A microstrip line-fed multi-resonant slot antenna in the 4G/LTE band for smartphones

A microstrip line-fed slot antenna is presented in this paper to operate in the entire 4G/LTE band. The slot antenna has the letter `L' shape, and when excited with a transmission line generates multiple modes. These modes are combined to obtain the large bandwidth for covering most of the 4G/LTE band. Several feedlines have been studied to enhance the bandwidth. The slot width is also varied to achieve large impedance bandwidth. The radiation patterns are provided showing the behavior of the antenna. This antenna can be further optimized to provide polarization diversity in the 4G/LTE systems. The slot antenna is located in the upper portion of the ground plane, leaving a large area available for accommodating electronic circuitry for wireless communications or display technology in modern smartphones. This area can also be utilized to incorporate millimeter wave antennas to make the device compatible for future 5G wireless systems.