Background For the application requirements of array antennas with high power capacity, high aperture efficiency and low profile, conventional slotted waveguide antennas (SWAs) suffer from limited power handling capability and inferior radiation performance. Structural innovations are urgently required to simultaneously improve these two core indicators.

Purpose To break through the above technical bottlenecks, this paper proposes a slotted waveguide antenna element integrated with horn cavities and alumina ceramic-filled grooves. The design aims to realize the co-optimization of gain, power capacity and aperture efficiency without enlarging the antenna aperture size.

Methods  First, the theoretical correlation between slot width and power capacity of conventional SWAs is derived. A prototype of the conventional antenna is designed, fabricated and measured. The consistency between measurement and simulation results is verified via tests of reflection coefficient, radiation pattern and gain, and power capacity experiments are carried out to check the accuracy of theoretical predictions. The proposed novel antenna retains the identical aperture size as the prototype. Horn cavities are added above each radiating slot, and symmetric alumina ceramic-filled grooves are arranged on both broad walls of the waveguide, with only a 0.09λ increase in overall profile height. Full-wave electromagnetic simulations are adopted to analyze the electromagnetic performance of the single element and the four-element array respectively.

Results All measured indicators of the conventional prototype are in good agreement with simulations and theoretical predictions, and its measured power capacity is no less than 2 MW. Simulation results show that the power capacity of the proposed element is increased by 1.7 times, and its aperture efficiency rises from 66.7% to 90.7%. The four-element array constructed with the proposed element achieves inter-element mutual coupling below −27.1 dB without additional decoupling structures. A peak gain of 25.64 dBi is obtained at 2.458 GHz, with an array aperture efficiency up to 96.1%.

Conclusions The proposed antenna structure can simultaneously satisfy the design requirements of high power capacity, high radiation efficiency and low profile, which verifies the effectiveness of the multi-structure collaborative optimization scheme. It possesses promising application prospects in high-performance high-power array antenna scenarios.