Extremely compact dual-band PIFAs for MIMO application

A MIMO structure consisting of two extremely compact planar inverted-F antennas (PIFAs) (lambda/60 times lambda/20 times lambda/60) is proposed for GSM 900 MHz and 2.4 GHz wireless local area network applications. The miniaturisation of each antenna is achieved through a spiral-shaped PIFA and a capacitive load, forming a LC resonator. Both antennas have a good impedance bandwidth of 0.88 - 0.945 and 2.39 - 2.48 GHz for 0.9 and 2.4 GHz band, respectively. The two PIFA antennas are polarised orthogonally to each other, and isolation better than -28 dB is achieved in both bands without any structure etched on the ground. The predicted results are compared with the measured data and good agreement is found.