Frank H. Sanders; Kenneth R. Calahan; Geoffrey A. Sanders; Savio Tran

Abstract: Introduction of Fifth Generation New Radio (5G NR) systems in the US between 3700 and 3980 MHz has raised concerns about electromagnetic compatibility with airborne radar altimeter (radalt) receivers operating between 4200 and 4400 MHz. This report describes work performed by the Department of Commerce’s Institute for Telecommunication Sciences (ITS) for the Joint Interagency 5G Radar Altimeter Interference (JI-FRAI) Quick Reaction Testing (QRT) program to address these concerns. Two collected data sets are described: radiated wideband, wide dynamic range 5G base station emission spectra; and three-dimensional radiation patterns around 5G base station antennas. The emission spectra show effective filtering that reduces out-of-band (OoB) 5G emissions in the radalt band by as much as -106 dB below the 5G fundamental, for an upper-bounded OoB 5G power density not exceeding -48.5 dBm/MHz when maximum measurement range was achieved. The 5G radiation patterns show significantly less power in the sky than in 5G main beams directed groundward, especially at array zeniths. These data can be used for receivers whose flight paths carry them laterally past, and even directly above, 5G base stations. Finally, we have documented a near-far effect in airborne measurements on pairs of 5G transmitters. This causes the nearer transmitters’ emissions to be dominant in receivers. When a single 5G transmitter is near a receiver, that single transmitter’s emitted power will tend to dominate over the cumulative, aggregated emissions from more-distant, aggregated 5G transmitters.

Keywords: 5G; 5G radiation; radar altimeter; radio altimeter; 5G NR; 5G emissions; 5G electromagnetic compatibility (EMC); 5G emission spectrum; 5G spectrum; airborne radar altimeter interference; airborne radio altimeter interference; JI-FRAI; MIMO antenna radiation patterns; radalt; radalt electromagnetic compatibility (EMC); radalt interference; radalt receiver interference; radalt spectrum

For technical information concerning this report, contact:

Frank H. Sanders
Institute for Telecommunication Sciences
(303) 497-7600
fsanders@ntia.doc.gov

To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572
LSegre@ntia.gov

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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