A Large-Aperture Multi-Subarray Radial Line Helical Array Antenna With Dielectric Windows for High-Power Microwave Applications

This article presents a large-aperture multi-subarray radial line helical array antenna equipped with dielectric windows for high-power microwave (HPM) applications. The design integrates additional subarrays, enhancing both the gain and power-handling capacity compared with those of conventional radial line helical arrays. Furthermore, a novel dielectric window with high transmission, high power-handling capacity, and compact structure is proposed. This window, along with radomes, establishes a balanced pressure $\text {SF}_{{6}}$ gas environment for the subarrays, offering a practical alternative to conventional vacuum environments and improving the practicality of the array. Modular design methods are employed to improve design efficiency, reduce system complexity, and enable potential future upgrades or modifications. To validate the proposed practical design of the radial line helical array antenna, an X-band array prototype consisting of 64 subarrays centered at 9.3 GHz was designed and experimentally evaluated. The experimental results show that the array achieved a gain of 36.60 dBi, an axial ratio (AR) of 0.14 dB, and a VSWR of 1.02 at 9.3 GHz. Additionally, the VSWR consistently remained below 1.3 across the 9.2–9.4-GHz bandwidth. Moreover, high-power experiments demonstrated that the power-handling capacity of the array exceeded 2.06 GW.