This letter presents a novel electromagnetic bandgap(EBG) structure in microstrip technology based on nonuniformone-dimensional (1-D) Koch fractal patterns whosedimensions and period are modulated by a tapering function thatsignificantly improves the width of the bandgap. This widebandgap is achieved by maintaining the r/a (radius to period)ratio of the Koch fractal patterns larger than 0.5 in the wholestructure. In the pass-band region, an improved flat response isobtained by tapering the dimensions of the Koch fractal patternsetched in the ground plane, together with the width of themicrostrip line, with a Kaiser distribution which also modulatesthe periodicity of the fractals. A major consequence of thismodulation of the periodicity of the pattern is that this structureis much more compact than a uniform conventional one.
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