SMALL-SIZE COUPLED-FED PRINTED PIFA FOR INTERNAL EIGHT-BAND LTE/GSM/UMTS MOBILE PHONE ANTENNA

摘要

A coupled-fed printed PIFA (planar inverted-F antenna) with a small footprint (about 415 mm~2) for eight-band operation covering the LTE700/2300/2500, GSM850/900/1800/1900, and UMTS bands in the mobile phone is presented. The proposed PIFA uses only a single radiating strip of length 45 mm which is short-circuited to the system ground plane of the mobile phone through a long inductive shorting strip and is capacitively excited by a long coupling strip. The capacitive excitation leads to the generation of the λ/8 resonant mode at about 850 MHz and the higher order resonant modes at about 1900 MHz for the printed PIFA. The inductive shorting strip contributes additional inductance to achieve enhanced impedance matching for the excited 850 MHz band to achieve a dual-resonant behavior, which results in a wide lower band to cover the LTE700/GSM850/900 operation. A higher order resonant mode at about 2650 MHz is also contributed by the long inductive shorting strip. This resonant mode incorporating the one at about 1900 MHz generated by using the coupling feed forms a wide upper band to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Compact integration of the proposed antenna with a nearby loudspeaker is also promising. Details of the results are presented.