Shape optimization of total radar cross section for antenna struts

In this article, we consider a perfect electric conducting (PEC) cylinder and reduce the blockage for a TE wave by shape optimization, i.e. by changing the shape of the cylinder boundary. To calculate the blockage caused by the strut we use the optical theorem, which gives the total scattering cross section of the cylinder as a function of the scattering in the forward direction. This means that we only have to calculate the scattered field in the forward direction to obtain the total scattering. For the optimization we use an adjoint problem to obtain the gradient of the goal function as continuous integrals over the boundaries of the PEC. The field solver used in the problem is a stable hybrid FEM-FDTD time-domain solver in 2D. The solver combines the body-conforming capabilities of the FEM with the efficiency of the FDTD method in large homogeneous domains.