Microwave antennas play a crucial role in satellite communication and radar systems, while millimeter-wave antennas are indispensable for advancing high-speed telecommunications and radar technologies, especially with the emergence of 5G networks. This research focuses on the development and evaluation of two distinct Multiple Input Multiple Output (MIMO) antennas tailored for Ultra-Wideband (UWB) and millimeter-wave network applications using High Frequency Solution Setup (HFSS) software. The Hexagonal MIMO antenna, measuring 40 x 36 x 1.6 mm³, and the Dual Band Notched MIMO antenna, measuring 35 x 23 x 1.6 mm³, both utilize double-port MIMO technology and operate at frequencies of 7.5 GHz and 30 GHz. Performance parameters including Gain, Directivity, Radiation Efficiency, Return loss, Reflection Coefficient, and Beam Area are examined, with a comparative analysis conducted at both frequencies. The findings reveal the consistent superiority of the Dual Band Notched MIMO antenna, exhibiting higher gain and directivity across both frequencies. Specifically, at 7.5 GHz, gains of 24.97 dB and 33.17 dB, directivities of 6.05 dB and 5.10 dB, radiation efficiencies of 18.9 dB and 28.07 dB, beam areas of 4.94 sq. deg and 5.89 sq. deg, reflection coefficients below -12 dB, and return loss values exceeding 12 dB are observed for the Hexagonal and Dual Band antennas, respectively, while at 30 GHz, gains are 32.49 dB and 24.92 dB, directivities are 6.79 dB and 7.9 dB, radiation efficiencies are 16.41 dB and 24.57 dB, beam areas are 4.20 sq. deg and 3.07 sq. deg, and reflection coefficients and return loss values show similar trends for Dual Band and Hexagonal antennas, respectively. This study provides valuable insights for optimizing MIMO antenna designs to enhance performance in UWB and millimeter-wave network applications.