Survivability of distributed VLF arrays under constrained random deployment

Abstract

This paper investigates the statistical radiation characteristics and survivability of a distributed very-low-frequency (VLF) transmitting array architecture. Traditionally, VLF stations rely on massive, centralized monolithic towers that are difficult to deploy and vulnerable to damage. We propose a distributed alternative that achieves megawatt-level effective radiated power through the coherent spatial power combining of multiple lower-power transmitting units. Each unit features a flexible antenna lofted by an aerostat, offering significant advantages in maneuverability, rapid deployment, and operational flexibility. To characterize the deployment randomness inherent in such mobile systems under stringent geographic and safety-spacing constraints, a grid-assisted random-walk model with a dynamic-jump mechanism is developed to generate feasible array topologies. Statistical analysis of the array factor reveals that for these constrained random layouts, the relative array gain follows an approximately Gaussian distribution, establishing a stable performance baseline for strategic link budgets. Furthermore, a survivability metric based on the median relative gain is introduced to quantitatively evaluate the system’s robustness against random unit outages via Monte Carlo simulations. A design-oriented case study of a 16-element lofted-antenna array, supported by 50 kW unit experimental measurements and full-wave simulations, demonstrates that the proposed distributed system maintains robust radiation capabilities even under extreme scenarios with a 50% unit failure rate. This research provides a theoretical and practical framework for the development of next-generation, resilient VLF communication infrastructures.