A small patch antenna is associated with passive (reactively loaded) elements (varactors) in order to auto adjust the resonant frequency in a single-channel multi-frequency configuration appropriate for biomedical applications. As a supplementary study of the authors in the field of detection of temperature abnormalities in human tissue phantom using microwave radiometry, this paper adds a contribution to frequency readjustment when a shift occur due to the fact that the human body is a complex and stratified dielectric object. The optimization of the array is performed using a Genetic Algorithm (GA) tool as a method of choice. The adjustment in the measurement frequency is performed by altering the values of the passive elements according to the shift needed.
2. Nikawa, Y., M. Chino, and K. Kikuchi, "Soft and dry phantom modeling material using silicone rubber with carbon fibre," IEEE Trans. Microw. Theory Tech., Vol. 44, No. 10, 1949-1953, 1996.
3. Lagendijk, J. J. W. and P. Nilsson, "Hyperthermia dough: A fat and bone equivalent phantom to test microwave/radiofrequency hyperthermia heating systems," Phys. Med. Biol., Vol. 30, No. 7, 709-712, 1985.
4. Preece, A. W., J. L. Green, N. Pothecary, and R. H. Johnson, "Microwave imaging for tumour detection," IEE Colloquium on Radar and Microwave Imaging, 9/1-9/4, The Institution of Electrical Engineers, Savoy Place, London WC2R OBL, UK, 1994.
5. Pozar, D. M., Microwave Engineering, 3rd Ed., John Wiley and Sons, 2004.
6. Gabriel, S., R. W. Lau, and C. Gabriel, "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues," Physics in Medicine and Biology, Vol. 41, No. 11, 2271-2293, 1996.
7. IFAC, "An internet resource for the calculation of the dielectric properties of body tissues," Italian National Research Council Institute for Applied Physics, Sep. 2011.
8. Hurt, W. D., "Multiterm debye dispersion relations for permittivity of muscle," IEEE Transactions on Biomedical Engineering, Vol. 32, No. 1, 60-64, Jan. 1985.
9. Cole, K. S. and R. H. Cole, "Dispersion and absorption in dielectrics. I. Alternating current characteristics," Journal Chem. Phyr., Vol. 9, 341-351, 1941.
10. Paulides, M. M., J. F. Bakker, N. Chavannes, and G. C. Van Rhoon, "A patch antenna design for application in a phased-array head and neck hyperthermia applicator," IEEE Transactions on Biomedical Engineering, Vol. 54, No. 11, 2057-2063, Nov. 2007.
11. Gabriel, C., S. Gabriely, and E. Corthout, "The dielectric properties of biological tissues: I. Literature survey," Phys. Med. Biol., Vol. 41, 2231-2249, 1996.
12. Miklavcic, D., N. Pavselj, and F. X. Hart, "Electric properties of tissues," Wiley Encyclopedia of Biomedical Engineering, John Wiley & Sons, Inc., Copyright, 2006.
13. Nikolopoulos, C. D. and C. N. Capsalis, "A novel antenna system for body temperature change detection appropriate for multi-channel microwave radiometry," Progress In Electromagnetics Research M, Vol. 33, 197-209, 2013.
14. Liang, J. and H. Y. D. Yang, "Varactor loaded tunable printed PIFA," Progress In Electromagnetics Research B, Vol. 15, 113-131, 2009.
15. El-Sharkawy, A. M., P. P. Sotiriadis, P. A. Bottomley, and E. Atalar, "A new RF radiometer for absolute noninvasive temperature sensing in biomedical applications," IEEE International Symposium on Circuits and Systems, ISCAS 2007, 329-332, 2007.
16. Curto, S., P. McEvoy, X. Bao, and M. J. Ammann, "Compact patch antenna for electromagnetic interaction with human tissue at 434 MHz," IEEE Transactions on Antennas and Propagation, Vol. 57, No. 9, 2564-2571, Sep. 2009.
17. Goldberg, D. E., Genetic Algorithms in Search, Optimization, and Machine Learning, Addison-Wesley Publishing Company, Inc., 1989.
18., "SuperNec v. 2.4 MOM technical reference manual,".
19. Fourie, A. and D. Nitch, "SuperNEC: Antenna and indoor-propagation simulation program," IEEE Antennas and Propagat. Mag., Vol. 42, No. 3, 31-48, Jun. 2000.
20. Rahmat-Samii, Y. and E. Michielssen, Electromagnetic Optimization by Genetic Algorithms, John Wiley & Sons, Inc., 1999.