We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Anomalous Long‐Distance Propagation of ILS LOC Signals by the Es Layer and Its Impact on Aviation Receivers.
- Authors
Saito, S.; Hosokawa, K.; Sakai, J.; Tomizawa, I.
- Abstract
Anomalous long‐distance propagation of Very High Frequency radio waves of aeronautical navigation systems was investigated by an airborne Instrument Landing System (ILS) localizer (ILS LOC) receiver installed on the ground at Kure, Japan (34.245°N, 132.528°E). Intense ILS LOC type signals were observed and the received power was strong enough for the aviation receiver to output course deviation. The radio source was identified by receiving the Morse Code for identification as the localizer‐type directional aid (LDA) serving the Runway‐21 of the Hualien Airport, Taiwan (24.0396°N, 121.6221°E) of which beam pointed close to the receiver. This result supports that the source of the signals often observed at the same frequency at the same location is most probably the LDA at the Hualien Airport. The maximum received power was −99 dBm for an omni‐directional antenna. It was strong enough to cause co‐channel interference. Considering stronger power (−70 dBm) found in previous observations at the same frequency at the same location, anomalous propagation of ILS LOC signals by the Es layer could be a cause of interference when a receiver was near the center of the ILS LOC beam. The course deviation output was consistent with the geometry between the beam of Runway‐21 LDA at the Hualien Airport and the receiver. However, the observed course deviation fluctuated remarkably even when the received power was strong enough. The fluctuation of the course deviation may indicate the structure of the Es layer, and observation of the course deviation could be used to diagnose the Es layer structure. Plain Language Summary: Intense signals of an instrument landing system localizer (ILS LOC) for aircraft navigation was detected over anomalously long distance (about 1,550 km). The ILS LOC equivalent signal from Hualien Airport, Taiwan was observed by an ILS LOC receiver for aviation on the ground at Kure, Japan. The signal was strong enough to provide deviation of the position from the center of the beam and was strong enough to cause co‐channel interference. Considering stronger power found in previous observations at the same frequency at the same location, anomalous propagation of ILS LOC signals by the sporadic E (Es) layer, which is an ionospheric layer with a high electron density and thin altitudinal thickness, could be a cause of interference when a receiver was near the center of the ILS LOC beam. The fluctuation of the course deviation may indicate the structure of the Es layer, and could be used to diagnose the Es layer structure. Key Points: Anomalous long‐distance propagation of Very High Frequency radio air navigation signals by the sporadic E layer was detected by an aviation receiverThe received signal was strong enough to cause interference to an aviation receiver at distances far outside the intended service areaVariation of course deviation information obtained from the ILS‐LOC signal could be used to study fine structures of the Es layer
- Subjects
TAIWAN; SHORTWAVE radio; INSTRUMENT landing systems; AERONAUTICAL navigation; CO-channel interference; RADIO waves; LONG-distance running; FINE structure (Physics)
- Publication
Space Weather: The International Journal of Research & Applications, 2023, Vol 21, Issue 11, p1
- ISSN
1539-4956
- Publication type
Article
- DOI
10.1029/2023SW003577