The use of the millimeter-wave and terahertz (THz) systems are becoming very important in various scientific and military applications. In many applications i.e. radio-astronomy, THz imaging, remote sensing, secure communication links, THz radars, plasma diagnostics etc. the use millimeter-wave and THz technologies are increasing rapidly and in these applications, integreted lens antennas are porividing attractive solutions. But perfect modeling  and simulation of the lens antenna and beam pattern calculation is still a challenge for the antenna engineers.

            In this thesis project thorough investigation has been done to optimize the simulation technique in the EM simulator CST MWS to get reliable and accurate simulation results which may replace the time consuming, complex and expensive measurements in sub-millimeter/THz frequency range. Different experiments are done by retriving from the publications related to this project for the result comparison.

            Later on with this optimized simulation process an extended hemispherical lens antenna integrated with log-spiral feed is designed for THz frequency range. Most of the desired goals are achieved during the design process as the design goal is to produce a constant radiation beam and polarization over the a broad bandwidth (500GHz-750GHz)