Development of Capacitor Coupling Element Antenna for Low-Frequency Operation to Reduce Mutual Coupling in Mobile Terminal

Lim, Yee Hau (2025) Development of Capacitor Coupling Element Antenna for Low-Frequency Operation to Reduce Mutual Coupling in Mobile Terminal. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

The rapid growth of mobile communication technology has increased the demand for compact and multifunctional devices, necessitating advanced antenna systems like MIMO to enhance performance. MIMO technology, essential in 4G and emerging 5G networks, improves channel capacity and spectral efficiency but faces mutual coupling issues due to limited space in mobile devices. Mutual coupling, which occurs when antennas are placed close together, causes interference, reduces efficiency, and degrades communication quality. Existing decoupling techniques like decoupling network (DN), orthogonal polarization structure (OPS), parasitic element structure (PES), defective ground structures (DGS) and other decoupling techniques such as split ring resonator (SRR) and neutralization line (NL) help but often require compact designs, which are not always feasible in real-world scenarios. This project focuses on developing a capacitive coupling element (CCE) antenna specifically for 0.829 GHz operation and using DN to mitigate mutual coupling, thereby enhancing performance and reliability in compact mobile terminals. By addressing these challenges, the project aims to advance mobile technology, supporting a wide range of wireless communication standards in smaller, more efficient devices. The simulation return loss of this two-element CCE antenna is -46.80 dB while the isolation is -26.30 dB. The diversity gain, ECC, and efficiency also indicate the CCE antenna has a good performance, which is 9.99 dBi, 0.0012, and 96.59 %, respectively. The prototype measurement demonstrates acceptable performance with return loss below -6 dB and isolation below -10 dB, where S11 is -7.82 dB, S21 is -12.93 dB, S12 is -12.62 dB, and S22 is -12.01 dB at 0.829 GHz.