Triple-Band MIMO Antenna with Integrated Decoupling Technology

Table 7

Isolation optimization process.

Optimization process
S-parameter results
Principle	The blue branches generate the frequency band of 5.4–6.1 GHz, while the red branches generate the frequency band of 7.0–7.4 GHz. In addition, the neutralization lines enable the antenna to operate within the 4.4–4.9 GHz frequency band	The neutralization lines are designed to introduce a 180° phase shift at 4.5 GHz and 5.7 GHz, effectively cancelling out the coupling current from port 1 to port 3 (||). As a result, || is reduced by 13 dB and 15 dB at 4.5 GHz and 5.7 GHz, respectively. Furthermore, the T-branch 3 enhances the isolation between port 1 and port 3 (||) by 12 dB in the 7.0–7.4 GHz frequency range
Optimization process
S-parameters
Principle	The coupling current from port 1 to port 4 (||) is effectively blocked by DGS 1 and DGS 2 at the frequencies of 4.4–4.9 GHz and 5.4–6.1 GHz, respectively. || is reduced by 17 dB at 4.3 GHz and reduced by 30 dB at 5.4 GHz	The presence of T-branches significantly decreases || in the operation frequency bands. T-branch 1 improves the isolation between port 1 and port 2 (||) by 23 dB in 4.4–4.9 GHz, while T-branch 2 improves the isolation by 5 dB in 5.4–6.1 GHz