Antenna And Appearance Design Of Wearable Devices

In recent years,wearable devices have become more and more popular,good performance and design are the basis for products who can stand on the market.Most of the wearable devices which act as an extension device for mobile phones require data transmission with the mobile phone.And the antenna serves as a terminal for signal transmission and reception,which plays a key role in the wearable device.According to the requirements of wearable devices,this paper designs a metal shell equipped with an antenna.The metal shell does not affect normal radiation of the antenna.The specific research contents include the following aspects.Firstly,based on the inverted-F antenna,a microstrip antenna operating at a center frequency of 2.45 GHz is designed.The design idea refers to meander antenna which can change the structure of the inverted-F antenna in radiating arm thereby the antenna size decreases.After simulation experiments,the size of the new antenna is 16.1 mm × 5 mm.Comparing to the conventional inverted-F antenna with the size of 20.8 mm × 5 mm,total length of the new antenna is decreased by 4.7 mm.Secondly,a metal reflector is added to decrease the Specific Absorption Ratio(SAR).A layer of insulating material is added on the side closing to the metal patch,and the metal reflective plate is covered on the side of the insulating layer away from the metal patch.And the radiation energy closing to the human body side is decreased by changing the antenna radiation pattern.The simulation results show that the traditional omni-directional antenna reflects the energy from the front half space to the back half space after adding reflector,which effectively decreases the radiation of electromagnetic waves to the human body.Finally,the 3D model of the metal shell is designed using CREO software.The metal shell is characterized in which the antenna and the shell are integrated.One end of the surface of the metal shell is provided with a slit,and the insulating layer is at the other end.The patch antenna is away from the appearance metal.Feed point and the ground point on the patch antenna are connected with the printed circuit board of the device with coaxial line.The simulation results show that the center frequency of the metal shell antenna is at 2.45 GHz and the return loss is less than-33.9 d B.Its bandwidth ranges within 2.32 GHz-2.77 GHz,and the maximum gain is 2.16 d B,which meets the design requirements.A theoretical model is fabricated and the vector network analyzer is employed to verify that the return loss parameters are basically consistent with the simulation results.The antenna is measured in microwave anechoic chamber,and the results agree well with simulation.