Quad-Band MIMO Antenna Array for Portable Wireless Communications Terminals

A low-profile quad-band antenna array for multiple-input-multiple-output (MIMO)-enabled wireless communication terminals has been presented in this letter. The proposed dual-element antenna array operates at the following frequency bands: 2.4-2.5 GHz, 3.4-3.6 GHz, 5.15-5.35 GHz, and 5.75-5.875 GHz. A combination of a C-shaped slot and a T-shaped slit is used to excite three current modes in a conventional single-band planar inverted-F antenna (PIFA). A lambda/4 resonator is integrated into the triband antenna structure in order to get an additional resonance for quad-band operation. The proposed array has been designed over a small ground plane measuring 50times100 mm², whereas each element in the array occupies a volume of 0.63 cm³. Mean effective gain (MEG) and envelop correlation analysis have been used for the array analysis in addition to the capacity and diversity gain measurements in a reverberation chamber. The prototype array exhibits quite low mutual coupling with good input return losses at the desired four frequency bands.