Wideband subterahertz antenna based on the symmetrical path-length lens for sidelobe level reduction

This letter presents a high-gain fully metallic antenna designed with a symmetrical path-length lens for subterahertz applications over a wide frequency range. The symmetrical path-length lens divides the E-plane horn into two symmetrical halves, which can compensate for the phase difference generated by the E-plane horn individually. Compared to the conventional asymmetrical path-length lens, the numerical results show the sidelobe level (SLL) can be reduced from -11 to -15.7 dB with the symmetrical path-length lens. Measured results show the proposed antenna exhibits a reflection coefficient of less than -10 dB from 110 to 170 GHz. In addition, the measured SLL is about -15 dB at 140 GHz. The measured results indicate that the symmetrical path-length metallic lens is an effective way to improve the poor lobe suppression resulting from an asymmetrical path-length lens.