Present study investigates the resonantly driven electromagnetic field in THz regime using the beat wave excitation of two co-propagating laser pulses in non-uniform warm collisional plasmas. An external electric field is also applied in wiggler form that acts as additional tuning parameter for resonance condition. Required wave number for plasma density ripple and electric field wiggler are estimated at resonance condition. THz field is estimated with respect to collisional frequency (nu)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\nu )$$\end{document} for different plasma temperature Te(1KeV-10KeV)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{e} (1 KeV-10 KeV)$$\end{document}. Peak THz field shifts towards the lower collisional frequency as temperature increases. Conversion efficiency for present THz emission mechanism is estimated as 2% for density modulation (nq/n0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$({n}_{q}/{n}_{0})$$\end{document} of 40%.