Near‐field uniformity analysis and compensation for finite‐sized beam combiner with the asymmetric layout

In a hardware‐in‐the‐loop simulation system, the insertion of an asymmetric layout beam combiner will seriously affect the near‐field uniformity. In this study, the effects of the aperture shape, transverse distance and size of the beam combiner on the near‐field uniformity were analysed. The square beam combiner with a transverse distance of 0.51 m and a size of 1.05 m × 1.05 m was regarded as the optimal design, but it still cannot meet the test requirements. In order to obtain excellent near‐field uniformity, an asymmetric Uniform + Linear taper compensation method was proposed. The maximum values of the amplitude fluctuation ( E pv ) and phase ripple ( φ pv ) decreased dramatically from 2.62 dB and 16.79° to 0.78 dB and 7.42°, respectively. Asymmetric Uniform + Linear taper was achieved through serrating the edge of the beam combiner. When the number of serrations N was 22, E pv and φ pv were <0.83 dB and 7.50°, respectively, which indicated that the near‐field uniformity can be significantly improved by asymmetric Uniform + Linear taper.