In this paper, aperture coupled microstrip patch antenna based on polyimide substrate is presented operating at 28GHz. The proposed antenna have multi-layered structure and this structure is realized by folding a single polyimide substrate. As a result of measurement, the proposed antenna is resonant at 27.8GHz, which is close to desired resonant frequency and shows good impedance matching with S_11 of -42.47dB. It is expected that the proposed antenna can be used widely because it can simplify fabrication and reduce fabrication cost making a single flexible dielectric a multilayer structure.