▎ 摘　　要

Based on the cylindrical graphene waveguide, the concept and analysis of a leaky wave antenna (LWA) at terahertz band are presented. The proposed structure overcomes the limitations of planar LWA characteristics, such as radiation efficiency and beam width. The values of attenuation and leakage constants can lead to the maximum radiation efficiency and beam width in the planar LWA equal to about 20% and 57 degrees, but in cylindrical LWA equal to about 50% and 12 degrees, respectively. The leaky wave is excited by a sinusoidally modulated graphene surface. A sinusoidally modulated reactance surface (SMRS) allows for a nearly independent control of the phase and leakage constants and thus adjusts the scan angle and radiation efficiency simultaneously. An SMRS was first realized by applying various bias voltages to different gating pads underneath the graphene sheet. Another desirable feature of an antenna is the high value of input impedance, so it can easily be matched to a photomixer. (C) 2019 Optical Society of America