In this paper, a dual-band complementary split ring resonator (C-SRR) is used to improve the band-notch effect relative to the traditional SRR. Meanwhile, we employ a brand-new SRR unit cell as an isolator for decoupling among multiple bands without enlarging the dimensions of the multiple-input-multiple-output (MIMO) antenna. Therefore, a compact ultra-wideband MIMO antenna is developed. Compared with the previous work, the proposed MIMO antenna also has obvious advantages such as high isolation and miniaturization (the dimensions are only 13.5 mm × 34 mm). The metamaterial-inspired UWB MIMO antenna presented here is suitable for small scaled mobile devices. 1. INTRODUCTION With the rapid development of wireless communications and the demands for high transmission rate and stable transmission quality, multiple-input-multiple-output (MIMO) technology has been widely employed [1, 2]. MIMO antennas use multiple antenna elements for transmitting and receiving signals in the wireless communication systems. The MIMO technology can improve the capacity of the communication system and the utilization ratio of the spectrum without increasing the transmitting power. Ultra-wideband (UWB) technology is used for short range wireless communication among multiple devices. UWB systems operate under a low power level (41.3 dBm/MHz) within a wide operation band (3.1 GHz-10.6 GHz) [3-5]. Since the UWB system operates at such a wide spectrum that covers many communication systems, it is necessary to find an efficient method to reduce the signal interference between the UWB system and other wireless communication systems. Despite of the utilization of the slots on the patch and/or on the ground to achieve the band-notch effects, other problems, such as high loss of the antenna radiation efficiency and reflection coefficient, still exist. So far, several studies of the applications of the MIMO technology to the UWB system have been done for enhancing the system stability [6, 7]. However, the problem of realizing high isolation in the whole operating spectrum within a compact structure is serious, and plenty of studies have been done. Zhang et al. used the tree-like structure which resonates at multiple frequencies to reduce the mutual coupling [8]. Liu et al. proposed a compact UWB MIMO antenna, and the orthogonal polarization is used for enhancing isolation [9]. Chacko et al. utilized both tree-like structure and orthogonal polarization for decoupling [10]. Iqbal et al. used F-shaped stubs to realize low mutual coupling with high gain [11]. Metamaterial has been widely used in the antenna field due to its unique electromagnetic characteristics. The researches show that the metamaterial can be used for improving the antenna performance such as enhancing radiation properties [12], extending bandwidth [13], reducing mutual coupling [14], miniaturization [15], band-notching [16, 17], and multiple bands realization [18]. In recent years, some attempts using metamaterials such as electromagnetic band gap [19], single negative materials [2...