Research On Mobile Terminal Antenna

The thesis mainly focuses on the design of smartphone terminal antennas.First of all,the interaction between three common mobile phone antennas and the human body is studied.The purpose is to provide pave and guidance for the design of mobile phone antennas.A multi-band wideband mobile phone antenna based on the concept of equivalent circuit is proposed.Then the equivalent circuit design method is introduced to complete the design of metal frame smartphone terminal antenna and metal-casing smartphone terminal antenna furtherly.In short,the main content of the thesis can be summarized as follows: 1.Based on the idea of equivalent circuit,a multi-band wide-band mobile phone antenna with compact structure is designed,and the guidance of equivalent circuit to antenna design is fully verified.The coupling of the T-shaped feeding branch and the lower radiation patch of the antenna is equivalent to a series capacitor,and microstrip patch is equivalent to a series inductor,grounded meander microstrip line is equivalent to a shunt inductor,the coupling between the lower radiation patch and the ground is equivalent to a shunt capacitor,then the equivalent circuit structure of composite right-and left-handed(CRLH)metamaterial transmission lines is established.The antenna can provide two wide operating bands of 698-960 MHz and 1710-2690 MHz.The total efficiency of the proposed antenna is better than 40% in both two operating bands.2.Two types of frame antennas for the LTE metal-rimmed and metal-covered smartphone are presented.The first type is metal-rimmed antenna.The antenna makes full use of the metal frame as the antenna coupling side,and the metal frame and the internal monopole feed branch form a coupling loop.Add a parasitic branch near the feeding point and adding ground points to the side frame to improve the high frequency band.In addition,the L-type matching network is introduced at the feed port to improve the low frequency bandwidth of the antenna.Finally,the antenna can provide a double-wideband LTE operation to cover 700~960 MHz and 1710~2690 MHz bands.The measured efficiencies reach 42.2%-78.4% at the low band and 45.0%-78% at the high band.The second type is metal-casing antenna.The antenna fully utilizes the bottom short frame in the metal covered structure,selects appropriate location of the feed point and the grounding point to construct the monopole and loop modes.Four additional component matching networks are added at the feed port to expand the low frequency bandwidth of the antenna.At the same time,in order to improve the high frequency band,reconfigurable technology is introduced that a tuning switch is added at a grounding point,and the working state of the antenna can been switched by controlling the on and off of the tuning switch.The antenna can completely cover the low frequency band 700~960MHz and the high frequency band 1710~2690MHz under two working conditions.The measured radiation efficiency within the operating bandwidth is more than 40%.It is well suited to the requirements of the mobile communication.