Near Field Radio Frequency Electromagnetic Field Exposure of a Western Honey Bee

2022 · Unclear · Low evidence

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UnclearLow evidencePaper 872

Study snapshot

Publicationmanual · 2022

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingLow

Abstract

Near Field Radio Frequency Electromagnetic Field Exposure of a Western Honey Bee D. Toribio, W. Joseph, A. Thielens. Near Field Radio Frequency Electromagnetic Field Exposure of a Western Honey Bee. IEEE Transactions on Antennas and Propagation. 70(2): 1320-1327. Feb. 2022, doi: 10.1109/TAP.2021.3111286. Abstract It has been suggested that the wireless network evolution to smaller carrier wavelengths (from 2G to 5G) increases radio frequency electromagnetic field (RF-EMF) absorption in western honey bees (Apis mellifera). It is unknown whether the radiation performance of antennas is stable when an insect appears in their vicinity. In this research, the absorbed power in a worker honey bee and the influence of the bee’s presence on antennas’ radiation performance are investigated for the newly used frequencies in 5G networks from 6 to 240 GHz. To these aims, numerical simulations using the finite-difference time-domain (FDTD) method were performed, in which a bee model, obtained by micro-CT scanning, was employed. These simulations showed that, in the near field, the absorbed power can increase by a factor of 53 from 6 to 240 GHz. This is a factor of 7 higher than the increase reported in the far-field in previous studies. Furthermore, the simulations revealed that antennas’ radiation efficiency can decrease by up to −40% when a bee appears in the near field. Likewise, it was found that the gain pattern depends on the separation distance between the bee and the antenna with a stronger dependency for higher frequencies. Conclusion Numerical simulations using FDTD analysis were executed to calculate the RF-EMFs in and around a worker Western Honey Bee (Apis mellifera). This lead to the quantification of the whole-body averaged absorbed radio- frequency power Pabs, under near-field exposure, in the frequency range of 6–240 GHz. The simulations showed that, in the near field, Pabs decreases as the separation distance between the bee and the dipole increases and increases as frequency increases. The frequency behavior of Pabs in the near field is, thus, different from its far field behavior, since, for a given accepted power and distance, in the near field Pabs increases with frequency (an average of 30.5 dB from 6 to 240 GHz), while, in the far field, Pabs in the worker bee is maximized at 12 GHz. This near-field increase in Pabs as a function of frequency can be a factor of 7 higher than the far-field increase. Moreover, these simulations allowed the study of the influence of the bee’s position (0.1λ –10λ from the dipoles) in the radiation performance of the dipoles. In particular, it was found that, as the separation distance increases, the dipoles’ isotropic gain decreases and approaches their free-space gain. Also, it was noted that, as a result of the near-field frequency behavior of Pabs, the dipoles’ radiation efficiency decreases with increasing frequency and increases with increasing separation distance. In addition, it was acknowledged that the gain pattern in the direction where the bee approaches the antenna depends on the separation distance between the bee and the antenna with a stronger dependency for higher frequencies. This is important for 5G telecommunication networks because they rely on infrastructure (antennas) whose performance can be influenced by the presence of free-flying insects. Future directions of this research project will include the experimental validation of the results from the simulations presented in this article by completing near-field RF-EMF exposure measurements of honey bees. Furthermore, the RF-EMF interactions between honey bees and phased arrays will be investigated since these are the type of antennas being deployed in high-frequency telecommunication networks. In addition, we aim to investigate the thermal increase in the bee due to near-field and far-field RF-EMF exposure, as a function of frequency, for instance, by means of infrared temperature measurements. Moreover, future work will also consist of performing simulations with heterogeneous honey bee phantoms with tissue-specific dielectric properties. ieeexplore.ieee.org

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

PopulationWorker Western honey bee (Apis mellifera) model (micro-CT based)

Sample sizeNot supplied

ExposureRF

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Finite-difference time-domain (FDTD) simulations using a micro-CT-based worker honey bee model found that near-field absorbed power increased with frequency (reported increase by a factor of 53 from 6 to 240 GHz; average 30.5 dB) and decreased with increasing separation distance from the dipole. Simulations also indicated that a bee in the near field can reduce antenna radiation efficiency by up to 40% and that the gain pattern depends on bee–antenna separation distance, with stronger dependency at higher frequencies.

Outcomes measured

Whole-body averaged absorbed radio-frequency power (Pabs) under near-field exposure (6–240 GHz)
Change in antenna radiation efficiency due to bee presence in near field
Change in antenna gain pattern / isotropic gain as a function of bee–antenna separation distance and frequency

Limitations

Numerical simulation study (FDTD) without experimental validation reported in the abstract
Exposure scenario focused on near-field dipole antennas; other antenna types (e.g., phased arrays) noted as future work
Thermal effects and heterogeneous/tissue-specific dielectric properties described as future work rather than results

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "5G antennas (near-field dipoles)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Worker Western honey bee (Apis mellifera) model (micro-CT based)",
  "sample_size": null,
  "outcomes": [
    "Whole-body averaged absorbed radio-frequency power (Pabs) under near-field exposure (6–240 GHz)",
    "Change in antenna radiation efficiency due to bee presence in near field",
    "Change in antenna gain pattern / isotropic gain as a function of bee–antenna separation distance and frequency"
  ],
  "main_findings": "Finite-difference time-domain (FDTD) simulations using a micro-CT-based worker honey bee model found that near-field absorbed power increased with frequency (reported increase by a factor of 53 from 6 to 240 GHz; average 30.5 dB) and decreased with increasing separation distance from the dipole. Simulations also indicated that a bee in the near field can reduce antenna radiation efficiency by up to 40% and that the gain pattern depends on bee–antenna separation distance, with stronger dependency at higher frequencies.",
  "effect_direction": "unclear",
  "limitations": [
    "Numerical simulation study (FDTD) without experimental validation reported in the abstract",
    "Exposure scenario focused on near-field dipole antennas; other antenna types (e.g., phased arrays) noted as future work",
    "Thermal effects and heterogeneous/tissue-specific dielectric properties described as future work rather than results"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "Apis mellifera",
    "western honey bee",
    "near-field",
    "RF-EMF",
    "5G",
    "6–240 GHz",
    "millimeter wave",
    "FDTD",
    "absorbed power",
    "antenna radiation efficiency",
    "gain pattern"
  ],
  "suggested_hubs": [
    {
      "slug": "5g-policy",
      "weight": 0.6,
      "reason": "Assesses RF-EMF absorption and antenna performance across newly used 5G frequencies (6–240 GHz)."
    }
  ]
}

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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: 10.1109/tap.2021.3111286
PubMed: Not supplied

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