Ham Radio General Class Practice Test

In a three-element, single-band Yagi antenna, which statement is true?

1. The reflector is normally the shortest parasitic element

2. The director is normally the shortest parasitic element

3. The driven element is the longest parasitic element

4. Low feed-point impedance increases bandwidth

The correct answer is: The director is normally the shortest parasitic element

In a three-element Yagi antenna configuration, the roles of the elements are crucial for determining the antenna's characteristics. The director, one of the parasitic elements, is designed to be shorter than the driven element and serves to direct the radio waves in the intended direction of radiation. By being shorter, it effectively helps to focus and enhance the forward gain of the antenna. In contrast, the reflector is typically longer than the driven element and serves to reflect the radio waves back towards the driven element, enhancing the overall gain in the forward direction. The driven element is generally the element that is directly connected to the transmission line and is usually of a size that is critical for tuning the antenna to resonate at the desired frequency. Therefore, the statement regarding the director being the shortest parasitic element is correct, as it accurately reflects the design and function of Yagi antennas. Providing a specific configuration where each element's length plays a vital role in the antenna's efficiency and radiation pattern is essential for understanding antenna design in ham radio operations.