# A Conceptual Design of Deployable Antenna Mechanisms
## 4 Conclusions and Future Work  
This work presents the conceptual design of large-scale deployable antenna mechanism with a conical frustum shape. The proposed mechanism consists of three planar drive mechanisms: a 6-bar linkage, a single pantograph, and a V-folding mechanism, which represents a single bay. The 6-bar linkage demonstrates that the mechanical functionality can be served as actuators, exhibiting unidirectional motion. In this view, it is worth noting that our deployable mechanism has the potential to ensure a lightweight structure. In particular, the deployable antenna exhibits the desired kinematic trajectories due to the single pantograph mechanism, which couples the other two mechanisms (i.e., 6-bar linkage and V-folding mechanisms). Therefore, given that the presence of the single pantograph mechanism can reduce the redundancy of movement constraints through gears or rails, which are commonly used to enhance deployment accuracy, the lightweight structure can be achieved. The V-folding mechanism exhibits kinematic trajectories in response to the motion of specific links in the 6-bar linkage used as the longeron. Additionally, a shock-corded pole mechanism is employed to the V-folding mechanism, minimizing the number of joints.  
The presented deployable antenna mechanism is hierarchically composed of 12 bays, which shows mechanical behaviors similar to the conventional double pantograph mechanism. Among the mechanisms, the kinematic characteristics of the 6-bar linkage ultimately determine the variation in areas at the top and bottom, resulting a conical frustum morphology. As a result of this simulation study, it is identified that better mechanical performance, in terms of mass and structural stability, can be achieved, compared to conventional double pantograph mechanisms. Conclusively, it is noted that the presented mechanism achieved both a lightweight design and stiffness through the kinematic constraints of the 6 bar linkage. We envision that the design principles introduced in this work can be further extended to large-scale deployable antenna structures. In this view, future work remains focused on the development of deployable antenna structures, including materials and fabrications, and experimental validation upon space environments.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/aerospace1110938/s1](https://www.mdpi.com/article/10.3390/aerospace1110938/s1)]([https://www.mdpi.com/article/10.3390/aerospace1110938/s1](https://www.mdpi.com/article/10.3390/aerospace1110938/s1)), Video S1: Proof-of-concept of deployable antenna mechanism incorporating six bar, single pantograph, and v-folding mechanisms.  
Conceptualization, H.K., B.H., S.K., H.L., K.K. and B.K.; methodology, H.K., B.H., S.K., S.J. and B.K.; software, H.K., S.K. and S.J.; validation, H.K., B.H. and S.J.; investigation, H.K., B.H., S.K. and S.J.; data curation, H.K., B.H., S.K. and S.J.; writing--original draft preparation, H.K., B.H., S.K. and S.J.; writing--review and editing, S.J. and B.K.; visualization, H.K., S.K. and S.J.; supervision, S.J. and B.K.; project administration, B.K.; funding acquisition, S.J. and B.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported by a grant-in-aid of HANWHA SYSTEMS, and by the Korea Research Institute for defense Technology planning and advancement and the Defense Acquisition Program Administration in 2021 (20-207-B00-011-001).  
Figure 5: Comparative analysis—Double pantograph (blue color bar) versus presented mechanism (pink color bar). The bar graphs show mechanical performances in terms of (**a**) height-to-radius ratio, (**b**) area-to-mass ratio, and (**c**) mass, respectively.