Gaussian process (GP) regression is proposed as a structured supervised learning alternative to neural networks for the modeling of CPW-fed slot antenna input characteristics. A Gaussian process is a stochastic process and entails the generalization of the Gaussian probability distribution to functions. Standard GP regression is applied to modeling S11 against frequency of a CPW-fed secondresonant slot dipole, while an approximate method for large datasets is applied to an ultrawideband (UWB) slot with U-shaped tuning stub --- a challenging problem given the highly non-linear underlying function that maps tunable geometry variables and frequency to S11/input impedance. Predictions using large test data sets yielded results of an accuracy comparable to the target moment-method-based full-wave simulations, with normalized root mean squared errors of 0.50% for the slot dipole, and below 1.8% for the UWB antenna. The GP methodology has various inherent benefits, including the need to learn only a handful of (hyper) parameters, and training errors that are effectively zero for noise-free observations. GP regression would be eminently suitable for integration in antenna design algorithms as a fast substitute for computationally intensive full-wave analyses.
2. Patnaik, A., D. E. Anagnostou, R. K. Mishra, C. G. Christodoulou, and J. C. Lyke, "Applications of neural networks in wireless communications," IEEE Antennas Propagat. Mag., Vol. 46, No. 3, 130-137, 2004.
3. He, Q. Q., Q. Wang, and B. Z. Wang, "Conformal array based on pattern reconfigurable antenna and its artificial neural model," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 1, 99-110, 2008.
4. Rayas-Sanchez, J. E., "EM-based optimization of microwave circuits using artificial neural networks: The state-of-the-art," IEEE Trans. Microw. Theory Tech., Vol. 52, No. 1, 420-435, 2004.
5. Kaya, S., M. Turkmen, K. Guney, and C. Yildiz, "Neural models for the elliptic- and circular-shaped microshield lines," Progress In Electromagnetics Research B, Vol. 6, 169-181, 2008.
6. Yildiz, C. and M. Turkmen, "Quasi-static models based on artificial neural neworks for calculating the characteristic parameters of multilayer cylindrical coplanar waveguide and strip line," Progress In Electromagnetics Research B, Vol. 3, 1-22, 2008.
7. Ayestaran, R. G., F. Las-Heras, and J. A. Martinez, "Non uniform-antenna array synthesis using neural networks," Journal of Electromagnetic Waves and Applications , Vol. 21, No. 8, 1001-1011, 2007.
8. Zainud-Deen, S. H., H. A. El-Azem Malhat, K. H. Awadalla, and E. S. El-Hadad, "Direction of arrival and state of polarization estimation using radial basis function neural network (RBFNN)," Progress In Electromagnetics Research B, Vol. 2, 137-150, 2008.
9. Kizilay, A. and S. Makal, "A neural network solution for identification and classification of cylindrical targets above perfectly conducting flat surfaces," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 14, 2147-2156, 2007.
10. Rostami, A. and A. Yazdanpanah-Goharrizi, "Hybridization of neural networks and genetic algorithms for identification of complex Bragg gratings," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 5-6, 643-664, 2008.
11. Rasmussen, C. E. and C. K. I. Williams, Gaussian Processes for Machine Learning, MIT Press, Cambridge, Massachussets, 2006.
12. Zhang, Q.-J., K. C. Gupta, and V. K. Devabhaktuni, "Artificial neural networks for RF and microwave design --- From theory to practice," IEEE Trans. Microw. Theory Tech., Vol. 51, No. 4, 1339-1350, 2003.
13. Angiulli, G., M. Cacciola, and M. Versaci, "Microwave devices and antennas modelling by support vector regression machines," IEEE Trans. Magnetics, Vol. 43, No. 4, 1589-1592, 2007.
14. Devabhaktuni, V. K., M. C. E. Yagoub, and Q.-J. Zhang, "A robust algorithm for automatic development of neural-network models for microwave applications," IEEE Trans. Microw. Theory Tech., Vol. 49, No. 12, 2282-2291, 2001.
15. MacKay, D. J. C., Information Theory, Inference, and Learning Algorithms, Cambridge University Press, 2003.
16. Qiu, M., M. Simcoe, and G. V. Eleftheriades, "High-gain meanderless slot arrays on electrically thick substrates at millimeter-wave frequencies," IEEE Trans. Microw. Theory Tech., Vol. 50, No. 2, 517-528, 2002.
17. Jacobs, J. P. and J. Joubert, "Design of a linear nonuniform CPW-fed slot array with reduced sidelobe levels," Microw. Opt. Tech. Lett., Vol. 51, No. 9, 2175-2178, 2009.
18. Zeland Software, IE3D Users Manual, Release 14, 2007.
19. Zhang, L., Y. C. Jiao, Y. L. Zhao, G. Zhao, Y. Song, Z. B. Wong, and F. S. Zhang, "Dual-band CPW-fed double H-shaped slot antenna for RFID application," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 8-9, 1050-1055, 2008.
20. Zhang, T. L., Z. H. Yan, L. Chen, and Y. Song, "A compact dual-band CPW-fed planar monopole antenna for WLAN applications," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 14-15, 2097-2104, 2008.
21. Zhang, G. M., J. S. Hong, B. Z. Wang, Q. Y. Qin, J. B. Mo, and D. M. Wan, "A novel multi-folded UBW antenna fed by CPW," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 14, 2109-2119, 2007.
22. Chen, Y.-I., C.-L. Ruan, and L. Peng, "A novel ultra-wideband bow-tie slot antenna in wireless communication systems," Progress In Electromagnetics Research Letters, Vol. 1, 101-108, 2008.
23. Lee, S. H., J. N. Lee, J. K. Park, and H. S. Kim, "Design of the compact UWB antenna with PI-shaped matching stub," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 10, 1440-1449, 2008.
24. Wang, X., Z. F. Yao, Z. Cui, L. Luo, and S. X. Zhang, "Band-notched characteristics for CPW-fed printed monopole antenna with E shape slot," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 16, 2171-2178, 2008.
25. Yao, Z. F., X. Wang, S. G. Zhou, B. H. Sun, and Q. Z. Liu, "Compact ultra-wideband slot antenna with dual band-notched characteristics," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 13, 1765-1774, 2008.
26. Yao, Z. F., S. G. Zhou, X. Wang, L. Sun, B. H. Sun, and Q. Z. Liu, "Study of the band-notched functions for CPW-fed UWB antenna," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 17-18, 2309-2321, 2008.
27. Yin, X.-C., C.-L. Ruan, C.-Y. Ding, and J.-H. Chu, "A planar U type monopole antenna for UWB applications," Progress In Electromagnetics Research Letters, Vol. 2, 1-10, 2008.
28. Chair, R., , A. A. Kisk, and K. F. Lee, "Ultrawide-band coplanar waveguide-fed rectangular slot antenna," IEEE Antennas Wireless Propagat. Lett., Vol. 3, 227-229, 2004.
29. Boyle, P. and M. Frean, "Dependent gaussian processes," Advances in Neural Information Processing Systems, Vol. 17, 217-224, 2005.
30. Jones, D. R., "A taxonomy of global optimization methods based on response surfaces," Journal of Global Optimization, Vol. 21, 345-383, 2001.