A Conformal Wideband Antenna for Wearable Applications at Sub-6 GHz: Characteristic Mode Analysis

Over the past few decades, a significant focus has been paid to conformal antennas for various applications. The emergence of the fifth generation (5G) has been beneficial for such applications due to its high data rate, low latency, and high-speed communications. The sub-6 GHz 5G band is a better choice in the current scenario due to its wider coverage and low infiltration losses. In this article, a compact flexible wideband Sub-6 GHz antenna with a profile of 30$\times 24 \times 0.25 mm^{3}$ is proposed for Sub-6 GHz 5G applications. Bending analysis of the antenna is performed over different bending degrees and the antenna shows acceptable performance even in bent conditions. Specific Absorption Rate (SAR) analysis of the antenna is performed with a three-layer tissue model and the SAR is found to be 0.836 W/kg and 0.391 W/kg for 10 g of tissue at 4.1 and 5.3 GHz respectively, which is less than the permissible international limits. The antenna is placed over a metallic helmet to understand the radiation characteristics of the antenna for wearable applications. Characteristic mode analysis of the proposed antenna is performed to study the physical phenomena of the antenna. The antenna has a gain of 2.62 and 3.46 dBi at 4.1 and 5.3 GHz, making it suitable for the above said application.