Slot-ring multiport driven antenna with improved airside radiation for terahertz communications

A slot-ring multiport driven (MPD) antenna is evaluated for operation in the terahertz band with emphasis on air-side radiation on a thick Indium Phosphide (InP) substrate. Geometrical modification to the known slot-ring are made by employing a circular outer ground and a backing ground plane to focus the radiation in the airside direction. Optimization of the modified structure is made to find the optimal size of the upper ground plane. The optimal design achieves maximum directivity of 10.8 dB which is an improvement of 3 dB from the original design. Moreover, the radiation is directed in the airside direction with a front-to-back lobe ratio of 14 dB. The slot-ring antenna design is verified by fabrication at 5 GHz and achieves 10.2 dB directivity.