On the averaging area for incident power density for human exposure limits at frequencies over 6 GHz

2017 · Unclear · Low evidence

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UnclearLow evidencePaper 1311

Study snapshot

Publicationmanual · 2017

Study typeengineering

Reported directionUnclear

Evidence ratingLow

Abstract

On the averaging area for incident power density for human exposure limits at frequencies over 6 GHz Hashimoto Y, Hirata A, Morimoto R, Aonuma S, Laakso I, Jokela K, Foster K. On the averaging area for incident power density for human exposure limits at frequencies over 6 GHz. Phys Med Biol. 2017 Feb 8. doi: 10.1088/1361-6560/aa5f21. Abstract Incident power density is used as the dosimetric quantity to specify the restrictions on human exposure to electromagnetic fields at frequencies above 3 or 10 GHz in order to prevent excessive temperature elevation at the body surface. However, international standards and guidelines have different definitions for the size of the area over which the power density should be averaged. This study reports computational evaluation of the relationship between the size of the area over which incident power density is averaged and the local peak temperature elevation in a multi-layer model simulating a human body. Three wave sources are considered in the frequency range from 3 to 300 GHz: an ideal beam, a half-wave dipole antenna, and an antenna array. One- dimensional analysis shows that averaging area of 20 mm × 20 mm is a good measure to correlate with the local peak temperature elevation when the field distribution is nearly uniform in that area. The averaging area is different from recommendations in the current international standards/guidelines, and not dependent on the frequency. For a non-uniform field distribution, such as a beam with small diameter, the incident power density should be compensated by multiplying a factor that can be derived from the ratio of the effective beam area to the averaging area. The findings in the present study suggest that the relationship obtained using the one- dimensional approximation is applicable for deriving the relationship between the incident power density and the local temperature elevation. ncbi.nlm.nih.gov

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureRF

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Computational modeling (multi-layer human body model) evaluated how the incident power density averaging area relates to local peak temperature elevation for sources from 3 to 300 GHz. A one-dimensional analysis indicated that averaging over 20 mm × 20 mm correlates well with local peak temperature elevation when the field distribution is nearly uniform, and this averaging area was reported as not dependent on frequency. For non-uniform fields (e.g., small-diameter beams), the study suggests compensating incident power density using a factor based on the ratio of effective beam area to averaging area.

Outcomes measured

incident power density averaging area
local peak temperature elevation (body surface)
relationship between averaged incident power density and temperature rise

Limitations

Computational evaluation using a multi-layer model; no human/epidemiologic data described in abstract
One-dimensional approximation used for deriving relationships; applicability beyond modeled scenarios not fully described in abstract
Results depend on assumptions about field uniformity and source types (ideal beam, half-wave dipole, antenna array)

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "incident power density averaging area",
    "local peak temperature elevation (body surface)",
    "relationship between averaged incident power density and temperature rise"
  ],
  "main_findings": "Computational modeling (multi-layer human body model) evaluated how the incident power density averaging area relates to local peak temperature elevation for sources from 3 to 300 GHz. A one-dimensional analysis indicated that averaging over 20 mm × 20 mm correlates well with local peak temperature elevation when the field distribution is nearly uniform, and this averaging area was reported as not dependent on frequency. For non-uniform fields (e.g., small-diameter beams), the study suggests compensating incident power density using a factor based on the ratio of effective beam area to averaging area.",
  "effect_direction": "unclear",
  "limitations": [
    "Computational evaluation using a multi-layer model; no human/epidemiologic data described in abstract",
    "One-dimensional approximation used for deriving relationships; applicability beyond modeled scenarios not fully described in abstract",
    "Results depend on assumptions about field uniformity and source types (ideal beam, half-wave dipole, antenna array)"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "incident power density",
    "averaging area",
    "human exposure limits",
    "temperature elevation",
    "3–300 GHz",
    "millimeter wave",
    "dosimetry",
    "computational modeling",
    "antenna array",
    "beam"
  ],
  "suggested_hubs": [
    {
      "slug": "5g-policy",
      "weight": 0.62,
      "reason": "Addresses exposure limits and incident power density averaging above 6 GHz (relevant to mmWave/5G discussions)."
    },
    {
      "slug": "who-icnirp",
      "weight": 0.55,
      "reason": "Compares/notes differences in international standards/guidelines for averaging area definitions."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1088/1361-6560/aa5f21
PubMed: Not supplied

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