An ultra‐thin flexible four port MIMO antenna for WBAN communications

Abstract

AbstractThis letter reports the design of a quasi Yagi‐Uda Antenna developed on an ultra‐thin flexible material for wireless body area networks (WBAN). The proposed planar Yagi‐Uda antenna operates at 2.45 GHz ISM band for medical applications. The microstrip line to slot line transition with circular geometry is used to obtain the necessary impedance matching. The proposed antenna has a footprint of 42 × 36 mm with a profile height of 0.05 mm. The quasi Yagi‐Uda antenna with a set of two directors exhibits 5% bandwidth with a unidirectional radiation pattern and a peak gain of 4 dBi. A four‐port multiple input and multiple output (MIMO) antenna is later developed to meet the diversity requirements of body‐centric communications. To improve the front‐to‐back ratio and specific absorption rate, the MIMO antenna is backed by a metallic reflector. The on‐body performance of the antenna are studied and the results are presented. The estimated envelope correlation coefficient is less than 0.4, apparent diversity gain is greater than 8 dB and effective diversity gain is above 7.2 dB for the proposed four‐element MIMO antenna. The prototype antenna is fabricated and the results indicate that the proposed antenna is suitable for WBAN communications.