Objectives   Aiming to resolve the adverse effects of frequency selective surface (FSS) radomes on array antenna beam scanning, a method for optimizing FSS radomes is proposed.

  Methods  First, an array antenna with 25 half-wave dipole elements is designed. At the same time, a wideband Jerusalem structure is designed as a frequency selection unit with the goal of bandwidth matching and stable filtering performance at high angle incidence. On this basis, HFSS software is used to optimize the distance between the FSS radome and array antenna with the lowest gain on the side lobes and back lobes. Finally, the size of the FSS radome is determined by the beam width and scanning angle of the array antenna, and the scanning angle error of a separate array antenna is compared with an FSS radome-array antenna system. In order to verify the accuracy of the theory, the array antenna pattern is tested with the FSS radome at different scanning angles.

  Results   The results show that when the distance of FSS radome between array antenna is 0.5λ, the influence of FSS radome on the secondary and rear lobe gains of the array antenna is minima; when the scanning angle is up to 40°, the FSS radome produces an error of about 0.25° to the array antenna scanning angle.

  Conclusions  The FSS radome designed by the appropriate method has little effect on the beam scanning direction of the array antenna. This method can also be used in the design of larger array antennas and FSS radomes.