A lossy transmission has negative effect on the overall performance and efficiency of base station subsystems. One key feature of 5G technologies is improved efficiency compared to 4G technology. The 5G massive-MIMO base station structure may suffer from these losses, which affect the inclusive performance and efficiency of the base substation. Furthermore, in the 5G technology, loss is anticipated due to the reflection of signals from the receiver (Rx) branch connected to the circulators in the 5G MIMO base station. This reflection loss is due to the mismatched load impedance of the Rx branch with the source impedance of transmitter (Tx) branch. The main objective of this research is to use MOSFET to absorb the reflected signal resulting from impedance mismatching between the Tx and Rx. After that, two comparisons have been made between source current and drain current of the MOSFET mathematically, whenever there is a reflection from the Rx branch of the base station. In addition, the proposed circuit model has been presented by connecting the Tx branch, antenna, Rx branch, and the MOSFET to each of the ports of a four-port circulator. A reflected RF power of 13 dBm at 1.4 V peak is rectified to its equivalent DC value 1.004 V. However, these values of current and voltage are pulsating and filtered at the output end of the rectifier with the use of an LC Filter.

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In order to improve the efficiency, reliability, and accuracy during fabrication of antenna in 5G regime of frequencies, a Double-Material Substrate (DMS) Cylindrical Surrounding micro-strip fed Patch Antenna (CSPA) has been designed for use in 2.4/5.8 GHz WLAN, 2.5/5.15 GHz WiMAX wireless standards, 5.9 GHz Intelligent Transportation Society (ITS) band (5.85-5.925 GHz) and middle band of 5G technology (2.3 GHz ~ 2.4 GHz and 2.5 GHz ~ 2.69 GHz). The proposed antenna addresses the negative effect of dimension inaccuracy caused by the high permittivity substrate material used in CSPA. The antenna was designed, simulated, and thoroughly analyzed on the basis of the radiation pattern, surface current distribution, and Q factor. Findings reveal that the DMS CSPA showed a worthy radiation pattern and Q-factor of 3.62 and 2.31 at 2.68 GHz and 5.55 GHz bands, respectively. The radiation plots of simulation results present the angular width values between 450 ~ 1040, showing a wider coverage area with minimal sidelobe level between -4.4 dB ~ 11.9 dB for the E-planes and H-planes at both resonance frequencies.

A block-by-block performance analysis of a novel Metal Oxide Semiconductor Field Effect Transistor (MOSFET)-based absorber antenna has been presented. The proposed integrated antenna is a solution to the negative effect of impedance mismatch between the power amplifier and antenna in the front end of communication systems. The clockwise diode base quasi circulator device used in the proposed design has been observed to have an insertion loss (S21 and S32) of 7 dB and 9.2 dB, respectively, with a return loss (S22) of 2.8 dB. The MOSFET-based absorber presented an insertion loss, return loss, and absorption efficiency of 2.75 dB, 3.3 dB, and > 90%, respectively. The switching speed for the proposed MOSFET-based absorber antenna model has been observed as 0.15 ns.