Sankar, Nagineni Siva2026-10-122026-10-122022http://nits.ndl.gov.in/handle/123456789/221To compensate for the substantial propagation losses, an Intelligent Reflecting Surface (IRS) assisted with Terahertz bands is projected to feature a large number of reflecting elements. The usual far-field assumption becomes erroneous when the IRS rises in size, then the spherical waveform model of radiated waves should be considered. We look at a spherical wave channel model in an elliptical path with a single antenna transmitter (TX) and a receiver (RX) at the focal points in this work. We develop an approximate but accurate close-form equation for system throughput and normalised gain under beam focusing for this purpose. Using the golden search (GS) technique, we show the optimal distance between the BS and the IRS based on the generated model. Numerical results back up our findings and reveal new information about the Performance and designing of IRS-assisted THz communications.enThesis