Effect of metal-framed spectacles on microwave radiation hazards to the eye of humans.

Abstract

A novel measurement technique using a monopole antenna probe has been applied to a full-size, image-plane type model of a human to determine the microwave fields near the eyes and to evaluate the effect of scattering structures, such as metal-framed spectacles, on those fields. The measurement technique relies on a 'subtraction' technique to determine the changes in fields when a scattering structure is introduced, and allows a large number of measurements to be performed in a relatively short space of time and with a high degree of accuracy. Investigations conducted in an anechoic chamber yield angles of incidence, test frequencies and wave polarisation values that give details of shielding, enhancement and depolarisation effects due to this particular scattering structure that appeared not to have been previously studied. It has been found that the introduction of a pair of metal-framed spectacles can, in certain cases, cause an increase in field levels by up to approximately 20 dB, a significant perturbation of the incident microwave field which should be accounted for in the setting of safety standards relating to acceptable levels of incident power.

AI evidence extraction

Main findings

Using a monopole antenna probe and subtraction method in an anechoic chamber, the study measured changes in microwave fields near the eyes when metal-framed spectacles were introduced. In certain cases, spectacles increased field levels by up to approximately 20 dB, indicating a significant perturbation that the authors state should be considered in safety standards for acceptable incident power.

Outcomes measured

• Microwave field levels near the eyes
• Shielding effects
• Field enhancement effects
• Depolarisation effects

Limitations

• Model-based measurements (human model rather than living humans)
• Specific scattering structure studied (metal-framed spectacles); generalisability to other eyewear not stated
• Test frequencies, angles of incidence, and polarisation values are mentioned but not specified in the abstract
• No direct health outcomes measured; only field perturbations near the eye

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "microwave",
        "source": "other",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Full-size, image-plane type model of a human (near-eye region)",
    "sample_size": null,
    "outcomes": [
        "Microwave field levels near the eyes",
        "Shielding effects",
        "Field enhancement effects",
        "Depolarisation effects"
    ],
    "main_findings": "Using a monopole antenna probe and subtraction method in an anechoic chamber, the study measured changes in microwave fields near the eyes when metal-framed spectacles were introduced. In certain cases, spectacles increased field levels by up to approximately 20 dB, indicating a significant perturbation that the authors state should be considered in safety standards for acceptable incident power.",
    "effect_direction": "harm",
    "limitations": [
        "Model-based measurements (human model rather than living humans)",
        "Specific scattering structure studied (metal-framed spectacles); generalisability to other eyewear not stated",
        "Test frequencies, angles of incidence, and polarisation values are mentioned but not specified in the abstract",
        "No direct health outcomes measured; only field perturbations near the eye"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave",
        "eye exposure",
        "spectacles",
        "metal frame",
        "scattering",
        "field enhancement",
        "anechoic chamber",
        "monopole antenna probe",
        "safety standards"
    ],
    "suggested_hubs": []
}

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