Design of Wide Bandpass Filter using Planar Metal Strip Grating by analyzing dispersion properties

In this work, design of wide bandpass filter using planar metal strip grating by analyzing dispersion properties is provided. Higher order modes of the metallic strip grating are analyzed using dispersion diagrams and higher order mode 1 is us to realize the bandpass filter. Effect of structural parameters on the cutoff frequencies of higher order modes are analyzed. Structural properties also analyzed by plotting transmission (S
21
) and reflection coefficient (S
11
) plots. The structure consists of a metallic grating strips on metal backed substrate. Trapezoidal structure is used to converting the signal from microstrip feedline to filter structure. Finally, wide bandpass filter is designed with wide upper rejection band through optimization of strip length, width and periodicity. The simulated 3dB bandwidth is 56.8% extending from 6.3GHz to 11.3GHz. The total size of the filter is 1.5 λg x 0.32 λg. The simulated upper stopband extends up to 15GHz with -12dB rejection.