A Multi-Band Body-Worn Distributed RF Exposure Meter: Design, On-Body Calibration and Study of Body Morphology

2018 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 2169

Study snapshot

Publicationmanual · 2018

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

A Multi-Band Body-Worn Distributed RF Exposure Meter: Design, On-Body Calibration and Study of Body Morphology Aminzadeh R, Thielens A, Agneessens S, Van Torre P, Van den Bossche M, Dongus S, Eeftens M, Huss A, Vermeulen R, de Seze R, Mazet P, Cardis E, Rogier H, Röösli M, Martens L Wout J. A Multi-Band Body-Worn Distributed Radio-Frequency Exposure Meter: Design, On-Body Calibration and Study of Body Morphology. Sensors. 18(1). Jan 2018. Abstract A multi-band Body-Worn Distributed exposure Meter (BWDM) calibrated for simultaneous measurement of the incident power density in 11 telecommunication frequency bands, is proposed. The BDWM consists of 22 textile antennas integrated in a garment and is calibrated on six human subjects in an anechoic chamber to assess its measurement uncertainty in terms of 68% confidence interval of the on-body antenna aperture. It is shown that by using multiple antennas in each frequency band, the uncertainty of the BWDM is 22 dB improved with respect to single nodes on the front and back of the torso and variations are decreased to maximum 8.8 dB. Moreover, deploying single antennas for different body morphologies results in a variation up to 9.3 dB, which is reduced to 3.6 dB using multiple antennas for six subjects with various body mass index values. The designed BWDM, has an improved uncertainty of up to 9.6 dB in comparison to commercially available personal exposure meters calibrated on body. As an application, an average incident power density in the range of 26.7-90.8 μW·m−2 is measured in Ghent, Belgium. The measurements show that commercial personal exposure meters underestimate the actual exposure by a factor of up to 20.6. Excerpt Two commercially available PEMs are used in this study: EME Spy 200 (MVG, Brest, France) and ExpoM-RF (Fields at Work GmbH, Zürich, Switzerland). Eleven frequency bands are studied in this paper ... For the BWDM, the mean measured power densities are in the range of 26.7 μW/m2 (800-DL) to 90.8 μW/m2 (900 DL). The large standard deviation is due to the city environment where several buildings with different heights are present. For the EME Spy 200, the mean power density ranges from 4.41 μW/m2 (1800-DL) to 60.1 μW/m2 (900-DL). ExpoM-RF registered mean power densities in the range of 14.53 μW/m2 (1800-DL) to 151.5 μW/m2 (900-DL). All the three devices measured the maximum mean power density for 900-DL band (2G). For the BWDM, the median Sinc is in the range of 3.21 μW/m2 (800-DL) to 29 μW/m2 for 2100-DL. Both PEMs registered the minimum p50 of Sinc for 1800-DL (EME Spy 200: 0.59 μW/m2, ExpoM-RF: 1.62 μW/m2) and the maximum median Sinc for 900-DL (EME Spy 200: 12.26 μW/m2, ExpoM-RF: 34.77 μW/m2). Conclusions For the first time, a multi-band body-worn distributed-exposure meter (BWDM) is proposed for simultaneous on-body measurements of the incident power density in 11 telecommunication bands. The BWDM is designed and calibrated on a male human subject, in an anechoic chamber. The optimized location of 22 nodes covering 11 frequency bands is determined on the front and on the back of the torso. The optimized BWDM is also calibrated on five more subjects in order to study the effect of human body morphology on the measurement uncertainty of the designed BWDM. The uncertainty is quantified as the 68% confidence interval of the on-body antenna aperture obtained during calibrations. It is shown that using multiple antennas improved the uncertainty up to 22 dB with respect to single nodes for all subjects in all frequency bands. We also demonstrated that, using single antennas, the variation on CI68 for the six people in this study was about 9.3 dB. This value reduced to the range of 1.2 to 3.6 dB for all the subjects, which is 5.7 dB improvement. Except for 1800-DL (3.6 dB) the maximum variation on the CI68 of subjects of this study is limited to below 2 dB. The designed BWDM has an improved CI68 of 9.6 dB compared to CI68 of commercially available PEMs calibrated on body. Using the proposed BWDM and two PEMs, fields along an outdoor route are measured in Ghent, Belgium including 800, 900, 1800 and 2100 MHz downlink bands. The BWDM measured a mean power density in the range of 26.7 to 90.8 μW/m2, which are below the issued reference levels by ICNIRP. The results show that commercial PEMs underestimate the actual incident power densities by a factor of 1.6 to 20.6. Moreover, the measured exposure to 2G and 3G signals are 3.8 to 9 times higher than the 4G signals. The study of the subject's posture and application of SAR measurement will be part of the future work. researchgate.net Frequency_Exposure_Meter_Design_On-Body_Calibration_and_Study_of_Body_Morphology

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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

PopulationSix human subjects (calibration in anechoic chamber); outdoor route measurements in Ghent, Belgium

Sample size6

ExposureRF

Evidence strengthInsufficientConfidence: 78% · Peer reviewed: yes

Main findings

A 22-antenna garment-based multi-band body-worn distributed exposure meter (BWDM) was calibrated on six subjects and showed reduced measurement uncertainty versus single-node configurations and versus commercially available personal exposure meters. In an outdoor application in Ghent, Belgium, the BWDM measured mean incident power densities of 26.7–90.8 μW/m² (selected downlink bands), and commercial personal exposure meters were reported to underestimate incident power density by factors of 1.6 to 20.6.

Outcomes measured

Incident power density measurement across 11 telecommunication frequency bands
Measurement uncertainty (68% confidence interval of on-body antenna aperture)
Effect of body morphology (BMI variation) on measurement uncertainty
Comparison of BWDM vs commercial personal exposure meters (EME Spy 200, ExpoM-RF)

Limitations

Frequency bands are described as 11 telecommunication bands but specific full band list/frequencies are not fully detailed in the provided abstract text
Outdoor measurements are described for an outdoor route in one city (Ghent, Belgium), which may limit generalizability
Future work noted for posture effects and SAR measurement, implying these were not addressed here

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "personal exposure meter / body-worn distributed exposure meter (telecommunication downlink bands)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Six human subjects (calibration in anechoic chamber); outdoor route measurements in Ghent, Belgium",
  "sample_size": 6,
  "outcomes": [
    "Incident power density measurement across 11 telecommunication frequency bands",
    "Measurement uncertainty (68% confidence interval of on-body antenna aperture)",
    "Effect of body morphology (BMI variation) on measurement uncertainty",
    "Comparison of BWDM vs commercial personal exposure meters (EME Spy 200, ExpoM-RF)"
  ],
  "main_findings": "A 22-antenna garment-based multi-band body-worn distributed exposure meter (BWDM) was calibrated on six subjects and showed reduced measurement uncertainty versus single-node configurations and versus commercially available personal exposure meters. In an outdoor application in Ghent, Belgium, the BWDM measured mean incident power densities of 26.7–90.8 μW/m² (selected downlink bands), and commercial personal exposure meters were reported to underestimate incident power density by factors of 1.6 to 20.6.",
  "effect_direction": "unclear",
  "limitations": [
    "Frequency bands are described as 11 telecommunication bands but specific full band list/frequencies are not fully detailed in the provided abstract text",
    "Outdoor measurements are described for an outdoor route in one city (Ghent, Belgium), which may limit generalizability",
    "Future work noted for posture effects and SAR measurement, implying these were not addressed here"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "body-worn distributed exposure meter",
    "BWDM",
    "personal exposure meter",
    "RF exposure assessment",
    "incident power density",
    "on-body calibration",
    "textile antennas",
    "telecommunication bands",
    "2G",
    "3G",
    "4G",
    "ICNIRP",
    "Ghent"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.62,
      "reason": "Mentions ICNIRP reference levels and compares measured power densities to them."
    },
    {
      "slug": "exposure-assessment",
      "weight": 0.85,
      "reason": "Design and calibration of a personal/body-worn RF exposure measurement system and comparison to commercial PEMs."
    }
  ]
}

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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.

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