Isolation Improvement in MIMO Antenna for WLAN Applications

In the present work, complementary split ring resonator-based defected ground structures have been employed to improve the isolation between two closely spaced multiple-input multiple-output antenna elements. The split-ring resonators offered lower isolation when they were used as decoupling elements in the top layer, as evident from full-wave simulations. A rectangular slotted structure in the ground provides lower isolation as compared to the complementary split-ring resonator. At 5.5 GHz, isolation between the 2 proximal antenna elements is -24.5 dB. The separation between the 2 adjacent edges of the radiating elements is 0.1375λ
0
. The suggested antenna design utilizes an FR-4 substrate of thickness 0.03 λ
0
with physical dimensions of 0.79λ
0
x 0.66λ
0
. The full-wave simulations indicate that the suggested antenna exhibits a gain of 3.40 dBi.The -10 dB impedance bandwidth of the proposed antenna is 200 MHz. A prototype has been fabricated and evaluated for proof of concept. Measured and simulated results depict close resemblance.