Wideband Monopole Antenna With Less Nonground Portion For Octa-Band WWAN/LTE Mobile Phones

An octa-band WWAN/LTE monopole antenna with a size of
$80\,\text{mm} \times 8\,\text{mm} \times 5.8\,\text{mm}$
for 5.7-inch mobile phones is proposed and studied. The proposed antenna consists of a folded metal plate with a lumped-element high-pass matching circuit. The working mechanism is analyzed based on the S-parameters and the surface current distributions. The 0.25-wavelength, 0.5-wavelength, and 1-wavelength modes of the monopole antenna are excited and used. The attractive merit of the proposed antenna is that the height of the nonground portion is only 8 mm. A prototype is fabricated and measured. Its measured
$-6\;\text{dB}$
impedance bandwidths are 290 MHz (0.69–0.98 GHz) and 1.11 GHz (1.63–2.74 GHz) which cover the LTE700, GSM850, GSM900, GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands. Within the two frequency bands, good radiation performances are obtained.