A separated cross-shaped isolation element for WLAN MIMO applications

In the article, two PIFA antennas fabricated on both ends of an FR4 substrate are introduced for MIMO application. The two identical PIFAs excite resonant bands (S₁₁ and S₂₂) both at 2.45 GHz for WLAN application. The isolation mechanism is accomplished through a separated cross-shaped isolation element, which is extended from the ground plane and located between the PIFAs. By adding the isolation element, the radiating emission between the PIFAs and the conducting current through the ground plane are decreased. The measured S₂₁ in WLAN band is below -15 dB. The overall dimensions (20×45 mm²) of the proposed MIMO antenna including an antenna portion (10×20 mm²) and a system ground (35×20 mm²) are suitable for applying in a wireless device. Beside, the radiation patterns, ECC (Envelope Correlation Coefficient) and radiation efficiency will be presented.