In this paper, a novel MMW flexible antenna has been proposed for energy harvesting applications. Antenna consists of a triangular patch printed on a flexible PET substrate. Defected ground structures (DGS) have been introduced to generate multiple resonances in order to improve bandwidth. It has been observed that the bandwidth and radiation characteristics are considerably improved by two square splitring slots incorporated as DGS. Antenna is fabricated by inkjet printing. Measurements show that the dual band operation has been achieved with bandwidth of 15.9-19.7 GHz and 22.5-34 GHz for Band-I and Band-II respectively. Distinctive features of omnidirectional radiation pattern, significant gain profile combined with the flexibility of integration at non-uniform surfaces present this versatile antenna as a valuable contribution in emerging energy harvesting for future wireless networks at MMW spectrum.