Abstract: The deployment smoothness is the key to the smooth deployment of space deployable antennas.The fold/deployment ratio of the antenna is a vital reference factor for the spatial configuration of launch vehicles.To reduce the vibration and shock during the deployment process，improve the deployment smoothness，and reduce the fold/ deployment ratio，the common configurations of deployable antenna truss mechanism were combed.A kind of scissors telescopic vertical rod hoop truss mechanism was proposed，and the basic unit and deployable method were introduced in detail.A detailed analysis of the fold/ deployment ratio shows that the height-to-diameter ratio of the mechanism was reduced by about 35% compared with the Astromesh antenna truss mechanism under the same caliber and deployment height.Through kinematics and dynamics modeling，the deployment smoothness of the mechanism was analyzed.The results indicate that under the same driving force，the root mean square value of the acceleration at each node is about 30% of the Astromesh antenna truss mechanism，with better deployment smoothness.A scaled model was developed.The experimental analysis and parameter test were carried out，demonstrating rationality of the designed mechanism and accuracy of the calculation results.

Key words: hoop truss, scissors mechanism, dynamics analysis, smoothness, deployable structures