A Radial Line Array With Cylindrical-Hole Probe- Fed Helical Elements for Enhancing Aperture Efficiency and Power-Handling Capacity

This letter presents a 60-element single-layer rectangular radial line helical array (RLHA). A new probe is designed to achieve single-layer RLHAs with a higher number of elements, with advantages of low coupling coefficient, simple structure, and easy fabrication. Moreover, the new probe has low reflection coefficient and high power capacity, making it well suited for application in high-power RLHAs. Compared with the typical single-layer rectangular RLHAs with limited element count, the proposed RLHA has demonstrated lower loss and higher aperture efficiency for array application. To address this, a 240-element array prototype combined by four 60-element single-layer rectangular RLHAs is designed and a series of experiment are conducted. The results indicate that at the center frequency of 5.8 GHz, the uniform aperture distribution is achieved with an axial gain of 29.54 dBic for the 240-element array, the input VSWR is less than 1.2 and the aperture efficiency is 73.2%. Under vacuum conditions, the simulated power-handling capacity of the 240-element array is above 1.6 GW.