Terahertz Antenna for 5G Cellular Communication Systems: A Holistic Review

The next cellular communication in the 5G and beyond can be in the sub-Terahertz (sub-THz) band, i.e. (100–350) GHz, because data rate of (20-100) Gbps is needed. Following atmospheric path loss in THz frequency band, which can reach more than 100 dB/km, there is a need to operate in frequency windows below 1 THz, where the atmospheric attenuation is relatively low, and the high-gain antennas that allow the propagation of the signal beyond 100 meters, because of lack of solid-state communication sources with a power of over 10 mW, as well as wide bandwidth (BW) antennas that will enable data rates of at least 20 Gbps. In this technical review, we explain what the demands and the challenges of antennas at 5G and beyond: how to improve the gain and BW of the antennas simultaneously, what is the minimum gain and BW of the antennas. According to the studies carried out in this field, the most preferable way is the planar microstrip antenna in future cellular communication systems in the sub-THz band, which have the advantages of small size, light weight, etc. According to the research that we have done, there are still no practical implementations of prototype planar microstrip array antennas (only designs and simulations with CST Microwave Studio or Ansoft HFSS) for sub-THz to validate the simulations results with practical measurements. The gain required for such antennas is at least (15.27–20.71) dB for frequency of (100-350) GHz @ BW=4.1 GHz for data rate of 20 Gbps, at least.