Basic Qualification · B-007 Radio wave propagation · B-007-004-004
While using a 2-metre hand-held transceiver in an urban setting, you notice that moving less than one metre can severely attenuate your received signal. What is the likely cause?
- A Overhead power lines create a Faraday cage
- B Underground conduits change ground conductivity
- C Passing vehicles absorb the radio signals
- D Signals arriving on different paths cancel one another
Correct answer: D — Signals arriving on different paths cancel one another. From the official ISED question bank, verified word for word.
Why
In a city, your radio signal bounces off buildings and other objects, creating multiple copies that arrive at your antenna at slightly different times. The full explanation — and one for every question — is in Pro.
Practise this section
How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.