Calibration Model for Detection of Potential Demodulating Behaviour in Biological Media Exposed to RF Energy

Chan H. See, Raed A. Abd-Alhameed, Arfan Ghani, Nazar Ali, Peter Excell, Neil J. McEwan, Quirino Balzano

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    Potential demodulating ability in biological tissue exposed to Radio Frequency (RF) signals intrinsically requires an unsymmetrical diodelike nonlinear response in tissue samples. This may be investigated by observing possible generation of the second harmonic in a cavity resonator designed to have fundamental and second harmonic resonant frequencies with collocated antinodes. Such a response would be of interest as being a mechanism that
    could enable demodulation of informationcarrying waveforms having modulating frequencies in ranges that could interfere with cellular processes. Previous work has developed an experimental system to test for such responses: the present work reports an electric circuit model devised to facilitate calibration of any putative nonlinear RF energy conversion occurring within a nonlinear testpiece inside the cavity. The method is validated computationally and experimentally using a wellcharacterised nonlinear device. The variations of the reflection coefficients of the fundamental and second harmonic responses of the cavity due to adding nonlinear and lossy material are also discussed. The proposed model demonstrates that the sensitivity of the measurement equipment plays a vital role in deciding the required input power to detect any second harmonic signal, which is expected to be very weak. The model developed here enables the establishment of a lookup table giving the level of the second harmonic signal in the detector as a function of the specific input power applied in a measurement. Experimental results are in good agreement with the simulated results.
    Original languageEnglish
    Article numberSMT-2017-0105
    Pages (from-to)900-906
    Number of pages7
    JournalIET Science, Measurement and Technology
    Issue number7
    Publication statusPublished - 17 May 2017

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    • biological techniques
    • table lookup
    • medical signal detection
    • harmonic generation
    • demodulation
    • cavity resonators
    • calibration
    • biological tissues


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