Lumped Elements Loaded Miniaturized Antenna for Bluetooth Enabled Hearing Aid Devices
Hearing loss is one of the most common physical and sensory impairments among all ages, especially elders. Hearing loss may affect only one ear or both ears of a patient at a different degree of impairment. This asymmetrical nature of hearing loss makes it more difficult for the patient to localize the source of the sound properly. One possible solution for this asymmetry of hearing problem is to use a pair of hearing aid devices. Each hearing aid device should be able to deal with such asymmetry of the ears, as well as the natural asymmetry induced by spectral sound differences. By using a pair of hearing aid devices operating at 2.4GHz- 2.5GHz Bluetooth band, wirelessly communicating with each other, the binaural processing will be improved for the person who suffers from unbalanced hearing loss between the two ears and one can properly localize the source of the sound. A novel lumped elements loaded miniaturized differential dipole antenna for Bluetooth enabled hearing aid devices is proposed. Miniaturization of the proposed antenna is achieved by planting lumped components directly on the optimized locations of the antenna traces. The lumped elements also serve as a matching circuit which matches the antenna’s input impedance directly to the radio, without need for an additional dedicated matching circuit. The effect of the human body is taken into consideration during the antenna design stages. The proposed antenna was simulated, fabricated and measured. There are some good agreements between simulated and measured results. Radio link tests were done after integrating the proposed antenna with a hearing aid package, and good link ranges were observed. Integrating tunable elements, for example voltage controlled capacitors; directly on the antenna structure to achieve adaptive matching according to different human bodies will be a valuable future work for this research.