The Effect of Implementing Resonator-Interdigital Capacitor and Complementary Split Ring Resonator (CSRR) on MIMO Antenna

Indoor Wi-Fi networks with 4G and 5G technology can work properly on wide coverage for high data rate services. Existing Wi-Fi devices need to implement Multiple-Input Multiple-Output (MIMO) antenna technology to provide high data rate. However, the antenna bandwidth and gain are relatively small. On previous research, the MIMO antennas with Resonator and Interdigital Capacitor have wide bandwidth, but gain of the antennas is low. In previous research, Complementary Split Ring Resonator (CSRR) on MIMO antennas provides high gain but the bandwidth decreases. This paper proposes an 2x2 MIMO monopole antenna design at 2.4 GHz for indoor Wi-Fi that implementing two combined methods, i.e., Resonator-Interdigital Capacitor with CSRR to improve the antenna performances. The idea is the addition of Resonators and Interdigital Capacitors is to increase the bandwidth, while CSRR is added to increase gain. The results show the proposed antenna has better return loss and decoupling values of 0.323 dB and 2.359 dB, respectively. The bandwidth and gain of the proposed antenna increase by 73.7 MHz and 0.361 dB, respectively when compared to Resonator Interdigital Capacitor MIMO antenna. The proposed antenna has return loss of -17.784 dB and decoupling value of -12.871 dB at 2.4 GHz, with the bandwidth of 644.3 MHz and gain of 1.996 dB.