Background With the rapid development of high-power microwave systems, array antennas are increasingly required to possess high power handling capability, high radiation efficiency, and low-profile characteristics. Open waveguide array antennas are widely used due to their high power capacity and structural robustness. However, conventional large-aperture open waveguide elements usually require complex multi-stage power distribution networks, which increase system height and may introduce higher-order modes, leading to reduced aperture efficiency and elevated grating lobes in array configurations.

Purpose This paper aims to develop a high power handling open waveguide antenna element with reduced structural complexity and suppressed grating lobes, and to construct a low-profile array with high aperture efficiency. The main objective is to design a one-to-four radiation open waveguide unit capable of simplifying the rear-end power distribution network while improving field uniformity and array radiation performance.

Methods A one-to-four high power handling open waveguide antenna element is proposed by incorporating crossed metal bars at the radiation aperture to achieve in-phase quadruple energy radiation. A three-stage matching cascade is introduced between the input port and the aperture plane to improve impedance matching. An E-plane metal block is added at the final matching stage to suppress higher-order modes at the independent small apertures, thereby ensuring a purer TE10 mode distribution. Based on the designed unit, a 16×16 array configuration is constructed to evaluate its radiation and grating lobe performance.

Results Simulation results show that the proposed open waveguide unit achieves a reflection coefficient lower than −17 dB within the frequency range of 9.2–9.8 GHz. At the center frequency of 9.5 GHz, the unit exhibits a gain of 12.9 dB and an aperture efficiency of 90.1%, with a profile height of 0.9 λ. The constructed 16×16 array demonstrates grating lobe levels below −22 dB, indicating effective suppression of unwanted radiation and stable array performance.

Conclusions The proposed open waveguide antenna element and array design effectively reduce the complexity of the power distribution network while maintaining high aperture efficiency and low grating lobe levels. The structure exhibits advantages of low profile, high efficiency, and strong grating lobe suppression, making it a promising candidate for high-power microwave array antenna applications.