In this article, different design configurations of rectangular microstrip patch antenna (RMSA) array operating at S-band frequency are presented. The substrate material utilized in the designs is Rogers-RT-5800 with dielectric permittivity (Ԑr= 2.2), thickness of (h=1.6 mm), and loss tangent of (δ = 0.009). The performances of a single element, (1×2), (2×2) and (1×4) array elements operating at (3.6 GHz) are investigated using the CST and HFSS numerical techniques. The simulation results indicates that the antenna gain of (8.68, 10.35, 10.43 and 10.52) dB, VSWR (1.045, 1.325, 1.095 and 1.945), return loss (-34.91, -17.15, -27.42 and -12.26) dB, and bandwidth (85.00, 200.00, 215 and 106.4) MHz are achieved with the implementation of HFSS for advanced single element, (1×2), (2×2) and (1×4) array elements, respectively. Besides, the corresponding antenna parameter values provided by CST are, gain (7.36, 9.8, 9.87 and 10.30) dB, VSWR (1.011, 1.304, 1.305 and 1.579), return loss (-44.97, -17.58, -17.55 and -14.01) dB, and bandwidth (92.28, 204, 229.49 and 129.12) MHz, respectively. The results also reveals that the higher gain and wider bandwidth are, respectively, achieved with (1×4) and (2×2) array configuration arrangement and with both simulation techniques. Additionally, a good agreement and an advancement between the obtained results with the ones previously studied for the same array types operating at S-band frequencies are also observed.
