Research On Pattern Reconfigurable Antenna For Mobile Phone

With the development of wireless technology,the function of mobile phone has been extended from the original single voice communication to the field of entertainment,video and other multimedia,and mobile phone function has been become more and more rich,and the number of phone users is growing very fast.Relationship between mobile phones and people have been inseparable,so that the time when people are exposed in cell phone radiation is becoming more and more long,but electromagnetic radiation produced by mobile phones will effect human body,which is has become a problem we cannot ignore.Insomnia,memory loss,anxiety,headache can be casued by the electromagnetic radiation.As people health consciousness enhancement,how to reduce mobile phone radiation to human body,to make people have more health call quality,to implement green communications,has become one of the new research directions of the development of the mobile phone.The pattern of the antenna represents the energy distribution,and pattern reconfigurable antenna has the potential to avoid the nosiy and jam and improve the performance of the system.In this paper we proposed the antennas which have the reconfigurable characteristics in order to reduce the electromagnetic radiation produced by mobile phones.This paper focuses on the technology of pattern and hybrid reconfigurable characteristics.The main research work and innovation points summarize as follows:1.The purpose of this paper is to design the antennas that have the reconfigurable chacteristics so that the enery around the antenna can be redistributed.The proposed reconfigurable functions are obtained by controlling the ON/OFF states of the radio frequency switches which are integrated on the excitation elements.When the cell phone is standby,the designed antenna can provide omni-directional radiation characteristics.When the portable device is used to communicate with other users,for instance calling other users for cell phone,the radiation pattern will be reconfigured as a directional radiation so that the electric field intensity toward the users can be weakened.2.We proposed a reconfigurable antenne which can operate at LTE2300?2.305-2.4GHz?,LTE2500?2.5-2.69GHz?,WIFI?2.4-2.484GHz?.The performance of the proposed antenna is investigated by the use of the high-frequency structure simulator?ANSYS HFSS15?and is test by Agilent Vector Network Analyzer.The experimental results demonstrated that the proposed antenna can achieve good SAR performance.3.As we known,the hybrid reconfigurable antennas has two or three reconfigurable characteristics,the proposed hybrid reconfigurable antenna with frequency and radiation pattern reconfigurable characteristic can operate at two frequencies,1.85GHz and 2.6GHz for supporting DCS1800?1.71-1.88GHz?and UMTS?1.92-2.17GHz?,LTE2300?2.305-2.4GHz?,LTE2500?2.5-2.69GHz?,WIFI?2.4-2.484GHz?.The radiation pattern reconfigurable characteristic is achieved by controlling the six radio frequency switches installed on the parasitic elements,resulting in three modes in the radiation pattern at each frequency band.The length of the parasitic elements is 0.44?₀,and it is reduced by 12%in comparison with the length of the traditional Yagi antenna.4.Based on the structure of the hybrid reconfigurable antenna in the chapter three,we design another one that has frequency and radiation pattern reconfigurable characteristics can operate at GSM850?0.824-0.894GHz?and DCS1800?1.71-1.88GHz?.The length of the reflector is 0.35?₀,where₀?is the wavelength at the resonance frequency,and is smaller than Yagi antenna.