Multiband flexible MIMO antenna for NB-IoT/ISM/5 G and wearable applications
Diwakar Kumar, Deepti Sharma, Rakesh N. Tiwari, Imran Ahmed Khan, Pradeep Kumar
Abstract
This paper presents a novel, flexible multiple-input multiple-output (MIMO) antenna with wideband and multiband capabilities. The designed antenna has compact footprints (0.3 λ 0 2 ) and works in the narrow band internet of things and radio frequency identification 1.8, 3.6 GHz for 5G sub-6 GHz and industrial, scientific, and medical 2.45 and 5.8 GHz bands. It can be easily incorporated into human clothing, allowing wireless wearable sensors to monitor human vital signs and establish a communication link with smart mobile devices. The MIMO antenna consists of two modified triangular radiators. To achieve high isolation among antenna elements, a defective ground structure is adopted to decouple the low frequency band, achieving isolation greater than 20dB. The single antenna dimensions are 0.375 λ 0 ×0.375 λ 0 ×0.00625 λ 0 , and the total dimensions of the two-port MIMO antenna are 0.875 λ 0 ×0.375 λ 0 ×0.00625 λ 0 . Both measured and simulated results demonstrate excellent performance with a realized gain of 0.70-9dBi and radiation efficiency of 20-41% in -10dB impedance bandwidths of 1.67-2.02, 2.17-3.81, and 5.44-6.06 GHz. To comprehensively assess the performance characteristics of the MIMO antenna system, including the various diversity parameters are evaluated. The specific absorption ratio (SAR) of the MIMO antenna is examined for 1/10g tissue at 1.8, 2.4, 3.6 and 5.8 GHz and found within the standard limits.