Sextuple band rejection functionality from a compact Koch anti-snowflake fractal UWB-MIMO antenna integrated with split-ring resonators and slots

In this article, a dual-port modified Koch Anti-snowflake fractal antenna is designed and experimentally verified for ultra-wideband performance with hexa-band suppression functionality. The designed array occupies a total area of 29.5 x 43.5 mm(2). Initially, it consists of two microstrip-fed modified Koch Anti-snowflake fractal (iterated up to 3rd order) patches and a defected ground plane, aimed to achieve 144.6% fractional bandwidth (2.48-15.42 GHz) with optimum isolation characteristics (S-21/S-12 <= -17 dB). The proposed fractal geometry minimizes the patch area by 42.4% as compared to the circular configuration. Further, each fractal patch is embedded with a Z-shaped and inverted L-shaped slit to suppress the unwanted WiMAX (3.3-3.77 GHz) and INSAT (4.57-4.9 GHz) band respectively. Two SRR pairs and a G-shaped slot are loaded in each feedline of the designed array to realize notches at 6.578 GHz (super-extended C-band), 8.23 GHz (ITU-8), and 10.22 GHz (amateur radio) respectively. A pair of L-shaped slits is removed from the reduced ground to eliminate the interfering WLAN (5.18-5.82 GHz) band. Various diversity parameters for the designed array are examined and are found within their permissible levels. The experimental results of the fabricated array (without and with notch elements) present an acceptable resemblance with the simulated ones, therefore assuring the practicability of the designed array in ultrawideband communication systems.