A Miniaturized Ultra-Wideband MIMO Antenna Design with Dual-Band Notched Characteristics
In this manuscript, a miniaturized Multi-Input Multi-Output (MIMO) antenna with dual-notch characteristics is designed for Ultra-Wideband (UWB) indoor positioning system. The proposed UWB MIMO antenna has a compact size of 35*35 mm2 with four orthogonally placed antenna elements on the print circuit board (PCB) with FR4. Each radiating element utilizes the combination of a rectangle and an irregular pentagon, and etches two inverted L-shaped slits to generate two notches in WLAN (5.00 GHz-5.82 GHz) and X-band (7.11 GHz-8.20 GHz). On the grounding planes, the rectangle grounding units are modified into L-shaped branches, on which stepped open-circuit slots and right-angled triangle truncations are etched to broaden the impedance bandwidth. Furthermore, three equidistant rectangular decoupling slits are etched to improve the isolation. The measured results are in good agreement with the simulated ones, which shows an impedance bandwidth of 116.68% (2.96-11.25 GHz) with isolation better than 17 dB. The antenna also has excellent characteristics of good radiation characteristics, total active reflection coefficient (TARC), diversity gain (DG>9.99), low envelope correlation coefficient (ECC<0.005) and channel capacity loss (CCL<0.4 bits/sec/Hz), which can be used in portable UWB-MIMO indoor positioning system.