the director is shorter than the driven element, being optimized to effectively constructively combine the signals in the desired direction without drawing excessive energy from the source. The option that states the reflector is the longest parasitic element accurately reflects these principles of Yagi antenna design. This structure is aimed at maximizing performance for the particular radio frequency band for which the antenna is designed. The other options misrepresent the characteristics and roles of the elements within a Yagi antenna configuration, as the reflector indeed cannot be the shortest or of the same length as the other elements in a well-designed three-element Yagi.