Mutual coupling reduction with a novel fractal electromagnetic bandgap structure

This work shows the effect of a novel fractal-based electromagnetic bandgap (FEBG) structure between dual planar inverted-F antenna (PIFA) elements. The FEBG structure without any shorting pins builds on a well-known fractal structure called Sierpinski carpet, where two iterations have been applied as a uniplanar EBG between dual PIFAs elements to increase the isolation. The proposed antenna can operate at ∼2.65 GHz for wireless long-term evolution application with compact design dimensions. The simulations are carried out with Ansoft HFSS ver. 17.0. The second iterative order FEBG band-gap characteristic is verified using more computationally efficient analysis. An investigation on coupling reduction showed more than 27 and 40 dB in E-plane and H-plane, respectively, between the dual antenna elements is achieved for an antenna spacing less than half wavelength. The proposed antennas with and without second iterative order FEBG are fabricated and measured. The measurement results are in good agreement with the simulated results. Moreover, the envelope correlation of antenna elements with the proposed FEBG is quite smaller than that of antenna elements without FEBG, which gives the proposed system an excellent diverse performance and suitable for the use in low-frequency narrow-band multiple-input, multiple-output applications.