Ground slot with capacitor for high isolation between MIMO antenna

In this paper a T-shaped ground slot with a chip capacitor to improve isolation between two closely packed planar inverted F antennas (PIFAs) is presented at the WLAN band of 2.4 GHz - 2.48 GHz for mobile phone applications. The calculated envelop correlation coefficient of the proposed antenna is less than 0.1 and the isolation between two PIFAs yields less than -20 dB over the whole WLAN band. The measured antenna gain and efficiency are about 2 dBi and 40% at 2.4 GHz, respectively. The size of the proposed slot with a chip capacitor is also reduced by 50% compared to the T-shaped slot without one.