X-band high-power-capacity low-profile continuous transverse stub antenna

Background With the development of high-power microwave (HPM) systems, antennas are required to achieve high gain and high power-handling capability while being as miniaturized and compact as possible. The continuous transverse stub (CTS) antenna, featuring high gain and high power capacity, meets the demands of HPM system development.

Purpose To address the structural complexity and lack of compactness in conventional CTS antenna feed systems, which hinder overall antenna miniaturization, this paper proposes a novel radial-line feed system. The aim is to output a quasi-TEM mode in a planar waveguide via two-stage reflecting surfaces, thereby significantly reducing the complexity of the multi-way power-dividing feed structure.

Methods The proposed feed system is based on quasi-optical principles. The incident coaxial waveguide TEM signal is first converted into a TEM mode propagating in the radial line. Subsequently, the first-stage parabolic reflecting surface adjusts the electric field amplitude within the radial line waveguide, while the second-stage shaped reflecting surface adjusts the electric field phase.

Results Simulation results show that within the 4–11 GHz frequency band, the output mode of the radial-line power-dividing feed system loaded with shaped reflecting surfaces is quasi-TEM. The electric field phase difference at the output port aperture is less than ±15 degrees, the variation in central electric field amplitude is within ±2 dB, and the port reflection coefficient remains below −20 dB. At 9.3 GHz, the CTS traveling-wave array antenna fed by this structure achieves an aperture efficiency of 87%, and the input port reflection coefficient is below −30 dB. Under a microwave pulse breakdown threshold of 60 MV/m, the overall power-handling capability of the antenna system is approximately 2 GW.

Conclusions The proposed radial-line feed system effectively simplifies the feed structure of the CTS antenna, achieving good output mode purity, electric field amplitude-phase consistency, and low reflection over a wide frequency band, while maintaining high aperture efficiency and power-handling capability. It satisfies the requirements of compactness and high performance for antennas used in high-power microwave systems.