A Miniaturized MIMO Antenna With Triple Band-Notched Characteristics for UWB Applications

In this paper, a novel compact four-element ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with triple band-notched characteristics is proposed. The proposed antenna is composed of four slot antenna elements with a common rhombic slot, each feeding by a microstrip-fed line to greatly reduce the overall size of the antenna. It has a compact size of 34 mm ×34 mm ×1.6 mm. The high isolation and polarization diversity are achieved by placing the four microstrip-fed lines perpendiculars to each other, while a parasitic strip is employed as a decoupling structure between adjacent microstrip-fed lines to further improve isolation. Moreover, the proposed antenna can achieve triple band-notched characteristics by embedding L-shaped and C-shaped slots on each radiator and loading electromagnetic band gap (EBG) structures next to micro-strip feeders respectively. As a result, the proposed antenna obtains three notched bands of 3.3-3.9 GHz, 5-6 GHz, and 7.4-8.5 GHz, which are in good agreement with the interference bands of WiMAX (3.3-3.7 GHz), WLAN (5.15-5.875 GHz) and X-band (7.3-8.5 GHz), respectively. The antenna prototype has been fabricated and measured. The results show that the antenna has an impedance bandwidth of 2.5-12 GHz (except for the three notched bands). Besides, the isolation among the elements, envelope correlation coefficient, radiation characteristics, efficiency, realized gain, and total active reflection coefficient are also investigated. The experimental results indicate that the proposed antenna can be a good candidate for UWB-MIMO wireless communication applications.