Performance Improvement of Ear-Bar TWS Earphone Antenna Using Parasitic Metal

An ear-bar TWS earphone antenna with improved ear-to-ear path gain (PG
_E2E
) and efficiency is presented. The proposed antenna consists of an inverted-L antenna and a parasitic metal. By applying the parasitic metal, the vertical electric field (E-field) around the head is enhanced and the E-field into the human head is weakened. Due to the stronger vertical E-field around the head, the proposed antenna achieves enhanced PG
_E2E
. Also, for the weak E-field in the head, the improved antenna efficiency is realized. Two prototypes without and with the parasitic metal are fabricated and measured. The measured −6 dB bandwidths of the two prototypes can cover the ISM band. With the help of the parasitic metal, the measured average efficiencies on the head within the 2400–2484 MHz band are improved from 19.1% to 30.9%. In the meanwhile, the measured PG
_E2E
on the head has improved from −56 dB to −49.7 dB. The proposed ear-bar TWS earphone antenna with enhanced PG
_E2E
and efficiency is promising for practical applications.