Generate transmission data using Chen's method* Increase period in y-direction (dy) only Increase period in x-direction (dx) only Increase period in both directions simultaneously  Fit the data using least squares analysis for resonant wavelength (l0), period (dx, dy), and aperture width (b)  Find empirical relationships between l0 and dx, dy, b  Next systematically vary aperture length (a)  Repeat process for resonant widths *See Chen, C. C., IEEE Trans. Microwave Theory Tech., MTT-18, 627-632 , Sept. 1970