A Flexible Thin-Film Conformal Antenna with Orientation-Dependent Polarization Characteristics

A lightweight flexible thin-film conformal antenna with orientation-dependent polarization characteristics is proposed for future spaceborne communication applications. The antenna is implemented on an ultrathin flexible substrate with a single-layer printed radiator, providing a low-profile, lightweight, and structurally simple architecture suitable for conformal integration with cylindrical platforms. Unlike conventional flexible circularly polarized (CP) antennas that mainly focus on preserving radiation performance under mechanical deformation, the proposed design exploits the bending orientation as an additional electromagnetic design degree of freedom. By bending the same planar flexible antenna along two orthogonal directions, two distinct conformal antenna forms are obtained, exhibiting left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP), respectively, without modifying the feeding structure or introducing active switching components. The measured 10-dB impedance bandwidths of the LHCP and RHCP antennas are 66.67% (1.5–3.0 GHz) and 72.34% (1.5–3.2 GHz), respectively. Within the investigated frequency range, the axial ratio of the LHCP antenna remains below 3 dB from 2.0 to 3.5 GHz, whereas that of the RHCP antenna remains below 3 dB from 2.2 to 3.5 GHz. The corresponding peak gains are 7.12 dBic and 8.74 dBic, respectively. Furthermore, the antenna concept is extended to two-element arrays, enabling LHCP, RHCP, and linear polarization (LP) radiation characteristics through different element arrangements, with a maximum peak gain of 9.7 dBic. The proposed antenna combines lightweight construction, structural simplicity, conformal adaptability, and polarization diversity, showing potential for compact and multifunctional antenna systems on space platforms.