Radiator of wireless power charging for mobile device and its efficiency characterization

The development of wireless power charging radiator for mobile device and its efficiency characterization are presented. The radiator which is designed using a microstrip patch in spiral shape is intended to work at operating frequency around 10MHz. Some investigations over the gap between 2 radiators are carried out to analyse the effect of varied gap separations to the reflection and transmission coefficients. After obtaining the optimum design, the radiator is deployed on a grounded FR4 Epoxy dielectric substrate with the dimension of 50mm × 60mm and the thickness of 0.8mm. The realized radiator is then measured experimentally to characterize its properties compared with the design ones and to obtain its radiation efficiency. From experimental characterization, the radiator works at operating frequency of 9.21MHz with the reflection and transmission coefficient values of −20.22dB and −2.72dB, respectively. This is comparable to the design one which works at operating frequency of 10MHz and the reflection and transmission coefficient values of −29.79dB and −1.62dB, respectively. Whilst the high efficiency is achieved when the gap separation between 2 stacked radiator is 0.8mm with the average efficiency around 58%.