This study proposes the idea of a thermotherapy device for the treatment of human knee joint disorders by the thermal effect of microwave radiation. The device is composed of a circular array of dipole antennas operating at 2.45 GHz. A high resolution three dimensional geometric, electric, and thermal model for a human right knee is constructed. Electromagnetic simulations are performed to calculate the specific absorption rate (SAR) distribution within the tissues of the human knee using the finite difference time domain (FDTD) method. The SAR distributions are calculated for four and eight elements circular arrays. The FDTD is applied to calculate the rise in temperature within different tissues of the human knee due to the exposure to different levels of heating microwave power. The effect of the tissue thermoregulatory response on the temperature rise is investigated for each individual tissue type. Moreover, the dependence of the induced steady state rises in tissue temperatures on the absorbed SAR is studied in the case of the SAR at a point in the muscle tissue (local SAR), and the SAR averaged over 1 g (SAR1 g) and over 10 g (SAR10 g). The rise in temperature distribution due to radiation from the circular array of dipoles is calculated at different cross sections.
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