Polyurethane membranes for flexible centimeter-wave patch antennas

In this paper, we present the original use of a recyclable and low cost soft polymer, polyurethane (PU) (ε_r ≈ 3.5 at 10 GHz), as part of a dielectric substrate of a microstrip patch antenna. The combination of simple membrane manufacturing process and the low Young's modulus of PU (E_PU ≈ 30 MPa) are employed in an X-band antenna application in this study. The PU dielectric characterizations indicate the high loss tangent value (tan δ ≈ 0.1 at 10 GHz). Membrane supported technology is used to reduce the influence of this high loss and increase the antenna efficiency. The measurement of antenna performances such as efficiency (η ≈ 31.7%) confirms the viability of the technological process and the specific patch antenna design developed in this work. Besides, the potential of the PU-based soft patch antenna for frequency agility (3.88%) via mechanical reconfiguration is also shown. (paper)