Hepta-Band Coupled-Fed Loop Antenna For LTE/WWAN Unbroken Metal-Rimmed Smartphone Applications

A hepta-band coupled-fed loop antenna for LTE/WWAN unbroken metal-rimmed smartphone applications is proposed. The unbroken metal rim is designed as a part of the loop antenna radiation structure, which is also composed of a system ground, a coupled-fed U-shaped microstrip line, and an L-shaped microstrip line. The feeding and L-shaped microstrip lines are located on an ungrounded area of 72 × 8 mm
²
along the top short edge of the system ground plane on an FR4 substrate. The operating band of the antenna is widened by the matching circuit elements on the feeding line. Combining multiple resonant modes generated by the coupling loop, the proposed antenna can operate on two wide operating bands of 824-960 and 1710-2690 MHz. The detailed working principles of the proposed antenna are described. Good antenna radiation characteristics are obtained. Both experimental and simulation results are presented and discussed.