What Are the Different Types of Antennas Used in Aviation

Radio communication is a salient requirement for all forms of aviation, including general, commercial, and military. This system, which is used to facilitate voice communication, location sending, and ground-based navigation, relies on a complex architecture of electromechanical components, namely antennas. The antennas used on aircraft are variable and specialized in performing specific functions. In this blog, we will discuss the various types of antennas that may be found on common aircraft.

The dipole antenna type plays a critical role in radio wave transmission. It is also the most common class found on aircraft worldwide. Although dipole antennas may come in a variety of forms, the one used in aviation is the half-wave dipole. It is named as such because the length of the conductor is roughly one-half that of the wavelength of the frequency being transmitted. These devices rely on alternating currents to produce electromagnetic fields of varying sizes throughout the antenna. Nearly all half-wave dipole antennas found on modern aircraft are of the VHF variant, which is used primarily as a navigation aid. The VHF antenna used for navigation is almost universally situated on the vertical tail. Unlike other aircraft systems, which have several layers of redundancy, VHF antenna failure would assuredly affect multiple navigation systems at once.

As many aircraft models begin to make the transition to Global Positioning System (GPS) based navigation, there has grown a strong demand for GPS antennas. These antennas are unique in their function and location due to the requirements placed on receivers of GPS satellites. Since the satellites employed in the GPS transmit weak signals, the receivers must also act as amplifiers. Additionally, the receivers must be placed on top of the fuselage to meet the line-of-sight conditions demanded by GPS satellites. In order to avoid aerodynamic disruption, the antennas are designed with a low profile.

Emergency locator transmitters are required in all but a small minority of civil aircraft in the United States. These specialty antennas broadcast distress signals on specific frequencies, including 121.5, 243.0, and 406 MHz. The 121.5 and 243.0 frequencies initially lacked the ability to provide a location to search and rescue crews, but later a paired satellite program was implemented that solved this issue. However, these two frequencies continued to present false signals, which tied up resources. As a result, the industry moved to the novel 406 MHz frequency, which is much more stable and produces fewer false alarms. Although the older frequencies have not yet been banned outright, they provide only limited safety assurances to crews in distress.

UHF antennas enable both transponder location and distance measuring equipment data. These devices can act as both transmitters and receivers, allowing the aircraft to send messages and receive interrogation from ATC towers. In a distance measuring system, UHF antennas broadcast a radio signal between 960-1215 MHz. After receiving a return signal from ground stations, an associated computer times the propagation delay between the signals, yielding a distance in meters. Both transponders and distance measuring equipment require a direct line of sight between the aircraft and ground stations, requiring the antennas to be situated under the fuselage.

Regardless of their use, antennas should be maintained in adequate condition to ensure proper functioning and system longevity. Antennas should be regularly inspected for any signs of cracking since water may enter and cause delamination. Additionally, the base of the antenna should be kept dry as often as possible to prevent corrosion, which may erode the electrical grounding of the aircraft. Finally, when painting the plane, it is critical to avoid painting over any antenna components since this may reduce their efficacy.

At Veritable Aerospace, we have immediate availability on a wide range of radio and antenna components for both civil and military aircraft. Browse our expansive part catalog, or use our powerful search engine to find the exact item you need and receive a quote at any time using our Instant RFQ service. Our expert team of account managers work around the clock to answer customer questions and provide customized quotations in just 15 minutes or less from submission. If you are facing an aircraft on ground (AOG) situation and need your order promptly, please let our team know in order to learn about our same-day shipping options for select in-stock products.


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October 29, 2021

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