The present disclosure describes the design and fabrication of a Terahertz (THz) beam steering device and a multifunctional patternless flat lens using electro-optic tunable fishnet materials (TFMM) to create a portable THz imaging system. The THz beam steering device and multifunctional patternless flat lens utilize a tunable resonant frequency of TFMM (with a negative refraction index) to achieve a maximum beam steering angle (field of view) and beam modulation. The portable THz scanning system is made by combining the TFMM beam steering device with a pair of continuous wave (CW) photomixer modules powered by two tunable CW lasers with built-in optical isolators, a fiber-optic beam combination and a multifunctional flat lens.