A Multi-Mode Horn Antenna with Increased Gain and Reduced Cross-Polarization

This work proposes a multi-mode horn antenna with the achievement of enhanced gain and low cross-polarization. Firstly, the traditional rectangular waveguide feeding of the horn antenna is transformed into the stepped structure, aiming to improve the reflection coefficient and broaden its impedance bandwidth. Besides, a variable flare angle scheme is introduced on the horn so as to achieve the uniform distribution for the electric field at the aperture by introducing appropriate higher order modes. As such, the cross-polarization of the antenna is decreased with the gain increased of 1dB over the same aperture area. Ultimately, the achievable peak gains at E-plane and H-plane of this multi-mode horn antenna are about 21.1 dB, and the cross-polarization at both the E-plane and H-plane is kept below -30 dB.