Photonic crystals in microstrip technology
T. Lopetegi, M. A. G. Laso, M. J. Erro, R. Gonzalo, J. Tirapu, A. Marcotegui, D. Benito, M. J. Garde, M. Sorolla.
Department of Electrical and Electronic Engineering, Public University of Navarre, Spain.
Phone: +34 948 169 324, Fax: +34 948 169 720, e-mail: firstname.lastname@example.org
Photonic Bandgaps (PBGs) in the microwave region have been proposed using micromachined dielectrics or holed ground planes in microstrip technology. These devices can be considered as Bragg reflectors (gratings) in microstrip technology. The extension to Bragg resonators is immediate .
1D realizations of PBGs reduce transversal dimensions of the device and meander topologies allow size reduction. A photonic model for PBG microstrip devices has been developed based on the Fiber Bragg Gratings (FBGs) and the Coupled-Wave Theory . Computational cost is drastically reduced compared with full-wave analysis.
Wide rejected bands are obtained by using chirping techniques in 1D PBG microstrip structures. Additional improvements result by introducing simultaneously a taper in the hole radius distribution .
Etching a continuous pattern in the ground plane instead of a discrete one as in the previous devices, an important reduction of the rejection levels at the harmonics of the design frequency has been demonstrated. This opens the door to the design of multiple-frequency-tuned structures by etching various-added-sine continuous pattern in the microstrip ground plane for filter applications.
Experimental time domain results of these structures show very interesting applications in fast pulse propagation and delay compensation .
Moreover, microstrip antennas using a PBG substrate can be employed for suppression of surface-wave effects. The gain and far-field radiation pattern can be improved by using this approach .
 P. De Maagt, R. Gonzalo, and A. Reynolds, "PBG crystals: periodic dielectric materials that control EM wave propagation", Microwave Engineering Europe, October 1999, pp. 35-43.
 M. A. G. Laso, M. J. Erro, D. Benito, M. J. Garde, T. Lopetegui, F. Falcone, M. Sorolla, "Analysis and design of 1-D photonic bandgap microstrip structures using a fibre grating model," Microwave and Optical Technology Lett., Vol. 22, No. 4, August 20 1999, pp. 223-226.
 M. A. G. Laso, T. Lopetegui, M. J. Erro, D. Benito, M. J. Garde, and M. Sorolla, "Novel Wideband Photonic Bandgap Microstrip Structures", Microwave and Optical Technology Lett, March 5 2000.
 J. Tirapu, T. Lopetegui, M. A. G. Laso, M. J. Erro, F. Falcone, M. Sorolla, "Study of Delay Characteristics of 1-D Photonic Bandgap Microstrip Structures" Microwave and Optical Technology Lett., December 20, 1999.
 R. Gonzalo, P. Maagt, M. Sorolla, "Enhanced Patch-Antenna Performance by Suppressing Surface Waves Using Photonic-Bandgap Substrates", IEEE Trans. Microwave Theory and Techniques, Vol. 47, No. 11, November 1999, pp. 2131-2138.