Simple monopole slot antenna for WWAN/LTE handset application

Promising techniques of using a band-stop matching circuit and a low-profile C-strip for bandwidth enhancement of a simple monopole slot handset antenna for the WWAN/LTE operation are demonstrated. The simple monopole slot has a small size of 4 × 50 mm² (200 mm²) and is embedded close to the bottom edge of the system ground plane of the handset. The band-stop circuit causes a parallel resonance at the high-frequency tail of the quarter-wavelength slot mode and generates an additional resonance nearby, thus resulting in a dual-resonance excitation of the quarter-wavelength slot mode. The C-strip having a low profile of 6 mm is disposed at the bottom edge of the system ground plane and can aid in generating the chassis (system ground plane) mode for further widening the bandwidth of the dual-resonant quarter-wavelength slot mode to achieve a wide lower band for the antenna. In addition, the C-strip provides a loop path which supports a loop resonant mode to combine with a higher-order resonant mode of the monopole slot to achieve a wide upper band. The antenna can hence cover the WWAN/LTE operation in the 704~960 and 1710~2690 MHz bands.