Simple tunable inverted-F antenna for LTE/WWAN mobile handset applications

A simple reconfigurable inverted-F antenna of the mobile handset for multi-band LTE/WWAN operation is presented. The antenna area is 7 × 70 mm
²
, while the protruded ground has an area of 7 × 10 mm
²
for mounting USB connector. The proposed antenna is consisted of a longer strip, a shorter strip, a feeding strip, a shorting strip, a capacitive shorting strip, and a tuning strip. The longer strip can generate a 0.25-wavelength IFA resonant mode to form the antenna's lower band and a higher order resonant mode to form the antenna's upper band to cover the LTE2500 band. The shorter strip can also excite a 0.25-wavelength IFA resonant mode to form the antenna's middle band to cover the GSM1800/1900/WCDMA Band1 bands. Moreover, when the tuning capacitor loaded to the tuning strip has been adjusted with various capacitances, the antenna's lower and upper bands can be shifted to lower frequency and cover the LTE700/GSM850/900/LTE2300 bands. This tunable technique can allow the proposed IFA to cover more operating bands without adding the antenna size.