Novel Compact Wide-Band EBG Structure Based on Tapered 1-D Koch Fractal Patterns

Abstract

Abstract-This letter presents a novel electromagnetic bandgap (EBG) structure in microstrip technology based on nonuniform one-dimensional (1-D) Koch fractal patterns whose dimensions and period are modulated by a tapering function that significantly improves the width of the bandgap. This wide bandgap is achieved by maintaining the r/a (radius to period) ratio of the Koch fractal patterns larger than 0.5 in the whole structure. In the pass-band region, an improved flat response is obtained by tapering the dimensions of the Koch fractal patterns etched in the ground plane, together with the width of the microstrip line, with a Kaiser distribution which also modulates the periodicity of the fractals. A major consequence of this modulation of the periodicity of the pattern is that this structure is much more compact than a uniform conventional one.

Synthesis of One Dimensional Electromagnetic Bandgap Structures with Fully Controlled Parameters

“…Unfortunately, this analytical design procedure does not provide any control over the ripple level in the passbands. Many efforts have been carried out using tapering functions (smooth variations of the amplitude or the size of the perturbation in the propagation direction) [36], [54], along with period alterations (variations of the periodicity along the propagation direction) [65], to reduce the ripple level out of the forbidden band by means of a non-controlled progressive matching between the periodic structure Bloch-waves and the characteristic impedance at the ports. Both strategies increase the degrees of freedom that can be used by optimization routines and they achieve good results [19], [53].…”

Wide stopband miniaturized “I”‐typed EBG with DGS

“…Then we found that it can use first half part of the structure in Refs. to implement the same feature of wide stopband. The EBG designed by using this method can not only filter waves in a wide band but also have better performance in low frequency.…”

Miniaturized lowpass filter with ultra-wide stopband using dual-plane defected structures

“…In many microwave applications, there is a great requirement for the LPF with a compact size, steep rejection and wide stopband. Due to their prominent stopband, electromagnetic band-gap (EBG) structure, defected ground structure (DGS) and defected microstrip structure (DMS) have been widely employed to implement the abovementioned LPF [1,2,3,4,5,6,7,8,9].…”

“…The uniform distribution of the periodic patterned structure may suffer from high passband ripples, which can be improved by adopting the non-uniform distribution of dimensions [2,3]. Since the shape of the structure unit holds the key to determining the stopband of LPF, different patterned structures are implemented to obtain a wider stopband [4,5,6,7]. However, a large num of the structure unit are often required to provide a good stopband, causing a relatively large physical size.…”