Effect of antenna polarization & body morphology on measurement uncertainty of wearable multi-band distributed exposure meter

2018 · Unclear · Low evidence

← Research stream

UnclearLow evidencePaper 1944

Study snapshot

Publicationmanual · 2018

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingLow

Abstract

Effect of antenna polarization & body morphology on measurement uncertainty of wearable multi-band distributed exposure meter Aminzadeh R, Thielens A, Agneessens S, et al. The effect of antenna polarization and body morphology on the measurement uncertainty of a wearable multi-band distributed exposure meter. Ann. Telecommun. Dec 2018. Abstract This paper studies the effect of antenna polarization on measurement uncertainty of a multi-band body-worn distributed exposure meter (BWDM). The BWDM is a device for assessing electromagnetic fields in real environments accurately. The BWDM consists of 8 nodes and is calibrated on the body for simultaneous measurement of the incident power density in four frequency bands. Each node contains an antenna that can have two potential antenna polarizations.The BWDM is calibrated on four human subjects in an anechoic chamber to determine its measurement uncertainty in terms of 68% confidence interval (CI68) of the on-body antenna aperture. The results show that using a fixed polarization of the antennas on body can lead to a different CI68 up to maximum 4.9 dB when worn by another person which is still 9.6 dB lower than the measurement uncertainty of commercial exposure meters. Excerpt The outdoor measurements of both BWDM and ExpoM are in good agreement. Considering the detection limits of both devices, the detection limit of the ExpoM is a factor of 1.85 lower than that of the on-body detection limit of the BWDM worn by sb1. However, a single ExpoM has a larger measurement uncertainty (7.5 dB larger) in this paper. Factors larger than 2 have been reported in the literature [4, 6] for the underestimation of the PEMs. Conclusions For the first time, the polarization dependency of a multi-band body-worn distributed exposure meter (BWDM) and the effect of body morphology on this dependency are assessed. The BDWM consists of 8 nodes measuring at four frequency band including downlink (DL) and uplink bands of 900 MHz, WiFi 2 GHz, and DL band of 2600 MHz. The BDWM is calibrated on four male subjects with different body mass indexes (BMIs). For each subject, the on-body antenna aperture and the uncertainty of the BWDM are determined for vertical and horizontal polarizations of the nodes in each of the above frequency bands. The obtained antenna apertures do not show an evident relationship with the BMI. Moreover, the results show that optimizing the polarization of the nodes on one subject could result in higher confidence interval values of the on-body antenna aperture for the subjects with different body morphologies. This is less than 0.5 dB and up to 2.62 dB for subjects with the same height and subjects with different height, respectively. From the results, we conclude that the location of the nodes on the body has a higher influence up to 3.7 dB on the directive gain of the antennas and consequently the measurement uncertainty of the BWDM rather than the height or BMI of the subjects. This could increase up to 4.9 dB if the locations of the nodes are not optimized on the body. The authors suggest to use antennas with dual polarization which register the orthogonal components of the RF fields with one antenna. As an application, a median power density of 39 μW/m2 is registered by the BWDM in a suburban residential area in Ghent which is below the issued reference levels by ICNIRP. link.springer.com

Machine Enhanced Logic

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 typeexposure_assessment

Effect directionunclear

PopulationFour male human subjects (calibration in anechoic chamber); outdoor measurements in a suburban residential area in Ghent

Sample size4

ExposureRF

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

A multi-band body-worn distributed exposure meter (8 nodes) was calibrated on four male subjects to quantify measurement uncertainty (CI68) across bands including 900 MHz (DL/UL), WiFi 2 GHz, and 2600 MHz (DL). Using a fixed antenna polarization optimized on one subject could change CI68 by up to 4.9 dB when worn by another person; node location influenced directive gain/uncertainty up to 3.7 dB, and outdoor BWDM and ExpoM measurements were in good agreement. A median power density of 39 μW/m2 was measured in a suburban residential area in Ghent, reported as below ICNIRP reference levels.

Outcomes measured

Measurement uncertainty (CI68) of on-body antenna aperture
Effect of antenna polarization (vertical vs horizontal) on uncertainty
Effect of body morphology (BMI/height) and node location on uncertainty
Median registered power density in a suburban residential area (Ghent)

Limitations

Calibration performed on four subjects (all male)
Calibration conducted in an anechoic chamber; real-world variability may differ
Specific device configuration (8-node BWDM) and selected frequency bands may limit generalizability

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "wearable exposure meter (BWDM); comparison with ExpoM personal exposure meter",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Four male human subjects (calibration in anechoic chamber); outdoor measurements in a suburban residential area in Ghent",
  "sample_size": 4,
  "outcomes": [
    "Measurement uncertainty (CI68) of on-body antenna aperture",
    "Effect of antenna polarization (vertical vs horizontal) on uncertainty",
    "Effect of body morphology (BMI/height) and node location on uncertainty",
    "Median registered power density in a suburban residential area (Ghent)"
  ],
  "main_findings": "A multi-band body-worn distributed exposure meter (8 nodes) was calibrated on four male subjects to quantify measurement uncertainty (CI68) across bands including 900 MHz (DL/UL), WiFi 2 GHz, and 2600 MHz (DL). Using a fixed antenna polarization optimized on one subject could change CI68 by up to 4.9 dB when worn by another person; node location influenced directive gain/uncertainty up to 3.7 dB, and outdoor BWDM and ExpoM measurements were in good agreement. A median power density of 39 μW/m2 was measured in a suburban residential area in Ghent, reported as below ICNIRP reference levels.",
  "effect_direction": "unclear",
  "limitations": [
    "Calibration performed on four subjects (all male)",
    "Calibration conducted in an anechoic chamber; real-world variability may differ",
    "Specific device configuration (8-node BWDM) and selected frequency bands may limit generalizability"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "body-worn distributed exposure meter",
    "BWDM",
    "personal exposure meter",
    "ExpoM",
    "antenna polarization",
    "measurement uncertainty",
    "on-body calibration",
    "power density",
    "900 MHz",
    "2 GHz WiFi",
    "2600 MHz",
    "ICNIRP"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.22,
      "reason": "Focuses on wearable RF exposure measurement instrumentation used on the body (relevant to personal/worker exposure assessment)."
    },
    {
      "slug": "who-icnirp",
      "weight": 0.3,
      "reason": "Mentions comparison of measured power density to ICNIRP reference levels."
    }
  ]
}

AI can be wrong. Always verify against the paper.

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: 10.1007/s12243-018-0691-y
PubMed: Not supplied

Read the original paper →

Related papers

← Back to the Research Library