A Compact MIMO antenna System with Three Closely Spaced Multi-band Antennas for WLAN Application

In this paper, a MIMO antenna system is designed for multi-band Wireless local area network (WLAN) application with standards of IEEE 802.11a/b/g/j. As shown in Fig. 1, three printed antennas, each covering the frequency bands of 2.45, 4.9, 5.25, 5.75 GHz, are designed in a compact area of 1 x h = 48mm x 28mm, which is a suitable size for PC card application. The measurement results show 10-dB return loss with bandwidth more than 350 MHz in the 2.45 GHz frequency band and more than 1.2 GHz in the 5 GHz frequency band. In addition, the radiation pattern of these antennas is complementary in all directions to realize pattern diversity. The coupling between any two of these antennas is below -8.5 dB. The proposed antenna has the properties of good performance, compact size, low profile, and low cost. Hence, it is suitable for practical MIMO applications in a WLAN system.