This paper is a continuation of our previous published work in which a water-loaded metal diagonal horn antenna has been designed at 2450 MHz for hyperthermia application and simulated results are compared with those measured. In the present study, theoretical investigations of Specific Absorption Rate (SAR) distribution in a homogeneous biological phantom (muscle) due to direct contact water-loaded metal diagonal horn antenna at 915 and 2450 MHz for hyperthermia application is presented. It is estimated theoretically that, at both the operating frequencies, a reasonable impedance matching is achieved at the interface between the antenna aperture and the biological phantom, where a computation of aperture admittance and reflection coefficient has been performed. Furthermore, it is confirmed through theoretical and simulation studies that the proposed horn antenna gives circularly symmetric SAR distribution in transverse plane in the biological phantom at 915 and 2450 MHz. The simulated and theoretical SAR distributions at 2450 MHz are compared with those determined at 915 MHz. In addition, thermal simulation results based on Pennes' Bio-heat equation (BHE) are applied to the realistic muscle model at 915 and 2450 MHz. The reduction of blood flow rate on temperature distribution is also studied.
2. Lehmann, J. F., A. W. Guy, J. B. Stonebride, and B. J. DeLateur, "Evaluation of a therapeutic direct contact 915 MHz microwave applicator for effective deep-tissue heating in humans," IEEE Trans. Microw. Theory Tech., Vol. 26, 556-563, 1978.
3. Stuchly, M. A., S. S. Stuchly, and G. Kantor, "Diathermy applicators with circular aperture and corrugated flange," IEEE Trans. Microw. Theory Tech., Vol. 28, 267-271, 1980.
4. Van Rhoon, G. C., P. J. Rietveld, and J. Van der Zee, "A 433 MHz lucite cone waveguide applicator for superficial hyperthermia," Int. J. Hyperthermia, Vol. 14, 13-27, UK, 1998.
5. Lin, J. C., G. Kantor, and A. Ghods, "A class of new microwave therapeutic applicators," Radio Science, Vol. 17, 119S-123S, 1982.
6. Nikawa, Y., H. Watanabe, M. Kikuchi, and S. Mori, "A direct-contact microwave lens applicator with a microcomputer-controlled heating system for local hyperthermia," IEEE Trans. Microw. Theory Tech., Vol. 34, 626-630, 1986.
7. Kantor, G. and D. M. Witters, "A 2450 MHz slab-loaded direct contact applicator with choke," IEEE Trans. Microw. Theory Tech., Vol. 28, 1418-1422, 1980.
8. Nikawa, Y. and F. Okada, "Dielectric-loaded lens applicator for microwave hyperthermia," IEEE Trans. Microw. Theory Tech., Vol. 39, 1173-1177, 1991.
9. Uzunoglu, N. K., E. A. Angelikas, and P. A. Cosmidis, "A 432MHz local hyperthermia system using an indirectly cooled water-loaded waveguide applicator," IEEE Trans. Microw. Theory Tech., Vol. 35, 106-111, 1987.
10. Nikita, K. S. and N. K. Uzunoglu, "Analysis of the power coupling from a waveguide hyperthermia applicator into a three-layered tissue model," IEEE Trans. Microw. Theory Tech., Vol. 37, 1794-1800, 1989.
11. Gupta, R. C. and S. P. Singh, "Analysis of the SAR distributions in three layered bio-media in direct contact with a water-loaded modified box-horn applicator," IEEE Trans. Microw. Theory Tech., Vol. 53, 2665-2671, 2005.
12. Gupta, R. C. and S. P. Singh, "Development and analysis of a microwave direct contact waterloaded box-horn applicator for therapeutic heating of bio-medium," Progress In Electromagnetics Research, Vol. 62, 217-235, 2006.
13. Ebrahimi-Ganjeh, M. A. and A. R. Attari, "Study of water bolus effect on SAR penetration depth and effective field size for local hyperthermia," Progress In Electromagnetics Research B, Vol. 4, 273-283, 2008.
14. Kantor, G., D. M. Witters, and J. W. Greiser, "The performance of a new direct-contact applicator for microwave diathermy," IEEE Trans. Microw. Theory Tech., Vol. 26, 563-568, 1978.
15. Singh, S. and S. P. Singh, "Water-loaded metal diagonal horn applicator for hyperthermia," IET Microwaves, Antennas and Propagation, Vol. 9, No. 8, 814-821, 2014.
16. CST [MWS], , Online, Available: http://www.cst.com.
17. Love, A. W., Electromagnetic Horn Antennas, IEEE Press, New York, 1976.
18. Gabriel, C., "Compilation of the dielectric properties of body tissues at RF and microwave frequencies,", Tech. Rep. AL/OE-TR-1996-0037, Brooks AFB, TX, 1996.
19. Compton, R. T., "The admittance of aperture antenna radiating into lossy media,", Rep. 1691-5, Antenna Laboratory Ohio State University Research Foundation Columbus, Ohio, 1964.
20. Harrington, R. F., Time-harmonic Electromagnetic Field, 123-135, McGraw-Hill Book Company, New York, 1961.
21. Pennes, H. H., "Analysis of tissue and arterial blood temperatures in the resting human forearm," J. Appl. Physiol., Vol. 85, 5-34, 1998.
22. Gong, Y. and G. Wang, "Superficial tumor hyperthermia with flat left-handed metamaterial lens," Progress In Electromagnetics Research, Vol. 98, 389-405, 2009.