SignalPrep
Basic Qualification · B-006 Feedlines and antenna systems · B-006-011-011

If the forward gain of a six-element Yagi is about 10 dBi, what would the gain of two of these antennas be if they were "stacked"?

  1. A13 dBi
  2. B7 dBi
  3. C20 dBi
  4. D10 dBi

Correct answer: A — 13 dBi. From the official ISED question bank, verified word for word.

Why

Stacking two identical antennas doubles the effective power in the desired direction, which adds exactly 3 decibels to the gain. The full explanation — and one for every question — is in Pro.

Practise this section

Feedlines and antenna systems is section B-006 of the Basic exam: Getting the signal out: antennas, feedlines, SWR, baluns, matching, and why antenna length depends on frequency.

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