A very compact MIMO antenna with triple band-notch function for portable UWB systems

Abstract

A very compact triple band-notched multiple input multiple output antenna (MIMO) for ultra-wideband (UWB) communications is fabricated on an FR4 dielectric substrate having the overall size of 18×21×0:8mm3. The proposed antenna consists of two rectangular metal monopoles which are excited by 50-Ω microstrip lines on top of a substrate, and a common protrude ground is at the bottom. To achieve low mutual coupling between radiating elements, a T-shaped stub is protruded from the ground plane. By etching two C-shaped slots on the radiating patches, band-notched functions at 5.15–6 GHz and 7.8–8.4 GHz are obtained. The third notch band from 3.3–3.7 GHz is realized by adding U- shaped metal strips to the ground. The measured and simulated results demonstrate that the proposed antenna offers good impedance bandwidth of |S11| ≤·–10 dB from 2.8–12.2 GHz covering whole UWB band except at the designed notch bands, while giving less mutual coupling (|S21|) of lower than –25 dB in the whole UWB band. The measured envelope correlation coe±cient (ECC < 0:013), nearly constant gain and stable radiation patterns show that the proposed MIMO antenna is an appropriate candidate for portable UWB systems.