Performance enhancement of dual-band antenna for IoT applications using closed loops

In this Letter, a dual-band antenna with improved performance is proposed by generating a stronger coupling with the ground plane using two closed loops. The antenna is designed in such a way that it is coupled with two orthogonal ground modes in the lower and higher bands. Two closed loops are attached at the end of the ground plane to control the frequencies of the two ground characteristic modes. Through simulation and experimental verification, the proposed antenna has obtained greatly improved performance in both bands compared to the reference antenna without closed loops.