Triple-Band Quad-Element Polarization/Pattern Diversity Directional MIMO Antenna for Sub-6 GHz Application

This paper presents a sequentially rotated quad-element, triple-band MIMO antenna, operating in the sub 6 GHz frequency band. The individual antenna elements have three resonant frequencies at 3.74, 4.87, and 5.87 GHz, with a frequency separation ratio of 1: 1.3: 1.56. The three frequency bands are achieved using an inverted F shaped structure connected to a rectangular microstrip patch, with a slot along the width of the patch. The antenna elements have an edge-to-edge gap of 1.9 mm. The achieved isolation between the antenna elements is more than 20 dB and 15 dB respectively at adjacent and diagonal element over all the three frequency bands. The proposed quad-element antenna provides a gain of 6.73, 6.06, and 5.83 dBi and efficiency of 84.6%, 80%, and 88% at 3.74, 4.87, and 5.87 GHz, respectively. The ECC, TARC and CCL values are less than 0.05, −10 dB, and 0.5 bits/s/Hz respectively over all three bands.