Triple-polarization mechanically-reconfigurable printed dipole antenna with integrated balun for X-Band LP/RHCP/LHCP...

This paper introduces a compact printed dipole antenna capable of mechanically switching among linear (LP), right-hand circular (RHCP), and left-hand circular (LHCP) polarizations in the X-band. The antenna incorporates a stepped-arm dipole and a passive 3-D modular converter to allow manual sense selection without bias networks. Its ultra-compact size measures 32×27×10.016 mm3 (0.90λ₀ × 0.76λ₀ × 0.28λ₀ at 8.5 GHz) and features a quasi-fractal stepped-arm dipole that achieves a wide Impedance Bandwidth (IBW) of 41.25% (7.87-11.96 GHz). A key innovation is the modular 3-D polarization converter, which facilitates on-demand polarization switching without structural modifications to the dipole. Two mirror-symmetric configurations of L-shaped parasitic elements produce orthogonal phase shifts, allowing conversion between LP and RHCP or LHCP. Measured results reveal Axial-Ratio Bandwidths (ARBWs) of 14.86% (9.53-11.06 GHz) for RHCP and 14.15% (9.59-11.05 GHz) for LHCP, with peak gains of 7.57 dBic (RHCP) and 7.60 dBic (LHCP). The antenna demonstrates over 15 dB of co-to-cross-polarization isolation and stable unidirectional radiation patterns. Compared to previous designs, this approach effectively combines wideband performance, mechanical simplicity, and the capability for field-reconfigurable (manual) switching between LP, RHCP, and LHCP, which are essential features for satellite communication (IoT uplinks and downlinks) and polarization-agile radar systems.