CHAPTER 6 Mutual Coupling Reduction Between Flexible MIMO Antennas

In this chapter, a novel µ-negative (MNG) metamaterial structure is proposed to reduce mutual coupling between two printed monopole antennas operating at 2.45 GHz. The unit cell consists of two split ring resonator (SRR) structures bridged at the centre, which mimics a cascaded filter; hence, termed as Bridged Split Ring Resonators (BSRRs). This approach enhances the magnitude and bandwidth of the electromagnetic suppression response. Unlike the bulky nature and vertical ori-entation of such structures, the proposed SRRs are positioned in a planar fashion with axes parallel to the magnetic field vector of the antennas which is necessary for BSRR structures ’ excitation. A reduction of 11.5 dB in the mutual coupling is achieved by inserting the proposed structures with a separation distance of 0.29□ between the radiating elements. Moreover, the proposed design offers an ultra thin and flexible profile since it is printed on a polyimide substrate with a thickness of 50.8 µm. It can be inferred that the proposed design is a reasonable candidate for flexible and wearable wireless systems. Good agreement is obtained between the experimental and numerical results