A Chip Antenna for Bluetooth Earphones with Cross-Head Interference Tested from Received-Signal Sensing

Abstract

In this paper, a novel chip antenna and its function in wireless connectivity are presented for Bluetooth (BLT) earphones. The chip antenna is a metamaterial so compact (<λ/8), as the size of 4.9 × 13.0 × 2.0 mm3, that when it is mounted on the realistic PCB, it can be held in the enclosure of the BLT earphone. This setting does not degrade the resonance (S11 < −10 dB) of the proposed antenna. As two earphones in a pair are demanded to communicate with each other, one shares an RF signal with the other and they take turns as the master and slave. The received signal sensing is conducted with the latest model of human head-ear-phantom located between the earphones to mimic the real use-case and cross-head interference. Electromagnetic simulation of the antenna is done and verified by fabrication and measurement. Particularly, received-signal strength indications between the proposed antennas in the earphones are experimentally obtained as −67.5 dBm and −70 dBm without and with the head-ear-phantom, respectively, much greater than −120 dBm, the limit of detection, and implying acceptable connectivity and invulnerability over cross-head-interference problems.

Miniaturized On-Ground 2.4 GHz IoT LTCC Chip Antenna and Its Positioning on a Ground Plane

“…Antennas for wearable applications are receiving more attention due to the increasing presence of wireless devices for health and sports tracking, including flexible [ 19 , 20 ] and textile [ 21 ] based solutions. Two solutions for earphone integration are presented in [ 22 , 23 ]: one with a chip antenna and another with a wideband loop antenna. Additionally, a planar solution on a semiflexible substrate is proposed in [ 24 ], featuring an I-shaped monopole and an inverted L-shaped slit with a size of 0.016 × 0.1 × 0.004 and a 5.7% bandwidth.…”