A Two-arm Slot Sinuous Antenna with Improved Polarization Stability

Sinuous antennas are among the most interesting ultra wide band antennas due to they excellent input impedance behavior over extremely large bandwidth. In two-arms configuration, either dipole or slot, they present a linearly polarized field, as opposed to the circularly polarized field of logarithmic spiral antennas. Yet polarization stability of sinuous antenna is at an issue as the polarization plane oscillates in frequency. In this contribution an improved geometry for the sinuous antenna is proposed, aimed at enhancing polarization stability.