Yes / Potential demodulating ability in biological tissue exposed to Radio Frequency (RF) signals intrinsically requires an unsymmetrical diode-like 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 information-carrying 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 test-piece inside the cavity. The method is validated computationally and experimentally using a well-characterised 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. / Engineering and Physical Science Research Council through Grant EP/E022936A
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/12058 |
| Date | 11 May 2017 |
| Creators | Abd-Alhameed, Raed, See, Chan H., Excell, Peter S., McEwan, Neil J., Ali, N.T. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, Accepted Manuscript |
| Rights | (c) 2017 IET. This paper is a post-print of a paper submitted to and accepted for publication in the IET Science, Measurement and Technology and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library. |
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