Question
Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?
Answer Options
- A) Digital modes are unusable
- B) Either vertically or horizontally polarized antennas may be used for transmission or reception
- C) FM voice is unusable
- D) Both the transmitting and receiving antennas must be of the same polarization
Correct Answer: B
Explanation
When an RF signal passes through the ionosphere, the interaction with the charged particles causes the signal’s polarization to slowly and randomly rotate. This phenomenon is called Faraday rotation, and the resulting signal is described as elliptically polarized.
Because the polarization is rotating randomly and continuously, it means that the receiving station can effectively use either vertically or horizontally polarized antennas for good reception. The random rotation ensures that the incoming signal’s electric field will momentarily align with any linear receiving antenna at regular intervals.
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