Ultra-wide bandstop frequency selective structure using a cascaded array of vertically stacked parallel strip lines

A novel three-dimensional frequency-selective structure with an ultra-wide bandstop response is proposed using a cascaded configuration of a two-dimensional array of vertically stacked parallel strip lines. The structure is designed to achieve a combined rejection response of two independently designed parallel strips etched on the same substrate material. The bandwidth and the position of the rejection band are configurable by controlling the lengths of the two cascaded parallel strips. An example design is presented with its measured result, achieving a -10 dB fractional bandwidth of 100% The structure demonstrates a stable angular response under fairly large oblique incident angles given the wide bandwidth. The operating principles and design procedures are briefly explained.