Double-Spiral Linearly Polarized RLSA

High gain linearly polarized radial line slot arrays (LP-RLSA) suffer from remarkable degradation of the return loss. To overcome this drawback, this communication presents a novel LP-RLSA design obtained by the superposition of two spirally arranged circularly polarized RLSAs. Indeed, it benefits from the intrinsically low reflection coefficient proper of these circularly polarized spirally arrayed RLSAs. Furthermore, the new layout shows high polarization purity, still maintaining the intrinsic manufacturing simplicity of a RLSA antenna. An antenna prototype has been manufactured and measured to validate the design idea.