[en] A compact, prebunched Free Electron Laser is being developed at Inter University Accelerator Centre (IUAC), New Delhi. A train of electron microbunches will be produced from the photocathode placed inside the RF cavity with the help of a fibre laser system capable of producing multi micro-pulse laser beam with variable separation. Consequently, the electron microbunches will also have variable temporal separation which will be made equal to the wavelength of the radiation to be produced by the electron beam. The train of electron microbunches will be injected in to a compact undulator magnet to produce THz radiation in the range of ∼ 0.18 to 3 THz. The study of emission of THz radiation from the micro bunched beam passing through the undulator magnet has been reported in this paper. (author)