ABSTRACTA terahertz substrateless transmitarray antenna using four layers of slot type elements is presented. Because the element contains no dielectric substrate, reflection loss on the surface of dielectric and transmission loss in the dielectric could be effectively avoided at terahertz band. A terahertz transmitarray antenna working at 340 GHz is designed and fabricated by photolithography technique and electroplating processes. DRIE process and wet anisotropic etching technique were used to remove the substrate. The measured directivity of the antenna prototype is 34.9 dB, and half power beam width (HPBW) of E‐plane and H‐plane are 3.3° and 3.4°, respectively. The measured sidelobe level is below −22 dB. The measured results show that good radiation characteristics are achieved by the proposed design and microfabrication processes. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2096–2100, 2016