Why can VHF signal strength change a lot when you move your antenna a few feet?

Multipath propagation cancels or reinforces the signal.

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  1. Water vapor levels change along the path
  2. The Doppler effect shifts the frequency
  3. Multipath propagation cancels or reinforces signals ✔

Why: Signals bounce off buildings and hills and reach you by different paths. Depending on where your antenna is, those copies add together or cancel out.

Huh, didn't know that: Multipath also makes errors more likely in data transmissions.

The dad joke
Why did the ham keep dancing? He was chasing a better signal.
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References

Answer: Multipath propagation cancels or reinforces signals. Signals bounce off buildings and hills and reach you by different paths. Depending on where your antenna is, those copies add together or cancel out.

  1. HamStudy 2026-2030 Technician pool, section T3A hamstudy.org/browse/E2_2026/T3A
    Multipath propagation cancels or reinforces signals
    Checked 2026-10-09.

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