Aircraft VHF communications antennas are polarized in which direction?

Aircraft VHF communications antennas are typically polarized vertically. This vertical polarization is essential for optimal performance in VHF communication systems because it aligns the antenna's electric field with the direction that signals are transmitted and received. Vertical polarization minimizes multipath interference, which can occur when signals bounce off surfaces, such as the ground or nearby buildings.

In aviation, VHF communication is crucial for air traffic control and pilot communications. By using vertically polarized antennas, aircraft can achieve better line-of-sight communications with ground stations and other aircraft. This vertical configuration allows the antennas to work effectively, particularly at the frequencies commonly used for VHF communication, which range from 118 to 137 MHz.

While other polarizations exist (such as horizontally or diagonally), they are less suitable for aircraft VHF communications, as they could lead to decreased signal strength and reliability in the specific contexts in which aircraft operate, such as high altitudes and varying terrain below. Therefore, vertical polarization is the standard for typical aircraft VHF antennas.