A Dual-Band MIMO Antenna System for 2.4/5 GHz WLAN Applications

A compact multiple-input-multiple-output (MIMO) microstrip antenna system covering the 2.4 and 5 GHz wireless local area network (WLAN) bands is presented in this article. To achieve dual-band characteristics, the TM01 and TM03 modes of a microstrip antenna are excited. A rectangular slot is etched in the center of the microstrip antenna for improving the radiation capability of the TM03 mode. Then, two probes are utilized to tune the resonant frequency of the TM01 mode with limited effect on the operating frequency of the TM03 mode. To realize high interport isolation at the two distinct WLAN bands in a methodological way, isolation enhancement is achieved successively at the lower and upper-frequency bands. Two split loops are introduced to reduce the mutual coupling at the 2.4 GHz band. Two dipole elements are added in the rectangular slot to obtain high isolation at the 5 GHz band. The decoupling mechanism of the proposed antenna is detailed analyzed. The proposed antenna system operates at 2.25-2.63 and at 5.14-6.06 GHz. The measured maximum value of mutual coupling between the two ports is less than -15.3 dB at both operating frequency bands.