# A Conceptual Design of Deployable Antenna Mechanisms  
[PERSON]  
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[PERSON]  
In general, such mechanisms can exhibit high deployment ratio; specifically, they achieved a deployment ratio of 10 compared to the aperture at the stowed phase, which is suitable for accommodating large-scale reflectors ranging from 4 m to 50 m. Due to these factors, it is possible to recognize a wide spectrum of frequencies, up to the Ka-band (26.5 to 40 GHz). The Astromesh represents a deployable mechanism utilizing ring-truss structures, which ensures structural stability by incorporating both hierarchical unit frames at the top and bottom and battems to engage the unit frames [16]. Moreover, it is worth noting that the linkages along the diagonal direction play a vital role in ensuring high structural rigidity, which has been widely addressed in truss structures [17; 18]. Despite such promising mechanical characteristics, the structural stability and rigidity of the Astromesh can be ensured in a quasi-static state, which corresponds to the neglect of dynamic conditions. Namely, the Astromesh could suffer from unstable dynamic characteristics, because each unit frame operates independently. To address this, a particular mechanism enabling each unit frame to deploy with identical displacement has been addressed. In [19], [PERSON] et al. achieved a synchronized deployment of each frame unit by employing, for example, gears, cables, and precision joints. Nonetheless, these mechanical components induce the overall weight increase, resulting in constraints, e.g., making them unsuitable for stowing in the payload. In particular, it must be noted that the presence of the mechanical components introduced leads to poor rigidity upon vibration, given the launch environment [20]. Moreover, the presence of the longer linkage (along the horizonal direction), which defines the aperture diameter of the overall mechanism, determines the configurations upon stowage and deployment, based on the rotation angle of the longeron linkage. As a result, the height of the stowed mechanism increases, making it challenging to accommodate within the payload of the launching vehicle. On the other hand, as the height of the longeron decreases, the deployment ratio reduces. Meanwhile, [PERSON] et al. presented a deployable mechanism in the form of the ring-truss structure, employing a double-shifted pantograph mechanism [21]. This mechanism allows for the height of the reflector structure to be reduced by half while achieving the same deployment ratio as conventional systems, and it ensures stable dynamic characteristics by deploying the unit components with identical displacements. However, challenges remain in achieving lightweight design due to the necessity of additional power sources for deployment. In a nutshell, the development of large-scale deployable antennas using pantograph mechanisms should break through the following challenges: (1) the necessity of additional constraints and auxiliary power sources to ensure stable operation, which makes it difficult to reduce the overall weight; (2) the structural vulnerability of the ring-shaped structure, which becomes more pronounced as the deployment ratio increases. With these findings in mind, this work presents a conceptual design of conical frustum-shaped deployable antenna mechanisms that ensure that the synchronized displacements at each node are lightweight and suitable for the payload or the launch vehicle at the stowage stage. The presented deployable antenna is hierarchically composed of twelve bays, each bay containing three mechanisms: a V-folding mechanism, a six-bar linkage mechanism, and a single pantograph mechanism. The folding mechanism is designed to ensure the rigidity of the node where the mesh antenna is installed, which has a lightweight structure with minimal components. Upon full deployment, the V-folding mechanism creates a ring structure that provides rigidity against loads along the horizontal and radial directions.