A Dual-Antenna System for LTE/WWAN/WLAN/WiMAX Smartphone Applications

A dual-antenna system for smartphones with Long Term Evolution (LTE)/Wireless Wide Area Network (WWAN)/Wireless Local Area Network (WLAN)/Worldwide Interoperability for Microwave Access (WiMAX) operations is presented and studied. The proposed dual-antenna system consists of two symmetric antenna elements and a folded dual inverted L-shaped ground branch (FDILGB). Each antenna element includes a driven branch and a parasitic ground branch. To improve the antenna efficiency, the parasitic ground branch is studied and optimized. The FDLGB is applied to reduce the mutual coupling between the two closely spaced antenna elements and achieve better impedance matching. The measured operating bands with |S₁₁| lower than - 6 dB cover 698-974 and 1699 - 4019 MHz for the fabricated prototype. Within the operating bands, the measured |S₂₁| is lower than - 10 dB. Based on the measured 3D radiation patterns, the envelop correlation coefficient, the mean effective gain and the diversity gain of the proposed dual-antenna system are calculated, and good results are obtained.