High-isolated, low correlation and wide frequency reconfigurable (2.1-4.2 GHz) MIMO antenna for cognitive radio applications

This paper proposes a unique and small (2508 mm(2)) penta-band frequency agile MIMO antenna based on RF switches for cognitive radio mobile, WLAN, WiMAX, and wireless sensing applications. Three RF switches generate five resonant bands at 2.1, 3, 3.5, 4, and 4.2 GHz in four usable states-100, 011, 111, 100, and 000, respectively. The proposed antenna's fractional bandwidth was 4.95 % (simulated) and 5.5 % (measured) in state-000, 3.09 % (simulated) and 2.8 % (measured) at a lower frequency (2.1 GHz), 2.12 % (simulated) and 2 % (measured) at higher frequency (4.2 GHz) in state-100, 12.5 % (simulated) and 12 % (measured) in state-011, and 4.6 % (simulated) and 4.7 % (measured) in state-111. A large peak gain of 3.6 dB at 4 GHz, maximum isolation of 32.2 dB at 3.5 GHz, significant radiation efficiency of 93.7% at 4GHz is obtained. At 4 GHz, a strong peak gain of 3.6 dB, maximum isolation of 32.2 dB at 3.5 GHz, and considerable radiation efficiency of 93.7 % are realised. For this work, MIMO parameters such as ECC (approx. 0), DG (approx.10dB), TARC (<0.5), MEG (-12 dB < MEG (dB) < -3 dB) and CCL (< 0.5 bit/s/Hz) were achieved. The suggested antenna was simulated, constructed, and tested, and the simulated results were found to be very close to the experimental findings.