Effect of the screen to metal-frame smartphone antennas

In a recent couple of years, the smartphone's screen-to-body ratio is continuously increasing. Large-screen, or even full-screen (also called all-screen or bezel-less) smartphones are popular. However, the large-size and metal-contained screen may affect the performance of metal-frame smartphone antennas. But until now, there has not been systematic research published on the effect of the screen to smartphone antennas. In this paper, firstly the structure of the smartphone's screen is studied. Based on that, the model of the screen is given for the purpose of antenna designing. Then, PIFA and monopole antenna are investigated for the screen's effect on the antennas with different spacing. At last, the reasons are given for such influence.