A Quad-Band Internal Antenna Having Independent Controllability of Low/High Resonant Frequencies

A compact quad-band internal antenna for 3G mobile phone is presented. A novel technique which can control low/high resonant frequencies of the multi-band antenna independently is employed for easy optimization of the antenna characteristics over all frequency bands. The designed single plate antenna consists of a planar antenna with U-shaped slot for high band and a vertically attached spiral monopole antenna for low band and its size is 38.0 times 9.0 times 6.0 mm
³
(2.052 cc). The measured bandwidth for S
₁₁
less than -6dB covers GSM900 (880-960 MHz), DCS1800 (1710-1880 MHz), DCS1900 (1850-1990 MHz), and UMTS (1920-2170 MHz)