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    Item type:Publication,
    Assessment of Electromagnetic Field Exposure from Multiple Sources Simultaneously in the High-Frequency Range Based on Safety Standards
    (2025-01-01) ;
    Aroonmitr, Pongsathorn
    This study presents a method for evaluating electromagnetic field (EMF) exposure from multiple sources operating simultaneously across a wide range of frequencies, based on the guidelines defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in its 2020 publication. The proposed approach adopts the normalized exposure ratio, which combines the exposure values from all relevant sources and frequency bands. A key issue addressed in this study is the lack of standardized measurement methods for absorbed power density (S<inf>ab</inf>) in high-frequency bands above 10 GHz, despite the existence of defined exposure limits. A comparison reveals that the difference between the limits for S<inf>ab</inf> and incident power density (S<inf>inc</inf>) for the general public is relatively small when compared to the gap between the general public and occupational exposure limits. Therefore, the use of S<inf>inc</inf> is proposed as a temporary surrogate for S<inf>ab</inf> in frequency ranges where direct measurement is not yet feasible. This approach enables comprehensive exposure assessment from multiple sources under both near-field and far-field conditions. It also serves as a practical alternative while S<inf>ab</inf> measurement techniques for high-frequency applications such as 5G, WiGig, and next-generation wireless technologies are still under development.
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    Item type:Publication,
    2.4 GHz Rat-Race Coupler with Complex Termination on IPD Process
    (2018-12-24) ;
    Wang, Sen
    This paper proposed a rat-race circuit implement on IPD (Integrated Passive Device) process. The termination loads of the circuit have a complex impedance value. Design equations for single frequency operation of distributed structure are provided. Lumped components representation of distributed structure is illustrated in the design example. The measured results yield-5.6 dB reflection coefficient at the input port and-14 dB transmission coefficient at the isolation port. The transmission coefficients at the output ports are better than-7 dB while the phase difference is less than 2 degrees.
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