A Low Profile Circularly Polarized SIW H-plane Horn Antenna with ALTSA Array

In this paper, a low-profile circularly polarized substrate integrated waveguide (SIW) H-plane horn antenna loaded with antipodal linearly tapered slot antenna (ALTSA) array is proposed. The low profile SIW horn antennas have poor impedance matching due to the strong discontinuity between horn aperture and free space. The impedance matching of the antenna is improved by loading metal patches in front of the horn aperture. In addition, ALTSA array acts as a horizontal polarization unit and combines with H-plane horn to form an endfire circularly polarized antenna. Simulation results show that the designed antenna has an impedance bandwidth of 11.4% (13.2–14.8 GHz), an axial ratio bandwidth of 8.1% (13.4–14.5 GHz) and a maximum gain of 8.7 dBi, achieving a stable left-handed circularly polarized radiation.