Design Of Smart Antenna For Mobile Handset

With the fast development of wireless communication technologies,new standards are gradually being introduced to meet the increasing demands for high quality services,such as 4G LTE and 5G.These standards all present the channel capacity is bigger,transmission rate is faster and the trend of signal coverage is wider,and that will give novel 4G and 5G mobile communication equipment design brings many challenges.In recent years,multi-input multi-output(MIMO)technology and beamforming technology as two key technologies to solve wireless communication have been widely concerned by the industry and academia.MIMO technology can use multiple antennas to achieve higher data transmission rate and channel capacity with the same spectrum and power resources,beamforming technology can use multiple antennas to direct the electromagnetic field energy to the desired direction to enhance the antenna gain and expand the signal coverage.The paper takes the terminal antenna system of handheld device as the research object,and requires miniaturization,multi-frequency and low profile,and combining the two key technologies of MIMO and beamforming to design an antenna array system with a size of 136 mm x 68.8mm x 1mm.The main innovations of the paper are as follows: 1.The new design idea is illustrated by an antenna array consisting of eight printed planar inverted-F(PIFA)elements operating at GSM1900(1880-1920 MHz)and LTE2300(2300-2400 MHz).The 8-element antenna array is printed on an FR4 substrate of dimensions 136 mm × 68.8 mm × 1 mm,which are typical for smart phones.The antenna array system conbines the MIMO technique and the beamforming technique,the beamforming function is used for transmitting while the MIMO function for receiving.2.The optimal distribution of excitations for the arrays in the desired direction can be obtained by using the method of maximum power transmission efficiency,which can then be realized by a feeding circuit board.The antenna beam can be directed to the desired direction and the maximum possible gain in the direction can be achieved.The direction diagrams of the antenna in the x,y and z directions at the center frequency of 1.9 and 2.35 GHz were tested and the actual gain was obtained.3.The effects of the human body on the performance of antenna array are also examined,such as antenna isolation,ECC and radiation pattern.The results indicate that the proposed design still exhibits good MIMO and beamforming performances under the effect of the human phantom.