A Frequency-Reconfigurable Tuner-Loaded Coupled-Fed Frame-Antenna for All-Metal-Shell Handsets

A frequency-reconfigurable frame-antenna integrated with a coupling strip and tuner loading is proposed for all-metal-shell mobile telephones. The coupling strip introduces additional capacitance to the feeding structure of the antenna, rendering the antenna to resonate at both the lower frequency band at “a quarter-wavelength resonant mode”and the higher frequency band at “a half-wavelength resonant mode”. Moreover, the antenna loaded with a tuner achieves broadband frequency-reconfiguration by tuning the effective length of radiating frame. The antenna is designed by taking into consideration all the metallic components, like front-and-back cameras, telephone receiver, and a steel sheet. The metal-frame and metal-shell of the handset coupled with a strip are used as parts of the antenna. This paper of a prototype operating in a practical handset test environment shows that the proposed antenna is able to cover the bandwidth of 824-960 MHz (GSM) and 1710-2690 MHz (DCS/PCS/UMTS/LTE) with acceptable radiation efficiency up to 40% and desirable patterns and specific absorption ratio, which is much lower than 1.6 W/kg for mobile communications.