Design of Highly Isolated Dual-Antenna System for Handset in Different Scenarios

To mitigate the interference between antennas working at the same frequency band but for different protocols, high isolations are in demand. In this letter, a dual-antenna system, operating for the WLAN/Bluetooth protocols, has been designed on the top part of the mobile handset frame based on the correlation method. A high isolation of above 30 dB is achieved in both free space and the hand-loading scenario. The first antenna is chosen on the corner of the frame for easy excitation of the modes. Afterwards, the location of the second port, which is least correlated with the first antenna, is calculated and determined from MATLAB, leading to low coupling with the first antenna in free space. To maintain the high isolations in the hand-loading scenario, the handset is slightly modified with one more breaking on the frame. The antennas can also be decoupled when the correlation method is directly applied to the hand-loaded antennas. The proposed dual-antenna system has been fabricated and measured, exhibiting good performances in different scenarios.