What happens when antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?

• A. Signal distortion occurs
• B. Received signal strength is reduced
• C. Signal clarity improves
• D. Communication is lost

Answer: (B)

When antennas at opposite ends of a VHF or UHF line of sight radio link utilize different polarizations, the received signal strength is indeed reduced. Polarization refers to the orientation of the electromagnetic waves radiated by the antenna. For optimal reception, both transmitting and receiving antennas should ideally be aligned in the same polarization, whether that is vertical, horizontal, or circular.

If one antenna is vertically polarized and the other is horizontally polarized, the mismatch causes a significant decrease in the effective capture of the signal by the receiving antenna. This results in a lower signal strength at the receiver, which can affect the overall performance of the communication link. While communication may still occur despite different polarizations, the efficiency and strength of the received signal is compromised, making B the correct choice.

In contrast, signal distortion, improvement in clarity, and the complete loss of communication are less direct results of polarization mismatches. While distortion may occur under various circumstances, it is not a guaranteed consequence of differing polarizations. Similarly, communication may still happen, albeit at reduced strength, which precludes the option of complete communication loss as an inevitable outcome of the mismatch.