What Are Aircraft Antennas and Their Types?

While the various essential flight components such as communication systems, navigation systems, and flight instruments are often discussed in length, the aircraft antennas that ensure their functionality are regularly underrepresented. On a typical aircraft, one may find dozens of antennas that are situated above and below the fuselage, as well as on other surfaces. There are different types of antenna to accommodate varying applications, and each may differ in its size, shape, and placement. While many attributes are decided upon by the manufacturer, certain attributes may be chosen for directional qualities and frequencies. In this blog, we will provide a brief overview of the common aircraft antenna types, allowing you to best understand their use and importance.

Communication Antenna

Communication antennas are the most widely known type, allowing for pilots and crew members to communicate with air traffic control and other individuals. Communication antennas may be placed on the top or bottom of the fuselage, though the former can be affected by aircraft shadowing. To ensure that all communication devices work as intended, each transmitter will have its own antenna and all will be strategically placed to avoid poor coverage.

GPS Antenna

GPS antennas are quite useful for navigation and chart plotting, though tend to create weak signals due to only transmitting under five watts of power. To boost the quality of GPS antennas, a built-in amplifier will increase signal power for the receiver. As GPS antennas transmit signals at high frequencies, they are regularly placed on the top of the fuselage. To avoid any interference with different types of antenna equipment, GPS and communications antennas should be placed as far away from each other as possible.

Loran Antenna

Loran antennas, or long-range navigation antennas, are similar in their exterior appearance to communications types. Loran antennas will regularly have an amplifier for their functionality, that of which may be built into the antenna base or will be placed under the fuselage skin. While such aircraft antenna types may be placed either on the top or bottom of the fuselage, they must be kept away from electrical charge buildup from dust or rain as it will cause P-static. Static buildup can also result from vertical fin vinyl stickers, thus optimal placement is crucial.

Loop Antenna

For the functionality of lightning detection systems, a looped-shape device known as a loop antenna may be used. Also known as directional antennas, such types will typically consist of two or three separated coils that are short and wide. Each coil will often contain oil and water for their operations, and they are designed to receive signals between coils at varying strengths. As the loop antenna type requires fluids for functionality and are at risk of buildups, accessory kit antenna seals should be used and maintained.

Marker Beacon Antenna

Marker beacons work together with the instrument landing system of an aircraft to provide pilots with a means to determine their position along a route. As a result, the marker beacon antenna must be placed on the fuselage belly to properly work. While such components may vary in their appearance, they are commonly around 10 inches long and are quite reliable.

Navigation Antenna

Navigation antennas are almost exclusively placed on the vertical tail surface of the aircraft, coming in three distinct types. The dual blade navigation antenna is a type where antennas are placed on either side of the tail, benefiting aerodynamics as they reduce air drag. The cat whisker type is another common variation, featuring rods that extend outwards from each side of the stabilizer at a 45 degree angle. Cat whisker navigation antennas are most optimal when flying low as such components are incapable of retrieving signals sent to their sides. The final major navigation antenna type is the towel bar, that of which is a balanced loop antenna capable of receiving signals from all directions. The towel bar antenna type is commonly associated with area navigation (RNAV) systems, and they consist of two antennas that are placed on each side of the aircraft tail.

Radio Altimeter

Radio altimeters are a type of antenna that are placed on the belly of the aircraft, having an appearance that is similar to square plates. Radio altimeters may either be a single or dual-antenna system which will transmit radio signals to the ground so that they may bounce off and be received again. By measuring the time between the signal transmission and its return, the distance between the aircraft and ground may be determined. As such antenna types rely on high frequencies, they must have a secure electrical bond to the skin of the fuselage to maintain accurate readings.

UHF Antenna

UHF antennas are quite small, serving as a four-inch component that extends from the bottom of the fuselage. Such antenna types are implemented for the functionality of distance-measuring equipment (DME) and transponders, coming in the form of either blade or spike types. While blade antennas are most suitable for DMEs, the spike antenna is only to be used with transponders. Due to their small construction, UHF antennas are at risk of being shadowed by landing gear. Additionally, transponder checks should be carried out at least twice a year on a biannual schedule so that any oil or water buildup may be removed. Buildup will easily detract from the signal quality of the antenna, distorting it as substances increase.

Antenna Adapters

When installing and implementing antennas, one may require adapter antenna components for the means of establishing connectors, cables, and other components. Ranging from adapter female antenna components to actuator antenna parts, there are a number of accessory kit antenna items that one may use to establish functioning systems.

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