A compact flexible fractal ultra-wideband antenna with band notch characteristic

A compact flexible fractal ultra-wideband antenna with band notch characteristic is presented. The antenna is printed on a 12.5 mu m flexible polyimide substrate, and an impedance bandwidth of 15.48 GHz (3.6-19.08 GHz) is achieved along with an overall antenna size of 20.5 x 13.9 mm(2). The design of the hexagonal radiator in the fourth iteration effectively enhances the impedance bandwidth of the antenna. By arranging two symmetrical complementary split ring resonators on the ground plane, the band rejection of the X-band uplink frequency from 7.9 to 8.41 GHz is achieved. The average gain of the antenna can reach 3 dBi in the pass band, while the gain in the notch band is greatly reduced to below 0 dBi. Compared with the existing structure, the antenna has a larger bandwidth and a smaller size. Furthermore, the antenna is tested under bending effects. Test results show that this antenna can be used for integration on flexible electronic devices.