Compact Quad-Element Triple-Band MIMO Antennas for WLAN/WiMAX Applications

In this paper, an extremely compact tri-band quad-element multiple-input-multiple-output (MIMO) antenna is proposed. The single element configuration of a proposed MIMO antenna consisting of a microstrip line feed, T-shaped monopole with dual inverted L-shaped slits is realized. The proposed MIMO antenna is resonating at the frequency 2.42 GHz, 5.32 GHz, and 3.51 GHz for wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The overall size of the proposed quad element MIMO antenna is $30\times 30\times 0.8\ \mathbf{mm}^{3}$ with minimum isolation of 13.5 dB among MIMO elements with respect to its operating bands. The envelope correlation coefficient (ECC) of the proposed MIMO antenna is lower than the acceptable limit across the triple operating bands. The simulated and measured S-parameters of the proposed antennas are found in good agreement.