Message received

Antennas transmit, receive signals—from the ground or space

June 7, 2023 By Jill W. Tallman

Jutting out like whiskers on a cat, antennas are how your airplane’s communications or GPS equipment picks up or transmits signals to and from the aircraft.

Photography by Chris Rose

Antennas aren’t all the same size or shape because the equipment they service have different functions. The frequencies at which the antennas operate and their directional qualities usually determine their shape and placement. For example, communications equipment antennas can be mounted on either the top or belly of the aircraft. A UHF antenna, such as those used by transponders and distance-measuring equipment, would be mounted on the belly. Finally, if it’s situated on the tail, the antenna is almost always for navigation equipment.

While many antennas are rod or blade-shaped, some GPS antennas are saucer shaped. These are attached to the fuselage, and they pick up signals from GPS satellites in a line-of-sight fashion.

When preflighting, check to make sure the seal at the base of the antenna is structurally strong and in place. Also look for damage to the antenna itself, and after engine start check equipment to ensure the antennas are receiving or transmitting properly.

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