volume | PIER Journals

Abstract

An equivalent-circuit model for a reconfigurable unit cell is proposed. This circuit model facilitates fast prediction of scattering parameters and dispersion analyses of a reconfigurable periodic structure. The cutoff frequencies obtained using equivalent-circuit models are in excellent agreement with those from measurements and full-wave numerical simulations. The proposed circuit model is then modified to include non-ideal, commercial RF FET switches. The effect of such a switch in each state, On or Off, is modeled by a frequency-dependant impedance, derived from the scattering parameters of the switch. The proposed technique can be used to analyze a reconfigurable periodic structure with any type of switches. For the structure with 24 unit cells considered here, the equivalent circuit model is about five orders of magnitude faster than full-wave simulations.

1. Eleftheriades, G., A. Iyer, and P. Kremer, "Planar negative refractive index media using periodically L-C loaded transmission lines," IEEE Trans. on Microwave Theory and Tech., Vol. 50, No. 12, 2702-2712, Dec. 2002.
doi:10.1109/TMTT.2002.805197

2. Sor, J., Y. Qian, and T. Itoh, "Miniature low-loss CPW periodic structures for filter applications," IEEE Trans. on Microwave Theory and Tech., Vol. 49, No. 12, 2336-2341, Dec. 2001.
doi:10.1109/22.971618

3. Karim, M., A.-Q. Liu, A. Alphones, and A. Yu, "A reconfigurable micromachined switching filter using periodic structures," IEEE Trans. on Microwave Theory and Tech., Vol. 55, No. 6, 1154-1162, Jun. 2007.
doi:10.1109/TMTT.2007.897670

4. Baccarelli, P., C. Di Nallo, S. Paulotto, and D. Jackson, "A full-wave numerical approach for modal analysis of 1-D periodic microstrip structures," IEEE Trans. on Microwave Theory and Tech., Vol. 54, No. 4, 1350-1362, Jun. 2006.
doi:10.1109/TMTT.2006.871353

5. Lee, H. and J. Kim, "Unit cell approach to full-wave analysis of meander delay line using FDTD periodic structure modeling method," IEEE Trans. on Advanced Packaging, Vol. 25, No. 2, 215-222, May 2002.
doi:10.1109/TADVP.2002.803272

6. Matekovits, L., G. Vecchi, M. Bercigli, and M. Bandinelli, "Efficient numerical analysis of large planar high impedance surface by the synthetic function expansion (SFX) technique," Microwave and Optical Technology Letters, Vol. 51, 2763-2769, Nov. 2009.

7. Shahparnia, S. and O. Ramahi, " A simple and effective model for electromagnetic bandgap structures embedded in printed circuit boards," Microwave and Wireless Components Letters, Vol. 15, No. 10, 621-623, Oct. 2005.
doi:10.1109/LMWC.2005.856695

8. Rogers, S., "Electromagnetic-bandgap layers for broad-band suppression of TEM modes in power planes," IEEE Trans. on Microwave Theory and Tech., Vol. 53, No. 8, 2495-2505, Aug. 2005.
doi:10.1109/TMTT.2005.852776

9. Mohajer-Iravani, B. and O. Ramahi, "Wideband circuit model for planar EBG structures," IEEE Trans. on Advanced Packaging, Vol. 33, No. 1, 169-179, Feb. 2010.
doi:10.1109/TADVP.2009.2021156

10. Sievenpiper, D., L. Zhang, R. Broas, N. Alexopolous, and E. Yablonovitch, "High-impedance electromagnetic surfaces with a forbidden frequency band," IEEE Trans. on Microwave Theory and Tech., Vol. 47, No. 11, 2059-2074, Nov. 1999.
doi:10.1109/22.798001

11. Gil, I., J. Bonache, J. Garcia-Garcia, and F. Martin, "Tunable metamaterial transmission lines based on varactor-loaded split-ring resonators," IEEE Trans. on Microwave Theory and Tech., Vol. 54, No. 6, 2665-2674, Jun. 2006.
doi:10.1109/TMTT.2006.872949

12. Matekovits, L., D. Thalakotuna, M. Heimlich, and K. Esselle, "Investigation on FET switch integration techniques for a tunable microwave periodic structure," Proc. International Workshop on Antenna Technology (iWAT), 44-47, Mar. 2012.

13. Matekovits, L., D. Thalakotuna, M. Heimlich, and K. P. Esselle, "Wideband matching of a tunable periodic structure in GaAs technology," Proc. International Workshop on Antenna Technology (iWAT), 376-379, Mar. 2011.

14. Thalakotuna, D., L. Matekovits, K. Esselle, and M. Heimlich, "Dynamic tuning of electromagnetic bandgap," Proc. of the 5th European Conference on Antennas and Propagation, 1065-1067, Apr. 2011.

15. Thalakotuna, D., L. Matekovits, K. Esselle, and M. Heimlich, "Effect of active device insertion losses on the electromagnetic bandgap characteristics of a tunable 1D periodic structure in the S band," Proc. 2011 IEEE International Symposium on Antennas and Propagation, 1808-1811, Jul. 2011.

16. Bahl, I. J., Lumped Elements for RF and Microwave Circuits, Artech House, 2003.

17. Collin, R. E., Foundation of Microwave Engineering, 1st Ed., McGrawHill, 1966.

18. Pozar, D. M., Microwave Engineering, John Wiley and Sons, 1998.

19. Thalakotuna, D., L. Matekovits, M. Heimlich, K. P. Esselle, and S. G. Hay, "Active switching devices in a tunable ebg structure: Placement strategies and modelling," Journal of Electromagnetic Waves and Applications, Vol. 25, No. 11-12, 1740-1751, 2011.
doi:10.1163/156939311797164873

20. Hong, J.-S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, John Wiley and Sons, 2001.
doi:10.1002/0471221619

21. Rosa, E., "The self and mutual inductances of linear conductors," Bulletin of the Bureau of Standards, Vol. 4, No. 2, 301, 1908.
doi:10.6028/bulletin.088

Prof. Ladislau Matekovits

Mr. Dushmantha Thalakotuna

Prof. Karu P. Esselle

Dr. Stuart G. Hay

Dr. Michale Heimlich