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The design of Massive MIMO Antennas presents challenges due to their large size, which can impede the design process. Additionally, the arrangement of multiple antenna elements in Massive MIMO Antennas poses a challenge, as it surpasses the capabilities of simulation software and involves complex procedures. Therefore, to address these issues, a scalability technique utilizing array factor theory is employed to determine the relationship between the configuration of MIMO antennas and the corresponding values of gain and half-power beamwidth (HPBW). By utilizing a simpler MIMO Antenna array with incremental configurations, such as 2x2, 4x4, 8x8, and 16x16 MIMO element schemes, the array factor theory allows for the prediction of the gain and HPBW values for a Massive MIMO Antenna array with a specific configuration. This research aims to explore the scalability process and derive equations that relate the gain and HPBW values to the different MIMO configurations. The designed MIMO antenna arrangement is based on rectangular antennas with truncated corners and circular antennas with X slots, allowing for the investigation of various configurations operating at a frequency of 3.5 GHz.

This study presented the development of the bowtie antenna system design as the transmitter in the Ground Penetrating Radar (GPR) system. The Artificial Magnetic Conductor (AMC) reflector was integrated into the antenna system as a ground plane to obtain a high gain, increase bandwidth and produce a low-profile antenna. The antenna is designed to work at a center frequency of 2.1 GHz with a range of 1.6 - 2.6 GHz and has ultrawideband (UWB) characteristics with a fractional bandwidth of ≥ 25%. In addition, the value of late-time ringing must also be reduced to -30 dB to prevent masking effects on the detected object. Antenna modeling and simulation was done to obtain the optimum prototype design. Bowtie antenna realization was carried out using RT Duroid 5880 as a substrate with dielectric constant (εr) = 2.2 and thickness (h) = 1.57 mm. The AMC reflector was fabricated with FR-4 Epoxy substrate with a dielectric constant (εr) = 4.4 and thickness (h) = 1.6 mm. The antenna realization results show that the antenna has bandwidth = 510 MHz, return loss = -15.17 dB and VSWR = 1.15. The AMC integrated bowtie antenna radiation pattern produces a unidirectional pattern with gain = 4.2 dB. However, the ringing level becomes high by -19.18 dB. Further development is needed to achieve ringing level values that meet the GPR antenna system specifications.