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Photonic Bandgap (PBG) Structures
Periodic transmission lines

This work was supported, in part, by NSF REU Grant #0452206.

A transmission line is a multiple conductor structure which transmits a signal from one place to another. Our transmission lines are all of the microstrip style, which is formed by a flat conducting line above a ground plane, usually with a dielectric material placed in between. A periodic transmission line has a regular disturbance in the geometry, and hence in the characteristic impedance of the line, resulting in forbidden frequency bands. The dispersion of a periodic transmission line resembles the dispersion of an electron in a crystal lattice, leading to a close parallel between these structures (which you can easily see and manipulate) and the quantum mechanical system of conduction electrons in a periodic potential. We are exploring that parallel, seeking its strengths as a pedagogical illustration of band theory, and seeking its limits.

Isaac Angert testing a 2-band crystal

Isaac Angert testing a 2-band photonic crystal.


Caitlin Ploch presenting at SURF 2012



Above: Electromagnetic field simulation will be used as a highly visual way for students to recognize the physical meaning of dispersion, or rather the nonlinear correspondence between 1/wavelength and frequency.


During summer '08, Isaac Angert taught himself to use photolighography to make the periodic transmission lines.

Isaac Angert


(Left) Isaac poses next to the bubbler where the etchant does its job. (Above) An example of a fixtured and connectorized circuit on Rogers RO 3003 board.

Strip#13 After fabrication, the striplines are measured on a calibrated vector network analyzer. This measurement yields complex transmission and reflection coefficients, which can be compared to the IE3D simulation. This graph shows the transmission from connector-to-connector, where 0 dB indicates complete transmission and -30 dB indicates 0.1% transmission. We get very good agreement between simulation and measurement, and the vector reflection and transmission coefficients are now being used to compute the dispersion, as well as the characteristic impedance, of the periodic transmission line.  

Research Students' Bibliographic Reference

Results from Summer 2008.
Results from Summer 2009.
Results from Summer 2010.


Chul-Sik Kee, et al, Essential Parameter in the Formation of Photonic Band Gaps, Phys. Rev. E, vol 59, no. 4, April 1999, pp. 4695-4698.

Chul-Sik Kee, et al, Essential Role of Impedance in the Formation of Acoustic Band Gaps, J. Appl. Phys. vol 87, no. 4, February 15, 2000, pp. 1593-1596.

Chul-Sik Kee, et al, Roles of Wave Impedance and Refractive Index in Photonic Crystals with Magnetic and Dielectric Properties IEEE Trans. Microwave Theory & Tech., vol. 47, no. 11, November 1999, pp. 2148-2149.

I.L. Lyubchanskii, et al, Magnetic Photonic Crystals, J. Phys. D: Appl. Phys, vol. 36, 2003, pp. R277-R287.

Peter Vukusic, Manipulating the Flow of Light with Photonic Crystals, Physics Today, October 2006, pp. 82-83.

Halim Boutayeb, et al, Band Structure Analysis of Crystals with Discontinuous Metallic Wires, IEEE Microwave and Wireless Component Lett, vol. 15, no. 7, July 2005, pp. 484-486.

Vesna Radisic, et al, Novel 2-D Photonic Bandgap Structure for Microstrip Lines, IEEE Microwave and Wireless Component Lett, vol. 8, no. 2, February 1998, pp. 69-71.