Electromagnetic field exposure monitoring of commercial 28-GHz band 5G base stations in Tokyo,

Abstract

Electromagnetic field exposure monitoring of commercial 28-GHz band 5G base stations in Tokyo, Japan Liu S, Tobita K, Onishi T, Taki M, Watanabe S. Electromagnetic field exposure monitoring of commercial 28-GHz band 5G base stations in Tokyo, Japan. Bioelectromagnetics. 2024 May 22. doi: 10.1002/bem.22505. Abstract Fifth generation (5G) wireless communication is being rolled out around the world. In this work, the latest radio frequency electromagnetic field (EMF) exposure measurement results on commercial 28- GHz band 5G base stations (BSs) deployed in the urban area of Tokyo, Japan, are presented. The measurements were conducted under realistic traffic conditions with a 5G smartphone and using both omnidirectional and horn antennas. First and foremost, in all cases, the electric-field (E-field) intensity is much lower (<-38 dB) than the exposure limits. The E-field intensities for traffic-off cases do not show any significant difference between the two antennas with the maximum being 3.6 dB. For traffic-on cases, the omnidirectional antenna can undesirably capture the radio wave from the smartphone in some cases, resulting in a 7-13 dB higher E-field intensity than that using the horn antenna. We also present comparative results between 4G long term evolution BSs and sub-6-GHz band and 28-GHz band 5G BSs and provide recommendations on acquiring meaningful EMF exposure data. This work is a further step toward the standardization of the measurement method regarding quasi- millimeter/millimeter wave 5G BSs. pubmed.ncbi.nlm.nih.gov Conclusions The latest EMF exposure measurement results on commercial 28-GHz band 5G FR2 BSs in Tokyo, Japan, were presented in this paper. The measurements were evaluated under realistic traffic conditions and in an isotropic state using both omnidirectional and horn antennas. In all cases (sites and spots, antennas, and traffic conditions), the E-field intensity was within the limits established by ICNIRP and IEEE/ICES. The maximal time-averaged E-field intensity (118 dBμV/m) reached only 0.016% of the limit. It was found that the E-field intensity varied with measurement height with a variance in amplitude reaching 10–25 dB over different measurement spots. The E-field intensities for traffic-off cases did not show any significant difference between the two antennas with the maximum being 3.6 dB. However, for traffic- on cases, the omnidirectional antenna may undesirably capture the radio wave from the smartphone in some cases, thus leading to a time-averaged E-field intensity 7–13 dB higher than that in the cases of using the horn antenna. Despite this, an omnidirectional antenna is always preferred as it can detect all the reflections and scatterings of the environment. A horn antenna is preferred only in situations where the reflections and scatterings are negligible. On the other hand, the distance between the smartphone and the antenna (50 cm in this study) may be increased to avoid the capture of the irradiation from the smartphone. For the horn antenna, there is generally a 23–27 dB rise in the time-averaged E-field intensity of traffic-on cases compared with that of traffic-off cases. The rise for the omnidirectional antenna is 19–37 dB. 5G, especially 5G FR2, is being continuously deployed. The measurements in this work were mainly limited to the urban area of Tokyo, Japan. With the expansion of the 5G service coverage, measurements in suburban and rural areas will be conducted in the future. Comparative studies between 5G FR1 and FR2 will also be of considerable interest and will be a future target. In summary, investigations will be successively conducted following the deployment of 5G.

AI evidence extraction

Main findings

In measurements of commercial 28-GHz band 5G base stations in urban Tokyo under realistic traffic conditions, E-field intensities were reported to be within ICNIRP and IEEE/ICES limits; the maximal time-averaged E-field intensity (118 dBμV/m) was stated to be 0.016% of the limit. For traffic-on cases, omnidirectional measurements could be 7–13 dB higher than horn-antenna measurements in some cases due to undesired capture of smartphone emissions; E-field intensity varied by 10–25 dB across measurement spots/heights.

Outcomes measured

• Electric-field (E-field) intensity measurements near commercial 28-GHz band 5G base stations under realistic traffic conditions
• Comparison of E-field intensity by antenna type (omnidirectional vs horn) and traffic condition (traffic-on vs traffic-off)
• Comparison of exposure measurements across 4G LTE, sub-6-GHz 5G, and 28-GHz 5G base stations
• Assessment of compliance with ICNIRP and IEEE/ICES exposure limits
• Variation of E-field intensity with measurement height and across measurement spots

Limitations

• Measurements were mainly limited to the urban area of Tokyo, Japan.
• Potential contamination of base-station measurements by smartphone emissions when using an omnidirectional antenna under traffic-on conditions (50 cm smartphone-to-antenna distance in this study).

Suggested hubs

• who-icnirp (0.6)
  Study explicitly evaluates measurements against ICNIRP (and IEEE/ICES) exposure limits.
• 5g-policy (0.45)
  Focuses on real-world exposure monitoring of commercial 28-GHz (FR2) 5G base stations and measurement standardization.

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    "study_type": "exposure_assessment",
    "exposure": {
        "band": "mmWave",
        "source": "base station",
        "frequency_mhz": 28000,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Electric-field (E-field) intensity measurements near commercial 28-GHz band 5G base stations under realistic traffic conditions",
        "Comparison of E-field intensity by antenna type (omnidirectional vs horn) and traffic condition (traffic-on vs traffic-off)",
        "Comparison of exposure measurements across 4G LTE, sub-6-GHz 5G, and 28-GHz 5G base stations",
        "Assessment of compliance with ICNIRP and IEEE/ICES exposure limits",
        "Variation of E-field intensity with measurement height and across measurement spots"
    ],
    "main_findings": "In measurements of commercial 28-GHz band 5G base stations in urban Tokyo under realistic traffic conditions, E-field intensities were reported to be within ICNIRP and IEEE/ICES limits; the maximal time-averaged E-field intensity (118 dBμV/m) was stated to be 0.016% of the limit. For traffic-on cases, omnidirectional measurements could be 7–13 dB higher than horn-antenna measurements in some cases due to undesired capture of smartphone emissions; E-field intensity varied by 10–25 dB across measurement spots/heights.",
    "effect_direction": "no_effect",
    "limitations": [
        "Measurements were mainly limited to the urban area of Tokyo, Japan.",
        "Potential contamination of base-station measurements by smartphone emissions when using an omnidirectional antenna under traffic-on conditions (50 cm smartphone-to-antenna distance in this study)."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "5G",
        "FR2",
        "28 GHz",
        "mmWave",
        "base station",
        "exposure monitoring",
        "E-field intensity",
        "ICNIRP",
        "IEEE/ICES",
        "Tokyo",
        "measurement method",
        "omnidirectional antenna",
        "horn antenna",
        "traffic conditions"
    ],
    "suggested_hubs": [
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            "reason": "Focuses on real-world exposure monitoring of commercial 28-GHz (FR2) 5G base stations and measurement standardization."
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}

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