Compact Wideband Loop Antenna for Earbuds

This paper presents the compact wideband loop antenna with a small size of 7.05mm's radius covering ultra-wideband above 6 GHz, Wi-Fi, and Bluetooth bands for earbuds. The wide bandwidth of the proposed compact loop antenna is obtained with the antenna structure consisting of the loop antenna and the capacitive loading pin inserted in the middle of the loop antenna. The loop antenna with the capacitive loading pin supports multi-resonant modes. A wider bandwidth can be obtained by adjusting the position of the capacitive loading pin. The half-wavelength resonant frequency of the basic loop can easily be tuned through the physical capacitance between the capacitive loading pin and loop antenna. Additionally, the impedance loop is considered for the impedance matching of the compact wideband loop antenna. The simulated and measured results are included to evaluate the performance of the proposed compact wideband loop antenna. Consequently, we obtained that the simulation and measurements results are consistent.