High-Power Radial-Line Helical Subarray for High-Frequency Applications

A 28-element radial-line helical subarray at Ku-band is designed. In order to realize high power capacity at high frequency, we present a new form of helical antenna, especially, for array applications, it has high power capacity and little mutual coupling. On the other hand, since there is inhomogeneous energy distribution inside the radial-line, an improved probe is used to help control the feed coupling, this probe has the advantages of simple structure, high coupling coefficient, and easy fabrication, which are suitable for high-frequency applications. The designs of the components are discussed in detail and the power capacity of the subarray is obtained by simulation. Compared with the typical radial-line helical arrays, the proposed subarray has not only higher power capacity but also fewer elements. Experimentally, the low-power results of an array prototype combined by four subarrays indicate that high gain as well as circular polarization has been successfully verified. From the high-power test, the array is powered by tens of megawatts of pulsed power that extracted from a transit-time oscillator. As expected, the power handling capacity of the combined array is found to be 75 MW in SF6 gas condition.