What can happen if the antennas at both ends of a VHF or UHF line of sight radio link are not using the same polarization?

Using antennas with different polarizations in a VHF or UHF line of sight radio link can significantly affect the signal strength received. When the polarizations at both ends are mismatched—such as one antenna being vertically polarized and the other horizontally polarized—a percentage of the signal can be lost due to this mismatch. Antennas are designed to radiate and receive signals optimally when both are aligned in the same polarization.

In practical terms, this misalignment leads to reduced signal reception, resulting in weaker communication quality. The loss occurs because the electromagnetic waves emitted by one polarization do not couple effectively with the antenna tuned for another polarization, severely impacting the efficiency of the communication link. Therefore, using matched polarization is essential for optimal signal strength and clarity in VHF and UHF communications.