CONCLUSION
A compact dual-port microstrip line fed MPA array with Koch curve fractals for portable UWB-MIMO systems is proposed in this article. The proposed fractal array occupies an overall area of 1433.5 mm2 (30.5 mm × 47 mm). The upper substrate layer consists of two semi-circular patches joined with Koch curve fractals (optimized up to 2nd order of iteration) and the lower substrate layer consists of a reduced ground plane with slots and a funnel-shaped decoupling structure. The radiating elements in the array are kept at a distance of λ/2 to mitigate the effect of mutual coupling between the ports. The simulated results show a wide frequency band of 4.395-10.184 GHz with a fractional bandwidth of 79.4 % (at a center frequency of 5.789 GHz), the peak radiation efficiency of 88.8 % (at 6.2 GHz frequency) and a high isolation level (S21/S12 ≤ -16.8 dB). The measured S-parameter results cover the frequency band from 4.6-10.45 GHz (port-1, S11) and 4.55-10.32 GHz (port-2, S22) with fractional bandwidths of 77.7% GHz and 77.6 % respectively and S21/S12 ≤ -19.3 dB. The proposed fractal array exhibits low ECC (≤ 0.0021 (simulated), ≤ 0.0023 (measured)), high DG (≥ 9.989 (simulated), ≥ 9.988 (measured)), high MEG (≥ -3.7 dB (simulated) and ≥ -3.85 dB (measured)), low CCL (≤ 0.4 bits/s/Hz (simulated, measured)) and acceptable TARC (-10 dB (simulated), -8.9 dB (measured)) values which makes it an appropriate choice for portable and high data rate UWB communication systems.