Research On The Multiband Mobile Antenna For4G Communications

In recent years, the mobile communication has entered3G era, and begin the transform to4G communication systems. In order to satisfy people with more functions like high speed transmission, Bluetooth,4G LTE and so on, the trend of the antenna design would be broad the bandwidth. As the limit of the size for the wideband antenna, it is very hard for us to design the antenna with wide bandwidth in the limited space. On the other hand, as the large development of the integrated circuit, the electronic products are becoming more and more compact. Antennas also should be very small as the terminal part for the wireless communication equipment. Additionally, people care about the large radiation of the mobile phone for human in recent years, so SAR (specific absorption rate) has been the enforced indicators for the mobile phone.First, we design the WLAN antenna at the proper position in the limited space of the mobile phone. We study the bandwidth, radiation pattern and the efficiency of this antenna. We also fabricated the antenna to demonstrate its function.The structures like PIFA、monopole and loop can cover LTE band, and the technology of couple-fed and adding matching network can broad the bandwidth of the antenna. We design two LTE antennas in the two ends of the system. The main antenna covers the bands of LTE700/GSM850/900/DCS/PCS/UMTS/LTE2300/WiMax2500, and the auxiliary antenna covers the bands of the GSM900/DCS/PCS/UMTS/LTE2300. We fabricated the main antenna and measured the bandwidth, radiation patterns, efficiency and gain. We also simulated the SAR value of the main antenna. For the auxiliary antenna, we only have simulated results.At last, we study the LTE MIMO consists of the main antenna and the auxiliary. We simulate the bandwidth, isolation and ECC. We balance these indicators by changing the place of the antenna and the structure of the auxiliary antenna.