Question T9A06
From subelement T9 - T9A
Which of the following types of antenna offers the greatest gain?
Why is this correct?
The Yagi antenna offers the greatest gain among these options because it uses multiple elements (directors and reflectors) to concentrate RF energy in one direction. An isotropic antenna is a theoretical reference with 0 dBi gain that radiates equally in all directions. The 5/8 wave vertical and J pole are both single-element antennas with modest gain compared to multi-element beam designs like the Yagi.
Memory tip
Remember the pattern: multi-element antennas generally have higher gain than single-element ones. Yagi antennas achieve their high gain through parasitic elements that focus energy directionally, similar to how a reflector focuses light in a flashlight.
Learn more
In practical amateur radio operation, Yagi antennas are the workhorses of HF and VHF weak-signal communication. Their high gain and sharp directivity make them ideal for long-distance contacts, moonbounce communication, and working through repeaters with marginal coverage. The trade-off is that they must be rotated to point toward different stations, which is why many operators use rotator systems for their Yagi arrays.
Think about it
Why do you think amateur radio operators often choose lower-gain antennas like verticals for local communication, even though Yagis offer superior gain?