Advanced Qualification · A-007 Feedlines and matching · A-007-007-001
For a 3-element Yagi antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flat ground?
- A It depends on E-region height, not antenna height
- B It decreases with increasing height
- C It increases with increasing height
- D It does not vary with height
Correct answer: B — It decreases with increasing height. From the official ISED question bank, verified word for word.
Why
Raising a horizontally mounted Yagi antenna higher above flat ground pushes the main signal lobe lower toward the horizon, which lowers the takeoff angle. The full explanation — and one for every question — is in Pro.
Practise this section
Feedlines and matching at the advanced level: transmission line theory, impedance transformation, stubs and matching networks.