Beam shaping for magnetoelectric transverse electromagnetic horn by using gradient refractive index lens

This paper presents a new type of flat gradient index lens used for the beam shaping of a miniaturized magnetoelectric transverse electromagnetic (ME-TEM) horn antenna. Novel metamaterial unit cells with variable sizes are proposed to achieve high refractive index distribution. After applying the novel meta-lens to the modified transverse electromagnetic horn, the inherent E-plane beam squint of the low-profile ME-TEM horn is corrected. The radiation patterns in E-plane and H-plane are focused and the peak gain at 4 GHz is improved to 17.3 dBi. The -10 $-10$ dB matching bandwidth of 0.4-4 GHz is achieved while the measured S11 ${S}_{11}$ is a little poor at 0.8 GHz. The length of the total antenna is still shorter than half of the largest wavelength. The application potential of the gradient index meta-lens in the low-frequency band is verified.