Compact loaded slot ring antenna for circularly polarised radiation

A novel slot-ring circularly polarised antenna is reported. With sectorial slots loading, the axial ratio (AR) bandwidth is increased and the circumference of the slot-ring is also reduced to 0.5 lambda₀ (lambda₀ is the free-space wavelength at the centre frequency). The antenna features a 22.4% impedance bandwidth for |S ₁₁| les -10 dB, a 10.6% bandwidth for AR les 3 dB and stable radiation patterns over the whole operating band.